Help! Trouble starting and high fuel pressure

[blazen71]

Hey guys. Recently I've been having a starting issue since the temp has got into the 90's here. When I start the car cold, the engine revs to 2000rpm then 1200 then 800. That's good. But when the car is up to temp and I go to start it goes to 2000rpm then goes right down to zero. I actually have to feather the gas pedal to keep it running. Once started it runs fine, but then I notice my fuel pressure is 50 to 60 psi. The car runs fine but why is it dying at start-up and why is the fuel pressure high? I cleaned the MAF and that seemed to just barely keep the car running at a warm start-up. Still has high fuel pressure, Any ideas?

[MOTOWN]

sounds like a bad idle air control valve

[mcgyver59]

The tune will raise fuel pressure based on iat temp. You can tune that out by setting all values to 40psi.
Your IAC is definitely not bad.

Tell your tuner the issues.and an.updated file should be easy to make.

[MOTOWN]

The tune will raise fuel pressure based on iat temp. You can tune that out by setting all values to 40psi.
Your IAC is definitely not bad.

Tell your tuner the issues.and an.updated file should be easy to make.

im sorry bud, did we read the same post?? , if the car has a custom tune thats news to me!:shake:

[fastblackmerc]

I think it's the IAC. Try cleaning it or replacing it.

[FordNut]

Not sure, it might be two separate issues. When it's really hot, the fuel pressure goes up. That's in the tune for sure, and it's there for a reason: higher pressure for any liquid raises its boiling point. The higher pressure helps prevent vapor lock. I wouldn't change that.

The startup and dying issue could be the IAC or it could be the tune. There are a couple of parameters that tell the tune how many rpm to add on startup and how long to keep the rpm up. I tried to adjust the time delay on my tune so it wouldn't rev up so long on warm startups and it kept dying like you're describing. I extended that time and the problem went away.

To the other poster, yes it has a custom tune. It has to since it has a ProCharger.

[Blackened300a]

He said it recently has problems, meaning it was fine for a while and then it started acting up so I think if it was a tune issue, he would have this problem all along. The fuel pressure sounds normal, Im leaning towards the IAC or a loose intake tube as well. Try cleaning it and see what happens, also make sure all your connections to the intake are tight. I had a issue like that when my intake tube was loose and the MAF had no idea what to do.

[blazen71]

I've been running with the same tune since 08'. Is it possible the tune needs to be tweaked? I haven't had the starting problem until now. I'm leaning toward a mechanical/sensor problem. I cleaned the IAC this spring,but I'll do it again tonight. I think if there was a open connection in the intercooler piping it wouldn't run at all or throw a CEL. I had a situation where the p/s pulley wore through one of the rubber elbows and I got CEL. I have a draw through MAF set-up. Thanks and please keep the ideas coming. Everything helps and I've been walked through a few situations here.

[Blackened300a]

You could try checking the TPS to see what voltage you have. When my intake tube was off it didnt throw a code, it just had hard startups and ran crappy.

[blazen71]

You could try checking the TPS to see what voltage you have. When my intake tube was off it didnt throw a code, it just had hard startups and ran crappy.

Will do on the TPS! The car runs great, just the warm start-up issue.

[Local Boy]

Just wondering...When was the last time you re-flashed your tune?

Aloha

[RacerX]

Just wondering...When was the last time you re-flashed your tune?

Aloha
For clearing the learned? Easier to pull the negative off? Just wondering! :beer:

[blazen71]

For clearing the learned? Easier to pull the negative off? Just wondering! :beer:

Had the battery out for the winter.

[Local Boy]

No,no,no.no...:P

I ask to see if your tuner had perhaps left the "Adaptive learning function" on in your computer...Some turn them off, some leave it on, when going S/C'ed...

Mine is left on to correct for temp, wearing sensors, etc...In my case, I re-flash my custom tune whenever I feel the car getting a little different, usually I can tell when to re-flash, when the A/F ratio changes from the norm. ...and POOF ...It's like I just drove off the dyno...

Just wondering if yours was the same way...

Good luck...

Aloha...:beer:

[mcgyver59]

You should ask what ect value for hot starts is set at in the tune. That is probably the cause of your woes.

[Blackened300a]

You guys are missing the fact that he's been running the same tune since 2008 with no problems. The tunes don't expire or go bad after 3 years.

[blazen71]

Update. I cleaned the IAC and the MAF. The car starts great when warm. Only one small change, the Temps dropped 30deg overnight here in WI. I'm not sure if the ambient temp plays a role with my starting issues? Brian, thanks for the explanation on fuel pressures at higher temps. Now that it's cooler outside my fuel pressure holds at 40 psi.

[blazen71]

I would have never guessed it, but my starting issue was due to a vacuum leak. And I would have never guessed the source. Turned out to be the bypass valve. I called Procharger and they don't have any rebuild kits left for the old version of the Pro-flow bypass valve. I replaced it with a Vortech mini-race and everything is perfect again. I really like this valve as it is a lot more quiet due to it being a 1.75" discharge instead of a 1.5".