2003 PT GT Backfire on 93 tune

[duster360]

Thanks, fortunately for me a long time friend owns a shop. I took it to him at noon today and he just called to say TPS is fine. Wiring is fine. He did find however that the small hard plastic line that reads the Air Intake Pressure had a crack. That is now fixed and would explain low boost.

It does not however, explain the spike and loss of power. He had told he that the normal course of action by the ECM when max boost is exceeded is to open the WG and shut down the injectors until boost is back to acceptable limits. If true in this case, it would explain my comment of loss of power and the WG dump.

So at this point I am not sure where to go next to figure this out?

2.4l Turbos have 2 " intake pressure sensors". The one in the intake manifold is called the MAP(manifold absolute pressure) the other is called the TIP(throttle inlet pressure) MAP is stuck directly into the manifold and the TIP is remotely located and has a small hose that connects to the hose from the IC to the throttle body.

If your buddy fixed the TIP line, then that could be part of your problem because the TIP is used by the PC for Boost control.

I'd retest and post another datalog showing a good 2-3sec of WOT

[4angels]

2.4l Turbos have 2 " intake pressure sensors". The one in the intake manifold is called the MAP(manifold absolute pressure) the other is called the TIP(throttle inlet pressure) MAP is stuck directly into the manifold and the TIP is remotely located and has a small hose that connects to the hose from the IC to the throttle body.

If your buddy fixed the TIP line, then that could be part of your problem because the TIP is used by the PC for Boost control.

I'd retest and post another datalog showing a good 2-3sec of WOT[/quote]

Thanks, think I have it figured out. going to run it for a couple days and see. Took it to the track tonight and put down a 9.77 in the 1/8th. Blew off the little line comming off the top of the TB, so need to secure it but now it is spiking to 21, down to 12-13 and then back up to about 15.

[4angels]

In a couple Hours I am going to take another log with what you suggested, 2-3 seconds of WOT. Over all it is getting better but it seems that when the WG is opening to let pressure down the sound out of the exhaust is still more of a backfire sound though definately not as bad as the earlier sound from the engine.

So once I post I would appreciate you taking a look for me.

Thank you

[cdd]

I had this problem after I adjusted my S2 wastegate spring up from 4 psi to 9 psi. I think you are hearing compressor surge and the spike is causing stuff to shut down. Check to see what your wastegate spring is holding. I had my tune adjusted for the stronger spring so I can hold higher boost in the upper rpms.

[4angels]

I had this problem after I adjusted my S2 wastegate spring up from 4 psi to 9 psi. I think you are hearing compressor surge and the spike is causing stuff to shut down. Check to see what your wastegate spring is holding. I had my tune adjusted for the stronger spring so I can hold higher boost in the upper rpms.

How do I check that? Sorry, I can not post another tune yet. Raining so much that WOT is too dangerous right now.