to-fst-4u

iTrader: (35)

Ok. I have a bit of a problem. Say for instance I take my car out of the garage, drive it somewhere and park in a parking lot for 10 minutes or so and come back out to go back home. After the car is warm and is turned off, then back on to drive somewhere else, its like the car has a miss or studder around 2400-3500 rpm then after it goes through its episode once, it quits and runs great. It only develops this studder after it is warm and has been turned off and back on and it only does it once. When it does it, it feels like the car is going to die, and then if you give it a little more gas it comes right back. Anybody know whats goin on and how I would go about fixin it?

Thanks.

Zach

to-fst-4u

iTrader: (35)

Oh and also it dosent throw any codes or anything. I have just recently replaced the fuel pump and injectors along with my new heads and cam and had it retuned after. It was doing this before my heads/cam swap and i thought it was the fuel pump but that wasnt my problem.

SSpdDmon

iTrader: (10)

You really need to capture the issue on a scanner or data logger. Then, post the log. It's a rather unique issue and we could guess all day and never tell you the right answer...if it's even in the tune.

to-fst-4u

iTrader: (35)

i have and its like when it does this, the O2 sensors go crazy and they are brand new, but like I said it only does it this after u cut it off when its warm.

SSpdDmon

iTrader: (10)

Ok...O2's go crazy. What does that mean? Do they peg high or low mV's? Or do they just start switching all of the sudden? If they just start switching all of the sudden and given the timing, it sounds like the car has a rough transition from a warm open loop, possibly rich AFR to closed loop operation locked in at 14.63:1. If that's the case, the VE table could be tuned incorrectly or the HPT proportional fueling setting may be off (assuming HPT was used).

to-fst-4u

iTrader: (35)

before all of this started, i was getting a code for insufficient switches but it no longer shows up when i scan it. it is like the mV's start switching all of the sudden.

SSpdDmon

iTrader: (10)

When they start switching all of the sudden, that's the closed loop timer kicking in where the car transitions from open loop to closed loop.

to-fst-4u

iTrader: (35)

ok. thanks for your help. but i dont know much about tuning so is this a problem that can be tuned out or what?

SSpdDmon

iTrader: (10)

Ideally, if the car was tuned right, you should not have any problems transitioning between open and closed loop.