E30 Hard start when warm, impossible when cold.

[Meeren]

Hey guys...I am new here, I am from S.A...kzn ...I have a e30 320i that really battles to start up...on a warm day, I will turning the key a couple of good times to get the car started, but when its cold, its impossible...she will not start at all...but engine will crank healthily...I've replaced my fuel pump. New spark plugs, airfilter and fuel filter...any advice would really be awesome...

[doctorx69]

a few things I would try: check compression in cylinders. Check and possibly replace the distributor cap and rotor (mine was pretty bad). Vacuum leak (this one is a bit of a stretch though). Finally, and i think this may be it... fuel pump is bad. I had a kia sedona do the exact thing when it got cold. After changing it out, the problem went away.

Just thought of another reason, old gas?

[superj]

what are you reading for fuel pressure? is your regulator bad? are you getting spark? and you do have good compression?

[bluptgm3]

I’d also look at Temperature Sensor and Thermal Timer Sensor (ETA only?) both on T-Stat Housing.


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[Meeren]

I dont have any access to any tools to check my compression at the moment but will update as soon as I get my hand on one...I did remove distributor cap and all seemed good, gave it a good clean, rubbed it off with some sand paper...and re-installed it...and when did this, it was a hot day...car did battle to start but did start and idled and drove perfectly and started perfectly after everytime until the next morning ...I had just replaced my fuel pump as well...gas is still fresh in the car

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I havent gotten about testing for fuel pressure but I can hear the fuel rushing through the lines, so I assume fuel pressure and fpr is all good... as for spark, yes I am... but sometimes it barely does spark...

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I was also looking into that, my coolant temp sensor...because I have noticed when I turn the key on, the temp gauge shoots to the red mark, and when I do try and start, it only cranks...but when I do get that lucky swing, I noticed the gauge does not move to the red as it used to the prior attempts...so would your coolant temp sensor cause an issue like that?

[tomstin]

I'm thinking more along the line of the cold start valve. Check the temp sensor for that, pull the cold start valve, place in a jar / bucket and see if its working.

[superj]

oh ya. a bad cold start valve, or the sensor that controls it, will make an eta take a super long time to start

[Meeren]

I'm not too sure this model has a cold start valve as models before 88 had a cold start valve, models in 88 and after had a coolant temp sensor...I may be wrong tho��...where would I start looking for the cold start valve???

[tomstin]

Seems you are correct, I poked around in REALOEM and I don't see a cold start valve for a 320i. On the M20B27s, popular here in the states, there is an extra injector that is only used when the engine temperature is below a certain point. The Bentley manual states something to the effect, "very difficult if not impossible to start a cold engine without the cold start valve". I think it may be worth you time to find a Bentley manual for the 320i. I would think they have something to add a little extra fuel on cold starts.

[Meeren]

Found out my issue Haha...was my airflow meter...whenever I unplug I try and start, occasionally it will catch but wont start or it will start but when it does and I do connect my airflow back, she straightens up....and if I do battle to start her up again...I just repeat that process and she starts up

[superj]

that's odd. maybe its just a bad connection at the plug?

[Meeren]

Not to sure...but I tested it out this morning...I tried starting her up as normal...wouldn't start...then I disconnected the airflow meter, she started up fine ...played with the throttle until I got the airflow plugged back in...the rest of the day she starts perfect...even after sitting a couple hours...