I'm going to solve the misfire and cold running issue

[soul4t]

Hi,

I have narrowed my lean misfire problem to either, AFM, ECU, or possibly the ICV.

I know this is alot to ask, but is there anyone who lives in Bristol (or nearby), who is willing to let me swap any of the above parts to eliminate the problem?

Thanks for any help!

FYI misfire journey...: http://www.e30zone.net/modules.php?name ... highlight=

[m8782538]

Wish i could help but mine is an M10 316i so gather parts are different, plus my car is mid restoration so i can't actually move it.

Clean ICV with carb cleaner (or something similar), clean up AFM and try again.

Last thing is going to be the ECU but they are pretty cheap anyway.

Have you cleaned the plugs and leads, dizzy, coil and earth connections?

Checked the Fuel pressure regulator and fuel rail?

[soul4t]

Hi mate,

Yep done all the above!

Thanks anyways...yea looks like it may be the ECU, I've found a guy with an M40 engine to check the ICV!

Cheers

[soul4t]

Ok, I'm re pursuing my cars condition.

Summary: I have a spluttery cold running condition.
When warm/normal operating temp, the car idles near enough perfectly.
At both hot and cold conditions there is a slight misfire.
I have replaced/examined almost all possible associated components.

The thing that I haven't done, is check that the signal from all associated components is actually reaching the ECU, mainly the Coolant temperature sensor and the Air flow sensor.

I have found some usefull schematics online which I'll attempt to post as well, but my main question is what is the best way to check the signal recieved from these two sensors at the ECU? I have (as you will see) the diagram which shows which pin the information reaches the ECU (CTS pin 45 and AFS pin 44).
Can I simply disconnect the battery, then the ecu, re-attach the battery and test for voltage at the ecu connector? Surely the circuit won't be complete without the ecu fully connected?
Also does anyone know what the 't2' or 't4' mean on the M1.3connector.pdf list?

All help will be highly appreciated!

Thanks!

P.S Didn't find out how to attach so here's where I got the schematics from: http://www.bimmerforums.co.uk/forum/f39 ... tics-t178/

Oh and here's the previous thread: http://www.e30zone.net/modules.php?name ... highlight=

[Grrrmachine]

You may find that the Wiki is far more accessible than most of the PDFs you find online:

http://www.e30zone.net/e30zonewiki/inde ... tronic_1.3

Pins 44 and 45 are indeed the TPS and AFM. You can't check LIVE readings at the ECU since the ECU needs to be connected to run the car, but you can do a basic continuity test with a multimeter to ensure the wiring isn't damaged.

Corrosion of the C191 plus is a prime suspect if the TPS signal isn't getting to the ECU.

[soul4t]

Hi Grrrmachine!

Thanks for the link! I'll give it a read!

Can I just clarify that you meant to type CTS instead of TPS (throttle position sensor) or did you in fact mean TPS? Sorry, I have to check!

Excellent, yea I'll unplug the connection to the CTS and check the continuity with pin 45. Do you by any chance know which number pins from the Air flow meter go to; from AFS to pin 7 on the ecu and from the ATS pin at Air flow meter goes to pin 44? I think there are 9 when I disconnect the plug from the AFS. (Hope this makes sense!)

Could you clarify what the C191 plus is? Is it the box channeling the wires from the engine sensors to the main loom? I think it's just under the intake manifold?

Thanks for your help!

[Grrrmachine]

I did mean CTS, sorry. On here it's known as the Blue Temp Sensor:

http://www.e30zone.net/e30zonewiki/inde ... emp_Sensor

As for the AFM (not AFS), I'm fairly sure it's got a 5-pin plug rather than 9. The feed to pin 44 is the air temperature (so that the ECU can calculate air density) so it's not particularly critical; ECU pin 7 is the AFM input signal.

As for C191; yes, it's that plug under the inlet manifold which connects the injectors and the temp sensors to the rest of the loom:

http://www.e30zone.net/e30zonewiki/index.php/C191

[soul4t]

Ahh I think I know what the 't2' or 't4' means on the pdf labelled M1.3connector.pdf I think it's the terminal that the wire comes from, so "7 AFS signal: (t2)" means that at the terminal number 2 at the Air Flow Meter end connects to pin 7 on the ECU. So that I can check! It states therefore that on the CTS (t2) I need to look for number terminal 2 on the wire plug that connects to the CTS. Am I right?

[soul4t]

Ahh Excellent!

Thank you Grrrmachine! Sorry I should have searched the e30wiki's first!

Cool yea probably 5 pin I haven't looked in a little while so my 9 pin was a guess really!

Cool, I'll take a look and check for continuity!

Thanks again and I'll keep you updated!

[Billwill]

You can check for voltage on wires at the ECU while the ECU is plugged in and power is on.

Carefully press a small pin or needle through the insulation of the required leads so that the pin touches on the wire inside and touch your meter lead onto the pin.

When you have finished you can insulate the small hole left in the insulation with some glue or wrap tape around the wire.

[soul4t]

Hi Billwill!

Thats a plan! If I can't detect any problem any other way like through the continuity testing, or I'm not convinced it's a good test, then I might have to do that!

Thanks for your input!

[soul4t]

Hi all,

Finally I have got some time to check out my wiring!

I've continuity tested from the plugs on sensors to the ECU pins for:

AFM - all pins 1-5 ok
CTS - Both pins ok - Throws up error 2d when started disconnected...code cleared. ok
TPS - Both pins ok
ICV - Checked pin 1 ok, my printout of the pin didn't have where pin 2 goes to, but found on wiki. (pin 22) will check when it's not raining!

So yet to check:
ICV pin 2 (Idle speed close control)
CID (Cylinder ID)

If my ECU logged a code for the CTS being unplugged, does this mean it recieves it's signal ok, ie not faulty ECU? I'm pretty sure when I unplugged the AFM with the engine running, I got a code, likewise, does this mean that the ECU is recieving and processing it's signal? (Car stalled when I disconnected AFM and ran poor when CTS was disconnected)

Anything else I should look at?

Just a reminder, the misfire is slight and almost certainly lean! (I have ensured the grey/black cable in the bulkhead relay section is connected to bypass O2 sensor input I believe)

Thanks!

[soul4t]

Update...

I have tested if a signal is getting from the CID to the ECU. I have continuity accross the 2 pins from the CID to the ECU, so I presume if there is a signal it will be getting the the ECU? I don't know how to actually test the sensor is working, but it was replaced with the HT lead set and worse case senario if it's not working is the injectors will all be firing, so wouldn't cause a lean miss.

On the wiki it says that pin 22 should control the ICV close, my pin 22 is empty which is what an equiptech pinout diagram says, but there is nothing on there about what would be the close control.

I also re-checked the CAS/CPS (not sure what CAS stands for, but it refers to the pulse sensor next to the toothed wheel which is mounted on the front of the engine in line with the crank). The resistance was spot on, I also checked that the signal was getting to the ECU, it was.
The gap was a little large, just over spec (1.0 -/+ 0.3mm) I don't actually see how I can move it closer? Also, would I have more severe problems if this sensor was faulty? And would the Tachometer work? Or is this a possibility?

I look forward to any input!

Thanks

[soul4t]

Hi,

I don't know if this helps but yesterday I drove to London and back with one other adult in the car, I've worked out that we did 40.9 mpg! We weren't driving super quick, but I wasn't making any huge effort to conserve petrol.

Ta

[soul4t]

I just checked the coil.

I measured 0.8 ohms between the primary connections and 6000ohms between the secondary connections.

The primary resistance should be 0.50ohms...it did say in the haynes manual not to worry about a small difference in resistance, as it varies with temperature, and I presume the primary connections are mainly used in starting? But I really don't know. Should I be concerned with that?

The terminals were clean as new and it looked in really good condition...it did say TCI coil though I have motronic system, but it's the correct on according to realoem.

I look forward to any input!

Thanks

[soul4t]

Ok,

I thought I'd eliminate the AFM for sure, so I popped the lid and checked the voltage increase to ensure it was smooth...all checked out ok. The resistance check looked as wobbly as it did before.
I decided to alter the arm to a different part of the carbon track after trying it out before on an M42 AFM which I got from ebay, I was relatively confident. I decided to do this as the part on the carbon track which looked the most worn, was the same area that was being used with the throttle maintaining at any rpm, which is where the misfire occurs.
After doing the procedure, which went well, I seem to have a better resistance change, voltage change still good.
Before trying it out I disconnected the ECU for about 20 - 30 minutes.
After re-attaching, there doesn't seem to be any change...I have heard something about it taking as much as 100 miles to re-adjust, but I'm sceptical.

I would like to know if anyone knows whether a misaligned/partly faulty CPS would completely stop the car from starting alltogether (not sensing TDC, like when it's disconnected), or if it could cause a misfire, secondly, is it possible that the speed element of the CPS can be faulty and the tachometer still function normally?

I do have a slight problem (I forgot about this one), when it's cold outside, the tachometer doesn't work straight away...sometimes it stays at 0, other times it is slow to react, but after a minute or so it works fine, reacts quickly.

Any help appreciated!

[Billwill]

The cables for the CPS and the sensor that goes over the one plug lead go around the front of the engine and run very close to the water pump pulley. Check that these wires do not actually rub on the water pulley.
You were going to test your AFM on another vehicle...have you done so yet or have you tried another AFM on your car?

My late 1991 M40 3i8i had an additional section of cable, about 18 inches long, going in series with the cable going from the AFM into the harness. This extra cable has the male/female screw-on connectors so it is possible to remove the cable completely.
I had major mis-fire problems on my M40 a while back and traced it to this extra section of cable which actually has a smal circuit board and components built into it.
I threw away this extra cable and have been running fine since then.

Check if you have this extra cable....I think it it was only fitted on certain SA models. While you are about it, check that the male/female connections on the AFM and the connector are clean from corrosion. I had to use fine emery paper to get corrosion off both sets of contacts and had to slightly press the sides of the female contacts inwards to get the female contacts to grip the male contacts solidly. Also pull back the rubber boot on the cable so as to see the rear of the connector and check that the wires are firmly crimped into the contacts....I had to solder one loose wire into place.

[soul4t]

Hi Billwill,

Thanks for your ideas,

I've checked those wires, they're clear of the pulley, I've checked that the same value is present at the ECU pins as is picked up from the sensors connector, so whatever signal is there should be getting to the ECU.

I haven't found another car that I can try my AFM on, but I did try an AFM on my car a couple of years ago when I first began looking at this problem.

I've checked for that cable, I don't have it...luckilly as it definitely seems to create problems when that chip goes bad!

I've checked continuity between all 5 pins on the AFM connector to the ECU pins, so the messages should be getting through!

A super helpfull zoner has offered to send me a few parts to try from his 316i M40 that he's breaking! I'll be able to try a different AFM, ICV and CPS... I think at this point it could be the CPS/toothed wheel, I'll swap in the replacement and clean the toothed wheel and let you all know!

Thanks for the help!

[Speedtouch]

I had a misfiring/kangarooing problem with my Fiat twin cam. It turned out to be because of an aftermarket fuel filter fitted between the fuel pump and carb.

Under certain conditions, I think the fuel was frothing inside the filter, causing partial fuel starvation.

Once removed, the car ran alot better! (The carb has a built-in filter anyway).

I know you've said you changed the fuel filter, but is it the correct one for the car, and is it a genuine BMW one or an aftermarket jobbie?

[Billwill]

Have you checked the cam belt? Is it tight and is the cam sitting 100% square when at TDC?

When I bought my M40 about 8 years ago I had no knowledge of its history so I took it to the BMW agents to replace the cam belt and idler pulleys. I had some rough running issues after that so I took off the cover over the cam belt/idlers and found that the belt was flapping around badly! How the agents tensioned the belt I do not know....I bought myself the Haynes manual and have done the timing and tensioning myself since then.

[soul4t]

Hi Guys,

Sorry about the late reply!

@Speedtouch, yea, they're aftermarket from GSF, I've changed it about 3 times over the last 4-5 years, and done the fuel pressure tests with them fitted, I would have thought it would have showed up a fault there shouldn't it?

@Billwill, yea, the cam belt was a thought at one stage, though I've driven so far since it's been done (almost 30k miles), I would have thought it would have shown up problems before, but I suppose they're either on, or broken! I also thought about it and it would have been misfiring more regularly surely, and on acceleration? Either way, I'm doing the belt in the next month hopefully (Weather permitting!) So I'll be able to say for sure then! Just a question about when you did the timing belt...did you tension it using a spring balance on an allen key as described in the Haynes manual? Or did you have a more accurate way? It would be great to know!

Thanks Guys!

[Speedtouch]

I would suggest trying a proper BMW fuel filter.

An aftermarket one may be built to a different design/standard, and may not flow right under certain conditions.

How come you've changed it 3 times? Normally, a decent filter will last yonks; I've had 20 year old BMWs with the original filter still working! I would suggest a replacement interval of perhaps once every 5 years or so.

[soul4t]

Hi Speedtouch,

I just change it depending on what I'll be doing after the service, tend to do it along with the air filter as their both cheap enough, maybe every 2 years...last time was before driving around france. Thought I'd do it again this year as I'll be doing lots of driving to and from cardiff soon. I haven't changed them on account of their poor performance. I'll try a proper BMW one if after changing the CPS and timing belt don't fix it.

I see what you mean about the different design/standard. When I had the fuel pressure tester on, I could simulate the misfire condition by mechanicly keeping the rpms at about 2k, the fuel pressure was constant, but like you say, certain conditions...we'll see. I think if I'm getting a genuine BMW fuel filter, I may as well get a genuine Oil filter too!

Thanks mate!

[Billwill]

Hi Guys,

Sorry about the late reply!

@Speedtouch, yea, they're aftermarket from GSF, I've changed it about 3 times over the last 4-5 years, and done the fuel pressure tests with them fitted, I would have thought it would have showed up a fault there shouldn't it?

@Billwill, yea, the cam belt was a thought at one stage, though I've driven so far since it's been done (almost 30k miles), I would have thought it would have shown up problems before, but I suppose they're either on, or broken! I also thought about it and it would have been misfiring more regularly surely, and on acceleration? Either way, I'm doing the belt in the next month hopefully (Weather permitting!) So I'll be able to say for sure then! Just a question about when you did the timing belt...did you tension it using a spring balance on an allen key as described in the Haynes manual? Or did you have a more accurate way? It would be great to know!

Thanks Guys!

I set it using the spring balance exactly is in the Haynes manual.
I do not have access to the cam-locking special tool but you can do without the tool. just make sure that when you have set the belt tension at TDC the square section of the cam shaft with the two dimples facing upwards is exactly level with the top of the head casting. I use a short straight edge across the cam and a vernier to measure the distance down to the head surface. If it is wrong, loosen the Torx bolt on the camshaft, move the cam straight, tighten Torx to 65 Nm as per Haynes and rotate the engine twice by hand and recheck.

The Wiki on this site has an exact copy of the Haynes manual procedure but they leave out the final cam adjustment in the special tool....I believe it is important......Brianmooooore believes it is not! If I ever visit the UK again I will try to buy Brian some drinks and see if I can twist his arm to agree with me!

[soul4t]

Ha,

Yea I noticed your conversation on another thread, nicely conducted

Another helpfull zoner who thought it could be the cam belt sent me a cam locking tool that he had made up to spec's, so I'm lucky to have one!

I've just bought a Cam belt kit and rocker cover gasket, just need to buy a spring balance (probably from amazon/ebay), then get hold of a tourque wrench, or buy one.

Thanks for the input, I'll keep you posted!

[Billwill]

I bought my spring balance from a fishing supplies shop....needs to measure 2.5 Kg so a max weight of 5 Kg will do.

[soul4t]

Ha, I tried a local fishing shop, but they didn't have anything that small.

I bought one from ebay, should be with me early next week, I got a 5kg one too.

Though, in my haynes manual it says 2kg?

Cheers!

[Billwill]

Ha, I tried a local fishing shop, but they didn't have anything that small.

I bought one from ebay, should be with me early next week, I got a 5kg one too.

Though, in my haynes manual it says 2kg?

Cheers!

If that is what Haynes says then 2kg it is....I was talking off the top of my head and that has got a lot thinner lately.

[soul4t]

Ha, great!

I'll let you know how I get on!

[soul4t]

Hi all!

I had some problem having the spring balance sent...it took 13 days! When it arrived it was the wrong one!...a 12.5kg instead of a 5kg one...so wouldn't be ideal for accurately measuring! Luckilly I visited the pound shop, stunned I found one there! I tested it as much as I could and it seemed accurate!

So I changed the timing belt today!

I removed all the necessaries and saw a curious set of marks...not quite lined up at Cylinder 1 TDC:
So there are two white marks on the covers and on the cam sprocket, they don't match by like 4 teeth! When the belt was changed last time, I wasn't confident that the garage knew what they were doing...when I first got it back, the car screamed at me when revving...too tight...took it back and they re did it, I wonder if this is a set of their marks?...mind you the engine would surely fail if it was set out that much...more likely the cam sprocket has been moved since the marks were made.



I then removed the rocker cover expecting to see a misaligned camshaft but it looked spot on!:



I fitted the cam locking tool a friendly zoner sent me!:



I took some pics of the cams to see whether people think they look ok...I ran my finger nail along them and they felt smooth, but one or two look finely scratched...:





New belt fitted and tensioned:



All done, turned over, retensioned and turned over again, put back together and ran fine...

No improvement on the misfire though!

I'm awaiting a CPS along with some other parts a greatly helpfull zoner is sending me!

I'll keep you posted!

[Brianmoooore]

they leave out the final cam adjustment in the special tool....I believe it is important......Brianmooooore believes it is not! If I ever visit the UK again I will try to buy Brian some drinks and see if I can twist his arm to agree with me!

Just seen this! It's not that I think the cam adjustment is unimportant; it's just that if it hasn't been moved since it left the factory with a new belt, it's unlikely to be far out now with a new belt.
Don't see any mention in this thread of the car having its injectors rebuilt. Next thing in line after CTS and TPS checks.

[Billwill]

Those cam shaft lobes look fine to me!

[soul4t]

Hi Guys,

@Brianmoooore... Ha, yea I saw that one before... I thought I would get an external torx socket set in case I needed to touch it, but as it was spot on when I took the valve cover off and I had the tool, I just left the tool in, swapped out the belt and checked it again once the new belt was on and had done 2 complete rotations, it hadn't changed. The belt was such a tight fit anyway...I struggled to get in on! I had to put it round the tensioner before the idle rollers.
Yep, the injectors were cleaned last year after it being recommended by yourself, by injectortune. The before's and after results weren't dramaticly different, but there was improvment and the car seemed to run a bit smoother...I'm glad I had it done!

@Billwill, Great! Thanks for the input!

[soul4t]

Update!

I recieved the CPS I'd been waiting for! The friendly zoner also sent me an AFM, FPR with fuel rail and injectors, ICV, Coil and some associated hoses! All from a car that he was breaking that ran smooth.

I've changed the CPS...absolutely no difference!

I'm going to check the coil and most probably clean up the other bits and try them, but I don't hold much hope as all these bits have been tested as working ok!

Anyone got any ideas left? I have a wild pop...would an exhaust manifold gasket leak cause this sort of problem? The top part...spark plug shield bit came off a year or so ago...problem is now about 3 years old, so I know it's not to do with the shield bit...any way of testing it? I have a fog machine, but am reluctant to try anything stoopid!

Thanks!

[soul4t]

Bump!