Walkabout

Pretty much the subject says it all. I need a little bit of help diagnosing this (as well as can be done from a brief description on the net).

Basically, under WOT, towards the top end of the RPM spectrum before a shift, say in the 5000 range, I start hearing a faint, but very distinct, crackling sound. It seems to be coming from the below, and towards the front of the car. Basically around the back of the engine, or front of the transmission, which is an A4.

I'm worried it could be the tranny. I recently had a fluid change on the transmission (about 6 or 7 months ago) by a local former Pontiac dealership. But they've since proven how bad their service is, and I won't ever go back there. That said, they did the service before I made that decision, and I'm worried this is going to be yet another unpleasant surprise I have coming from them.

So, any ideas on that sort of sound? I know that's sort of a vague description, but some idea as to where I might start looking, would certainly help. Thanks all.

zracer323

iTrader: (12)

Do you feel an difference in acceleration when it does this? How many miles are on the car? Also, how often has the tranny fluid been changed?

Walkabout

I have not, as yet, felt or noticed any difference in acceleration. It remains smooth and strong from before the sound, to when the sounds start, through the shift, and to the point I let off the gas. The car now has 88,000 miles on it, and that was the second full transmission fluid change the car has undergone (I've owned it since it was brand new. I know, I'm sort of in the wrong forum, given that fact, doh!)

Intimidator02SS

Possibly spark knock from low octane fuel?

VaderZ

iTrader: (3)

Is your car tuned? Could be the timing that is off.

Jon@Texas-Speed

iTrader: (18)

Could the detonation. Be sure to put premium fuel in and see if it goes away. I wouldn't keep beating on it if you think it might be detonation. Could result in a broken ring or piston which could mean a new engine...

Jon

Walkabout

That's something I've been considering too; gas quality. I've always put the highest octane I could in it; in this case it's 91, good old California. But with the way gas has been lately, just nuts, I've honestly wondered about the quality of the stuff. Mostly that's just paranoia I suppose, but you never know.

That said, I'm going to try putting in a bottle of octane booster, and see if it helps any. I certainly wouldn't have anything to lose. I'll see how the car handles that and get back to you all here.

Should I order up a good set up new plugs maybe? Like the octane booster, I wouldn't think it would hurt anything, and might just help. Detonation is a bad thing, for sure .

I've been babying it though, as an FYI, just because I'd rather not facilitate any breakage if I can avoid it. Thanks for the advice all, like I said, I'll get back to you in a couple days.

silverz28ls1

i had that same problem and after beating on it for a couple weeks i spun a rod

Walkabout

Hey all, an update with good news. So, for the moment (I'll continue to keep a close ear out of course), the issue appears to have been lousy California gas. I've always put premium in it, which is of course the 91 octane around here, bleh. I guess it was just a lousy batch or something, I donno.

After coming across this thread regarding octane boosters, and how different brands and types compared to each other, http://sportscarforums.com/f13/tolue...oice-3257.html I went ahead and picked up some of the amsoil.

This stuff if anyone is interested: http://www.amsoil.com/catalog.aspx?GroupID=82

Everything is quiet and smooth at the moment. No crackling, no noise, no detonation that I'm otherwise aware of now. I'm going to get things checked out anyways, as I'm planning some upcoming work on the car.

Anyways, there you have it. Looks like crappy Cali gas may have bit my poor car. Just in case anyone is interested, if I learn anything further that's related, I'll post it up. Thanks for all of the advice :-)