WOT problem

[MC-97-GSX]

Problem is, when i hit full throttle, around 4-5k rpm and boost is full i get a nasty sputter, its kinda feels like fuel-cut... Thing is, it just started doing this on and off about 2 weeks ago, so i replaced spark plugs & wires, and the o2's look fine... I had a boost leak test done, few minor leaks fixed, intake mani. gasket is fine, turbo is fine... I was thinking maybe safc was assing too much correction for the cold weather? AMS didnt think so, they say its a tuning issue... I do however have a bad exhaust leak due to throwing cat back on for emmissions in november... Do any of you think maybe the o2's getting bad readings could do this? I want to try more things b4 i spend the money on tuning, ams said they wernt positive about tuning, but i need the power restored because i need to sell the car soon for money for school... Just let me know what you guys think, i need some opinions or maybe past experience with similar problems...

Thanks - Matt

 

[dirtypunx1]

Im having the same problem. At around 4500 to 5000 rpm's right when boost is at its max it will sputter and even backfire a little. This has only started recently, Recently the only thing i have done is messed with the TPS. What happend was my TPS became unplugged and unscrewed itself and is sitting on the road somewhere. So for a temporary solution i took a bolt and screwed it in where i could keep the throttle open so it wouldnt die on me. The only problem i had was, idle surge at start up but once it was at operating temp. it was smooth idle at around 1700. and another problem was at a quick stop it would almost die and sometimes would, but that was it. But now i have put in a new TPS. Plugged it in re-timed the motor, so it would idle smooth. Because once i plugged it back in i had an idle surge. And now it idle's fine but at high boost and WOT it will sputter and backfire. I was thinking maybe my injectors?? any help??

 

[94Jettameowpsst]

My car does the exact same thing around 5k rpm, in every gear and its auto. Idk about any of you, but i have Maf-t 2.02 so i believe thats my problem, cause it didnt do it w/ the stock maf.

 

[GTM]

Problem is, when i hit full throttle, around 4-5k rpm and boost is full i get a nasty sputter, its kinda feels like fuel-cut... Thing is, it just started doing this on and off about 2 weeks ago, so i replaced spark plugs & wires, and the o2's look fine...
...
, but i need the power restored because i need to sell the car soon for money for school... Just let me know what you guys think, i need some opinions or maybe past experience with similar problems...

Have you checked your fuel pressure? What plugs did you use and gap? What adjustments have you made or attempted to make? Yes, not exactly the car to have around campus for you will sped more time keeping the car running than doing homework.

As for the other 2 posters indicating they have the same problem, it's difficult enough trying to deal with 1 person's problem and keeping score. Since I'm not convinced your problems are similar other than the description it might be better if you started your own thread where you can give more details. Unless that 1700 was a typo that's a good place to start besides the biss screw.

Cheers,
GTM

 

[TurbochargedJt]

I've been having a simialar problem with my 98spyder gs-t. Whenever I get the boost past 11-13psi my boost gauge will start to flick by down to 9-10psi and then jumps back up to 11-13psi, and back down. (this happens real fast). At the same time the boost gauge is doing this there is a sputtering/jerking/ or knocking feeling from under the hood, very similar to how a car reacts when you hit the speed govenenor and it cuts the fuel off. I have to let off the throttle or the car won't even get power to the wheels because the turbo is to busy starting and slowing because of the incosistent boost levels.

It feels like I"m giving my turbo to much boost and it can't handle it, or the stock injectors aren't supplying enough fuel for the amount of boost the turbo is producing at that moment.
That's my best guess It feel like the injectors aren't supplying enough fuel or the fuel pump isn't doing it's job.

However, by turning my turboxs boost controller down low, I can hold 10psi fine if I regulate how much throttle I'm giving my car. But I shouldn't have to do this I should be able to drive my cars turbo to it's full potential. If anyone finds a solution to this problem please post it, because I will be forced to trade my car in if I can't get the full use of the engine.

 

[GTM]

...
If anyone finds a solution to this problem please post it, because I will be forced to trade my car in if I can't get the full use of the engine.

Now now now don't get hysterical said in the spirit of good fun.

Have you ever heard you BOV (blow off valve) release? On some cars it can be just a pffft sound like passing gas and for other cars it can scare you out of your witts for it soundsl like a 12 gage shotgun going off under the hood. If your mufflers are loud you might not hear the pressure release. Frequently it will be a series of put put puts which then will cause the engine to nose dive, the turbo slows down and then the turbo has to build back up. Whereas if you sneak upon it it will hold steady. Problem is you run out of road room or you are endanger of attracting Leo.

Even a dirty fuel filter can produce similar results as engine demand is met until the pedal goes to the metal. The additional fuel demand washes some of the sediments collected on the bottom of the filter up into some of the remaining few holes and you have fuel starvation also much like fue cut.

Off the top I can't tell you if these will throw codes but should be checked.

Cheers,
GTM

 

[TurbochargedJt]

I can definitely hear the BOV release. I have the turbo XS H-34, and I can hear it discharge even though I'm reccurculating becuase I have an Injen intake filter.