Overfuelling and Idle issues

[Shaheenk]

Hi Guys

Please can you help with my diagnosis. This may be a bit long winded but I will run throught the symtoms and the checks I have done .

1. Car is a 325i with stock M20 motor and MOtronic 1.3.
2. The issue started a while back but it seems to be causing much headaches

The car is overfueling to the point where it will not start, it cranks and cranks and eventually when you do get it started its rough until what I assume is the fuel evaporating.

When it does not start it simply will not , we had to remove the sparkplugs to clean the fuel off as it seems the motor is flooding. This is odd because as I undstand its nearly impossible to get them to overfuel to the point of flooding.

I initially suspected a fault AFM so replaced with with a good working unit , this did not cure the problem.

I have since done the follwoing checks,

1. Checked the TPS and it's operation, I noticed that sometimes the switch closes but the pins do not form continuity, opened the unit up and cleaned it out seemsed to have solved this.
2. The ICV buzzes continuously , from my understanding it should not buzz if the throttle is opened as this will open the circuit which tells the ECU to adjust the ICV.
3. The Blue Temp control plug is within spec and has the vaules of 3K when cold and 200Ohm when warm, if you can get the car warm without it dying on you.

TPS clicks when the throlle is shut.

when you do eventually get the car started there are plumes of black smoke out the tailpipe , yesterday was initally some white smoke then black , not enough to darken the skies of mordor but still visable. They get less when the car is fully warmed up , if you blip the throlle she will die then crank over and over and not start till you take the plugs out , clean the fuel off and start again.

There are no vacume leaks as this one only has a single vacume hose from the intake to the FPR and on the TB there are the hoses to the ICV and the 2 to the brake booster.

The intake rubber boot has been checked and is free from cracks and splits.

When running she purrs away with no hint of being abnormal, if you gently accelerate she does so without hesitation or misfiring.

I dont know what else to check and am wondering if its time to chuck out motronic and go to a standalone unit.
Any Advice on what to check next

The only things that I have not swapped out are

1. Blue temp sensor
2. FPR

[Grrrmachine]

The only things that I have not swapped out are

1. Blue temp sensor
2. FPR

Swapping out parts creates more problems than it fixes. The very first port of call should have been to TEST the blue temp sensor at the ECU plug before swapping around anything. Do this now:

http://www.e30zone.net/e30zonewiki/inde ... or#Testing

[Brianmoooore]

Chances are that this will be solved involving no outlay on parts and just an hour or so's work with a soldering iron.
As Grrrr says, TEST to find a fault, don't guess.

[Shaheenk]

HI Guys

So pulled out the multimeter yesterday and started with the blue plug.

Checked the ohamge at the plug and the connector onto the plug.

The plug checked out fine when cold , next step was connector which also checked out fine.

Went to the ECU and found there was no reading on the ECU pinouts mentioned, traced back to the injector harness , unplugged this and confimred there was a reading leading to the plug.

Plugged this back into the harness and confirmed there was readings on both sides of the plug, went back into the car and checked and now there was a reading on the ECU pinouts.

My guess is the plug was not correctly seated/connected.

However this did not solve the overfuelling, car hesitated to start but eventually did, still missfiring a bit , then calmed down , idle was normal and could blip the throttle without it dying, however still loads of smoke until warm.

Once it had warmed up the smoke cleared but you could smell the fuel from the exhaust .

We also then had the oil light flickering and I am not sure if thats just the oil being too thin, or a pressure switch , rev it up and it goes off

Drove the car around and she would still stall at the lights.

[Brianmoooore]

Wiki article clearly states that you should not do the first tests anywhere near the blue plug!!

Take the plug and socket under the manifold apart again, peel back the rubber boot on the lower half, and describe the condition of the wires under it.

[Grrrmachine]

If the blue plug wasnt connected for whatever reason, then connecting it will not instantly fix the problem. You need to give the ecu time to learn its new settings, generally by resetting the ecu with a cold engine. Once that's done, idle the car for ten minutes, then take it for a good hoon. Your idle /stall should be fixed after that.

But as Brian says, corrosion at the wires will mean your problem will come back very soon unless you repair or replace the wiring.

[Shaheenk]

Wires under the loom are not rusty or coroded, they actually in really good condition, I checked the plug itself a well and there is no corrosion on either end.

Remember being in South Africa means we dont have the issues with rust.

Car was idled from cold up to warm, went on a good hoon, car feels really sluggish to be honest. I am guessing I need to get her on a gas analyser to see if the "new" AFM was not tampered with.

Also checked the marking on the AFM, the little engraving on the top is aparently where the air bypass is set at the factory, I never knew that.

Will keep investigating, bought a regualtor but never needed to fit it.

[minesapint]

Also checked the marking on the AFM, the little engraving on the top is aparently where the air bypass is set at the factory, I never knew that.

Neither did I.
Have looked on mine can't see anything, could you post a photo of said engraving please.
Cheers