Over Boost to 20psi

[dgc333]

I have an 03 PT Cruiser GT with the inter cooled 2.4l turbo motor. I installed a Diablosport tune in it about a year ago.

The car has run fine up until today when I get on it it will over boost to 20psi and I get the ignition cut out. The car sat most of last week at the airport while I traveled for work and I never got on it on the way home. It then sat for the past 4 days while I was away with the wife. I drove it around for a while to see if it just need to be driven a bit but soon as the rpm pass 4000 at WOT the boost will spike right to 20. The diablo tune allows 15 psi. For Yuma I reinstalled the stock tune and the boost is controlled nicely at 10-12 psi. I looked over all the vacuum lines particularly the one from the waste gate to the control solenoid and didn't see any signs of leaks or cracks.

Anyone have words of wisdom or hints of what to look at? For the time being I am going to leave the stock tune in place.

An

[roachjuice]

Reflash it and see what it does.

[dgc333]

Well I reflashed it back to the Diablo tune and everything seems to be fine.

Anyone got any idea why all of a sudden it would start over boosting?

[turbovanman²]

Shitt happens, best excuse ever.

[bakes]

Well I reflashed it back to the Diablo tune and everything seems to be fine.

Anyone got any idea why all of a sudden it would start over boosting?

waste gate got stuck??

[dgc333]

Stuck waste gate was what I first thought but it was consistently over boosting and as soon as I reflashed back to stock it controlled smoothly.

I will watch it closely.

[roachjuice]

Maybe something happened with the tune. Shyt happens lol.

[dgc333]

Still running fine so I guess I will blame it on the turbo gremlins.

First warm day of the spring so I have the 'Cuda out.

[roachjuice]

Yea I wouldn't worry about it. The car just lost it's way for a min lol. Just carry the programmer around with you just incase it does it again you can just reflash it.

[Keito]

Temperature change?
Remember, the PCM's are trying to meet a target HP/TQ.
If it's warmer, the air is less dense, the PCM will try to compensate with more boost.
I have the DSP tune on my SRT-4, but I don't drive it from Nov-May so I don't see temp changes affecting boost.
This was one of the first thing people who bought SRT-4's were complaining about during the winter of 2003.
They were saying "my car is only boosting 10 psi", well thats because it was 20 degrees F.
Not saying that's the issue here, obviously the reflash worked, but it can be a factor.

[dgc333]

Thanks, didn't realize that the PCM would vary the boost based on temperature.

[dgc333]

Well after a week the boost has started to spike to 20 psi again. What I had thought was over boost protection is still there but now the miss fire happens sometimes at 15 psi.

I posted on Diablo's forum and got a response from their tech support that it sounded like lack of fuel at the higher boost.

I am going to check the fuel pressure and it's been quite awhile since I changed the plugs.

Also, another post was talking about identifying injectors I know the the MP Stage 1 for the 03's came with injectors and that the 04+ came stock with an injector that flowed about 10% more. I will look into swapping for the 04 injectors if I don't find anything else.

[dgc333]

Well guess what? It was the plugs, new set of Champions and it is running great. Strange in that when the plugs acted up in the past I would get the occasional skip at idle and cruising. First time they only miss fired at high boost.