Random lean and barely running bad ptu?

[614talon90]

The other day I fired my car up and let it run for a few. I then hopped into it and drove up to the gas station to fill up. On my way back as I was slowing down for a light it almost became totally undrivable. It was misfiring terribly and seemed like it was running on only two cylinders and was also running super lean. I managed to get it off to the side of the road and it died. After letting it sit for a few I fired it back up and it ran as if nothing had ever happened. On my way home right before pulling into my drive it started again. I shut the car down and let it sit for a few. Then I fired it up again and it was running fine but would intermittently start stumbling and then stop and run fine. After letting it sit for about a week I fired it up and no problems and fired it up many times since then and let it run for around an hour no problems. Everything in the ignition system is new except for the ptu. Could this piece possibly be going bad?

 

[luv2rallye]

Very possible. Test here and use hairdryer heat to bring it out: http://www.dsmtuners.com/forums/articles-electrical-wiring/229419-how-test-power-transistors.html

 

[614talon90]

Thanks for the great suggestion I did not even think of trying this. I went ahead and gave it a shot and heated the crap outta the ptu and it seems to be functioning perfectly. Any other ideas what may have happened to make my car act the way it did? I still haven't had another issue with it and I've taken it out a few times with no malfunctions. I just know sooner or later whatever it was will probably happen again and I'd like to track this down before I get stranded.

 

[luv2rallye]

You might check all the intake hose clamps for being tight (from air filter all the way to throttle body). When one gets loose it runs like crap and lean. A boost leak test would uncover other air leaks. Or perhaps an injector is being intermittent. Any error codes? Does it only happen when car is moving? When it happens can you floor it to kick in the turbo (to overwhelm air leaks) or won't it even let you get to that rpm? Any other clues or conditions?

 

[614talon90]

Well I took it out today and ran it. At first it was perfect went WOT a few times no issues. Then the last time I got into boost right around 7k is started breaking up so I got out of it and then it was fine. Then I turned onto the next road and got up to speed and then it randomly pegged rich like 10.0. Got it to the driveway and let it sit there and run. I did notice that my base fuel pressure was reading a few psi lower than what I had set it for. I did a boost leak test and nothing. No cels. This time it got stuck rich instead of lean.... I'm beginning to think maybe the fuel pressure regulator is sticking one way and then the other? I have no idea. It's an aeromotive fpr with a some years of use on it.

 

[614talon90]

Face palm.. It's ALWAYS something with a dsm...

 

[614talon90]

Well I think I may have found the problem. Took apart the regulator and the diaphragm spring was broken into two pieces. Guess I'll try to get a new spring or maybe another regulator and see what happens.