on my way back home tonight(5hr trip), from a start in first gear the car would stutter, backfire out of the intake then take off normally. When coming to a stop the car idles very roughly at 500 rpms. If you know how the 4g63 idles when the throttle position screw is loose, thats how my car would idle. The car would idle then drop a few hundred rpms then come right back up and do the same over and over. I really thought my clutch was to blame for my problems but after this and no CEL's im back to the beggining. Maybe tps, iac, map? What does this sound like to you?

no one?

well going back to carb type motors, not totally different mind you. A backfire out the intake usually meant a lean condition. How is your O2? Timing could do this, have you worked on timing belt recently, leak in intake manifold could do it, lot of possabilies really.

Eliminate the poss of leaks, you can make a boost leak detector or spray carb cleaner around the gasket surphaces of the intake and around vac lines. if the idle changes when you spray a spot then there is a problem. Obviously do not sprak surfaces like the exhaust manifold.

If you have access to a datlogger or scanner see what your o2 sits at when idling, it should fluctuate from lean to rich fairly rapidly. If you can check it when the car has been sitting all night see what the value is, I think i have some baseline spec of what a cold o2 should be in my papers collected over the years or i can bounce it off what my car is with a new o2 sensor, wont be the same but it should be close.

If you have done a timing belt you might want to check the timing marks to make sure its not off a tooth.

Next you want to make sure your IAC port is clean and the IAC is moving, a datalogger should read the IAC values as the motor moves, if not a scanner will.

check your fuel pressure and when was the last time you did a fuel filter?

Terry
96 Eagle talon ESI
Star Stage II - Boost/oil/EGT gauges

97 Eclipse
Greddy header - Apexi N1 3" exhaust - SFMU/return line - Apexi SAFC - Stage 2 6 puck Sprung hub MIBA clutch - Shortened shifter - Koni Yellows w/eibach prokit - Stillen Fr/Rr swaybars - ceramic intake - DEI Keyless entry alarm - Niche 17" Shoks

Waiting to be installed: HKS EVC IV, 450 Turbo injectors, GSX Front brakes (need rotors)

Mitchell on Demand copies available

i recently checked all gasket areas with carb spray, and i didnt have any leaks. I havent changed my fuel filter in quite a while, i guess i should go ahead and do it soon. My o2 sensor checked out the last time i ohmed it, seemed to be within specifications when cold and warm. I have a spare iac that im going to swap out today if i can, and im also changing my plug wires again, my stockers ohmed out prette wierd last night. Thanks for the detailed response.

Also, i havent messed with the timing for at least four months, i can rule that out as a possibility.

deff do the fuel filter.....i have seen that a lot in the past. may just be most of your prob!

Terry

96 Eagle talon ESI
Star Stage II - Boost/oil/EGT gauges

97 Eclipse
Greddy header - Apexi N1 3" exhaust - SFMU/return line - Apexi SAFC - Stage 2 6 puck Sprung hub MIBA clutch - Shortened shifter - Koni Yellows w/eibach prokit - Stillen Fr/Rr swaybars - ceramic intake - DEI Keyless entry alarm - Niche 17" Shoks

Waiting to be installed: HKS EVC IV, 450 Turbo injectors, GSX Front brakes (need rotors)

Mitchell on Demand copies available

i changed out my plug wires today and the stutter is gone. My idle still bogs when i push the clutch in while driving. My iac is coming out very soon, and i'll go ahead and get the fuel filter changed when i do that as well.

take your catalytic convertor off and see what it does. mine did the same and thats what the problem was. it was clogged to hell

my cat has been gutted for months and months

that takes that out of the picture! lol. hmm...dono then.. sorry