E30 Zone

Hi all!

I have been chasing this problem for a while, I had a starting issue after the car had been turned off for 10/15mins and a misfire. I thought they were connected problems but now I'm not so sure...here's the start problem posts if relevant:
http://www.e30zone.net/modules.php?name ... 77#2108977
http://www.bimmerforums.co.uk/forum/...urning-t74007/

After replacing (relevant parts listed..for complete list see above post):

HT leads
Spark plugs (twice...at least in 3 months)
Rotor arm
Distributor cap
Coolant temp sensor
Fuel filter
Thermostat
DME relay
Fuel Pump relay
All vacuum hoses (except the one from the ICV...I took it off to clean it and it was fine)
Air filter
Both intake manifold gaskets
Injector seals
Small fuel hoses
Installed a check valve on the fuel supply line
Both V-Belts

and Cleaning:

ICV
Intake ports with seafoam...twice...lots of smoke!
Injectors
Engine flush

then checking:

Pulse sensor (basically like the crank sensor) (no camshaft sensor fitted)
AFM (tried one from a working M40)

I thought I had better set about reading the codes and clearing them, No codes found
(...easier said than done...see this post for more info):
http://www.bimmerforums.co.uk/forum/...0-with-t78648/

I thought my only option is to have a garage perform a smoke test to make sure there are definitely noooo vacuum leaks whatsoever and also have a fuel pressure test done and check the FPR.

I phoned a diagnostic and everything else garage and asked them how much for the Smoke test to check for vacuum leaks and a fuel pressure test to check the FPR, they said £40 + VAT.

Took the car in this afternoon, I explained all the parts I had replaced and what my suspicions were: Vacuum leak or fuel pressure regulator and that I just wanted them checked, they went off to do the smoke test, which it turns out is another word for emmissions test in their book, so they came back and told me that it was running lean....well I was pretty sure of that before. So I questioned them about checking for vacuum leaks, they said "you would be able to hear a vacuum leak". I said...really...hmm. (Surely you wouldn't hear it if it is small enough to cause a slight leaness). So they went back and had it hooked up to the emissions tester again and fiddled for about 10mins, then they came back and announced that they had put the C-O mix back up to near enough where it should be. I asked them if they could check the Fuel pressure, they said that they need a gauge for that and they didn't have one. So I asked the guy I initially spoke to about the FPR, he said, "if your FPR wasn't working, the car wouldn't run, it'll either not start, or you would smell petrol in the cabin". He suggested that I run it for a day or so and see if it's fixed it.

So I drove it home and the misfire still remained but the Idle was slightly improved. When I got home, I was a little confused, so I called the garage and said "I'm a bit confused, when I called initially I asked to have a smoke test done to check for vacuum leaks, and a fuel pressure check done and to check the FPR, neither of those things have been done" He just replied with the same explination as before about hearing a vacuum leak and the car not running if it had a problem with the FPR.

In summary I just think that they adjusted the C-O mix to hide the real problem!

Is this me being silly, or am I still none the wiser as to how to fix my problem, any help is appreciated!

Thanks!

following on from the other forum, and from the links provided about the ECU check light not working, have you tested the throttle position switch under the throttle body?

if its faulty the ecu wont know if you are idling, cruising or trashing the nuts off it and settle on a default map

I haven't actually, good point...I think I will check it, but wouldn't I notice more problems, like the ICV not kicking in...though I guess the ECU default map would probably sort that...It clicks when the throttle plate returns and the lamp I connected to the ECU acknowleged the depressing and releasing of the Accelerator pedal...but definitely worth a check!

Thanks again!

Today is the day of testing...

I connected the Fuel Pressure gauge to the fuel feed line just before the fuel rail. When I operated the fuel pump by bridging terminals 30 and 87 on the Fuel pump relay I have 3.0 bar fuel pressure steady. The fuel pressure gauge isn't made particularly well and I had to use plumming thread sealer on the threads to try to ensure a tight fit. It turns out that it wasn't enough thread tape...it was leaking slightly, so I did the fittings up as much as possible. After stopping the fuel pump the fuel pressure slowly (period of about 2 mins) dropped to 1.5 bar and eventually seemed to settle at around 1 bar....possibly due to the very slight leakage, but it seemed too much of a drop.

I then replaced the Fuel pump relay and turned the car on. The pressure was maintained at 2.4 bar, this was consistent up until normal operating temp. The pressure shot up to 3 bar when disconnecting the vacuum hose from the FPR...great! It also increased towards 3 bar when opening the throttle, if opening the throttle hard it would shoot up to 3 bar....great! When holding throttle open to maintain say 2000rpm the pressure remained at 2.4 bar, this seems to be correct operation! I set the throttle mechanically so that I could check the exhaust to hear the slight misfire at it's worst rpm range ( 1750rpm - 2250rpm), then I tested the difference between normal 2.4 bar pressure and 3 bar pressure (by removing the vac hose from the FPR) it seemed to behave almost the same. If I'm not mistaken, this would indicate that my problem is not fuel pressure!

I loosend the throttle stop screw to see what would happen (I was also going to check the TPS again) and the fuel pressure wasn't so steady it was flucuating very quickly around 2.4 bar +/- 0.5 bar.

After switching off, the pressure remained at 2.4 bar for a minute, then very slowly dropped to around 1.5 bar, so I may have a slight issue with the residual hold pressure from the FPR (I know it probably isn't the Check valve in the fuel pump as I fitted a new one just after the fuel pump). But to be honest that doesn't bother me as it still starts just about ok...not worth £99.

I then checked the TPS again...still nothing, so I've removed it from the car with the throttle body and I'm going to see if I can get into it to clean it...

Do all my conclusions seem correct?

AFAIK you should have 3 bar fuel pressure constant at idle and WOT ...... but might be mistaken

Tommek wrote:AFAIK you should have 3 bar fuel pressure constant at idle and WOT ...... but might be mistaken

Fuel pressure should be a constant 3.0 bar across the injectors, and one end of an injector is inside the inlet manifold. This is not the same a constant 3.0 bar measured with a gauge, as that is measuring relevant to ambient air pressure, so a gauge should read something like half a bar less when the engine is idling.
You say in the OP that you have cleaned the injectors. Professionally cleaned and rebuilt, or a DIY thing?

Brianmoooore wrote:

Tommek wrote:AFAIK you should have 3 bar fuel pressure constant at idle and WOT ...... but might be mistaken

Fuel pressure should be a constant 3.0 bar across the injectors, and one end of an injector is inside the inlet manifold. This is not the same a constant 3.0 bar measured with a gauge, as that is measuring relevant to ambient air pressure, so a gauge should read something like half a bar less when the engine is idling.
You say in the OP that you have cleaned the injectors. Professionally cleaned and rebuilt, or a DIY thing?

Ahh the legendary Brianmooooore! I was trying to find you before to see if you could cast your eye over my problem...thanks for your input!

It was a DIY thing...

The injectors had slight build up of carbon on one side of the tips, when I shook them in my hand, I could hear the ball inside moving...sounded quite free...though clearly I'm no expert so this is probably not a decent test
I thought though to be honest that as the car hasn't covered that many miles that they would probably be ok, but then again I guess it depends on how the car has been driven for that time.

I couldn't get into the TPS yesterday as it seems to be sealed up...probably for a good reason, there was yellow paint on the retaining screws that hold it to the Throttle body, which I imagine means that it hasn't been adjusted since it was set in the factory. As a result I couldn't get one of the screws off! Either way, it's definitely not working as it is...I tried ensuring that the butterfly was fully closed by loosening the stop screw (also had paint on at one point...I think this is supposed to stop the butterfly fully closing and making contact with the TB...), but still no continuity. I'm looking at a couple on ebay, but I seem to have difficulty confirming that they are in good working order, I may just buy a new one and look into tackling that screw that wouldn't budge!...It did have a squirt with WD40, so maybe next time it will be more cooperative...

Thanks again!

Also, do you think that the missing could be caused by a slightly stretched/damaged timing belt....it was done about 20'000 miles ago, but I wasn't confident in the garage that did it...?

Yeah, the timing belt could mess the valve timing if one tooth was slipped and can cause bad running of the engine

Hmm,

How bad would it be though...this problem is only slight, the trouble is I don't remember whether it was like it before it was done.

Thank you

Also, I was just thinking...wouldn't it also affect the car on acceleration and especially at high revs?

Currently the car is smooth accelerating and does well at around 75 - 80 mph...

Just some thoughts....

I can properly answer this one, a long time ago i had a ford serria, it started life as a 1600 and ended up a2000/1600 hybrid. As the 2000 had a slightly longer stroke it had a cam sprocket which had a different key way to the 1600, i found out that using the 1600 cam sprocket in the 2000 head moved the cam timing 1/2 a tooth, so now i could advance/retard the cam timing a whole tooth in either direction by slipping the belt of and repositioning it.

with the cam retarded, you had more bottom end torque and a reduced rev limit and with it advanced it made the engine a bit of a screamer.

at no time did the engine misfire or cause bad running on either setting.

The cam timing on the M40 is fairly critical if you have slipped a tooth then you have properly had piston to valve contact and bent the valves.

to check the timing you need to do the following.

find TDC on number 1 cylinder, best looking at the rotor arm with the cap removed.
on the right side of the engine at the back (looking from the front) under the starter motor (at approx. the 3 o'clock position)are 2 pieces of webbing next to a bell housing retaining bolt, if you stick you finger in here there should be a small plastic cap, pull it out.

Insert a 8mm drill bit through the whole so it touches the flywheel, move crank pulley back and forth until the drill bit goes through the small hole in the fly wheel and leave be.

remove the cam cover, at the front of the cam is a square section, this must be 90 degrees to the cam cover face, get a set-square and check it, if the belt has slipped it will be bloody obvious, however a small amount of misalignment would be the belt stretching or the mechanic not using the special tool to time the cam when changing the belt.

Ahh mate,

Thank you!

This makes soo much sense, great explination! I'll check this soon, I've got a busy few days coming up, still trying to get a TPS...

Thank you all!

OK, Update, here it comes...

I have just fitted a new TPS to the Throttle body I had...I ended up heating the screw, hammering a philips adaptor bit onto it and using the rachet to undo a screw that hadn't moved for 20 years or so!...but it doesn't appear to have made any difference. I have disconnected the battery for at least 30 minutes (while I faffed about dropping screws...seems to be my day for that), and have turned it on and let it run to operating temperature, but still a little misfire!

I'm wondering if tcejuv's problem wasn't necessarilly a faulty CPS (pulse sensor), but a dirty one (I hear they get quite mucked up), I'm going to have a poke around and see if I can get it off to clean it up.

I don't have long to sort this problem out now as I've pretty much run out of money to fund it and I'm leaving london in 3 weeks, getting married 2 weeks after that, then moving to France for a year (with the car)...lucky me! (unecessary information, but I feel like some have been on this journey with me and I like to share).

I'll keep the post updated!

Right,

I had a go at getting the CPS out and giving it a good clean, I couldn't move it at all, but I gave it a good clean in situe and checked that it was the correct distance from the toothed wheel. I asked tcejuv exactly what his symptoms were, he said that the problem only occured when the car started to warm up and that it occured at a certain rpm. This makes me believe that it is a different problem to mine.

Well I'm quite stuck now, not quite sure where to go from here. On the plus point, my code reader now reads the codes! Of which there aren't any, which doesn't help. I may try the stomp test again, but I don't hold any hope for that really.

I'm sure it can't be a stretched/incorrectly fitted cam belt.

All I know is that the car is running lean. It doesn't seem to be any of the sensors. Presumably (though I know presuming is dangerous) the ECU would log a fault code if the wiring loom wasn't transmitting the signals from the sensors, but possibly not, so that is a possiblity. Or it could be the ECU itself!

Any suggestions?

Thanks

Ok,

I bought a vacuum tester to be absolutely sure that I don't have a vacuum leak.

I attached it where the FPR vacuum hose would enter the intake manifold.

At idle, which at the moment is around 650rpm, the needle is shaking between around 15 inches Hg and 18, if I manually increase the rpm (using the accelerator adjustment) to around 800rpm (where it should be), it is much smoother, almost steady, with a very slight shimmer at around 18 - 18.5 inches Hg. If I adjust the rpm to around 1500rpm, it holds steady at around 19 ins Hg, now, when I increase the rpm to around 2000 or 2500, and leave it steady, the vacuum is still around 19, but when I slowly decrease the rpm, the vacuum increases to around 20 (nearer where it should be I think), then it will stay at around 20 as I decrease (slowly using the accelerator adjustment) all the way untill around 1000 rpm where it drops again. When the accelerator adjustment is down to normal (allowing the TPS to pick up closed throttle) the car hunts and grumbles, leaving a poor vacuum.

I am assuming that this shouldn't have anything to do with poor compression, either by the piston rings or the valve seals, or even the tappets sticking, as it smooths out with higher revs, is this a correct assumption or should I be concerned?

Also, does anyone know what the correct idle manifold vacuum should be...the gauge suggests that it should be between 18 and 21 ins Hg.

So, do I have a vac leak?

All help as always, greatly appreciated!

Thanks!

Ok, glad to here the new TPS fixed the code reading problem, i believe that on some E30's there is a CO2 mixture control screw on the AFM body, properly hidden by a cap or not if someone's fiddled with it) try realoem for a visual.

Have you tried you friendly local garage/MOT station to probe the exhaust when its misfiring, because you have fixed the TPS now, the CO2 would need be set correctly (if possible) as this adjustment may have an effect over the entire rev range used by the AFM.

I'm properly clutching at straws now and properly get shot down in flames.

As for the manifold vacuum, sorry no idea, the wobbly gauge reading at idle is the pulsing in the manifold, a little like the fuel pressure test you did, a smoke pressure test would be the only way to tell if the is a leak and i believe your local garage have no idea how to do this.

Hi Lem!

Yea thanks, I'm glad I can get the codes for the future!

The Garage adjusted the AFM screw to richen it up when they had the probe in the exhaust. They couldn't get it as rich as it should be, but it didn't make any difference, or certainly didn't seem to.

I may ask a decent garage to perform a smoke test and emmisions tweak.

I shouldn't worry about straws and flames! It's a learning community!

I agree about the wobbly reading being the pulsing in the manifold, as the tool instructions suggest that you should set the idle at 850rpm which was about where the pulsing stopped!

Thanks alot for the input!

There's a guy who had a similar problem on bimmerforums, but his problem happened when the car was warm, and misfired at a particular rev range, his solution was his 'CPS' (actually - pulse sensor that works as a Crankshaft Position Sensor and a speed sensor), what are your thoughts on this, I'm not really at the stage where I can keep replacing stuff..as tempting as it is as there's not much left!

Thanks!

Quick update...

I just thought I'd try to track down any vacuum leak...

I connected the vacuum gauge and ran the engine, I used butane as it is very combustable...it was recommended as some of the intake cleaners are now made a bit less combustable, but I would not recommend doing it as if you spray in the wrong direction you could get into trouble.

I sprayed all around the gaskets and vac hoses and nothing...not a peep.

I thought while I was there, I would try to richen up the mixture again using the C-O adjustment on the AFM, I turned it clockwise many times, but no improvement, then I thought I'd lean it off and see what happened. The vacuum dropped and the idle dropped even further (than 650rpm)! It was certainly not happy. The vacuum was now at around 15.5 inches Hg, with the AFM adjusted lean, I set the rpm at around 2000 to see how bad the misfire was. It was much worse, definite popping at the tailpipe!
I richened it up again and all was back to normal, though it's interesting...

I then thought that if a vac leak is causing the lean mixture then if I close the Throttle butterfly fully (the way it is set I believe to be correct, that is, not closed absolutely, but with the smallest way open from absolute imaginable), it should bring the vacuum back where it should be. So I undid the throttle butterfly stop screw and allowed the butterfly to close fully, it didn't make any difference to the rpm, the vacuum fluctuated and I think I heard the ICV working harder to let air through it, then it levelled back to normal.

I'm thinking that the rich setting on the AFM is telling the ECU to open the injectors for longer under all conditions, this is making the mix more combustable, and burning the mix efficiently is maintaining the vacuum in the intake manifold.

I could be wrong and I'd love someone to correct me on this but I think this is pointing to a sensor telling ECU information that affects the mix, rather than a vacuum leak.

Apologies for the long post!

AFM has an Air temperature sensor, to adjust the mixture in hot conditions, engine block has a temperature sensor to turn the choke off, only 2 temperature related sensors there are.

CPS attached to no 4 spark plug lead make the injectors fire in pairs as opposed to all together for slightly better fuel economy, try disconnecting it to richen the mixture slightly.

Try measuring the AFM temperature sensor now, should be lowest reading during the day. should be 2.2-2.8k @20 degrees C, as a bodge you could add a 5k resister in series to make the engine think its cold and richen the mixture slightly.

If there is no air leaks, the ECU is ok, the temperature senders ok, the injectors are ok, the fuel pressure regulator is ok, this only leaves the AFM or a mechanical fault like extremely worn valve guides sucking in air through the head.

Regarding the vacuum gauge, the engine is a pump regardless if burning fuel or not, if it was turning at 850rpm the pressure differential across the throttle body would be the same.

When its idling the ICV will vary the pressure across the throttle body because it leaking air to stabilize the idle. what you are measuring is the relative pressure from the manifold to atmospheric and not detecting any leaks across the intake system.

Thinking about you cannot detect a leak in the intake system using the gauge, you would have to connect the atmospheric end into the air box before the filter, then the other after the filter and get a reading, then move the connection to after the AFM, to get a base pressure drop across the filter and AFM, then move the connection to just after the ICV take off in the elephant trunk (this reading should be the same as the previous unless there was a leak in the ICV pipe) and them connect just before the throttle body, you would have to do this with the ICV bypass blocked off and the engine running. Apart from turning all your intake system into swiss cheese with all the tapping points, it would be less effective than the butane method.

I think I understand you correctly, but there wouldn't be that much difference in atmospheric pressure past the filter and AFM surely, but I guess it is possible!

I found this earlier: http://www.secondchancegarage.com/public/186.cfm

Judging by this link, the vacuum at 650rpm idle is like senario 3, but a couple of inches Hg higher, it seems to behave properly on hard acceleration and deceleration, though not as much vacuum as I'd like on deceleration, gladly it doesn't behave like senario's 6 to 14, but it does behave a bit like senario 15 when it's just started up (for like 10 seconds).

Yes there is a pulse sensor attached to lead 4, it's interesting to read the injectors firing in pairs as opposed to all together. I thought they only fired altogether for startup, then individualy. I may try disconnecting that to see if it makes any difference.
I also have a pulse sensor which monitors the crankshaft notches and is supposed to give the ecu engine speed readings and crankshaft position. There is a guy on Bimmerforums who had a problem with this sensor, he tested it and cleaned it, it read the correct resistance, the same as mine, but he changed it anyway and it solved his problem! I'm thinking that this may be a key part in the ECU's determination of how much fuel is needed

Thanks for your help!

T

if you care to read through this http://homepage.ntlworld.com/lemmingsdi ... tronic.pdf
explains how the injection system works.

Crank sensor tells ECU where TDC is and the ECU uses the fuel map to fire injectors and how much, CPS tells ECU the reference in the injector sequence where no 4 is, so it can fire injectors in pairs so there isn't waste fuel sitting in the manifold when a cylinder is not on its induction stroke.

OK another intensely stupid question, the E30 M40 with fuel injection was available in 1.6 and 1.8, have you pulled the ECU and checked the Bosch part number (on Google) to see if the correct ECU is fitted?

I wouldn't class it as a stupid question! You never know...I'll check that out just to make sure!

Though as I have the 1.6, if it was a 1.8, it may be overfulling instead of underfulling...

I'll defo give the Motronic injection system explination a read though, Very usefull stuff! Thanks mate!

So it looks like it could be the crank sensor then, I'll have a read and a good think!

Thanks alot for all your help!

more information from an engine tuning site and a general observation on the vacuum test

quote "The LE injection system measures the air flow by means of an air flap which opens progressively as more air flows into the engine. The ECU then hopefully injects the right amount of fuel based on what the air flap meter is telling it. This works fine except at low rpm with long duration cams. The reason is that the air flap likes the airflow to be steady and in one direction all the time. Big cams cause the airflow to pulse strongly at low rpm and this makes the flap vibrate which confuses the ECU and leads to erratic idling. At higher rpm once the engine has "come on the cam" everything smoothes out and works fine again."

This might indicate the AFM flap damping mechanism is loosing its damping effect, i.e. the springs getting weak.

regarding this "as I decrease (slowly using the accelerator adjustment) all the way untill around 1000 rpm where it drops again. When the accelerator adjustment is down to normal (allowing the TPS to pick up closed throttle) the car hunts and grumbles, leaving a poor vacuum. " this sounds like the ICV is sticking partly open/closed and not responding to the TPS input, although i could be wrong.

Ahh, interesting...

It would definitely explain the rough idle! Assuming that I have a long duration cam...how do you know if it's long medium or short duration (forgive my ignorance)? The miss is happening throughout the driving range, or at least up until 4000rpm, so I don't think it's the full story...do you agree?

I'll have a feel of the AFM springs definitely, I've had the ICV out a couple of times and it's fairly nicely clean. I used to have the accelerator cable adjusted too tight and the ICV reacted well...you could feel it kicking in at about 1200rpms, now it doesn't seem to kick in as much and the revs drop to around 600rpm, then bounce up to about 700/750rpm, finally settling at 700/650rpm.

It is grumbley when it's cold and if I've just started it and press lightly on the accelerator it misses and almost stalls, if I maintain the light touch on the accelerator it misses, but then revs fine after 1/2 a second. So I leave it a minute or two before driving it from cold.

AFM is at maximum opening just after 3500rpm, from then on its on ECU fuel map only.

and the missing on pickup when stone cold is a weak mixture.

Check the part number on the AFM to see if its a 1.8 version

Nice one mate,

I'll check the part numbers to clarify...

I disconnected the Pulse sensor wire while the car was idleling and it made no difference, same when I reconnected it...it was new a couple of months ago when I did the ignition leads...

I'm just reading through the Motronic manual section you provided...very insightful!

It does seem like the ISCV isn't always working, but could it be because the ECM isn't recieving the correct signal from the CPS or CAS (not sure what it stands for but it's detailed in the manual!). I would have thought that the car wouldn't start at all if it wasn't recieving a speed reading, it must be recieving the Crank position, otherwise surely it woudn't start, like when I disconnected it. Do you know if the tachometer recieves it's information from the ECU via the CPS/CAS?

Also, ...just trying to dismiss the idea of it being the CPS/CAS...wouldn't the ECU log a fault code if this sensor was giving it bad info, or would it not know?

I bought a botched (wasn't aware at the time) AFM off ebay...got a half refund so ended up paying £5, have you ever done the DIY moving the wheel to a new part of the track if it's worn? But I'm thinking that I tried that friends AFM and it didn't improve it...his was a 1.6 M40 engine too....weird...definitely gonna check the part numbers...though everything on this car seems genuine, origional parts.

Thanks again for your help!

I disconnected the Pulse sensor wire while the car was idleling and it made no difference, same when I reconnected it...it was new a couple of months ago when I did the ignition leads...

same for me, but you would need to drive it in the misfire range to discount it.

I would have thought that the car wouldn't start at all if it wasn't recieving a speed reading, it must be recieving the Crank position, otherwise surely it woudn't start, like when I disconnected it. Do you know if the tachometer recieves it's information from the ECU via the CPS/CAS?

Engine wont start will a faulty crank sensor and yes, tach is driven from the ECU from the crank sensor input

have you ever done the DIY moving the wheel to a new part of the track if it's worn?

no sorry cant help here

.definitely gonna check the part numbers...though everything on this car seems genuine, origional parts.

its 20 years old and been looked after by morons before you, anythings possible.

Love it,

Thanks, I'll do some more investigations!

Tom

Tom,

this place here is run by an ex-bmw mechanic, I'm told he is the dogs testicles and can fix anything, might be worth a ring to see if he can give you any pointers, as I'm out of ideas

http://www.janddvehiclerepairs.com/html/contact_us.asp

Mike

Ahh,

Nice one mate!

I'll probably give the fella a ring tomorrow!

Just out of interest, you say that you disconnected the AFM when the engine was running, did this stall the car? IIRC when I disconnected my AFM, the car spluttered and stalled, and it logged a faulty AFM code! Just shows how unpredictable these codes can be!

Thanks for all your help, I'll definitely keep everything updated on these posts as I'm sure it may help someone in the future!

Thanks

Tom

I've just been out to check the part numbers... the ecu matches up, but I couldn't find the AFM part number on the AFM...weird

Another weird thing is I tried serching in realoem my vin as stated on the metalwork just under the wipers and on the ecu, it comes up as a 04/1989 4dr M40 rather than the 10/1990 2dr that I thought I had!...Still the part numbers are all the same.

I noticed, previously and forgot to mention, that I've noticed some odorless liquid appearing at the tailpipe during warm up. I assum this is water from some sort of condensation in the engine...presumably nothing to worry about.

I looked at the AFM whilst the car was idleing and the flap does move a little, but it seems like it's reacting only to the vacuum flucuations which I suppose is normal isn't it? I moved the flap a little and it started chugging...when I disconnected the ICV, the revs go up as expected, then the flap opened a bit more...then I moved it a little more and the revs increased, but when moved any further the revs dropped once more.

The AFM adjustment, well risky procedure should I call it is here: http://www.e30clubsa.co.za/forum/index. ... low-meter/

It is tempting, I think I might give it a go on the £5 afm with the faulty flap before considering trying it on mine! I read somewhere that you can retrieve much more accurate readings with the top off by measuring a smooth voltage change....but I thought the ECU picked up the resistance change...anyway I'll have a think.

I took off the pulse sensor attached to lead 4 and it still didn't make a difference and misfired the same (in the rpm range of most poor missing).

I'll keep learning!

Thanks,

soul4t wrote:Another weird thing is I tried serching in realoem my vin as stated on the metalwork just under the wipers and on the ecu, it comes up as a 04/1989 4dr M40 rather than the 10/1990 2dr that I thought I had!..

Oh dear!!! The VIN should be on the ECU as well. Does that match?
Odourless liquid is water, and just a normal product of burning petrol. Petrol is a mixture of many hydrocarbons, but taking octane (C8H18) for instance, one molecule of octane will produce nine molecules of water.
If your AFM tests OK, I strongly recommend you follow the old maxim of "if it ain't broke, don't fix it!". Testing with a voltage across the pot, and monitoring the voltage on the wiper as the flap is carefully moved by hand is the way to test it, and exactly how the ECU uses it when in use.
Way back at the beginning of this thread I asked if the injectors had been professionally rebuilt. Until this is done, and you have known good injectors, you are going to be chasing your problems around in circles.

Hi Brian!

Thanks for the input!

Yea the ECU has the same VIN...bit weird, not sure what it could mean...everything on the car seems genuine!

I will probably test the AFM using the voltage method and if it's ok, I'll take your good strong advice and leave it well alone!

Thanks,

I'll check out how much it will cost to get the injectors properly cleaned, is there any particular place or method I should be looking for?

Thanks mate!

soul4t wrote:
I'll check out how much it will cost to get the injectors properly cleaned, is there any particular place or method I should be looking for?

Thanks mate!

£10 each. Look in the traders' section.