Hey guys I don't post much on here at all but I've encountered my first problem with my balt and figured I could use some expertise. Starting yesterday my lsj has been sputtering when I get in the 4k and up rpm range. Its like it cuts out then goes back to normal and just repeats till I let off the throttle. Best way to describe it its like the car just falls on its face. Its boosting normal according to the gauge until the car cuts out. Idk if its fuel related like a clogged injector bc under 4k rpm it runs normal. Mods are gm stage 2, injen intake and s3 h/e and otherwise stock. Mods were done over a yr ago so this issue just happened out of the blue. Post up what u guys think, thx

 

Clogged Cat maybe

no CEL?

 

No CEL. But I was thinkin possibly the cat too cus even if they go bad doesn't mean it will throw a code.

*Edit* It does have the factory dp and cat with 70k on it.

 

I remember that being a common problem, if there is a way to test it you might still be under the emissions warranty.

 

Ya after some research it looks like it may be covered under the emissions act (8yr/80K mile warranty) if thats indeed the problem. I'll have to drive over an hr away to get an E-check, then if I fail I will have to call the dealer and see if it can be covered.

 

Yep clogged cat

 

U think? I've did some more research and what the main things I came up with was plugs, fuel filter, knock sensor and the cat. Fuel filter isn't that old, plugs seem fine, could be knock sensor causing timing issues I guess and cat seems most likely. Also, after toying around a bit rolling on the throttle it doesn't have an issue, only at WOT at 4k+ rpms.

 

My car sputters at 2k-2500k in 3rd gear at consistent throttle like crazy. It's like a bucking horse. But once i get past 2500k roms its fine. Is that what yours feels like?

 

op's problem is a plug in the exhaust somewhere. Easy way to check. next time you hit it if it boosts to like 20+ psi its clogged.

 

True, OP are you building more boost than normal?

Can you check to see if the car is pulling timing?

If not the cat is most likely the culprit.

Quick fix is to either replace the downpipe or just gut the cat.

 

Yes this exactly!

Good to know I will check next time I'm out driving.

As far as timing no, I wish I had an interceptor right now to check the knock. Anyways, what would be considered a normal knock measurement? I may just replace with a zzp downpipe worst case. I'll definitely check for over boost later.

Thanks for the input guys!