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

[soul4t]

Yep, all connected up, when I unplug it, it rumbles about, not running well.

[Billwill]

Do you have the original OEM plug leads...specifically the leads have the sensor around the long plug lead going to number 4 cylinder?

I am not too sure what effect this sensor has if it is not connected as I have read posts where owners do not have this sensor fitted when they change to other makes of plug leads.

However it may be worth measuring the plug on this sensor....there are three wires, the one going to the far end of the plug if I remember correctly is a shield and goes nowhere.

The other two connector points go to a small coil which wraps around a ferrite core that the plug lead goes through. This is a very small coil so measuring resistance over these two connector possitions gives a reading of only about 1 Ohm.

Have you changed the distributer cap, rotor and coil?

[soul4t]

Hi BW...
Yep I have changed the original ones for OEM ones which include the sensor...all around the same time as trying recommended Bosch plugs and then a set of NGK's the rotor and cap were replaced too and both still look good, but no change in the performance this was all done just before discovering that the TPS wasn't working...so is akso replaced.

AFAIK the sensor is attached to lead 4 and informs the ECU of the firing position so that it can open the injectors in pairs...apparently when it's disconnected the injectors fire simultaneously...suffice to say with mine unplugged it made no difference...I checked something on the ECU plug to do the that sensor I think it's called cam position sensor and it Checked out ok.

Thanks for the ideas!

[soul4t]

I do have a spare coil...mine measures spot on, but may as well swap it in!

[soul4t]

Just a quick update,

I adjusted the AFM to run as rich as it can...it now catches the idle properly (when the revs drop say if you dip the clutch) from near the warm edge of the blue bit on the temp gauge, it still splutters when cold, hesitating and generally being moody. Altogether the idle is good when warm...if I adjust the AFM back even just 1 turn, it starts hunting and can't cope with accessories being used, like at night, lights, fan etc...when I tested it leaner for a day or two it stalled when heavy steering with blowers and lights on! LEAN!

I've ordered a compression tester before I go any further...not that there's much further to go!

...it runs sweet as a nut at full throttle!

[soul4t]

Right,

I've done a compression test...eventually!

I took pictures of the spark plugs too:

Cylinder 1 to 4 left to right





The compression is high:

Cylinder 1: 178 psi
Cylinder 2: 188 psi
Cylinder 3: 180 psi
Cylinder 4: 180 psi

The spark plug from cylinder 4 has a much lighter spot on one side...does this mean anything?

The threads on the plugs had carbon deposits on them, would I be correct in saying that I most likely have alot of carbon build up?

Would any of this have anything to do with the cold running and misfire?

[mcbonio]

Plugs look fine, sounds like your AFM is faulty though.!

[Speedtouch]

Perhaps those twin electrode plugs aren't best suited to your engine - they are normally reserved for higher power engines, and may have the wrong heat rating. I would try a set of standard single-electrode ones specifically designed for the M40B16, preferably NGK or Bosch.

[soul4t]

Cool, Yea I thought the plugs were fine...what makes you think about the AFM? I've tried 2 known good ones and re placed the contact on the resistor track...

[soul4t]

Hi Speedtouch, I had some single electrode bosch ones in there which only did a couple of hundred miles...when it didn't sort it I got these NKG ones that were recommended by C3...a BM performace company near where I used to live...I'll pop the Bosch ones back in for good measure though! What. About the compression? I noticed a surprising amount of carbon build up on the injectors...only a year or so after being ultrasonicly cleaned...

[Speedtouch]

The compression is fine. C3 specialise in M3s, so the twin electrode plugs are probably intended for those. An M40B16 will only need the standard single-electrode type.

As for the high carbon build up, what sort of driving have you been doing? If only used for short runs, they do tend to soot up a bit. Perhaps it just needs a good high speed run to clear out the cobwebs...

[soul4t]

Ahh ok, cool, I'll pop the Bosch's in for sure...

I drive to and from work mainly, 7 miles, 5 of which are on motorway...I don't drive economicaly at the moment, enjoying the foot to floor moments! Don't spend long in traffic as I work wonky hours... but I suppose it's not getting a long blast when fully warm...do you advocate the seafoam/the like treatment? To be fair, if there's not problem at the mo, then maybe it's best to leave it be...at least there's not clear drop on any cylinder!

[Speedtouch]

I haven't tried seafoam, though gather it's quite effective. I would just stick some Redex or injector cleaner in, and take it for an Italian tune-up, i.e., a damn good thrashing.

[soul4t]

Aye! Can't complain at that idea! Haven't red-lined it in a while!

[soul4t]

Quick update, popped the Bosch plugs in, no difference...

If the idle rises when I unplug the fpr vac pipe introducing a small air leak, the idle rises slightly, (the effect isn't caused by any rise in fuel pressure as when I cover the hole up again the rpm returns to as it was) Would I be correct in assuming that the misfire/stumble/lean running, isn't caused by an air leak? As surely if there was already an air leak causing the problem, introducing another one is going to make it worse?
Hope that made sense!

[soul4t]

Right...Ahhhhhh!

I thought I'd conclusively test the ICV and the messages it's recieving!

I connected up both ICV's at the same time, using small wires to bridge the terminals to the second ICV, so that I could see exactly what the ECU was telling the ICV to do (assuming that both ICV's were/are good).

When cranking, the ICV opened fully, then closed to almost fully closed...leaving about a 2mm gap. This gap reduced slowly as it warmed up. When revving when cold, the ICV remained the same, the car coughed and spluttered, the ICV only opened more just before the car stalled.

I then swapped the ICV's over to see whether the same happened. The second ICV had a slightly different fit into the manifold...the same kind of end as went into the hose going to the intake boot. When I fitted it and ran the car, it reacted as if there was no ICV fitted...hunting between 1600rpm and 1000rpm. I then bridged the connections to wire up the second ICV to see what was going on and started the car. It ran a constant higher idle...I think doing what it should do. I disconnected the second ICV as I thought it might be interfering with the input signal from the ECU, it continued to run 'properly'.

I then disconnected the additional wiring and started it once more. It hunted for a minute or so then steadied, I thought that was it!

It was idleing high so I adjusted the AFM CO screw...as I know I adjusted it to the extreme richness, the idle dropped and went down to about 450rpm! Then it steadied at about 600rpm...I'm going to set everything properly, fit this other ICV after having the Battery disconnected and start, wait 10 mins, then take it to a garage to adjust the AFM to 1% C0.

I can't help thinking that this might have given false hope as bridging the ICV connections may have interfered with the instructions from ECU, lessening the voltage, thus closing the ICV less than it thought it was....we'll see!

[Speedtouch]

Well, you certainly took a bit of a risk with the ECU, running two ICVs in parallel - it would certainly push the output driver to the limit, as they are designed to handle a certain level of current, and the solenoid in an ICV, being of low impedance, is quite a high load.

But, if it established that they work OK, then all's well and good.

[soul4t]

Yea maybe I shouldn't have done that, I didn't think of it causing a bigger current going through the ECU circuit! Is it possible that my problem is due to a malfunction in this circuit? Maybe the plug to the ICV got shorted by a moisture sometime ago? Just stabbing in the dark as you no doubt can tell...I didn't notice any damage to the ECU board, but would it be obvious?

If the ICV opening is controlled by the ECU according to the CTS, TS closed signal and the Pulse sensor speed signal, all of which are going to the ECU, and after having tried 2 known good ICV's, the only thing left is surely the ECU?

I would have expected the ICV opening to be bigger, nearer to where it is when it's disconnected to raise the idle to it's proper cold rpm circa 1200rpm. Rather than it currently being almost closed, to fully closed when warm.

Also does anyone else have any experience with the car hunting when the ICV is unplugged, when the temp is on the rise? Do you think it is due to the fuel shut off economy thing?...not really too important, unless it points to another thing to check...not that I haven't already checked everything!

Many thanks for all the time and thought thus far!

[Speedtouch]

I know some of the later 380 and 381 ECUs fitted to 320i and 325i models had common faults with the diodes in the idle circuit blowing, but not sure if this applies to M40 engines or not.

The ICV operation is pretty critical to getting a nice, smooth, steady idle.

[Brianmoooore]

I would have expected the ICV opening to be bigger, nearer to where it is when it's disconnected to raise the idle to it's proper cold rpm circa 1200rpm. Rather than it currently being almost closed, to fully closed when warm.

This suggests that the throttle butterfly adjustment has been set too far open at idle (or there's air leaking in downwind of the butterfly). Any evidence that the screw has been played with?

[soul4t]

Hi Brianmoooore!

Yes it has been changed from the original settings...I know...when I replaced the TPS (as it wasn't showing idle), I reset it according to a motronic 1.3 guide...but I noticed that it was different to the original setting...which after reading many threads I now know I should have left it! Either way, I didn't and what it did was meant that my idle was higher (800rpm, before 650rpm) when warm, so I left it until I could solve the real problem. I intend to set it properly though as I realise that it could be skewing results of tests like this one:

However, when I was testing the ICV's, I wound the screw out to allow the Throttle plate to close even more (obviously, the TS still showed closed position)...the idle went down to around 450 and remained...I would have expected the ICV to compensate to bring the idle up.

[soul4t]

I thought I'd give the background as to when this problem first surfaced:

When I first bought the car, it was running fine (6 years ago). I wasn't a discerning e30 owner and only noticed any problem when I was driving to London on the Motorway, it started to hesitate if I had been driving at a constant 60mph for more than an hour, trying to preserve petrol, I would try to keep the MPG gauge above 30, then all of a sudden it would start hesitating (misfiring), it would get worse until I drove flat out for about 10 mins (well at least hard acceleration every so often). About a year after that I discovered that the thermostat wasn't functioning as it should...until then I didn't realise that the normal op temp was half way...

I wonder if the ECU became faulty due to constantly trying to read one part of the fuel map, due to being driven like a gran and run constantly under normal op temp (It would typically be around the first white mark on the temp gauge)?

[mcbonio]

Shouldn't think that would be an issue, have you tried resetting the ECU by disconnecting the battery for a while?

[soul4t]

Yea, I have had it disconnected for a few hours, more than once...no change...

[soul4t]

Just a quick update,

Just changed the last vacuum hose (between the Intake boot and the ICV) and have put a replacement ICV from a known good running car. No improvement.

I have noticed that even when the car is warm, putting the fans on number 4 means that the idle drops (more demand from the alternator), almost stalls, then jumps up to around 700rpm, then drops again, so it hunts repeatedly! The ECU should be telling the ICV to open more consistently, rather than just to prevent it from stalling! The TPS is set properly, I double checked it when I lubed up the throttle assembly. All the messages are getting to the ECU plug, but somethings not right!

Hopefully this week I should be meeting a fellow zoner who has been able to reset the ECU's adaption values as he's solved his problem, which appears to be the same...as always, I'll keep the post updated.

[abelai]

http://www.opel-scanner.com/files/DME_1.1_1.3.pdf

It's a long read but gives you a good understanding of exactly what the DME is trying to do and how it is trying to achieve it.

[soul4t]

Ahh, yea I've got a copy of that! It's a useful document! I also found this: http://www.mediafire.com/view/?52m0nzzl2cgtmk2

With the replacement ICV on it actually idles worse, even when warm as soon as lights go on it starts hunting, blowers and lights and best of luck!

[abelai]

I have a theory that what is actually happening is the DME is running the ISCV in LOS.

Therefore with a default duty cycle which is just good enough to idle when cold but there is not enough air so car will sound rough and smell rich.
Once warm it might be open a little too much so it will then idle slightly high but as the idle speed is not actually reacting to rpm alternator loads will reduce the idle speed.

Other effects of this LOS will therefore be poor return to idle while in gear making the car jerk when the injectors kick back in.

Emissions will also be poor at idle as air flow is not properly regulated hence people playing like crazy with the co pot.

Every ISCV will be slightly different so the same voltage and duty cycle on 2 different ISCV will give a different effect as in normal operation DME constantly adjust the ISCV to attain a preset RPM according to the CTS.

I have no documented proof of this what so ever but after 6 years of looking into it it's my theory.

[soul4t]

Yea,

Your theory is interesting, I can't help but think that my problem seems to relate to the DME ignoring a sensor, or being in LOS.

I do get the jerking when the injectors kick in again, and the hunting idle could be parially the DME using injector duration to increase idle speed a little too...anyway I get carried away with theories and quickly run out of knowledge to properly form one!

We'll see mate, we'll see!

[soul4t]

Right,

Friendly zoner (abelai) and I, spent a little while scratching out heads over the car this eve...we erased the adaption values and checked for codes. All cleared, but made no difference. There is a thought that there may be a crankcase vacuum leak as when we removed the dipstick at idle, there was no change in the engine...we were expecting a drop and stumble. Puzzling though as there are no leaks...

It's confusing how the ICV is being held closed until the revs drop below 500rpm, so an anti-stall kicks in. Why isn't is told to open before!

More to scratch about!

[Nightshift]

Really admiring your perseverance on this; lots of useful info for the rest of us as well.

Good luck with it mate.

[soul4t]

Thanks mate!

[soul4t]

Right,

Quickish update...Since resetting the adjustment values of the ECU, the idle behaviour has changed...

It doesn't cope with demand from any ancillaries at all, any load is causing a large dip, then a recovery only when it's about to stall...sometimes it doesn't recover, as it using power steering when parking!

During normal, straight road, traffic light driving, when coming to a stop the idle rarely catches within normal range, instead it drops to around 400/500rpm, before kicking back up, then down...hunting for a while, as it gets worse...almost stalling, it tends to jump up to where it should be (around 750/800rpm), stays there for 2/3 seconds before repeating it's affliction.
Occasionaly it will actually catch the normal idle, but only for a couple of seconds...

The cold running is as above, except that when you press the accelerator it's misses and hesitates.

I am wondering now whether I have checked the TPS as much as I can...the wiring...the left and right pins on the sensor are getting to the ECU, but I don't think I tested the middle one...just assuming it would be ground as there's nothing particular in the ECU pinouts...does anyone know where it goes?

It would entirely explain my problem!!!! If the ECU doesn't know it's idling, it won't pass control to the ICV, the mixture won't be predictable either, so hesitation...so TPS, the middle pin...where does it go!?

On a side note...I reset, well abelai reset my service indicators...on Tuesday, today, the yellow inspection light came on! Is this a sign of the batteries needing a change?

Thanks all!

[soul4t]

Sorry, guys, just rechecked the ECU Pinouts on the wiki, it says that TPS pin 2 is ground...can I just check continuity to a ground point/neg on the battery?

[DaniTD]

Hey on the ECU I verified the TPS worked at idle checking continuity between the TPS idle pin and a metal part of the car (metallic plate above the ECU)