Toby, whats up? Whats the verdit?? What did the jury have to say??

 

Still there! Replaced my fuel pump & filter, cleaned the IAC, changed my TPS.. etc etc. Can't quite afford to swap a FPR or a new MAF right now but there ain't much left for there to be replaced in my car! Brand new plugs, did the stumble before and after my rebuild. Car runs great under WOT, milage ain't the best though. When i had the scanner the car was reading way lean.. and i suspect its doing the same still even after the fuel pump was replaced (although the car now doesnt feel "weak" after 4000 rpm... was definatly fuel pressure related). When I did have the scanner i took down every dang reading I could and compared it to what the "normal" should be... every sensor seemed to check out ok the best i could tell.. from the MAP, IAT, IAC, O2's, etc etc.. .except that my BLMS were going to 160 during the stumble (the way lean condition). And were not doing it anywhere else in the blocks.

I haven't been able to get a fuel pressure guage long enough to reach to my windshield.. i suppose thats next, to see if its the regulatoro or not.
Something's off and i don't know what it is Been way busy with work this month as well so haven't had as much time to try and hammer away at it.

SO my next list here of todo's:
1. Get a reading of the fuel pressure under load while the stumbles happening.
2. Try and get the scanner again to confirm that its still because she's going way lean.
3. Try and find someone with a goood maf to swap in. (THe one time i cleaned the maf she ran like a dream, but only for a day and then seemed to go back to her stumbly old self).
4. Swap in a new IAT... although I had a 1LE intake elbow added to the car and the stumble was there before and after the elbow :/
5. Take it to GM, bend over and find out what the hell it is.

 

I had this problem when comin off the line so my temporary remedy was to rev it to 1500 and the pop clutch and slam gas.. didnt hook up well but Id rather that then the bogging.. I talked to a LT1 Edit guy and he said its the MAF (ported)even with LT1 edit it wont fix it... I saved up and bought a granatelli MAF and everything is fine... I can cruise off the clutch and slam the gas and there is almost no delay.. no hesitation... Also i was having a previous hesitation/bog and it turned out the be the rear end.. 4.10's fixed that, then it pulled all through the power band.. another hesitation came along(maf) and that is fixed now too. you guys might want to check those two things out... WHAT A LONG THREAD!!!

EDIT::: Now that i said i have no hesitation im sure i will when i drive my car again so when it happens ill try to figure it out then ill keep you guys posted on the new hesitations cause...lol

 

has anyone put in a 160* stat and seen if it went away? I dont see this part in anyones sig (for the entire page i looked at )

 

i got this low rpm stumble too.. anyone find the cure... i have newer opti/icm/plugs/wires/ gonna do coil tommorow.. I think my o2's are bad.. I was having a shake at idle.. which now is a stumble... fuel filter is good.. intake manafold is good. i dont have air pump or egr..

 

I just gave up...My car is on sale now, I bought a new car. The 160 stat is in there right now. I also read that it may have to do with the LT1 owners that have headers. Anyone out there have the hesitation thang and stock exhaust manifolds?

I replaced:

New Opti
New plugs & new wires & new coil.
New fuel filter.
New IAT sensor.
New O2 sensors.
New EVAP canister.
New MAP sensor.
Cleaned out the throttle body & IAC valve.

I'm done, the car is on sale.

I heard other suggestions that it may be a faulty/clogged injector...

 

I have had this stumble all summer. I went from a 14.6 basiclly stock at the track in May to a 15.7 in July. I installed LT's true dual w/ x-pipe, new plugs, new wires, new O2's, and removed all the tree hugging equipment and still had the hesitation after. My quarter times went down a little but only to a best of 15.2. I then heard about the IAT sensor and tried that. It seemed to make it a lot better but it slowly got worse again. I also tried the coolant temp sensor (talked to a GM mechanic and he said it effects the fuel managment) but no change.

I finally bought a cable to scan the car and see what the PCM was seeing. I pulled a datamaster log and someone noticed that my IAT was going nuts every time I stepped on the gas. The temps would spike down to -40 degrees and then jump back up. I bypassed the IAT with a resistor to simulate a specific air temp and the car ran like a dream. I figured that the new IAT I got was bad so I went out and bought a AC Delco one (the prior one was a Autozone sensor) and installed it. Well, the car started running kinda crappy so I put the resistor back in and it didnt help at all. The car was still running $hitty. I went home and scanned it again and the new IAT sensor was working properly... no spiking of the air temps and everything else looked perfect.

The only thing strange is teh car is running a little rich but not a whole hell of a lot.

I started looking into a possible spark problem causing a misfire and so far I have checked all the wires at the spark plug end and every one of them have a great spark. The plugs will probably come back out this weekend if I have time after installing the stall converter I have waiting but the stall is my solution to the hesitation at the track. It will get me out of the RPM range of the hesitation. I am also going to see if I can get someone to autotap my car with the OBD2 PCM in the car and see if that sees any missfire conditions.

This has me beat bad... I have been working on it almost every day for the past 2 weeks and I am fixing problems but it isnt helping the main problem.

Yes, this was long but every little bit of help might get someone else to get a solution to this problem we are all having. One day we will figure it out.

 

I have the stock exhaust and almost stock everything else except for whats in the sig. THe problem i've had started before ANY of my mods though, except maybe the K&N....

 

My friend replaced his alternator and battery because the battery was corroted and he got a good deal on the altenator and he was going to deal with the stumble but once he put the stuff in it stopped... he is happy as hell!!

 

faulty PCM?

 

i have the same problem for about a few months now. ive fixed many parts and seems to not be running good....idle is rough ...feels like a rocket ship...but yet still hesitation when im around 2000rpms.....

 

bump. Anyone have any new ideas/solutions??

 

I did the resistor trick to turn off the knock sensor, hoping my problem was retarded timing, but it didn't help Has anyone recently solved this? I'm so unlucky. I used to have the high rpm miss. now thiss.

 

did plugs, 02s, IAT. Still there. Help!

 

i had the same problem in my firebird. it really does suck and i hope you guys figure it out because it really makes you not wanna drive the car