Hello, I having a definite problem with my turbocharger.

I have an APS TT on a 2004 350Z. I have been running 10.5lbs of boost(no cats) now for ~ 30,000 miles. Anyway when I get into high boost, around 9psi, the boost kicks back to vacuum and the engine rpm will not accelrate past 2500rpm unitl i shut the car off for a few minutes. The rpm will hit around 2500rpm (while the boost gauge is reading between vac and boost) and just flutter, almost sounds like overrevving.

Im thinking a possbile bad turbo or a leak in the vacuum lines or boost lines.

Anyone have any experience with this problem or kno of any possbilties?

Jeff

 

we are in orlando and can figure out everything if you bring the car up to us...


thanks

 

could be a leak or could be your boost cut but i would take it somewhere to get it looked at.

 

are you getting a check engine light? sounds like safe mode.

 

Are you still running off of MAF? My car used to do that occasionally when it was on MAF and the Unichip. Once in a blue moon the car will go "limp" and won't rev, and if you try to accelerate the car will JERK badly. On EVOs they have this problem when they try to vent to atmospheric on the BOV but run a MAF sensor, I'm not sure about Z's . .

 

+1 ECU in safe mode for some reason.

JET

 

i have SES but that is P0442 leak in the EVAP control system. It isnt safe mode because the car runs normally until I hit high boost pressure, and will run normally, i.e. rev past 2500rpm, until i gun it and hit around 9psi.

 

Yeah... then it goes ito safe mode likely due to detonation.

JET

 

I had it checked out at my local shop. The MAF was good as well as the throttle body and the TPS. They pressure tested the lines and thre were no leaks.

There was some water in the intercooler piping and some oil on one of the air intakes.

The shop owner thought it could be from building to much boost to fast (i.e. it was previously at 9psi but when i installed the test pipes it now boosts 10.5psi- been that way for 20,000 miles) or that the spark plugs maybe to fouled and cause some kind of problem.

He also called a few dealers and other shops that install the kit and none of them had heard of the problem like this where the MAF wasn't bad.

 

how do you get rid of the maf on a z? through the utec??

 

Haltech pnp standalone will allow you to remove the factory MAF. Since it controls fuel/ignition/cam timing 100% you can tune based on the on-board MAP sensor and it can also be setup to feed an acceptable calculated MAF signal back into the stock ECU to keep it happy.

Most UTECs are setup to run off the factory computer up until boost, so you would need the MAF.

 

I replaced my PCV valve wihtt a new one and changed my spark plugs and the problem went away. Wish I would have done it one at a time and then test it.

So either it was a problem with either one of those or the problem just randonly fixed itself.


Also, does anyone knows the proper pin combination on the APS boost controller to get the boost down to 9 psi after installing test pipes?

 

your UTEC is cutting your boost. It sees detonation / knock and it throws your car in safe mode. If you try to boost past 9psi you'll hit this safety feature untill you retune for more boost.

I had the same problem after i modified my exhaust.

 

Aren't spark plugs supposed to be changed every 10k miles on FI applications as a rule of thumb?

I know I do

 

i would say 5000 miles...

 

+1 to that. Better safe than sorry

 

edit: problem already fixed

 

5000 miles plug change? I check mine every ~10,000 miles and they're great everytime. Why change?

 

cheap insurance?

 

I'd say so. You can tell a lot by the state of your plugs. Especially if you don't monitor your setup constantly.

I don't know if there is a need to check all 6, but pulling out 1 from each bank might be a wise idea. Or if you have time, do all 6.