gtp engine miss

[petethetoolman]

hi everybody

i have a 97 grandprix gtp i've been having a problem lately ,when i push hard on the throttle the car miss , so i decide to replace ignition wires ,sparkplug (ac delco iridium)good thing is that a have a lot of spare parts for that engine so i replace ignition coil,ignition module ,pcm,injector,fuel pressure regulator, egr valve,and still the same so i decide the replace the fuel filter, the filter was almost plug ,put in the newin filter and still the same ,so after reading some post on this forum i realise that the fuel pump as two speed , and at the same time i also realise that the car miss when the supercharger kick in , so i replace the fuel pump relay but still the same i did try the fuel pump resistor bypass and the car is still the same ,the thing is the car run great when you drive normaly and start good ,and thinking maybe a electrical problem???
hope somebody can help me

thank you Pierre

[richtazz]

Welcome to AF.

You're probably in need of a fuel pump. The resistor bypass wouldn't affect hard acceleration, it is only used in low speed mode. I would get a fuel pressure guage and check fuel pressure before just arbitrarily replacing the pump, but with everything else you've already done, it's what I believe is your issue. Also, if you do find it's a fuel pump, there is an early and late model pump for your year, so make sure you get the correct unit.

[tblake]

Have you had it scanned for DTC's. Let us know what DTC's come up. Does the SES light flash when the missfire occurs?

[l67cooled]

Did you replace all 3 coils? If your fuel pressure checks out, check the voltage going to the coils. See if any two have a lower output than the others. The ignitions is very prone to cause a miss.

[grandprixgtx00]

Originally Posted by petethetoolman

i also realise that the car miss when the supercharger kick in

in addition to what has been suggested above, are there any mods on your GTP? If so, have you scanned for KR?

[petethetoolman]

hi guys
no my car doesnt have any modification ,i scan and there is no code ,i did not have a chance yet to do a pressure test ,like i said it miss a soon a see the light come on in the boost meter ,i release the gaz and it run good ,it look like the fuel pump since now then a know that there a high speed when the supercharger kick in ,i should be able to do a pressure test next week ,so i'll know ,if the pump is ok ,then the only thing a could think is the crank sensor , the reason is my rpm stop working a couple time in the last year (maybe 3 or 4 time ) if i'm not mistaking the rpm take the signal from the crank sensor but that i'm not sure
one other thing when the car miss there is no check engine light so i dont think that is a misfire . i let you know