325 running rich please help

[Watthefucklike]

Hi everyone, i have an 87 325i which is running rich and there is alot of things i have checked myself, if i give you all a list of what ive done, can you please give any input. Before i start i am a diesel mechanic so am mechanically minded, but still need some help.

So....

The reason i think its running rich is damage to cylinder walls on inspection, black soot fouling of the plugs, and eye watering poisonous gas coming from exhaust whilst at idle.

Things i have checked and found so far, which i think are ok...

Smoke test of the intake and vacuum system was carried out with no leaks found. All pipe joints ect to throttle body are glued and sealed with resin.

Injectors removed, sent off to be overhauled, and refitted, then removed again and replaced with new aftermarket injectors with matching part numbers.

Blue temp sensor resistance checked at ecu and values are acceptable.

Airflow meter voltage values checked across reference point against other pins, and voltage levels are acceptable. Continuity has been checked between the unit and ecu and all wires are good. The idle mixture adjustment screw is 18.1 mm from the top of the hole as stamped, and adjusting the spring tension inside the unit smoothes out idling but doesn't get rid of the problem.

The throttle body is currently removed by me to check the position sensor. Closed position switch is working, but WOT switch is not making contact, due to oil contamination. I will clean this, but is not going to be the source of the problem.

The throttle stop bolt has been moved by somebody, so will set this up correctly, looking for tips on this at the moment. As it stands the butterfly closes a fraction off making contact with walls, so is probably ok anyway.

Things which i think maybe causing the problem and would love some help with....

Fuel pressure was checked using a t piece at the fuel inlet pipe on the rail. The fuel pressure is 2.5 bar, so under by 0.5. When you disconnect the vacuum control pipe at the regulator, the pressure come up to 3 bar. I am wondering if i have too strong a vacuum, due to reasons stated below. (Any thoughts on this?)

My idle control valve has been checked for resistance across the pins, these values are good. The unit buzzes with ignition, and the rotary valve inside is very free and moves stop to stop with a finger. When unplugged i move it to open position, and with ignition on, i plug it in and it shifts to a fraction off closed. ( Is this right? Surely it should be around half way? I am wondering if my engine is being starved of air due to this, hence causing high vacuum at the regulator)

Is there any way we can check the 'ignition on' position of the idle control valve on a good running engine please? Is there anybody who has the 'ignition on' voltages out of the ecu to the valve with it all plugged in? I am wondering if my ecu is at fault, or my valve, or am i missing something else?

Cheers all.

[martauto]

Welcome to the zone mate and I know someone will be along soon ish to help you .
Pic`s of your car are part of the zone membership (not) but we all like to see pics , dont we ??

Mart.

[Watthefucklike]

Here is the beast

[Watthefucklike]

And cheers for the welcome

[onthames]

regarding tps WOT, you can drill a hole on the S of the bosch logo on the underside of the tps plastic cover to drain the oil and allow future oil to drail. Also if not making contact at WOT then you can adjust the TPS simply by loosening the bolts holding it on and twisting it until it makes contact on WOT and then tighten.
Regarding the AFM. did you test with a DMM as this is not a viable test as you're looking for dropouts that aren't picked up by a multimeter (multimeters use averages). You need to hook it up to an oscilloscope to test properly.
Take the ICV off and apply 12 volts, should close with voltage applied and be open with no voltage. With the ICV off turn ignition on and test with multimeter on positive terminal to ground.
Check the wiring from the idle control module to the valve, should be near the ECU, check for continunity between the idle control valve plug and the idle control module plug on both wires individually.

Also the butterfly needs to be really closed I think. Not sure how to adjust you'd have to google. But you want .0015" gap between throttle plate and housing.

[martauto]

And cheers for the welcome

Nice car mate , where are you located ?
Do you really think just one pic of this is enough ??

Mart.

[Watthefucklike]

regarding tps WOT, you can drill a hole on the S of the bosch logo on the underside of the tps plastic cover to drain the oil and allow future oil to drail. Also if not making contact at WOT then you can adjust the TPS simply by loosening the bolts holding it on and twisting it until it makes contact on WOT and then tighten.
Regarding the AFM. did you test with a DMM as this is not a viable test as you're looking for dropouts that aren't picked up by a multimeter (multimeters use averages). You need to hook it up to an oscilloscope to test properly.
Take the ICV off and apply 12 volts, should close with voltage applied and be open with no voltage. With the ICV off turn ignition on and test with multimeter on positive terminal to ground.
Check the wiring from the idle control module to the valve, should be near the ECU, check for continunity between the idle control valve plug and the idle control module plug on both wires individually.

Also the butterfly needs to be really closed I think. Not sure how to adjust you'd have to google. But you want .0015" gap between throttle plate and housing.

Good tip with the hole drill, sorry when i said not making contact, i meant the switch is being hit, its just the contacts need cleaning.

Yes i did test with a dmm, i dont have access to a scope, so cool thats something i need to do,

The icv has 3 pins, and with no voltage just moves freely, it doesn't go to open position. Im assuming it needs voltage across certain pins to close, and certain pins to open, and must be varied. This car doesnt have an idle control module, it is controlled directly from the ecu, im sure the external modules are only on a 325e?

[Watthefucklike]

And cheers for the welcome

Nice car mate , where are you located ?
Do you really think just one pic of this is enough ??

Mart.

Here you go mart, im in sunny wales

[onthames]

regarding tps WOT, you can drill a hole on the S of the bosch logo on the underside of the tps plastic cover to drain the oil and allow future oil to drail. Also if not making contact at WOT then you can adjust the TPS simply by loosening the bolts holding it on and twisting it until it makes contact on WOT and then tighten.
Regarding the AFM. did you test with a DMM as this is not a viable test as you're looking for dropouts that aren't picked up by a multimeter (multimeters use averages). You need to hook it up to an oscilloscope to test properly.
Take the ICV off and apply 12 volts, should close with voltage applied and be open with no voltage. With the ICV off turn ignition on and test with multimeter on positive terminal to ground.
Check the wiring from the idle control module to the valve, should be near the ECU, check for continunity between the idle control valve plug and the idle control module plug on both wires individually.

Also the butterfly needs to be really closed I think. Not sure how to adjust you'd have to google. But you want .0015" gap between throttle plate and housing.

Good tip with the hole drill, sorry when i said not making contact, i meant the switch is being hit, its just the contacts need cleaning.

Yes i did test with a dmm, i dont have access to a scope, so cool thats something i need to do,

The icv has 3 pins, and with no voltage just moves freely, it doesn't go to open position. Im assuming it needs voltage across certain pins to close, and certain pins to open, and must be varied. This car doesnt have an idle control module, it is controlled directly from the ecu, im sure the external modules are only on a 325e?

I think thats how the ICV is supposed to be. not 100% sure tho. you're correct its for 325e's only. With the butterfly in throttle closed, the ECU should read TPS as closed, and tell the ICV to open by putting voltage across it.
Did you test blue temp sensor at the sensor itself and at the ECU to ensure values are the same?

Try disconnect the ICV and start. should idle at about 2k

[onthames]

Is your TPS 100% outputting throttle closed when at rest?

[onthames]

image_148159.jpg

[Watthefucklike]

[

I think thats how the ICV is supposed to be. not 100% sure tho. you're correct its for 325e's only. With the butterfly in throttle closed, the ECU should read TPS as closed, and tell the ICV to open by putting voltage across it.
Did you test blue temp sensor at the sensor itself and at the ECU to ensure values are the same?

Try disconnect the ICV and start. should idle at about 2k
[/quote]

Yes i checked the blue temp sensor at both ends its all good.

Like i said about the icv, with the throttle closed and ignition on, the ecu puts it in almost closed position, if you put your mouth on it and blow, theres a fair amount of resistance. Im sure i tried unplugging it and the idle stayed the same, but cant remember to be sure, il have another go when i put the throttle back together.

Im starting to think that maybe its the tps because there was a fractional 0.5ohm resistance on the closed side. Maybe thats enough to interupt the signal to the ecu. Il clean it all, so its perfect, put it back together and try.

[Watthefucklike]

Thanks for the photo onthames, thats amazing info there!

[Watthefucklike]

What book is that

[onthames]

Hmm. Some people online say it should be half open with throttle closed ignition on. One of those things where different people saying different things. I'm sure someone else will chime in here who knows more than me!

That photo is from the Haynes manual

[Watthefucklike]

Hmm. Some people online say it should be half open with throttle closed ignition on. One of those things where different people saying different things. I'm sure someone else will chime in here who knows more than me!

That photo is from the Haynes manual

Yeah i read it should be half open, but like you say we cant be sure. Cheers for your help butty. And il check them voltages tomorrow when i have a bash.

[Watthefucklike]

Cleaned the switch up, even took the microswitch apart and cleaned the contacts. That microswitch is a bastard thing to get back together. Anyways my WOT is working now, but as i said the closed throttle was working anyway so dont think this is the source of the problem.

[Watthefucklike]

Right, finally had a spare hour to spend some more time diagnosing this fault.

I set the butterfly up with a 0.04mm feeler gauge, bolted on the newly refurbished tps, and put back together, the car is still running rough and rich.

So i looked further into the possible problem with the idc, and as 'onthames' kindly pointed out there is some nice info in the hanes manual. Im supposed to have 12v at the center pin to ground, and at the center pin to each of the outer pins im supposed to have 10v. All is there, except on the one outer (white and yellow wire) instead of 10v i only have 3.9v. so i checked at the ecu where it comes out on pin 4, i still only have 3.9v. i then cut the wire at the ecu loom, to make sure nothing down the line was upsetting the voltage, and tested my now dead end yellow and white wire coming out, and still have only 3.9v reading when i put the other multimeter wire on a battery pos.

So looks like my ecu is at fault, unless some information my ecu is receiving is telling it to lower the feed. Any thoughts?

[davidt]

Check the plastic cover on the top of the AFM and check to see if it has been disturbed, if it has someone may have adjusted the flap tension to alter the fuel mixture. have a look at this link as it will give you a good idea on how the AFM works.

[paultv]

Take your car to your local and have them do an emmisions test...at idle you should have CO of 1.

I imagine your air bypass setting inscribed on the AFM is no longer valid after years of system wear.

At least get the idle mixture correct before messing everything else up.

Just a thought

Paul

[Watthefucklike]

Cheers paul. If it were you, would you rebuild the bottom end first then take for emmisions setting? Or the other way round?

[paultv]

If you're taking the lump out for a rebuild, I'd do that first, and buy new injectors or have your old ones refurbushed if you've not done so already.

Rule of thumb for AFM is wind it in closed, then unscrew for 3 and a half turns then gas test idle, BUT only if you have zero air leaks, correct fuel pressure and remember a cold ecu ( after the battery has been disconnected ) will run high idle until its been driven for half an hour with lots of starts and stops...it needs to learn a little.

Paul

[Watthefucklike]

I got new injectors already. Fuel pressure is 2.5bar against atmosphere, so i should be good for a smoke test once rebuilt