ok so at 3800 and around 5000 rpms in every gear ,everytime my 420a starts goin crazy i have tried looking around other sites and saw that its a common problem but no one has a solution for it not even my reg mechanic could figure it out specs on motor ;cold air intake , full exuast and rest unknown but should be stock ,, i have changed the coil pack checked plugs scanned cel codes changed cpsany ideas or has anyone even heard of this problem ... please help i want to start spending money on customizations for this car already !!

More explanation is needed. What exactly is the car doing? Is it something that happens all the time or every now and then?

well it happens all the time and sometimes even at a lower rpm but i can bank on 3800 rpms basically it just falls on its face and actually looks like it stalls the cel light goes off and all but it happens really fast

Is the car bucking? Making noises? Feels like its running on 2 cylinders? Sorry for all the questions its hard to give advice with not a lot of info.

Yes, the car is bucking at 3800 to 4000 rmp. Then it's smooth to around 5000 then it does it again. No abnormal sounds other than the popcorn popping sound from the bucking. Imagine it as a gremlin plugging and unplugging the ECU a few times fast.

Idk if it would be the same as my 4g63, but my car would do the same thing get to a certain rpm and just spit and sputter real bad then smooth out, i checked everything, my plugs even looked good, but i changed them just incase, and apparently it was my plugs, havent had a problem since

@SpoolMonster I think I will try that in the morning.

Even if it doesnt fix the problem atleast u have new plugs and can rule that out of the equation, also check ur plug wires, make sure they are in good condition, and check all ur grounds. a ground for the most retarded thing can cause the dumbest issues.

Thank you both very much for your suggestions, I will let you know how it goes tomorrow.

Yes, plugs are always a good thing to replace when having issues like this. If it doesnt fix your issue, at least you know theu are new and they are only a few bucks.

A friend of mine had similar issues with his 420a i believe. Between installing the aftermarket exhaust and intake, he would have a check engine light. Another culprate could be a bad o2 sensor, dirty air filter, clogged fuel filter, etc.

Does your check engine light stay on? I would take it to a parts store and have them read the check engine light codes for ya. Hell, do it when you go get your new plugs.

420a's are notorious for fudging coil packs. Check your with a multi meter. If its happening at wot, it won't be o2 sensor related. Check your cas, plugs and wires, and coil pack. If you change spark plugs DO NOT get anything other than NGK.

+2 on NGK.

Topic moved to problem diagnosis.

thank you for moving me to the correct area ... well new plugs (ngk) gapped @.44 no change so then i tried a different set of wires... no change . i tried different driving styles ... no change. so to this point i still am having the chattering problem and it is driving me nuts any other ideas /??

Check your cam angle sensor, crank angle sensor, and coil pack with a multimeter.