Okay, so I haven't done any mods or anything new to my car in almost a year and I have been driving it almost daily since I bought it a few years ago. Car is an 06 M6 z51.

All of the sudden the last couple weeks the car has started acting very strange. I think it might be heat related (100+ temps almost everyday here in Texas). But, I am not sure.

When I start the car it surges a little bit and shakes like crazy at idle, almost as if it has a huge cam, but it is stock heads cam, only a bolt on car. When I pull up to make a stop and I throw it into neutral when I'm off the gas and clutch doing nothing but lightly apply breaks or not even touching the breaks at all, the RPMS jump up to like 2.2k and like stick there almost and it just continues to stay like that, if I throw it back in say 1st and move the clutch out a little bit the RPMS will drop back down.

The engine bay itself seems to be a little bit different of a sound too, like almost as if there is a whistling sound, not sure if that is related... Almost, I have noticed a LOT more and LOUDER popping on decel in 3rd and 4th gear, like it used to pop every once in awhile, but now its almost every single time I let off the gas it pops so much louder and its so much more noticable, I'm not sure if that is related as well.

What could be causing this? Is it just the heat? I also noticed it seems to do the RPM problem more frequently when the A/C is on.

Also, in an unrelated problem... are there motors in the trunk arms? Because my trunk is basically dead weight now, it will close like normal but when I open it... You have to hold it up or else it just falls right down and closes, it will no longer support itself and stay up on its own... How do I fix this?

BTW - My warranty was just up in June.

Please let me know what you guys think, thanks so much!

 

I would only be guessing here, but it almost sounds like a vacuum leak.

 

Vacuum leak will cause the problems you list with idle speed.

The rear hatch is supposed to be held up by the strut rods, if they've failed there is nothing to support the weight.

 

The rear hatch struts are pretty cheap. You might only have one that has gone bad, but if you are replacing them might as well do both. I agree with the vacuum diagnosis.

 

Hmm, what could have caused the vacuum leak? And how would I go about fixing that?

 

A backfire would cause a leak, has it done it??
have you worked on it at all??

 

Do you happen to have a Vararam CAI with a throttle body spacer?

 

A hose could have ruptured or a fitting came loose. The first thing is to locate and identify the source of the problem. If you're hearing a whistling sound see if you can pinpoint where it's coming from. Good luck.

 

Yes this sounds exactly like a vacuum leak. You will likely get getting a check engine light with p0174 also soon.

The throttle body spacer was my first thought as well.

Do you have a FAST?

 

Yes, I do have a FAST! And thats where the sound seems to be coming from, somewhere around the FAST or at least thats what it sounds like to me.

I do have a Vararam, but I did not use the throttlebody spacer.

I don't think my car has ever back fired? I am hearing a lot more poping from the exhaust on decel, would that be related to a leak as well?

 

Yes the popping means lean and that's what says vacuum leak to me.

Here's your problem I'm pretty sure.

http://forums.corvetteforum.com/c6-t...ue-update.html

 

Since it's had mods, do you know if someone has done a tune?

 

Try checking all 4 bolts around the throttle body. Even without the spacer they still came loose on me.

 

Your good!

 

Yes, I would definitely check for the simple things like hoses and vacuum leaks.

In the old days, we used to spray carb cleaner around various manifold seams and vacuum hoses to pin-point vacuum leaks. The engine speed would change when we found it.

I have used an ordinary 2 ft rubber hose to pin point sources of unusual noises under the hood. Like a doctors stethoscope. Hold the hose to one ear and point the other end at suspected source of noises. You should find the source pretty quickly.

You have to be careful when tightening the throttle body bolts. It can distort the plastic manifold and cause a leak. I would take it easy with the wrench. If you have a modded FAST with the patch on the rear by the fire wall, you may want to look close for the patch separating.

The reason I mentioned the tune is if the IAT temp table vs. ignition advance was modified and there is too much advance as the temp goes up, the engine will act up. I changed mine to reduce the advance pulled out at high temps and ended up putting it back in the factory table where it runs much better in the 100+ degree days.

 

Thanks for the info guys!

I am having a friend with hp tuners take a look at it hopefully tonight... and I messaged spinmonster as well, since he did the spinfast for me. I'll make sure to report what it turns out to be.