alright i got a question for you guys

MuscleInc1320 · Oct 7, 2009

alright im kinda confused on this one. my car is running great at WOT, i mean like it has never run better. this whole situation seem to start after i had a shop put on some header gaskets for me. (lol cuz i was to lazy to do it) but the thing that gets me is that while im crusing at any speed, in any gear my car surges as if i am tapping the throttle. i usually notice this when the car is around 2000 rpm. the idle isnt bad either like every now and then it surges but mostly when i first start the car after it has been sitting for a couple days. a random note is that ever sense i got my hci setup the car seems to have a harder time starting. for example i have prime the fuel pump by cycling the car on and off a couple times to start the car after it for a few hours. i am suspecting that it might be the tps, iacv, or fuel pump. the only reason that i am leaning away from the fuel pump is that when i step on the gas the car doesnt stubble at all. oh and yes i did get the car tuned after the hci setup and my mechanic says that the car might just need some fine tuning after i have been driving it awhile and everything settled in?

MuscleInc1320 · Oct 7, 2009

another thing i suspect it to be might be o2 sensors. another note is that while the car is bucking the rpm stay the same like i mean tach doesnt flutter or anything

2002BLGT · Oct 7, 2009

Im going to take a guess and say you installed larger injectors and a the C&L mass air meter you have listed in your sig ?

MuscleInc1320 · Oct 7, 2009

stock injectors and the maf has been calibrated for them.

Win · Oct 7, 2009

MuscleInc1320 said:
alright im kinda confused on this one. my car is running great at WOT, i mean like it has never run better. this whole situation seem to start after i had a shop put on some header gaskets for me. (lol cuz i was to lazy to do it) but the thing that gets me is that while im crusing at any speed, in any gear my car surges as if i am tapping the throttle. i usually notice this when the car is around 2000 rpm. the idle isnt bad either like every now and then it surges but mostly when i first start the car after it has been sitting for a couple days. a random note is that ever sense i got my hci setup the car seems to have a harder time starting. for example i have prime the fuel pump by cycling the car on and off a couple times to start the car after it for a few hours. i am suspecting that it might be the tps, iacv, or fuel pump. the only reason that i am leaning away from the fuel pump is that when i step on the gas the car doesnt stubble at all. oh and yes i did get the car tuned after the hci setup and my mechanic says that the car might just need some fine tuning after i have been driving it awhile and everything settled in?

I would grab a Fuel Pressure Gauge and check what you have at idle then without vacumn and also when you turn it off to see if your FPR is bad. If those check out good i would Look into replacing the Fuel Filter. Still doing it possible Fuel Pump. You can check the voltage on the TPS also. Have you always run a filter in your Air Box?? Did you change it regularly?? If you ran without the Filter you might have gotten junk all over the MAF and it needs to be cleaned or replaced. You can also check your voltage at your coil also. It could be the Stator.

First things first though i would change the Fuel Filter and do a Fuel Pressure test and go from there.

MuscleInc1320 · Oct 7, 2009

tps voltage is .84 and 4.66 with throttle open. cleaned the maf and i run cold air intake with a brand new k&n filter. i am thinging tho that if it was fuel then the problem would always be there even more so at wot. the fpr should be good...it's a bbk one that is only about 3 years old. just check fuel pressure and it is a constant 39-40. i sprayed carb cleaner all around the intake and vac lines while the car was running to see if i had a leak. didnt find any. but i notice that the car idle is fluctuating and that even in neutral if i give it a little gas and hold it that it still makes that shuttering bucking sound. plus my check engine light is off so i know it has nothing to do with the evap system...or at least i hope

Win · Oct 7, 2009

I had a similar problem that at the most random times my car would run like crap. It ended up being a Bad Fuel Pump.

toyman · Oct 7, 2009

You mentioned that the car was tuned after the HCI install. I assume this means a chip was installed. Is that correct? I had a similar issue and it turned out to be the ECU ground. If a chip was installed and the ECU removed that means the the ground was likely disconnected. Pull the passenger kick panel and confirm that the ground to the chassis is solid.

MuscleInc1320 · Oct 8, 2009

yea i had a chip put in. i will check tomorrow about that ground. i seem to have horrible gas mileage too right now.

LAFENATU · Oct 8, 2009

So this an on going issue or since the header gasket replacement?

MuscleInc1320 · Oct 9, 2009

sense the header replacement. tomorrow i am gonna work on it a little more and have my mechanic look at it. i am leaning towards a vacuum leak of some type because today my brake pedal was hard to press as if the booster wasnt working. i will let you guys know tomorrow.