ls1 knock codes and no power over 5k rpm
 

So ive got an ls1 from an 04 gto plus a t56 trans. I got on it the other day and noticed it feels like i hit a brick wall at 5k rpm. The thing is though, it only happens under load (ie, when i have traction). If i try it with tires spinning, i can get it past 5k no problem, but soon as i catch traction it goes right back to 5k rpm and cant really accelerate past this. I pulled out the code scanner and came up with both knock sensors throwing codes. I can delete the codes, turn the car off and back on and the codes show right back up without even rev'ing the engine. I havent tried replacing the sensors or looking at the wiring harness yet, but will soon. Also, the car runs super rich (dont know exact afr, but its noticeably rich). Engine has an ls6 intake and supposedly ported 241 heads + torquer v2 cam. Any guesses if the the knock sensor codes and the 5k rpm problem related or separate?

Usually, when the codes for both knock sensors set at the same time the problem is with the wiring harness which the sensors share. See attached. There are some tests that can be run with a digial multi-meter. Another common problem is the accumulation of water benath the intake manifold where the knock sensors are located.

Are the knock sensors and harness the same for the 98-02 Ls1 and the 2004 gto ls1?

Well a lil update...I was trying to get some new door lock clips on and was pissed the unversal package didnt come with the right sizes. So i decided to start the car up and re-scan. All I got this time around was a P0135 - bank 1 O2. No knock sensor codes.

Sounds like your fuel pump is going out. My car had the exact same symptoms when mine went out.

But it never has any problems starting or going to 5k rpm. Plus my fuel pump is set to continuously prime itself as long as the key is in the on position (engine not running). Plus im assuming its decently new as a stock rx7 pump prolly cant supply enough fuel to a LS1. I have an adjustable FPR on it, it stays pretty steady at 60ish psi at idle and slight revving. Normal?

Possibly fuel filter? I had HUGE power loss on my Jeep before (through all rpm ranges though), code came up for #6 coil pack. Replaced it, didn't fix it. Replaced all coils and the fuel filter and ran like a champ. But since I replaced filter and all coil packs at same time, im not sure what the real culprit was.

So another update...ive found it only feels like i run into a brick wall in 2nd gear. I can only go about 3/4 throttle in 1st to avoid spinning, but no problems. No problems in 3rd gear, went to about 5600-5800 just fine before i shut it down. I currently only have a P0327 code.

put a fuel pressure gauge on your fuel rail and see what the pressure is throughout all RPM's before you get stuck on the road. Just a suggestion.

I thought i mentioned that, sorry, but its at 60psi.

So I think Ive got it figured out. Went to go get a tune. Turns out that whoever tried to tune it before half assed it because it was half speed density and half MAF tune. As if they gave up halfway through tuning. Oh well, its running right now. Made 375rwhp. I highly doubt the heads are ported, so not too bad for what my tuner thinks is a 228 cam and ls6 intake.