s52 hard start...

[jakeb]

Another update.... I let it sit for a couple hours and then I jumped the fuel pump relay and the pump seemed pretty loud. You could actually hear it building up pressure, louder at first and then a little quieter. Replaced the relay and it started right up.

So I am thinking it is the pump or the FPR loosing pressure. The intake pump was replaced about 3-4 months ago but it very well could be bad. I only replaced the pump portion of it and not the entire thing.

Should you be able to actually hear an intake pump whining from outside the car? Normally when they get loud it means they are failing right? I have an extra pump that I can try or I may just get the pump i bought recently replaced.

Does the pump itself hold the pressure...is there a check valve in it or is it that funny little accumulator looking thing that holds the pressure?

I feel if I keep updating this thread it will help others that might have this same issue in the future...

[1990m3]

just out of curiousity, did you try my method of holding the key on for 3 seconds before firing?

I am using the stock 3.0l temp sensor for the DME and the m42 temp sensor so the gauge is accurate. once it starts it seems to run fine. I don't know what color it is, it's been in there for too many years I just can't remember anymore.

[jakeb]

yes I did try to wait 3 seconds and start it....doesn't help.

I replaced the fuel pump....still the same issue. The pump is still very loud tho. But maybe that is just the way this type sounds.

Either way when I was pushing it today the check engine light flashed up near 6k rpm. Right when I came off it the light when out...shift back to 6k and the light is back.

I just did the stomp test and came up with 1215 which comes back as:

1215 - Indicates problem relating to Air / Mass Flow Meter - AFM or MAF depending on your e30 model. Causes could be cable wire damage, short circuit in the unit, or air / vacuum leak (check air intake hose - big L-shaped one)

could that be causing my hard starts as well? It is only happening after the car has been driven and heated up. The problem does not happen when the car is dead cold...after sitting for 8+ hours. Or if I just start it and then shut it right off and come back and try again in 2-3 hours.

Only when the car is fully warmed up and then sits for anything more than say.....15 minutes.

[jakeb]

waited some more... unplugged the MAF and tried.. Same long cranking to get it to start.

This is driving me nuts.

[jakeb]

I am at a loss now....

I replaced the main and fuel pump relay with known good ones. Still the same issue.

here is a recap...
obdI s52 (TRM chip) 318is swapped from an m50 that had ran without a flaw for a year.

It will start perfect when it is dead cold. Sitting for at least 6-8 hours. If it is warm and sits for anything more then 20 minutes it takes a lot longer to start. Maybe...15 seconds of cranking. Once it starts it runs fine. Pulls fine... no issues really

replaced injectors with another set, then checked the ones I pulled and they checked out
swapped the coolant sensor with another
replaced the fuel pump
fixed a very very small vacuum leak at the purge valve
replaced the main and fuel pump relays

same F'in issue.

I am really at a loss at what to do next.

Once time when I primed the fuel pump it did start better. I am going to try that again in about 30 minutes and see what happens. Or I may probe the fuel pump and see if it is even turning on when it is cranking after being hot.

Could the FPR be causing something weird when it is hot but not cold?

Could it be bad plugs. I am running NGK iridiums... I was unsure when I went with them but run them in my wifes 328i (m52) and there are no issues.

Could the coils be having an issue?

Should I put an m50 chip in the dme and try that.

This all worked fine with the m50...the one things that changed were:
s52, different injectors, different coils, different spark plugs, TRM chip

Can anyone help me here??

TIA

[jakeb]

The pump is turning on right when I start cranking, check with a MM, as well as putting my hand on the pump when turning it over. So the dme is telling that to turn on. So that would mean the the crank pos sensor is ok?

[1990m3]

which ECU are you running? I've been through my car as well and can't find the issue, I gave up on it.

I have a silver 413 ECU with a TMS, EWS delete chip. Maybe if I try a different ECU???

What have you got?

[jakeb]

red label with TRM chip

[jakeb]

So when I know it is going to hard start if I jump the fuel pressure relay it starts right up. So from that I think it is dropping fuel pressure (not sure why it would start fine cold tho, does the pump run longer at first turn of the key? or spray more)

I ordered a new FPR today and will have that tomorrow to try. Could it still be the idea of a leaky fuel injector? I can see one or two but wouldn't that just cause a misfire? When I swapped the plugs the didn't smell gassy or anything.

[jakeb]

FIXED!! Replaced the FPR last night and there was a little fuel in the vacuum line and drove it all around today and let it sit for a hour more than once and it started perfect both times.

So the FPR was the issue.