I've e-mailed them now!
I hope they can give me a quick service as I'll be moving around a fair bit in a week or so!
Thanks for the help! I definitley think we're in the right direction...
E30 M40B16 Random lean Misfire problem
Moderator: martauto
Nice one Brian,
I've e-mailed them now!
I hope they can give me a quick service as I'll be moving around a fair bit in a week or so!
Thanks for the help! I definitley think we're in the right direction...
I've e-mailed them now!
I hope they can give me a quick service as I'll be moving around a fair bit in a week or so!
Thanks for the help! I definitley think we're in the right direction...
Tom, just to clarify,
1. I agree with Brian, have the injectors ultrasonic cleaned with test report to totally discount them.
2. AFM is a variable resistor, you can measure the resistance across its sweep, or apply a voltage and measure the increasing/decreasing voltage as the flap moves. Applying voltage will show errors better as its under an electrical load, as opposed to the low output from a digital multimeter measuring the resistance.
3. Yes my car did splutter to a stop when removing the AFM plug, and it logged no code at the time (yes i was disappointed and confused as i was checking the ECU logged codes at the time)
4. Water in the exhaust would only be a problem if it was accompanied by volumes of water vapour a pressurised cooling system and yellow custard on the oil filler cap indicating a head gasket failure.
Not to be confused with volumes or water vapour on a cold start in the winter and/or a grey/yellow deposit on the oil filer cap which means your only doing short journeys and not heating the oil enough.
1. I agree with Brian, have the injectors ultrasonic cleaned with test report to totally discount them.
2. AFM is a variable resistor, you can measure the resistance across its sweep, or apply a voltage and measure the increasing/decreasing voltage as the flap moves. Applying voltage will show errors better as its under an electrical load, as opposed to the low output from a digital multimeter measuring the resistance.
3. Yes my car did splutter to a stop when removing the AFM plug, and it logged no code at the time (yes i was disappointed and confused as i was checking the ECU logged codes at the time)
4. Water in the exhaust would only be a problem if it was accompanied by volumes of water vapour a pressurised cooling system and yellow custard on the oil filler cap indicating a head gasket failure.
Not to be confused with volumes or water vapour on a cold start in the winter and/or a grey/yellow deposit on the oil filer cap which means your only doing short journeys and not heating the oil enough.
Thanks Mike,
Well worth clarifying that for me,
1. Hopefully they're going off special delivery tomorrow afternoon, all going well...which it should as I've recently taken them out whilst doing the intake gaskets..
2. I see, yep this would make sense, I remember reading about a guy who suspected his AFM, took the lid off as the resistance readings were all over the place, and he thought he'd try measuring the voltage difference, and it showed up smooth as! I'm fairly confident about the AFM, as I think it would probably be causing me bigger problems, not to mention the fact that I did try Bigwinn's AFM on mine and he witnessed the missing and didn't have the problem on his car.
3. Good and bad...a nuisence about the code clarification! I got a couple of randoms up yesterday when I put everything back to normal, but I couldn't really match them up with anything as the tables are not really made for the M40, or any Euro spec cars, though they can be found to match in some cases...
4. Cool, good point to note, not to get confused!
Thanks for the clarity, I appreciate it!
Well worth clarifying that for me,
1. Hopefully they're going off special delivery tomorrow afternoon, all going well...which it should as I've recently taken them out whilst doing the intake gaskets..
2. I see, yep this would make sense, I remember reading about a guy who suspected his AFM, took the lid off as the resistance readings were all over the place, and he thought he'd try measuring the voltage difference, and it showed up smooth as! I'm fairly confident about the AFM, as I think it would probably be causing me bigger problems, not to mention the fact that I did try Bigwinn's AFM on mine and he witnessed the missing and didn't have the problem on his car.
3. Good and bad...a nuisence about the code clarification! I got a couple of randoms up yesterday when I put everything back to normal, but I couldn't really match them up with anything as the tables are not really made for the M40, or any Euro spec cars, though they can be found to match in some cases...
4. Cool, good point to note, not to get confused!
Thanks for the clarity, I appreciate it!
Right,
I whipped the injectors out about 2 hours ago, came out nice and easy as I knew what I was doing this time!
I've just sent them to the injectortune place and they're still doing the e30zone discount.
When I took them out, I noticed that the injector ports and surrounding areas were a bit grubby, how can I clean them without dropping stuff down into the cylinders?
Is there anything else I should clean whilst I've got the intake off? If I take the lower intake manifold off which is easy now as it's the last bit to take off, is there anything I can use to clean the injection ports from the inside or is it best left alone?
Thanks for the help!
I whipped the injectors out about 2 hours ago, came out nice and easy as I knew what I was doing this time!
I've just sent them to the injectortune place and they're still doing the e30zone discount.
When I took them out, I noticed that the injector ports and surrounding areas were a bit grubby, how can I clean them without dropping stuff down into the cylinders?
Is there anything else I should clean whilst I've got the intake off? If I take the lower intake manifold off which is easy now as it's the last bit to take off, is there anything I can use to clean the injection ports from the inside or is it best left alone?
Thanks for the help!
Tom, sorry can't help with this one, not stripped the engine that far.
I just became unqualified to answer BMW related questions as I'm now a "Cough" Peug*** Dturbo owner and the beemer is in the hands of an Hungarian chav.
I cried a lot on friday when it drove away, but cheered up today as i realised that the 3 gallons of diesel i put in had lasted 120miles and still going....
I just became unqualified to answer BMW related questions as I'm now a "Cough" Peug*** Dturbo owner and the beemer is in the hands of an Hungarian chav.
I cried a lot on friday when it drove away, but cheered up today as i realised that the 3 gallons of diesel i put in had lasted 120miles and still going....
Ahh,
Brilliant! Comedy, Lucky Hungarian, Ha, depending on how much he paid...in which case lucky you!
Yea, the mpg on diesels is noticeably different, thanks for all you help mate, it's been quite a journey!
I just missed the delivery of the fuel injectors, so they should be in my hands tomorrow afternoon, so I'll know soon if it helps!
All the best with the Pug!
If you go back to BM's, you'll know an awfull lot about what to look out for when you buy one!
Take Care,
Brilliant!
Comedy, Lucky Hungarian, Ha, depending on how much he paid...in which case lucky you! Yea, the mpg on diesels is noticeably different, thanks for all you help mate, it's been quite a journey!
I just missed the delivery of the fuel injectors, so they should be in my hands tomorrow afternoon, so I'll know soon if it helps!
All the best with the Pug!
If you go back to BM's, you'll know an awfull lot about what to look out for when you buy one!
Take Care,
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£700 for a 1993 316i E36, 138k miles, needs a new pair of front shocks, front disks & pads and judging by the way he drove away a new clutch will be require next week....Lucky Hungarian, Ha, depending on how much he paid...in which case lucky you!
and i want too see this through, so not going anywhere at the moment as the Pug forums are full of chavs with K&N air filters and brain teasing questions like "i have a problem, my exhaust is scraping on the ground and the batteries flat, it was fine last week when i fitted my 4000w amp and the 25' base booster in the boot?"
Ha!!!
Thats hillarious!
Thanks for sticking at it!
I've just fitted the injectors, which I must say, looked greatly serviced, they included the old parts and a record of before and after test!
I haven't driven the car, but I started it and let it warm up, the idle is still too low, but i think that may be potentially to do with a mis adjusted TPS/Throttle plate. Though I did read how to do it on the link to the motronic system you gave me, and it seemed to set properly, but the accelerator cable is very loose just so that it will make the sensor click. The misfire is almost gone, but it seems like it's still present!
I'll be driving it to Bristol on Friday for a nice long drive, with some fish, so I'll be driving steady, I'll see how it's running and we'll go from there...I guess there is a possibility that the Crank Angle sensor (impulse sensor) is sending wrong information...but I don't know if this is possible, the guys's problem on the other forum seems to suggest that it's possible, but without knowing exactly how it works, who knows?...I don't seem to be able to get any detailed information on how it works from the internet.
I'll get thinking and test driving!
Thanks!
Thats hillarious!
Thanks for sticking at it!
I've just fitted the injectors, which I must say, looked greatly serviced, they included the old parts and a record of before and after test!
I haven't driven the car, but I started it and let it warm up, the idle is still too low, but i think that may be potentially to do with a mis adjusted TPS/Throttle plate. Though I did read how to do it on the link to the motronic system you gave me, and it seemed to set properly, but the accelerator cable is very loose just so that it will make the sensor click. The misfire is almost gone, but it seems like it's still present!
I'll be driving it to Bristol on Friday for a nice long drive, with some fish, so I'll be driving steady, I'll see how it's running and we'll go from there...I guess there is a possibility that the Crank Angle sensor (impulse sensor) is sending wrong information...but I don't know if this is possible, the guys's problem on the other forum seems to suggest that it's possible, but without knowing exactly how it works, who knows?...I don't seem to be able to get any detailed information on how it works from the internet.
I'll get thinking and test driving!
Thanks!
Tom, as far as i remember the Crank sensor is a magnet wound with copper wire to make a field coil, the crank Pulley has teeth all the way round except at TDC. The ECU senses the rotational movement by loads of little pulses and determines TDC as where the gap in the teeth are. (A bit like ^^^^^^^^TDC^^^^^^^^). To get a good reading both the sensor and the pulley teeth need to be clean and have the right gap between sensor and pulley. It might be worth checking is the bracket is slightly bent away from the pulley.
If the field coil was breaking down it would keep throwing the TDC signal in randomly, causing bad misfires, poor starting or a dead engine.
As the idle is controlled by the ECU and the ICV, if its low then it just could be you rev counter slightly out or the ICV sticking. (most wear is going to be the idle position where its used most)
without spending loads of money, finding a friend and swapping the ICV, AFM and crank sensor, would be the only way to find the defective part(s) or at least eliminate items known to be good.
The only other thing i can think of is if you can collect live data from the diagnostic port, another friend required with a laptop and the software, but IDK if is possible with E30
If the field coil was breaking down it would keep throwing the TDC signal in randomly, causing bad misfires, poor starting or a dead engine.
As the idle is controlled by the ECU and the ICV, if its low then it just could be you rev counter slightly out or the ICV sticking. (most wear is going to be the idle position where its used most)
without spending loads of money, finding a friend and swapping the ICV, AFM and crank sensor, would be the only way to find the defective part(s) or at least eliminate items known to be good.
The only other thing i can think of is if you can collect live data from the diagnostic port, another friend required with a laptop and the software, but IDK if is possible with E30
Hmm,
Thanks Lemmy,
I've driven it back to bristol and around a bit, it seems a bit better, but it hunts a little, only a little, and it still misses a bit. I set the TPS, but I think it set it incorrectly, I was moving out the same evening, so I'll re-read the manual and do it with some time...I'll clean the ICV again and maybe finish the cleaning with WD40 as it has a slight lubricating film that stays on...previously I've finished the clean with some electrical contact spray which removes all grease..therefore lubrication...that might help the idle.
Yea, I agree about the swapping bits to eliminate the problem, also i'm pretty sure that you're spot on with how the Crank sensor works.
Brianmoooore, do you have any more suggestions as to what to look at next? Also, am I correct about what to do with the ICV and WD40? What is your experience with this?
Thank you greatly!
PS I forgot to attach the AFM when I put the injectors back in, the car started, but then when I re-attached it, rpms increased, then dropped again...I turned it off and it logged a code (7), so I've cleared that.
Thanks Lemmy,
I've driven it back to bristol and around a bit, it seems a bit better, but it hunts a little, only a little, and it still misses a bit. I set the TPS, but I think it set it incorrectly, I was moving out the same evening, so I'll re-read the manual and do it with some time...I'll clean the ICV again and maybe finish the cleaning with WD40 as it has a slight lubricating film that stays on...previously I've finished the clean with some electrical contact spray which removes all grease..therefore lubrication...that might help the idle.
Yea, I agree about the swapping bits to eliminate the problem, also i'm pretty sure that you're spot on with how the Crank sensor works.
Brianmoooore, do you have any more suggestions as to what to look at next? Also, am I correct about what to do with the ICV and WD40? What is your experience with this?
Thank you greatly!
PS I forgot to attach the AFM when I put the injectors back in, the car started, but then when I re-attached it, rpms increased, then dropped again...I turned it off and it logged a code (7), so I've cleared that.
Ahh, ok, good point,
Yea, I'll probably try that, thanks!
Yea, I'll probably try that, thanks!
Quick update,
I set the Throttle plate stop screw and Throttle switch yesterday.
I had previously set it using the first part of the instruction found in the Bosh Motronic manual that lemmy99 posted before. It stated that you undo the stop screw until the throttle plate is fully closed and won't close any more (you will have a gap appear between the end of the stop screw and the stop part). You then begin doing up the stop screw until it touches the throttle stop part, then turn it a further half turn. This should give you between 0.05mm and 0.15mm gap between the throttle plate and the side of the throttle body (ie an air gap). So initially I did the extra half turn, but the throttle plate didn't show any air gap whatsoever (I think this is the reason that my idle was soo low), after discovering this I then checked with a feeler gauge until i had about 0.1mm clearance and set it there. Then you need to set the Throttle switch so that it registers 'just off the closed throttle' position (luckily an audiable click can be heard), as soon as the throttle plate moves. So I set the Throttle switch as described and put it back together!
The result is a much better controlled idle! It is in fact too fast now! It sits at around 1000rpm's so I'll have to make small adjustments to get it right, then reposition the Throttle switch.
The misfire remains!
I set the Throttle plate stop screw and Throttle switch yesterday.
I had previously set it using the first part of the instruction found in the Bosh Motronic manual that lemmy99 posted before. It stated that you undo the stop screw until the throttle plate is fully closed and won't close any more (you will have a gap appear between the end of the stop screw and the stop part). You then begin doing up the stop screw until it touches the throttle stop part, then turn it a further half turn. This should give you between 0.05mm and 0.15mm gap between the throttle plate and the side of the throttle body (ie an air gap). So initially I did the extra half turn, but the throttle plate didn't show any air gap whatsoever (I think this is the reason that my idle was soo low), after discovering this I then checked with a feeler gauge until i had about 0.1mm clearance and set it there. Then you need to set the Throttle switch so that it registers 'just off the closed throttle' position (luckily an audiable click can be heard), as soon as the throttle plate moves. So I set the Throttle switch as described and put it back together!
The result is a much better controlled idle! It is in fact too fast now! It sits at around 1000rpm's so I'll have to make small adjustments to get it right, then reposition the Throttle switch.
The misfire remains!
-
Brianmoooore
- E30 Zone Team Member
- Posts: 49358
- Joined: Mon Jan 10, 2005 11:00 pm
If it's idling above the correct speed, you've probably set the throttle butterfly stop to far in. The ICV can only increase the basic idle speed - it can't reduce it.
Hi Guys,
Sorry it's taken so long to reply...just got married!
@Lemmy99, the car struggles and eventually stalls when you remove the oil filler cap. I may have to take the top off and check the AFM. The reason why I'm not jumping at the AFM is because I tried a known good AFM on it and it didn't improve, but then again, I didn't check the other guys car to see if it was definitely good on his.
@Brianmoooore, yea I know the ICV can only change the idle speed up, not down, I'll reposition the stop screw to get it right, then reset the throttle switch again, I've adjusted the stop screw and it idles much better at operating temp.
I have an interesting idle now: When the engine is cold, it idles very low and if you touch the throttle it tends to 'choke', so it hesitates to say the least and almost stalls it's like a big misfire, if you rev it slightly, the rpms drop to about 500, then it kicks back to about 600rpm. This improves gradually as the car warms up, then at operating temp it is great! when you feather the throttle, there's very little to no hesitation and the rpms drop to about 800rpms and rise slightly, then settle.
Should the ICV have been able to keep the idle speed at 800rpm before, when I had the throttle stop screw too far out? also, shouldn't it be making the idle much higher anyway at cold and gradually let it fall as it warms up?
It does seem like I have a faulty ICV, unless you can correct my assumptions above!
Of course, the misfire still remains.
Just a thought, if the ICV is at it's default position (slightly open), could this be letting in too much air when it's warm and causing a lean mixture?
Thanks alot for all your help!
Tom
Sorry it's taken so long to reply...just got married!
@Lemmy99, the car struggles and eventually stalls when you remove the oil filler cap. I may have to take the top off and check the AFM. The reason why I'm not jumping at the AFM is because I tried a known good AFM on it and it didn't improve, but then again, I didn't check the other guys car to see if it was definitely good on his.
@Brianmoooore, yea I know the ICV can only change the idle speed up, not down, I'll reposition the stop screw to get it right, then reset the throttle switch again, I've adjusted the stop screw and it idles much better at operating temp.
I have an interesting idle now: When the engine is cold, it idles very low and if you touch the throttle it tends to 'choke', so it hesitates to say the least and almost stalls it's like a big misfire, if you rev it slightly, the rpms drop to about 500, then it kicks back to about 600rpm. This improves gradually as the car warms up, then at operating temp it is great! when you feather the throttle, there's very little to no hesitation and the rpms drop to about 800rpms and rise slightly, then settle.
Should the ICV have been able to keep the idle speed at 800rpm before, when I had the throttle stop screw too far out? also, shouldn't it be making the idle much higher anyway at cold and gradually let it fall as it warms up?
It does seem like I have a faulty ICV, unless you can correct my assumptions above!
Of course, the misfire still remains.
Just a thought, if the ICV is at it's default position (slightly open), could this be letting in too much air when it's warm and causing a lean mixture?
Thanks alot for all your help!
Tom
Tom, sounds like you have a lean cold start, possible caused by the ICV not working or the blue temperature sender out of range
If the ICV was stuck open then it would bypass air and cause a lean unmetered mixture at part throttle.
Only thing i can think of is to disconnect the ICV, block the air pipes, and go for a drive to see if you still have the lean missfire.
Congratulation on the joining to your spouse, i have been married for 29 years (you only get 25 for murder), you properly wont have BMW worries soon as she will want you to buy a Vauxhall astra estate to get the shopping, the kids and the dog in.
I sold the Pug last week because daughter number 4 bought a 1.2 Clio to learn to drive in, so I'm running around in a gay girls car at the moment.
Good news is that I'm gonna have my mid life crisis now and looking at sport bikes on ebay, cant insure 2 cars, too expensive, but looking at £66 a year for something in the 400-600cc range.
If the ICV was stuck open then it would bypass air and cause a lean unmetered mixture at part throttle.
Yes to this, in conjunction with the ECU telling it what to do.Should the ICV have been able to keep the idle speed at 800rpm before, when I had the throttle stop screw too far out? also, shouldn't it be making the idle much higher anyway at cold and gradually let it fall as it warms up?
Only thing i can think of is to disconnect the ICV, block the air pipes, and go for a drive to see if you still have the lean missfire.
Congratulation on the joining to your spouse, i have been married for 29 years (you only get 25 for murder), you properly wont have BMW worries soon as she will want you to buy a Vauxhall astra estate to get the shopping, the kids and the dog in.
I sold the Pug last week because daughter number 4 bought a 1.2 Clio to learn to drive in, so I'm running around in a gay girls car at the moment.
Good news is that I'm gonna have my mid life crisis now and looking at sport bikes on ebay, cant insure 2 cars, too expensive, but looking at £66 a year for something in the 400-600cc range.
Hello Mate,
Cool, thanks for the input! I think I'll definitely try the ICV test.
Ha, love the next car projection! Thank you!
Enjoy the Clio, gotta love renaults...not the easiest to work on afaik, hopefully you won't need to!
Wow, bikes are great at your probable age range
Ha, mid life affordable hobby! I imagine bikes at 400 - 600cc would be awesome! Maybe end up with a BMW? seemingly efforless power here it comes!
Speak soon,
Tom
Cool, thanks for the input! I think I'll definitely try the ICV test.
Ha, love the next car projection! Thank you!
Enjoy the Clio, gotta love renaults...not the easiest to work on afaik, hopefully you won't need to!
Wow, bikes are great at your probable age range
Ha, mid life affordable hobby! I imagine bikes at 400 - 600cc would be awesome! Maybe end up with a BMW? seemingly efforless power here it comes!Speak soon,
Tom
Hi,
I haven't got around to do the ICV test yet, but I'll be doing it next week.
I just had the car MOT'd and it went straight through! Great!
I've just compared last years MOT emmisions test with this years, since I've done alot of work and it appears to have a lean misfire...I wanted to confirm this is up to date assumption!
Last years CO was 0.144% from a permissable 3.500% HC was 296ppm
This year CO is 3.286% and HC 218
Well is this just because of the CO adjustment screw and very clean injectors or is this telling me something else?
Thanks for any help!
I haven't got around to do the ICV test yet, but I'll be doing it next week.
I just had the car MOT'd and it went straight through! Great!
I've just compared last years MOT emmisions test with this years, since I've done alot of work and it appears to have a lean misfire...I wanted to confirm this is up to date assumption!
Last years CO was 0.144% from a permissable 3.500% HC was 296ppm
This year CO is 3.286% and HC 218
Well is this just because of the CO adjustment screw and very clean injectors or is this telling me something else?
Thanks for any help!
well your allowed 3.5% and 1200ppm, so tweaking in the mixture screw 1/2 turn should sort it.
although the CO2 (carbon monoxide from rich mixture) was up the HC (unburned fuel and oil) was down, properly due to the clean injectors.
And i scored one of these last week (1990 GPX250F3 Ninja), just finished doing the valves and service, just need to see if its starts (cleaning out the tank and carbs) as its only done 250 miles since 1998 and been stored since 2004.
Red line is 14000rpm
although the CO2 (carbon monoxide from rich mixture) was up the HC (unburned fuel and oil) was down, properly due to the clean injectors.
And i scored one of these last week (1990 GPX250F3 Ninja), just finished doing the valves and service, just need to see if its starts (cleaning out the tank and carbs) as its only done 250 miles since 1998 and been stored since 2004.
Red line is 14000rpm
Wow! Nice!
Infinite revvs'!
Great find, Thanks for the info, hope all is well!
Cheers!
Infinite revvs'!
Great find, Thanks for the info, hope all is well!
Cheers!
Ok,
Here's an interesting one,
Drove from London to Bristol trying my best to conserve petrol...
I was feathering the throttle to keep it between 30 and 50 mpg about 2 hours into the motorway journey the misfire got alot worse and the car was losing power and gaining it, surging quite alot, normally when this used to happen I would just drive full throttle for a bit and ease off, then drive full throttle again...this worked again this time, so I drove quicker for about 5 minutes, then it was running fine again (no noticeable surging)!
I'm still looking into the ICV this week as I guess this is a possibility, if it's behaving strangely, but is there something else that it could be pointing at...I haven't read any codes from it today, but I will do, just to make sure.
Thanks!
Here's an interesting one,
Drove from London to Bristol trying my best to conserve petrol...
I was feathering the throttle to keep it between 30 and 50 mpg about 2 hours into the motorway journey the misfire got alot worse and the car was losing power and gaining it, surging quite alot, normally when this used to happen I would just drive full throttle for a bit and ease off, then drive full throttle again...this worked again this time, so I drove quicker for about 5 minutes, then it was running fine again (no noticeable surging)!
I'm still looking into the ICV this week as I guess this is a possibility, if it's behaving strangely, but is there something else that it could be pointing at...I haven't read any codes from it today, but I will do, just to make sure.
Thanks!
hum, only thing driving faster is going to do is, move to a different part of the fuel map, above 3500rpm and your off the AFM and on fuel map only. Wild guess the plugs are overheating at part throttle, moving to full throttle would throw loads of fuel at them and cool them down.
so,
ECU broke and cant read the part throttle fuel map correctly
ICV sticking slightly open and bypassing air at part throttle
AFM telling lies to the ECU
things we know its not:-
Fuel injectors cleaned
fuel pump and regulator tested
crank sensor failing would make the misfire worst if you tried to accelerate
blue temp sensor ok, else would die from rich mixture and not pass mot emissions
and has the misses mentioned buying a labrador and a astra estate yet?
so,
ECU broke and cant read the part throttle fuel map correctly
ICV sticking slightly open and bypassing air at part throttle
AFM telling lies to the ECU
things we know its not:-
Fuel injectors cleaned
fuel pump and regulator tested
crank sensor failing would make the misfire worst if you tried to accelerate
blue temp sensor ok, else would die from rich mixture and not pass mot emissions
laughed at this bittrying my best to conserve petrol
and has the misses mentioned buying a labrador and a astra estate yet?
Ha!
Na, no Labrador, and she's currently trusting me entirely so far as the car is concerned! We're about to start a wonderfull year or so in France, my Dad's asked me to help him set up a music recording studio...my dream come true...anyway...
Agree with the above diagnosis, I'll have to get narrowing it down! I'm thinking it might be good to see if anyone else in Bristol has the same engine..without the problem just to double check the AFM...possibly also the ecu.
Is there a cooling system for the plugs? Or is it just the head temperature?
I managed to get about 40 - 45 mpg on the M4! Average speed of 60mph though, the car feels happier at 80mph, but I think that's just the momentum!
Cheers mate, swift reply!
Na, no Labrador, and she's currently trusting me entirely so far as the car is concerned! We're about to start a wonderfull year or so in France, my Dad's asked me to help him set up a music recording studio...my dream come true...anyway...
Agree with the above diagnosis, I'll have to get narrowing it down! I'm thinking it might be good to see if anyone else in Bristol has the same engine..without the problem just to double check the AFM...possibly also the ecu.
Is there a cooling system for the plugs? Or is it just the head temperature?
I managed to get about 40 - 45 mpg on the M4! Average speed of 60mph though, the car feels happier at 80mph, but I think that's just the momentum!
Cheers mate, swift reply!
no, just lives in the head and cooled by the water jacket, the leaner the mixture gets the hotter the plugs run, the insulation may break down and cause pre-ignition. In your case aggravate the misfire.Is there a cooling system for the plugs? Or is it just the head temperature?
I have two suggestions you may try.
If you cannot get the O2 reading correct by turning the potentiometer screw in or out...you need to open the AFM by carefully splitting apart the two plastic sections. Mark the position of the large
spring and try move it one notch clockwise or anti clockwise....I believe moving it clockwise makes it leaner. Also inspect the carbon track to check that it is not too damaged but you did say that you tried out a second AFM and it made no difference.Seal the plastic sections back together with silicon sealer.
Secondly, I do not know if this affects the 1.6i motor but I had a problem on my 1.8i 318i M40 with severe misfiring. On the later M40s the factory fitted an additional section of cable going between the AFM and the harness...this is obviously a form of Engineering change probably to smooth out the signal from the AFM to the ECU. This extra cable is about 18 inches long and has the male/female plugs on it so as to connect in series with the existing cable. This extra cable has a "bump" in it which is actually a small circuit board with and IC, transistor or two and resistors. There is no mention of this cable in the Haynes manual when they tell you how to check continuity from the AFM to the ECU...with this extra circuitry installed there is no direct connection to the ECU.
The point is...if you have this extra cable installed...try removing it and see how things go. I did this with my M40 and have been running without it for years now...if I put it back I get misfiring and spluttering!
As stated before, check that the camshaft is sitting exactly level with the top of the head when at TDC...if it is a bit out you need to loosen the Torx bolt on the cam pulley...rotate the cam slightly and tighten the Torx bolt to 65 Nm.....use a small straight edge and vernier to measure the distances of the straight edge to the top surface of the head.
If you cannot get the O2 reading correct by turning the potentiometer screw in or out...you need to open the AFM by carefully splitting apart the two plastic sections. Mark the position of the large
spring and try move it one notch clockwise or anti clockwise....I believe moving it clockwise makes it leaner. Also inspect the carbon track to check that it is not too damaged but you did say that you tried out a second AFM and it made no difference.Seal the plastic sections back together with silicon sealer.
Secondly, I do not know if this affects the 1.6i motor but I had a problem on my 1.8i 318i M40 with severe misfiring. On the later M40s the factory fitted an additional section of cable going between the AFM and the harness...this is obviously a form of Engineering change probably to smooth out the signal from the AFM to the ECU. This extra cable is about 18 inches long and has the male/female plugs on it so as to connect in series with the existing cable. This extra cable has a "bump" in it which is actually a small circuit board with and IC, transistor or two and resistors. There is no mention of this cable in the Haynes manual when they tell you how to check continuity from the AFM to the ECU...with this extra circuitry installed there is no direct connection to the ECU.
The point is...if you have this extra cable installed...try removing it and see how things go. I did this with my M40 and have been running without it for years now...if I put it back I get misfiring and spluttering!
As stated before, check that the camshaft is sitting exactly level with the top of the head when at TDC...if it is a bit out you need to loosen the Torx bolt on the cam pulley...rotate the cam slightly and tighten the Torx bolt to 65 Nm.....use a small straight edge and vernier to measure the distances of the straight edge to the top surface of the head.
Hi Guys,
Great! Thanks for the information!
@Billwill, I tried an AFM from a different M40 today (318i) and the misfire was more prominent (presumably because the AFM is not set to it's richest state), my AFM CO screw definitely works as it was used to temporarily help the problem (by making it richer).
I'm going to go back to the same guy, who has kindly agreed to let me swap in his ICV as well, to see if that makes any difference.
I have heard of this additional wire, it's situated under the plastic cover isn't it, I think though as I've tried 2 known good AFM's, it's safely ruled out, the other thing, is that it's a reasonably low mileage (the problem was evident from cira 50k miles), so it's unlikely to have a worn track, but is possibly going to have the newer wire as it was made (or registered) in October 1990, but then again, having tried the other AFM's, it's almost definitely not it!
So I'll update you after (hopefully tomorrow) trying the guys ICV. I noticed that today when I pulled out the wire to the ICV, the car hunted instead of maintaining the higher revs that it should have, this is quite strange as as far as I know, when you remove the wire, the valve inside allows a standard amount of air through it as a kind of limp home mode, this kind of indicates that it somehow opens and closes all by itself! (The hunting was regular).
If it's not the ICV, I'll have to get the valve cover off and check the cam position like you say.
Thanks for all the great advice!
Great! Thanks for the information!
@Billwill, I tried an AFM from a different M40 today (318i) and the misfire was more prominent (presumably because the AFM is not set to it's richest state), my AFM CO screw definitely works as it was used to temporarily help the problem (by making it richer).
I'm going to go back to the same guy, who has kindly agreed to let me swap in his ICV as well, to see if that makes any difference.
I have heard of this additional wire, it's situated under the plastic cover isn't it, I think though as I've tried 2 known good AFM's, it's safely ruled out, the other thing, is that it's a reasonably low mileage (the problem was evident from cira 50k miles), so it's unlikely to have a worn track, but is possibly going to have the newer wire as it was made (or registered) in October 1990, but then again, having tried the other AFM's, it's almost definitely not it!
So I'll update you after (hopefully tomorrow) trying the guys ICV. I noticed that today when I pulled out the wire to the ICV, the car hunted instead of maintaining the higher revs that it should have, this is quite strange as as far as I know, when you remove the wire, the valve inside allows a standard amount of air through it as a kind of limp home mode, this kind of indicates that it somehow opens and closes all by itself! (The hunting was regular).
If it's not the ICV, I'll have to get the valve cover off and check the cam position like you say.
Thanks for all the great advice!
Tom, i still have the special tool i made to lock the cam, PM your address and i can send it too you.
you just need a 6mm rod to lock the flywheel behind the starter.
Ok just looked at realoem and the 318 and 316 AFM's have different part numbers, as the 318 will flow more air it may well have a stronger spring, or be calibrated differently.
As you 316 will have less 'suck' than a 318 this may well make the misfire worse not better so you cant rule out the AFM yet.
I could lay money on that it you fitted your AFM to his car is would run rich.
you just need a 6mm rod to lock the flywheel behind the starter.
Ok just looked at realoem and the 318 and 316 AFM's have different part numbers, as the 318 will flow more air it may well have a stronger spring, or be calibrated differently.
As you 316 will have less 'suck' than a 318 this may well make the misfire worse not better so you cant rule out the AFM yet.
I could lay money on that it you fitted your AFM to his car is would run rich.
The additional wire I reffered to is a cable with the screw on/off male/female connectors. If this extra cble is there it screws onto the AFM, goes about 18 inches and screws into another cable which goes into the harness. In other words it extends the existing original cable while introducing a few extra electronic components in the process...which may have failed!soul4t wrote:Hi Guys,
Great! Thanks for the information!
@Billwill, I tried an AFM from a different M40 today (318i) and the misfire was more prominent (presumably because the AFM is not set to it's richest state), my AFM CO screw definitely works as it was used to temporarily help the problem (by making it richer).
I'm going to go back to the same guy, who has kindly agreed to let me swap in his ICV as well, to see if that makes any difference.
I have heard of this additional wire, it's situated under the plastic cover isn't it, I think though as I've tried 2 known good AFM's, it's safely ruled out, the other thing, is that it's a reasonably low mileage (the problem was evident from cira 50k miles), so it's unlikely to have a worn track, but is possibly going to have the newer wire as it was made (or registered) in October 1990, but then again, having tried the other AFM's, it's almost definitely not it!
So I'll update you after (hopefully tomorrow) trying the guys ICV. I noticed that today when I pulled out the wire to the ICV, the car hunted instead of maintaining the higher revs that it should have, this is quite strange as as far as I know, when you remove the wire, the valve inside allows a standard amount of air through it as a kind of limp home mode, this kind of indicates that it somehow opens and closes all by itself! (The hunting was regular).
If it's not the ICV, I'll have to get the valve cover off and check the cam position like you say.
Thanks for all the great advice!
I agree with the comments that your 160i AFM has a different PN to the 318i and hence may not be swopable!
Hi Guys,
Thanks Lem for the offer, I'll PM you my address, etc...
I can see the logic about the AFM, the first AFM I tried was from a 316i M40 and made no difference.
I tried the other guys ICV in my car and it behaved exactly like mine did (was dirtier though).
I listened to his car when it was idleing, nice and smooth with no miss at all, the throttle was more responsive as well.
I know a guy who has an ECU that came off a known good car, but is a 318i M40...there are also a couple of 316i M40 ECU's on ebay. Will the 318i one work properly, or would it make it run theoretically richer as it will think that there is more air coming in then there actually is? And it thinks there is more cylinder capacity then there is as well?
I'm thinking that if it was a timing issue, wouldn't it be more regular? Rhythmic?
Thanks for all the advice and help guys!
Thanks Lem for the offer, I'll PM you my address, etc...
I can see the logic about the AFM, the first AFM I tried was from a 316i M40 and made no difference.
I tried the other guys ICV in my car and it behaved exactly like mine did (was dirtier though).
I listened to his car when it was idleing, nice and smooth with no miss at all, the throttle was more responsive as well.
I know a guy who has an ECU that came off a known good car, but is a 318i M40...there are also a couple of 316i M40 ECU's on ebay. Will the 318i one work properly, or would it make it run theoretically richer as it will think that there is more air coming in then there actually is? And it thinks there is more cylinder capacity then there is as well?
I'm thinking that if it was a timing issue, wouldn't it be more regular? Rhythmic?
Thanks for all the advice and help guys!
-
Speedtouch
- Old Skooler
- Posts: 14022
- Joined: Tue Feb 14, 2006 11:00 pm
- Location: Canterbury
I notice you've changed alot of parts, but no mention of a replacement ignition coil.
It's rare for them to fail, but they do sometimes.
I have a car that occasionally misfired, which got steadily worse, and hard to start, and one day it wouldn't start at all. I checked for sparks and they were present, so I assumed all was well with the ignition, so proceeded to rebuild the carb; still no joy. I was about to remove the cylinder head, when I thought I'd just check the sparks again; this time, no spark at all! A quick swap of coil later, and the car's been running fine ever since.
It's rare for them to fail, but they do sometimes.
I have a car that occasionally misfired, which got steadily worse, and hard to start, and one day it wouldn't start at all. I checked for sparks and they were present, so I assumed all was well with the ignition, so proceeded to rebuild the carb; still no joy. I was about to remove the cylinder head, when I thought I'd just check the sparks again; this time, no spark at all! A quick swap of coil later, and the car's been running fine ever since.
///M aurice
ECU Upgrade EPROM Chips, £40 posted within the UK. Note these are not Zone chips.
viewtopic.php?f=6&t=279421
ECU Upgrade EPROM Chips, £40 posted within the UK. Note these are not Zone chips.
viewtopic.php?f=6&t=279421
Wow,
Thats usefull to bear in mind!
I checked it and it did score slightly below the primary resistance specifications. I should have another one that I can swap in within the next week, so that should determine whether it is the coil that's causing the problem!
Thanks for reading through this beast of a post!
Thats usefull to bear in mind!
I checked it and it did score slightly below the primary resistance specifications. I should have another one that I can swap in within the next week, so that should determine whether it is the coil that's causing the problem!
Thanks for reading through this beast of a post!