M20B27 SETA Warm Start

[barreto]

A bit of a long story, but I'll include as much info as I can. I picked up an 88 SETA with plans to do a 327i build a few months ago. The only issue the car had before the swap was that it would not start after it was warm. Compression was good across the board, injectors were rebuilt, cleaned the afm and icv so I thought perhaps it had something to do with the head or intake.

I pulled an entire top end from a '90 325i at a pick-a-part and had the head rebuilt with new valves and springs. I finished the build over the weekend and everything went together well. I had an issue at first with a possible bad afm or an issue with the M30 injectors I tried to use but after swapping out the afm and installing the regular 325i injectors that came with the head I pulled, it started and idled perfectly. Everything seems to be running fine but after warming up, it still doesn't want to start after I shut it off. It appears that something is still telling it not to start after warming up. It has a new coolant temp sensor and the signal is good cold and warm at the DME pins.

Here's a list of things I changed-
Rebuilt 325i head
325i intake
325i Throttle Body
325i AFM
325i ICV
325i Intake boot
brake booster/throttle body hoses
173 DME
325i injectors

This leaves a few things left from the original setup but the odds are that it's something still there producing the same problem.

Things I need to check- injector signal after warming up, spark after warming.

What else should I be looking at/for?

[TheTacoMan]

Currently on head swap #2 on my car seta, your list looks complete however I don't think you will need the brake booster lines for the throttle body, I never changed mine. Ive had everything from a chip and a m30 afm to the miller maf setup and now megasquirt on a seta. IF you have any questions dont hesitate to ask me.

[barreto]

I went ahead and did the brake booster lines because I had the parts and I didn't see a reason not to.

My issue is something telling the car not to start after it warms up. I had the same issue before the swap so it must be something from before I started the swap. I'll have it narrowed down a bit more when I check to see if it's getting spark and/or fuel.

[jlevie]

Since the problem existed existed before and sing you have changed out the entire engine management system, there is little chance that being the problem. Checks at this point would be a smoke test of the engine, diagnostic tests of the fuel system, and verification of the condition of the fusible link.

You did change to the 3.0bar FPR, right?

[barreto]

Yes, I did use a 3.0bar FPR. I'll be checking the entire fuel system tonight. I'm still trying to figure out what else would change between the engine being cold and being warm. It starts immediately when it's cold. No hesitation.

[digger]

does it run well when warm and hot? in other words it only has the problem starting?

does the engine need to sit a bit after shutting it off to get the no start scenario? for example on a hot engine if you shut it off and restart immediately the problem exists?

[barreto]

Good questions. It runs well when it's warm/hot. It will usually start again within a minute or so of shutting off but not after that until it cools off. When you try to restart it hot, it coughs once like it's going to start immediately but then just keeps cranking.

[digger]

sounds like a fuel issue i had many years ago. i had a problem that warm starts would crank forever, yet cold and hot starts were fine and the car ran as normal. car would need to sit for about 10-15min after running only to have issues upon starting. it turned out to be my injectors which incidentally had them cleaned etc but not until i borrowed a different set of injectors from a FORD of some description did the problem actually dissappear.

i dont actually know what was wrong with the injectors to cause the issue as the refurb guy said there was nothing wrong with them but i tried alot of things to no avail before fixing the issue so i was happy

[barreto]

Possible. It did the same thing before the swap with the "e" injectors as well if that is in fact the problem, but maybe both sets of injectors have problems.

[digger]

Possible. It did the same thing before the swap with the "e" injectors as well if that is in fact the problem, but maybe both sets of injectors have problems.

unlikely but not impossible

[digger]

have you tried priming the fuel pump before cranking?

[barreto]

Turning the key back and forth several times before cranking? or is there a manual way to prime the fuel pump?

[digger]

Turning the key back and forth several times before cranking? or is there a manual way to prime the fuel pump?

the bentley will tell you how to jump the relay its very easy. i dont recall specifics though

[barreto]

Fuel pump does not prime but kicks in as soon as it starts cranking. Spark is good on all cylinders. Fuse able link at the battery appears to be in good condition. Seems like it should have enough to start but it doesn't...

[barreto]

I was going to pick up an inline fuel pressure gauge to see what the pressure looks like.