M20b25 Running Rich / Failing MOT emissions test

[JakeusSnakeus]

I cant get this dam thing to come apart ffs!


Has any one taken a 164 apart? feels like I'm going to snap the board

[Speedtouch]

Why do you want to take it apart? Can't you just peer in between the boards to see if it has the standard EPROM?

[JakeusSnakeus]

Tbh your right I don't want to take it apart but you can't see anything. The EPROM has a plastic cover over it too.

[Speedtouch]

That unclips easily using a flat-bladed screwdriver to gently prize it up with.

Chances are, it will be a stock BMW chip underneath, since aftermarket chips for the 164 ECUs are hard to come by.

[JakeusSnakeus]

I'm starting to think the same thing... The case didn't looked like it had been opened either

[Speedtouch]

Aye, if the retaining tabs are all unmarked, then it will most likely be the standard chip inside.

You're best off replacing the 164 ECU for the later 173/380 version, which is a straightforward plug & play swap, and will enable you to chip it, should you wish to.

[JakeusSnakeus]

Yea chances are its the standard chip i just wanted to be 100% sure but nvm i cant be arsed to end up breaking the board in half

I guess the next step is to get the Injectors cleaned and tested then... anyone have any recommendations on who to use? I saw that injectortune offer a postal service.

I'm still a bit baffled as to why it fouls up all the plugs tho...


@speedtouch I'm planning to go down the MS route and then boost eventually

[mcspike]

Got mine cleaned via injectortune and it was fast and painless. Didn't drive before i cleaned them so couldn't say what difference it makes but Brianmoooore raves about it.

[JakeusSnakeus]

**News flash**

Cant believe i didn't notice this before but I'm almost certain that the injector in cyl 3 is the problem. I disconnected the injector and it runs badly (as normal) all the others appear to make a significant difference to the way it runs when disconnected...

[HairyScreech]

Does sound like injector problems then, that or at least we know its cylinder 3 that is misfiring the most.

[Brianmoooore]

If those gas measurements were done at idle then it can be a false rich.

Air leaks (unmetered air not from the AFM) on these things seems to cause an idle misfire, that actually tests as rich despite the reason for the misfire being a lean condition.

Is it rough at idle?

You need to get that hole plugged then pop the battery off, let the ecu discharge and then let it relearn the idle without that big leak.

If that does not cure it then the next places I would be looking is the gaskets from the inlet manifold to the head, these go hard and crack, leaking air like a sieve.

I have been through this one myself.
A big enough air leak will give a roving misfire that dumps fuel into the exhaust and tests rich.

I'd agree with the above if it wasn't for this: " All 6 plugs are black with soot after running for a short time."
Fully agree that a mixture that is too weak to ignite will, of course, pass straight through and raise the HC sky high, but not the CO so much, or give black plugs.

So it's looking like the black plugs might be a red herring, that's misled us? If the engine has been given a lot of cold starts lately and not much full temp. running, it's possible that this could have made them blacker than would normally be expected, although I'd expect to see a difference with #3, if that's the problem injector.
Does this car have the plug and socket mounted on the metalwork under the inlet manifold, that connects the injector loom to the engine loom? It looks like a small version of the 20 pin C101 engine loom to body plug and socket next to the fusebox, but I've been assuming that this engine is too early to have it fitted.

[Speedtouch]

**News flash**

Cant believe i didn't notice this before but I'm almost certain that the injector in cyl 3 is the problem. I disconnected the injector and it runs badly (as normal) all the others appear to make a significant difference to the way it runs when disconnected...

Sounds like you need to check the injectors connector (C191) underneath the inlet manifold; they often get water in and corrode, leading to such issues.

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

[JakeusSnakeus]

**News flash**

Cant believe i didn't notice this before but I'm almost certain that the injector in cyl 3 is the problem. I disconnected the injector and it runs badly (as normal) all the others appear to make a significant difference to the way it runs when disconnected...

Sounds like you need to check the injectors connector (C191) underneath the inlet manifold; they often get water in and corrode, leading to such issues.

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

From what i can see the 191 looks in good nick but admittedly i haven't checked every inch of it.

I disconnected everything off the intake manifold and went to take it out the other week when I was checking the valve clearances, but found that some bellend has rounded one of the nuts off so i ended up just putting it back together and not bothering.

I want to paint it so it doesn't look so scruffy and it will make life easier when taking the injectors out and checking the 191. I'll give it another go tonight. Maybe hammer an imperial socket over it and hope for the best

[Brianmoooore]

For some reason I'd got the idea that this car didn't have a C191 (only fitted to later engines), but looking back at your OP, it can actually be seen in your second pic.
It's underneath the lower rubber boot of the C191 that needs the closest attention. If a modification detailed in a TIS issued to dealers hasn't been carried out, then water collects in here, leading to an electro-chemical reaction of the copper of the wires.

[JakeusSnakeus]

Hi All

been busy with other things so haven't been on here in a while.

Anyway after several hours of swearing I finally got the intake off.. I ended up having to get some nut removal socket jobbys:



As you can see from how bad the nuts where


And I'm glad I did take the intake off cause it took ages to get the injectors out of the dam thing even sitting on a table... so it would have been a nightmare on the car



Injectors are off to Injectortune today for some refurby goodness so once I've got them back ill let you know how the car runs.
I've actually decided I'm not bothering to MOT the thing anyway as I've put a towbar on the daily and I'm looking for a trailer, but in the interest of science I'll put it back on the gas analyzer and post the results

[Liftedwj21]

I'm dealing with running to rich also hope you figure it out I've tried just about everything.

[JakeusSnakeus]

Ho Ho Ho Had the Injectors back



Put my badly painted intake back on and started the car hoping for everything to be fixed.


The splutter at low RPM is exactly the same as before and the fumes still smell as rich as ever.

I pulled the HT leads off each plug one by one with it running and there is a noticeable change in engine note on each cylinder so slight improvement

[Brianmoooore]

There will be an improvement in the running of the engine with the injectors rebuilt, and it's money well spent, but they don't appear to have been seriously faulty in the first place.
Have you checked out the C191 properly yet? Especially under the lower boot.

[JakeusSnakeus]

The lower boot being the bottom half of the Round connector?

[Brianmoooore]

Yes. The boot should have been modified with a small nick cut out of the rubber at the lowest point, to prevent water being trapped in there, but most weren't.

[JakeusSnakeus]

Yea when I took the intake off i checked it there is some slight blue corrosion on the pins inside but nothing major

[Brianmoooore]

So, we have correct, rebuilt injectors, a new blue temp. sensor and checked wiring, correct fuel pressure, and an AFM that has been tested.
Any sign of the cover having been removed on the AFM? I'm thinking that the spring could have been slackened by a previous owner.
It's a pity that you don't have the gas test results from previous MOT tests, so that we could see if it just scraped through, or passed way inside the limits like an E30 should.

[Andyboy]

From distant memory, early plastic bumper E30's and E34's (87/88 ) had a cold start issue. The BMW response was to fit an inline extra wiring loom with a resistor to fool the ECU into thinking the engine was colder than it was. I think there was also a relay - it's so long since I've seen one but I had a 1988 E reg Touring ion once that ran so rich it hurt your eyes to be in the a same building with it running. I took the extra loom out, plugged in the original stuff and away it went.

Have you checked that the throttle position switch is working properly? You should hear a very faint click as out opens off idle. That click is the microswitch within telling the ECU to switch from idle to part load fuel maps. If it's wrongly set, or full of oil (most are) the engine will be idling on part load maps, stinking rich and off the scale CO wise.

[Brianmoooore]

TPS was tested half way down page one, but, looking back, only by sound and not electrically.

I've come across several cases of BMW's cold start bodge, and in all cases have removed it without causing subsequent problems. The relay should have been mounted on the fixing point on the side of the fusebox, with a loom going down to the starter motor, and another one, with a 'break out' plug and socket arrangement (similar to that used for adding headlamp washers, etc., to the washer pump wiring) going to the 'blue' temp. sensor.

[JakeusSnakeus]

Have you checked that the throttle position switch is working properly? You should hear a very faint click as out opens off idle. That click is the microswitch within telling the ECU to switch from idle to part load fuel maps. If it's wrongly set, or full of oil (most are) the engine will be idling on part load maps, stinking rich and off the scale CO wise.

Yea I've got a feeling this is whats happening, its got to be something causing the ECU to over fuel.

I have checked resistance from the TPS but didn't write down any of the numbers i just checked that they fluctuated. As far as it being covered in oil its quite clean and looks ok.

Any one know what kind of figures a working one should give?

Brian I haven't seen anything like what you're describing about the cold start bodge anywhere on the car but ill double check. There's nothing attached to the outside of the fuse box or any other wiring accept what go's in and out of the box.

AFM looks un touched

[Brianmoooore]

I have checked resistance from the TPS but didn't write down any of the numbers i just checked that they fluctuated. As far as it being covered in oil its quite clean and looks ok.

Only readings from an E30 TPS that isn't on a M42 engine, should be short circuit (zero ohms) and open circuit (meter reading whatever it does to indicate out of range.)
It's not the outside of the TPS that gets oily, it's the inside. Oil in the throttle body, from the crank case vent system, runs down the throttle butterfly shaft, and into the casing of the TPS, not too cleverly positioned underneath the throttle body. This is sealed from below, so eventually can fill up, get inside the casing of the idle miniature microswitch, and stop it working. This will eventually stop it clicking, but there can be a period where it still clicks, but doesn't make contact.

[JakeusSnakeus]

Ok Interesting ill test it again

[DMW]

just read this thread , has it been fixed ?

[JakeusSnakeus]

just read this thread , has it been fixed ?

I'll be checking the TPS today or tomorrow so ill post an update as soon as.

I haven't been sober enough to start undoing bolts yet

[Andyboy]

Take the TB off and unscrew the TPS. Split the two halves open with a very small flat blade screwdriver and wash all the oil out with carb/brake cleaner or petrol. It will be full of oil and need a good wash out - leave it to soak for a couple of hours before drying out, refitting and setting it up again.

[JakeusSnakeus]

Take the TB off and unscrew the TPS. Split the two halves open with a very small flat blade screwdriver and wash all the oil out with carb/brake cleaner or petrol. It will be full of oil and need a good wash out - leave it to soak for a couple of hours before drying out, refitting and setting it up again.

Is this thing glued together or something? Wont budge..

[Andyboy]

Definitely not glued - should come apart.

[bosers]

I couldn't open my Tps either, in the end I drilled a 3mm hole in center of underside and sprayed cleaner into it. Seemed to help a bit. I had same trouble with overfuelling, changed all gaskets and serviced injectors with not much improvment as well. I found air getting past seals on throttle body and getting in past breather pipe from inlet manifold to sump, changed them made quite a difference. Also changing my Ecu from 380 to 173 really cleaned up the fumes, think my Ecu was slightly faulty as well as the other little things. With chip from Speedtouch just flew through emmisions test, CO .91% and HC 168ppm. Hope this is of some help. Good luck.

[Speedtouch]

Indeed, the later 380/381 ECUs sometimes blow diodes in the idle control circuit, which can cause such issues.

Glad you found the chip to your satisfaction.

[JakeusSnakeus]

I Managed to prise it open with some circlip pliers in the end. It must have been glued because bits of the lid are still stuck to the housing.

I tested the switch and the metal prong thing inside from their terminals for continuity and resistance was low and when the switch isn't depressed it shows open circuit so i think that confirms its fine. wasn't too much oil in there either.

This isn't mine its just a picture i found online


When i test the actual connector pins i just get open circuit though..

Bosers - I've got a friend who i can borrow another ecu from. It's got a green label, not sure if that gives away what model it is? Ill see if that makes any difference.

I have also changed all the gaskets on the intake manifold when i put the injectors back in.