Weird cooling issue

Recently I was having a problem with my 2008 speed3, it has 150k miles on it and the wastegate was not working properly. I ended up replacing the turbo recently and the wastegate problem was fixed but a new problem arose. The car runs fine, I just made a 7 hour road trip with no problems at all, the coolant temp was stable between 190-200 *F and the oil temp was below half the entire drive, but after I parked the car and left it for a couple of hours and tried to start it back up the car acted like it was overheating. Would turn over then immediately cut back off, no idle and no throttle response. Remapping the tune from the stock tune to another tune then back to the stock tune seems to fix the problem until I turn the car off again for a long period of time.

 

Any codes? Whats the coolant temp reading when it's doing that? How's your oil level?

 

coolant temp when i start it back up is in the 150-160 range and it's not throwing any codes. Theres a possibilty that there is too much oil

 

"tried to start it back up the car acted like it was overheating" <- Can you better define that statement?

"Would turn over then immediately cut back off, no idle and no throttle response" <- That doesnt sound like its getting hot enough to act like its over heating.

"Remapping the tune from the stock tune to another tune then back to the stock tune seems to fix the problem until I turn the car off again for a long period of time." <- this makes it sounds like its an ECU learning issue.

I'm remembering an issue with fuel pressure dipping once engine reaches operating temp. Anyone else remember specifics?

 

The car starts, idles for about half a second and the engine spurts out, i originally thought that it could have been a maf sensor issue. Is there any way I can test to see if the ECU is going bad?

 

You've tried unplugging the MAF and starting it?

 

Just unplugged the MAF and it ran fine for a couple mins so i dont think that is the issue.

 

The car starts, idles for about half a second and the engine spurts out, <- So its idling for more than a half second when you unplug the MAF?

 

Its hard to explain, its a very weird circumstance where the car wont idle properly. The car was idling properly today both before i took the MAF off and after. It only struggles after the car has been driven a decent amount and then is turned off for 30+ minutes. Thats the only instance i've seen where the car does not want to work. And in those situations I just switch the tune and then its fine.

 

What @jsmith is getting at is by uplugging the MAF sensor you are forcing the car into open loop. This method works great when you have an issue with a shit ton of unmetered air getting passed your MAF sensor or have some sort of sensor issue. Have you checked all hoses, and made sure you do not have any major leaks?

You do not have to keep reflashing, just do a simple battery pull (pull negative cable, depress brake pedal for a few seconds) to reset your tune.

Please list mods.

How are you LTFT and STFT during your long trips? When the car is hot and not wanting to run with KOEO (Key on Engine off) what does you MAF, MAP, and hpfp display.



Sent from my iPhone using Tapatalk Pro

 

I'll have to check my LTFT and STFT on my drive home at the end of the week as its 7 hours back. The only mods I have are a replacement OEM turbo and a COBB turbo back exhaust. I'm beginning to think it could be the fuel pump as I have not upgraded it yet and many places recommend or require an upgraded fuel pump after upgrading the exhaust.

 

ZZB! Yup get those internals in there asap for that exhaust edit: jokes aside as Easter Bunny has said below me this isn't causing the issue.

 

Lack of upgraded fuel pump internals is not causing your problem

 

Check your grounds. Specifically the one at the fuel pump area/.