high rpm miss

[1quickpt]

replaced my spark plugs yesterday. The ones I pulled out were gapped at .44, so I installed the new ones at .44 and took it out for a drive. Terrible high rpm miss. I then regapped the at .40 and it helped but still an ocasional miss. Any thoughts?

[bigdogdad]

Oh boy, qsd is going to get you on this one[]

[quicksilverdon]

Hey, don't wanna disappoint...
Did you change the wires? Bet that'll do it. The stock wires are crap.
Place an order for Crane wires w/RaceAndStreet.Com, and you'll have them in a couple of days. Probably will be the last wires you'll need.
I see you have a GT - many feel the best gap for a GT is .028
You'll need wires at some point anyway - the Crane's are only 25 ohms/ft.

[Mean Green]

Probably the crappy OEM wires. I thought the .028 was for the Irridium plugs. Factory plugs I'd keep at .040 and get new wires. I had the high rpm miss and gapped at .040 and the miss disappeared and that's why I think it is wires.

[quicksilverdon]

quote:Originally posted by Mean Green

Probably the crappy OEM wires. I thought the .028 was for the Irridium plugs. Factory plugs I'd keep at .040 and get new wires. I had the high rpm miss and gapped at .040 and the miss disappeared and that's why I think it is wires.

Yeah, I'm not sold on the gap - I think with crappy stock wires and their resistance, the lower gap makes it easier for what's left to spark. I gap mine 0.040 - I was just reporting what others have said.

[1quickpt]

I just replaced my wires with 8.5mm msd's about 15k ago.

[littleblueGT]

I am using the NGK iridiums (LZTR6AIX-13,#2315) gapped at .045 with the Bosch premium plug wires that have a life time warrenty. So far the combination works very well. The Bosch wires cost the same as the crappy stock plug wires. You may find that going too small on the gap will reduce performance and fuel economy. Look for all around performance,normal low speed as well as high speed. There appears to be a narrow band in the plug gap with my PT, .045 to .047. I have never seen a car that was so sensitive to plug gap. I experimented starting from .052 to .032 in .002 increments,checking normal driving response and full throttle performance.

[Easymover]

I had a problem with high rpm miss. Dealer replaced wires and plugs under warranty (19000) miles. Runs like new again.

[dfunkdj]

You may want to check your pcm there was a recall on earlly 03 turbos for missing at high rpms and it was a pcm problem i got mine done then 2 weeks later put on stage1..

Don

[DTs_PTGT]

quote:Originally posted by dfunkdj

You may want to check your pcm there was a recall on earlly 03 turbos for missing at high rpms and it was a pcm problem i got mine done then 2 weeks later put on stage1..

Don

If the miss happens at 5200 RPM you could fall under a TSB that was released in mid 2003. I had to argue a bit with my dealer but they finally replaced my car's brain (PCM?) under the TSB and the miss has been gone since 2003. Do a search in the forums here as I know I posted on it when I was getting my dealer to admit to the problem.