1998 Gt missing only when warm

[Mileshigh]

Like the title says i have a 1998 Gt that has started missing a 3k rpm when accelerating, The car does it in every gear and you can press the gas to the floor and it will still accelerate. if you just cruise around doing about 2-2.5k rpms the car jumps. I have replaced spark plugs with autolite platinum's and new wires, new egr valve, idle air control valve, tps sensor, new coil packs. Im now out of ideas and need some advice.

The missing problem only starts once the engine is warm, if i start it up in the morning after its been sitting all night i can run it up to 8k rpm without missing a lick in any gear, but after its warmed up the problem starts. If i hold the gas a 3K rpms when it starts to miss after a bit it will stop missing a that rpm.....

Car mod's include, pi head swap with bullit intake with twin 62mm throttle body, pro flow mass air, bbk intake with k&n, msd ignition, steeda timing adjuster.

Thanks

 

[DBMSTNG]

i can run it up to 8k rpm without missing a lick in any gear

um, yeah. i wouldn't do that if i were you.


have you tried running higher octane? it may be a load/timing issue with the timing adjuster.

 

[Mileshigh]

yea im not running it up to 8k i just saying it doesnt skip, run higher octane and even seafoamed it, using my timing light i can tell you the timing in stock and has not be adjusted

 

[trinity_gt]

Is this miss string enough to cause a SES light? Does the SES light flash when it's missing? Have you read the codes from the PCM, code which, if present, may tell you which cylinder(s) are missing and thus allowing you to zero in to the problem area instead of throwing blankets at it?

You said "using my timing light i can tell you the timing in stock and has not be adjusted" but you say in your list of mods that the car has a Steeda timing adjuster. It may not be necessarily that the timing is advanced too much (or whatever) but the presence of the timing adjuster hardware itself: Is the crank bolt properly tightened? Is the bracket holding the sensor tight so the sensor isn't loose and vibrating at certain engine RPM?

 

[Mileshigh]

No codes or flashing of the check engine light, the steeda adjuster is present but it looks like it was just put on by the previous owner ie i didnt install it... I have check the (3) allen bolts that hold the timing adjuster on and they are tight..i have not checked the actual sensor, though i did consider that the sender was maybe going bad...the car has 93k miles on it...i have read that the O2 sensors can cause grief but wouldnt this throw a code??? i have also cleaned the mass air flow.