Okay so for the past few weeks my 00' z28 m6 has been making a strange noise like a crackle at 4.5-5k through each gear until I shift (5,800-6,000 range) at WOT under load only. It doesn't make the noise when stopped in neutral and revved.

Some things ive done so far-
Cleaned my K&N and MAF
Replaced wires and plugs (plugs looked great)
Replaced fuel filter and ran Amsoil fuel treatment.
Been through a few tanks of gas and even though here in colorado we only get 91 octane but it never did this before and I always fill up at the best gas stations.
Checked for any vaccum leaks checked exhaust for anything loose/rattly.
Transmission fluid. I also always change my oil every 3k miles or less always still looks pretty good.
Popped my valve covers everything looks perfect and the oil in the heads looked like it just came fresh from the bottle.
probably more im forgetting.

Its not throwing anything code wise to set of a check engine light either or anything like that. I know ive done alot of searching and alot of people have had this issue, But none of them seem to report back on how it was resolved.

I went in and talked to the dealer, and got an appointment for 9 o'clock tomorrow. They said 120$ if they can diagnose the issue and if not I dont pay. Seems fair enough I guess. Im thinking it could possibly be a knock sensor issue, has anyone else had this?

Thanks.

 

Okay so I went to the dealer this morning and took the tech for a spin. Its pinging, only at high rpm in WOT. They weren't able to successfully diagnose a problem but my fuel trims are lean. So I didn't pay at least that's a plus. After finding this out I picked up a bottle of Lucas octane booster and filled my tank up at shell with 91 (all we have available here) and I decided to do a quick WOT run in 3rd just to see if the pinging was gone. It is, so my problem must just be shitty colorado gas? Should i just get a mail order tune from frost, I read that he increases the fueling at WOT so this should resolve my issue?

Thanks.

 

K and n filters damage your mass air sensor because they are oily. Switch back to a paper

A failing 02 sensor can also cause the problems you are seeing

Your not being very descriptive with your issue, a crackle to me could mean a metallic noise like your exhaust banging on the drive shift slightly under load

 

The sound is a pinging. After running fuel trims im running lean. I checked the fuel pressure and its at a solid 60. Colorado gas blows, I guess its time for a tune.

 

If it just started doing it it doesn't make sense that you suddenly need a tune. Has your fuel filter been changed recently? Have you ever had an induction cleaning?

If you are running lean which means your LTFT's should be +. What were they?

 

3 common causes of spark knock on these cars:

MAF
Fuel pump
Fuel filter

Replace the fuel filter FIRST. Continue with diagnosis if the noise is still present. Monitor the fuel pressure. If fuel pressure drops below 52psi at any time, replace the fuel pump. If the noise is still present, replace the MAF.

The MAF is the most likely culprit, even if it has been cleaned. MAF sensors degrade over time (especially with oiled air filters) and are notorious for reading incorrectly on these cars. Cleaning them is a diagnostic step, NOT a fix.