Bucking at 4k rpms
 

00 Lightning, belongs to my brother, just the middle man here.

6# lower pulleys, had the chip flashed by some shop in georgia, cat back exh, not a whole lot of mods. We just put in ngk plugs and a fuel filter. At about 4k it bucks and won't rev anymore it does sound like it is pinging, pcm retards timing. I don't won't to pull the plugs back out, but that is the last thing i did. We have 91 octane in Kansas, he had 93 in Georgia. Don't know if the colder plugs and the crap gas, or that the plugs haven't been changed untill 90k miles. It may have a bad tune. I rewally just need help or even a guess at this point.

I really don't want to do plugs again....thx

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93 or 94 would be great :(, see if some nearby stations carry race fuel. Near Wichita in Schulte they have 110 unleaded at the pump a gallon or two of that should help rule out detonation (if not some torco would work)Also check the plug gap, 0.034 to 0.036 is what most Lightnings with a #4 or #6 pulley run. Also you may want to check out nloc.net there are a ton of lightning owners over there that should be able to help you trouble shoot more. I have just started to mod so i have yet to experience any difficulties like your facing (knock on wood). Be careful if it is detonating these trucks do not have a working knock sensor so if its detonating you'll have to listen for it. Good luck.

is this happening while driving or in the driveway reving the throttle?

if the vehicle is not under a load such as driveway reving you are hitting the rev limiter.

spark plug gap it right. does it when driving.

Sounds like a call to that Georgia shop with questions about their reflash of the PCM is in order.

thx for the help guys, just didn't know if anybody had any ideas or had run into this before. thx again

I think that program is f--ed up. you should have gotten your own tuner and did it yourself. I isnt hard to do.I have the same set up but a 4 pound pulley.I have the K&N filter charge kit, and glass packs. I used the superchips tuner and the 4hp tune in it. I have had no problems at all. I run 13.5s in the 1/4 mile at 102mph. with 92 octane. I wouldnt run your truck that much like that or you will break something.

I isn't being driven until i figure out what is going on. I starting to think it is the tune. I will talk to my brother and see if he wants the predator, it sounds like the one most people have. I will be checking this post from time to time.