Help! ZL1 high rpm stutter / hesation
 

Like the title says, my ZL1 has a bad hesitation in the upper rpms almost always in 3rd and 4th gear. It has happened a couple times at the top of 2nd, but normally I can pull through the top of 1st and 2nd without any stutters. The stutter / hesitation almost feels like the car is hitting a fuel cut, like all power stops then the rpms climb again, then it hesitates, then begins climbing again. Very annoying and this happened a few times when the car was stock also, I just didn't notice it much because I was waiting for some mods before I got on it.

Mods: roto-fab CAI and JBA HFC mids stock tune

The sutter / hesitation was there well before the JBA mids, but i certainly noticed it there right after the Roto-fab install.

Sounds like a tune or fuel delivery issue. Anyway to get a data log of a run?

+ 1

unfortunately I don't have any data logging tools or software .. I didn't think the ZL1s stock tune would be experiencing any hiccups with just a CAI..

Check to make sure that you don't have any air leaks from the air filter to the throttle body.

Dumb question, but have you gone back through and checked all the connections for the RotoFab and ensure the mass air sensor is correct and tight?

All else fails, pull the RF off and see if the problem is still there with the stock air box. Narrow you problem down....

The only issue I could think of is the 90 degree plastic coupling that installs on the intake elbow would not thread in correctly when I was installing it. So I just kept turning it until it felt snug.. There is no doubt that the threads on the plastic coupling were stripped, so I guess at the upper RPM range there might be a tiny bit of air coming in through there? This is the plastic piece that allows you to connect the vacuum fitting.

I have contacted rotofab and they are sending me a new 90 degree plastic fitting.

the stock tune should deal with the rotofab just fine. the JBA mids????? hard to say. one member killed the cats in one track day so I am not sure that is the best product on the market.

try to see if you know anybody who has some datalogging tools. it should tell the story.


If it did it stock I would return to stock and make GM work the issue out or bite the bullet and buy a tune and a tuner and get it ironed out.

honeslty a pulley upgrade and a tune will be the best thing you ever did to your car if you like power.

Ted at jannetty racing strait up advised me no to run the JBA catted midpipe. He said go catless or better yet get some longtubes. I though maybe he was being over cautions until stephen burned his up in one track day. then I said to myself.......self maybe ted knows what he is talking about ha ha.

LOL! One of those "doh" moments with the JBA mid pipes...they were a total waste. They would make a nice set of off road pipes if I cleaned out all of the cat media that is broken internally. Double check to make sure all of your connections both electrical and air intake related are snug and correct. Take it off and reinstall everything there if you aren't sure to double check. Check out the rpm limiter to make sure you aren't bumping into the 6K-6.2K rev limit. Sounds like the same sound when the PTM engages which happens in PTM 1,2,&3 especially. Any check engine lights?

No CEL I'm going to swap out the RF CAI for the stocker real quick and make a run. As for the jba mids they sounds great! If or when they fail I will gut them and make them straight pipes.

sound great...I agree...can't take the heat and abuse however. Street driving will be fine and you can always gut them if they fail.

If it was happening before when the car was stock, I leads me to believe that it has nothing to do with anything you modified. Infact if you had a defect stock part, replacing should have fixed the problem, so again I would look to something that has not been changed out.

Check out this Topic it sounds like the same issue and he resolved it...

http://www.camaro5.com/forums/images/icons/icon5.gif New problem, any ideas of cause?
Hi,

I have a new issue and I'm hoping someone has an idea what's causing it before I take it into the dealer again.

If I'm in 3rd or 4th gear, doing highway speeds and I accelerate hard, the power cuts out and the speedometer drops. There aren't any codes or any lights, just the power cuts and speedo needle drops down.
Power is restored almost immediately. I at first thought it was TCS, but even if I turn the traction control off, the issue still happens.

Anybody heard of anything like that or anything I should check?

Thanks for the help!

Well I did a few things, I put the stock air intake back on and I filled up with shell and fuse pull.. No more hesitation.. Pulls beautifully through the top of third and fourth.