Hello everybody. Been around here for quite some time but never had a problem that I couldn't find the answer to by searching, this one I'm having trouble with.
I have a 95 Z m6 with 90k on the clock and only a CAI and catback (I'm poor... ) Just recently it has started making a knock/tick only when cold and only when under load. At idle or when revved in neutral the noise either isn't there or is inaudible. Almost sounds like an electrical arc but I've been all over it in the dark and cannot see one anywhere, also I'm not sure if an arc would be audible over the exhaust. Anyway, soon after this tick started I began having a slight stumble off a complete stop and it is quickly getting worse. As it is right now if I give it more than 1/3 throttle when below 2k RPMs it stutters and vibrates badly. Almost exactly after I pass the 2k mark it smooths out and runs perfect as far as I can tell, though I haven't really dogged on it since I don't know what my problem is and I don't want to hurt anything (worse). I though maybe the knock sensor retarding timing but it stumbles after its warm and the tick is no longer audible, I wouldn't think the KS is THAT sensitive. Should I try bypassing the KS and see if I still have the problem?
I'm taking it Friday to a guy my father knows that has one of those super expensive diagnostic tools to have it checked out. I wanted to check with the LT-1 gurus for any ideas what it might be first.

Thanks for any advice!
-James

 

Check your spark plug wires. I would say 80% of the time that's the problem. But so many things can cause hesitation...

 

Oops sorry. Meant to mention that plugs and wires were changed less than 1k miles ago and I've triple checked them. No burns or nicks and they're all tight. Pretty sure my problem isn't there.

Edit:I realize that its not easy to diagnose a problem without having a look at the car first hand. Just looking for some ideas before I take it to get looked at.

 

More than anything I'm curious what could cause this tick only when cold and only under load. Most things I could think of seemed like they would do it when parked too. Pretty sure whatever that is its the root of my problem.

 

if you didnt have the problem 1000 miles ago when you changed plug wires, they could still be an option. maybe one got kinked.... if i were you i would check them one more time, and plugs.

does it seem to be running rich? (exhaust backfires, gas smell, loss of power?)

 

I had a similar thing happening. I discovered that the the farthest rear bolt on my exhaust manifold, somehow vibrated loose and fell out. When I started the car cold, I would get a rickety tickety under even the slightest acceloration.
Once the engine warmed up even a little bit, it would go away.
Might not be you answer, but give those manifold bolts a good torquing.
Won't hurt

 

change coil wire that fix my low rpm miss.

 

Same question with over 100 replies and 3,800 page views:

http://web.camaross.com/forums/showt...light=trounced

It was my Opti Spark.

Have the car scanned before changing anything, even a $5 part. For proof that this is the best policy, I refer everyone back to my eight-page thread linked above.

 

It turned out to be my EGR valve I think. It finally gave me a code (32) so I pulled it off and it was completely full of crap. Ordered the part so I'll find out tomorrow if that's it. I hope its not unrelated..

 

I will give a look at that since I think my stumble and tick weren't related to each other. Thanks!

I'll update tomorrow and let ya'll know if the new EGR valve fixes it. It makes sense to me because detonation would cause a hell of a vibration right? I never really replicated the stutter much because I didn't know what was wrong so it may not have been only below 2k. I know at approx. 1/3 throttle the stutter would clear up as I passed 2k but at more throttle it may have done it still. Oh well no sense speculating anymore right now, I'll find for sure first thing tomorrow morning.

Thanks for the replies everyone.

 

i had some plug wires running right next to each other, and with time they started arching across to one another. It took me a little while to get her straightened out, but i was looking at it in complete darkness and i could see some faint blue jumping between the two wires...


trav

 

My car is doing the exact same thing and just started a couple of weeks age but if you mash the pedal under 2k rpm it vibrates and hesitates extreamly bad but as soon as you hit 2k rpms it takes off. I have noticed the knock/tick when cold for a couple of months but it goes away when warmed up. If you figure anything out please let me know. Thanks.

 

I'll keep you updated with what I find bro. Went to pick up the EGR valve this morning and it won't be in 'till tomorrow. Another day without my car.

 

If any of you have gotten the SES light, get your car scanned. That should be the first thing you do.

 

I went past Advanced Auto yesterday and had them scan my car and it came up with a code 36.