Need help with a hard start issue

[6erwebb]

To date, Ive cleaned and swapped the idle control valve. swapped the injectors out. Full tune up with factory recommended parts.

My sister has a 1989 325i that were trying to sell but getting what she has in it back out with this problem is rediculous so I need to fix it quick.

Basically it doesnt start easily but it does start every time eventually. It will crank about 3-5 seconds and stumble around then start a rough idle. I have noticed if it has been days since it last ran it will puff a bit of white ish grey smoke (indicating a rich condition?) however when it does run it seems to run very smoothly. I really dont know much about fuel injection or m20s.

Im sure someone else here has tackled this problem, any help is appreciated.

Thanks, -Webb

[BonnschE30]

The smoke is probably just condensation which is present it pretty much every e30 that I've owned, so probably wouldn't worry about it unless it reeks like coolant or oil.

As far as the hard start goes, I've dealt with a similar issue for the past year so I'll keep my mouth closed and ears open in hopes of gaining some insight as well. But expect a reply recommending a test for vacuum leaks and to check your fuel pressure when cranking...good luck!!

[6erwebb]

Ah, good suggestions. I also forgot to say Ive checked for vacuum leaks as well as made sure the engine was getting a good ground.

I havnt checked the cranking fuel pressure though..

[BonnschE30]

Remember that just because you can't noticeably see or hear a vacuum leak doesn't necessarily indicate that it doesn't exist.

Other possible diagnostics include swapping the main and fuel pump relays with new units, cleaning your Mass Air Flow Sensor, and checking for the correct resistance for your Crank Position Sensor and Engine Coolant Sensor.

Probably wouldn't hurt to pull a couple spark plugs before and after cranking to look for any variations in the cylinders.

[BavBeater85]

first thing I always do is check the spark plugs....reading those can you you a lot bout whats going on inside the engine....for example I was having hard start issues, pulled the plugs and found fuel on them...connected that to my thremostat being out and causing the car to run extra rich...cleaned the plugs off and put the themostat back in started right up and ran great...now i gotta get the air outta the system

[Sagaris]

make sure the idle switch on the throttle position sensor under the throttle body is engaging when the car is at idle/closed throttle. Use a continuity tester to test 2 of the 3 pins on the sensor itself. one is a ground, the other is for idle, the other is for full throttle. There should be continuity between the ground pin and the idle pin of the sensor with the throttle closed. If not, the switch may be bad or needs slight adjustment. I have had a switch work 1 out of every 5 or 6 times so when you check the sensor make sure you check it a few times to be sure it isn't only working part of the time.

If the idle switch is not engaged the ECU is trying to use part-throttle timing and fueling parameters which do not work well at low rpm such as starting and idle.