Thread: Running weird at full throttle

I just got my car back from the shop and now it is acting weird at WOT. Under normal driving it drives and feels awesome. Background: 2 weeks ago my car had a bad misfire. Turns out it was injector 6 that went bad. Took it to the shop this past friday and they put a new injector in( I know because I bought the injector myself) and as they test drove it the fuel pump resistor went out. So that got replaced as well. I was driving it for 2 weeks babying the crap out of it because its my only car. When im at full throttle it acts as if its starving, like surges of power and then no power. I dont have a scan gauge or wideband, im saving up for them though. So I cant tell you any numbers or anything like that. Basically my question is, is there something I can do to fix it? Like can I unplug the PCM or does it need to re learn on its own or what? I have a w body store tuned PCM. And before the injector went out the car ran absolutely perfect. No issues at all. What could be causing the car to do this? Im looking for help from you guys before you tell me to take it back to the shop lol

What plugs and fuel are you running?

I only run sunoco 93 and i have NGK TR6 plugs

Clogged fuel filter?

Is the injector you got out of a gtp? The na motor has different fuel injectors.

I work at a GM dealer. I got the part brand new from GM. Its the correct injector. As far as I know anyway lol. The fuel filter looks semi new, I only bought the car in October. Now thats not saying it is new. That might be something to check. I just dont understand how it ran awesome before the injector failed and now it stumbles like that. I was right there watching our parts guy order the injector

Originally Posted by thatguy

I work at a GM dealer.

Not to be rude. But You work at a GM Dealer, Awesome. Now You have all the tools at your disposal. Check Fuel Pressure. Hook Up Tech II. See whats out of whack. A Stumble/Sputter at WOT Usualy shows a Low Fuel Pressure scenario. Check Fuel pressure at idle and at WOT. Make sure that the fuel pump speed control relay is switching from LOW to HI

PS, Forum Search is Searchtastic!

http://www.grandprixforums.net/help-...wot-12123.html

I work in the body shop. So these tools are not things I have. I would still have to pay for them to diagnose the problem. Otherwise I would have hooked it up to a comouter. Which is why I asked if there is something I can do to fix it for free. I just wanted to have a step in the right direction. I searched a little bit but not for too long as I am doing all this on my iPod.

You never stated if you had a CEL. or SES Light. If so Run it to orilleys and have them run it. On theyre innova scanner, Have them go to Advanced>GM> ADVANCED> Pending Conditions Cant remember the exact lay out but. We have one of the 3-400$ Innova Scanners at my shop, Guess thats the loyalties of working for a (Not My) Family owned Body shop/Car lot.

No check engine light has come on. I've been researching and the fuel pump resistor and high speed relay are connected. So tomorrow I am going to further research this at work. I will update when I figure something out. Thank you guys for pointing me in the right direction

Update: I replaced the high speed fuel pump relay, I only got it for a couple bucks. That did not fix the problem. Yes I know im gonna get crap because I replaced something that didnt need to be replaced. I dont know what else to do, I guess im just going to have to get it hooked up to a computer. I dont have an orilleys anywhere near here. And all the autozones and crap only have the cheap computers. However I now have a history code, it made the SES light flash for like 10 seconds and then it turned off. I know that means multi cyl missfire. Though i got on the gas a little during this time to hear if it was missfiring and it was not. Before I got my injector replaced when the light was flashing it ran so bad. But this time it ran normal.