Kingpin08

I'm looking for some real knowledgeable help with an issue on my 418 LS3 swapped 99 FRC.

I have a newly installed 418 LS3 swapped into a 99 FRC vette track car that originally had an 350 LS1 with a 78mm throttle. The engine was professionally built by a very reputable builder and usually runs fine. However, at WOT at high rpm's the car will completely shut the pcm down and go into limp mode, sputtering and missing until the car is shut off. It then fires right back up as normal and runs great until you repeat the high rpm WOT. It seems to need to have WOT and about 5200rpm both to occur. NO FAULTS ARE SET

We have had 2 different throttles, 3 different pcms, and cals ranging from the current tune back to stock and nothing helps. I have one of South Texas's best tuners working on this, as well as the engine builder, and we are all stumped.

If anyone has any input or incite I would appreciate it.

Thanks,

Mike

NicD

iTrader: (7)

Could be tons of different things, until you post up the current tune all you will get is lots of guesses.

Kingpin08

Can't get to the car or my laptop right now, it's at the shop.

Any general suggestions or ideas?

2xLS1

iTrader: (25)

Are you using a LS3 throttle body? There are problems using an LS3 throttle body with LS1 PCMs. But they usually set a P1516 code. Go to HP Tuners forum and search on P1516.

Unaffliated Racing

iTrader: (15)

I'm going to say either the LS3 tb or the MAF is hitting the fail point. At that shut off point see how many hertz it's reading. May need to be patched under the OS tab of hpt

edcmat-l1

iTrader: (10)

If one of south Texas' "best" tuners is working on it, maybe you should travel to north Texas. It's an easy fix.

Vengeance Racing

MAF is my guess

TraMotorsports

iTrader: (1)

Can we get an explaination on this guess?