I just bought a new evo, fully built motor etc. But am having a very strange issue at cold starts. The car tries to start and stumbles, it won't start and keep running unless I keep it at 2k rpm or so for 20 seconds. Logged it and saw that during this time it starts out with ZERO oil pressure and just slowly builds, so slowly that after 30 seconds when it will idle by itself it only has 6psi or so. I let it warm up for a few minutes and it reads 25-35 psi at idle. After that all oil pressure readings seem normal, and if I hot start the car it starts fine and I get instant oil pressure. I thought maybe there was an issue with the oil drainback valve in the filter but I did an oil change and replaced it with a new filter that I am sure has a drainback valve and the same thing keeps happening.

Has anyone heard of an issue like this? I am not super familiar with the oil path on the 4g63 but is there a seal or something somewhere that could be causing this drainback and slow pressure build issue? Thanks

 

The stumbling while starting could be a lot of things. A poor cold start tune, a bad IAC, a bad MAP sensor, incorrectly set BISS, or a bad coolant temp sensor are what come to mind.

As for the oil pressure thing, I don't know. It seems like you maybe have an issue with the pickup tube leaking and when warm it grows enough to seal? Considering you get good warm pressure, I don't think its an oil pump issue? Hopefully someone with a better idea of what's going on can chime in on that part for you.

 

pickup seal is a good idea, I’ll check that out, thanks!