Warm Start Problem: Crank & No Start, Always Starts Second Try

[wolffbimmer]

Howdy folks, I have another thread going on M3forum but looking for any help in this one as well. It seems many are experiencing this and cannot get a fix. I've replaced the fuel pump with a lower mileage unit, new fuel pressure regulator, new fuel filter, lower mileage injectors swapped in, new spark plugs, cleaned the ICV, ruled out the intake air temp sensor (I have the relocation kit and unplugged it so it was using the one in the MAF and problem still occurred)

Issue: In warmer weather after the car has been driven has sat for 6-8 hours (work day) sometimes it will crank and crank and crank but no start, the second attempt it always fires up with no issues/misfires. One time I let it crank for a good 30 seconds and then it started after the second try and stunk of fuel. Other times it lets out one chug like it attempts but doesn't. Not sure If I can rule out fuel now or rule out spark, or if this is air related. I tested the relay by putting a test light into the fuel pump connector and I was indeed getting power during a no start situation.

Tests: I had a fuel pressure gauge on and it was consistently leaking down a fair amount (it was a piece of junk harbor freight gauge I can't trust though because it was reading 50 psi when I first installed it and eventually was reading 25 psi after a couple days of using it while running. I'm going to get a better gauge on it to test again but this is why I changed all that I did in the fuel system)

I have zero codes, no driving issues, it runs good and strong. Sometimes it will do a slight idle bounce for 10-15 seconds and smooth out after it's been started/stopped shortly when it's hot out. Say a restart after 30 minutes or so. This lead me to the ICV but I cleaned it and still experiencing that. Not sure if I should replace it next to see if that fixes the bounce but not sure if that would create a no start situation unless it's stuck open/closed and a restart of the car fixes it. The only other ambient related items I have thought about but haven't replaced is the engine coolant temp sensor under the manifold (the one that adjusts fuel trims) it's a cheap 11 dollar part on FCP euro)

I would appreciate any help!

[dworthy]

Just to ensure I understand correctly, if the car sits overnight, it will start right away?

[wolffbimmer]

That is correct. Someone said in the morning when the car is cold it primes stronger but not sure.

[dworthy]

Okay, so I would get a proper pressure gauge, as is sounds like a weak pump to me.

Also, do you have the ability to watch live data?

[wolffbimmer]

I can't watch live data unfortunately. I am going to look around for a better gauge to get a good read on this pressure and what it's exactly doing. It's just odd the morning never poses a non start it's always after several hours of when it's been driven (work/visiting GF). Today I actually broke down going into work, the replacement pump died completely lol. Luckily my Dad was nearby and we pushed it out the way and I threw my original pump back in and got it home. Makes me think it's not the pump as the car did this non start with both of them. Does anyone know if an EWS issue could cause a crank of the starter but cut fuel/ignition and not start. I was under the impression if EWS is immobilizing it cuts everything.

[dworthy]

The EWS cuts the starter out on the E-46's. On the E-36's it would just cut the fuel out, so no the EWS isn't the issue here IMO.

The reason for asking about live data, is you would be able to see what is going on when this happens, and at least have an idea of where to start. Since there is no codes, I don't think it is electronic, but something mechanical here.

[wolffbimmer]

Gotcha looking around online and watching videos people seemed to have mixed ideas about what the EWS would cut or not. I wish a code or something would pop up. I'll find a better gauge and report back what pressure and leak down I'm getting, I just feel like even if pressure leaked down after cranking and cranking the pump would get the fuel pressure back up and start eventually. Some folks said to try the engine coolant temp sensor under the manifold as it may be over fueling if its thinking its cold and flooding it but I feel like I'd always have problem starts when it was warm out, a simple restart wouldn't change the sensors reading I'd think.

[dworthy]

I have replaced mine, only because it kept popping a code for that, but never had an issue with hot/warm restarting.

If the motor was flooding out, it can be from weak plugs, those have a 60k replacement mileage.

[wolffbimmer]

Was it a check engine light that showed up on the dash? I don't have the specialized INPA or whatever software the computer hook up would use, just a simple obd2 code reader. I'm curious if any codes would show up on the BMW software but are not creating check engine lights on the dash. I will have proper fuel pressure test numbers today after I get an adapter properly working, it's too long causing the schrader to not be fully depressed so I've never got a good reading.

[wolffbimmer]

I finally got the pressure gauge to work, the adapter just doesn't fit on properly that comes with the kits so I just took the damn schrader out completely and hose clamped onto the threads of the port. I was getting between 60-70 psi while idling (it flutters between) shut off it read 66 psi and only dropped to 63 psi after 30 minutes. This certainly passes the test for what the manual says but I'm curious in certain conditions (hot) it leaks quicker.. not sure. I'll leave the gauge on and monitor what happens overnight.

It dropped down to 46 psi after 3 hours and 20 psi after another 3 hours. Started right up no issue though at 20 psi. It will be tough to ever get a good read on what pressure is doing when I have a no start condition because it only happens after I drive for a little while and it gets warmed up then shut off for extended periods. I can’t drive around with the gauge underneath.

[TerraPhantm]

The EWS cuts the starter out on the E-46's. On the E-36's it would just cut the fuel out, so no the EWS isn't the issue here IMO.

Not quite. It depends on where the failure is. If the EWS doesn't recognize the key, then yeah, the starter isn't engaged. If the DME doesn't recognize the start code from the DME, then the engine starts and then fuel is cut off immediately (on the M3 anyway - on non-Ms, fuel and spark are cut before you even get a start, so it's just a crank no start situation).

[wolffbimmer]

Are you 100% sure of this. I’ve heard it both ways. If it is happening what the hell is at fault? The DME, the EWS module. It literally only does this during the warm months. Would a bmw scanner pick up this error if it is happening?

[TerraPhantm]

Are you 100% sure of this. I’ve heard it both ways. If it is happening what the hell is at fault? The DME, the EWS module. It literally only does this during the warm months. Would a bmw scanner pick up this error if it is happening?

I’m 100% certain on the EWS failure modes. I don’t think your car has an EWS problem problem.

If I had to take a guess, I’d say crankshaft position sensor is intermittently failing.

[wolffbimmer]

The car has a brand new crankshaft pos sensor, along with intake cam pos sensor, haven't done the exhaust one.

[dworthy]

Thank-you Mirza for clearing that up!

What brand of sensor did you use? This is very important that you don't use a generic here, for the tolerances are very tight.

[wolffbimmer]

I swore I had done genuine BMW but I just looked and I got it from FCP Euro, it was their OEM brand and not the BMW one. Not quite sure how I missed that (but reading now their OEM part listings are identical manufacture, not aftermarket) but the problem existed before changing this sensor out. It was only really done because I had the manifold off changing the starter and it was a while I'm in there replacement kind of deal. Forgot to mention I bought a new fuel pump I'm awaiting to come in, I don't feel like sticking with my original if a lower mileage one crapped out, so maybe that will fix my warm start issue.

(you had me worried so I emailed FCP about the part and they verified the OEM one I bought is in fact the exact same as the Genuine one they offer)

[dworthy]

FCP is a good company to work with, as they tend to only sell OE/OEM stuff. What I was worried about is you went to NAPA and got one of theirs. The only sensor I trust to work are made by Bosch, Seimens, and VDO. I have see too many "Made in China" stuff fail straight out of the box.

Just make sure you put a new fuel filter in there with the new pump.

[wolffbimmer]

Filter was replaced a couple weeks ago when I put in the lower mileage replacement pump that crapped out on me. Hoping for good results with the new pump! Will report back if it still occurs or not after I've driven it a few days.

[wolffbimmer]

New pump installed. So far so good, it started right up after sitting when leaving my GF's which is almost always did the crank and no start. Will monitor over the next week and report back if it does it again or not.

[dworthy]

Good to hear!