318is running rich n rough

[Eevo]

hi guys, need your input.

ive picked up a 1994 bmw e36 318is.

when i got the car, it was a need a bit of throttle (not much) on startup for 30sec or so or it would die. this would happen regardless of how long or short i had been driving. i thought this might of been a dying fuel pump. im guessing not holding pressure when turned off. i have not yet replaced the fuel pump.

i also believe it has a stuck open thermostat as it would take a long time to get up to temp. this might be complicating the below problem.


yesterday, the car would start but not keep running. it was very rich, rough running. at first i thought it was missing, so i pulled the ignition harnesses one at a time, no obvious problem here.

as the engine warmed up, the engine smoothed out and ran perfectly. i started thinking engine coolant temp sensor (ECT).

today, engine would not smooth out when warm. i tested the ECT, the 5v reference was correct, and the resistance at 2 different temperatures (10c and 40c) also correct.

bugger i thought.

i tested the TPS, testing correctly.
i tested the air flow sensor (volume air flow type sensor with integrated intake air temperature), testing correctly.
i disconnected the o2 sensor and ran the engine again. little to no improvement.


what else can i test, as i think ive covered all the sensors that affect fuel injection?

[MacMan]

I know nothing about the 318 but had use of a 320i while the Disco was off the road having the engine rebuild. What an utter bastard of a car. Delightful to drive... when it would go. It had a litany of electrical faults and was a foul abomination to work on. The FSU was faulty so it flattened its battery at random times. I broke a rib in the process of fixing that. As soon as that was fixed it started doing exactly what you described at start up, but it would also stumble and die in traffic. About that time I was thrilled to give it back to the owner. It turned out to need new cam position sensors and that fixed the problem at about $700 worth of parts and labour. I learned tonight that the problem has returned and it now needs a new crank angle sensor. I'm told that's a "hard to get to" job. We have two old tech BMW bikes which we both love, but I would never, ever contemplate a BMW car.

[MacMan]

I forgot to add, get someone who knows what they're doing to read the fault codes. Otherwise you'll be throwing parts at it until you find something that sticks.

[Eevo]

thanks for the reply.

[strangy]

It will probably have an idle air control valve (used for cold starts,idle up for Air C.) confirm this is working and not clogged. Check EGR operational and not blocked..
I dont know about the BMW but many EFI engines in this era also have a cold start injector/nozzle/jet in the inlet manifold.

Confirm vacuum lines are all connected and not cracked.

[Eevo]

It will probably have an idle air control valve (used for cold starts,idle up for Air C.) confirm this is working and not clogged. Check EGR operational and not blocked..
I dont know about the BMW but many EFI engines in this era also have a cold start injector/nozzle/jet in the inlet manifold.

Confirm vacuum lines are all connected and not cracked.

cheers, idle air control valve is next on the list to look at. just need to find time.