cepowers18

Now from the sounds of it, it would appear that it would be a pinging or detonation problem, but I'm not exactly convinced it's either one of those.

So what's happening is that on occasion (it doesn't happen all the time), somewhere in the 4000-5000 rpm, I hear a noise coming from the engine bay that sounds almost like a light scraping of metal-on-metal. Zeke (Grn N Gry 5.OH) has ridden in the car with me when it happens, and he seems to think that it's not detonation b/c it doesn't happen all the time and b/c the car would spurt/stutter/hesitate if it was detonating. And it's definitely not a ping.

I'm only running 12* timing on 93 octane. Is it even possible that too high of an octane is bad or could be causing this? I have to be running a high enough octane to account for the timing - I mean, it's not like I'm running 14* or higher.

Any help is MUCH appreciated

88BlueGT

Im not exactally sure but you do not need to run that high of octane... I know that for a fact lol.

Did you try retarding your timing anyway down to maybe 10 and see if it doesnt... it might not be it but it wouldnt hurt to try. Do that and drop down to 89.

cepowers18

I may try retarding the timing like that (and running lower octane). Regardless of whether or not retarding the timing works, does anyone have any ideas as to why my car may be doing this when I advance the timing?

I'm seriously lost on this. This has been happening for awhile, but I never thought it was a huge problem b/c like I said, it doesn't happen all the time.

cepowers18

Anyone else? I'm struggling here

cepowers18

Ok, so apparently nobody knows?? [:-]

7upedition

have you checked your base timing in regards to your total timing?

7upedition

the computer will add upto 16* of timing depending on conditions (coolant temp, intake temp, air/fuel ratio, etc.) , in addition to the base timing, total timing at 3000-3500 rpms is more important than base timing at idle. That may be why at WOT your getting detonation, it may be a rich to lean condition as the rpms increase....

cepowers18

huh, I didn't know that. So how would I go about checking the computer? Is a tuner or programmer needed for that, or is it a matter of checking a code?

Thanks for the input, btw.

whiteout 5.0

i know exactly what your talking about...i have it too does it sound like almost a rattle?

red50stang

You seem to be pretty set on this, but are you sure that it is your timing? I had that same noise it sounded like a metal scraping and a chatter sound, and it just happened to be valve chatter from lack of lubrication. I had a leak in the oil pan seal and it caused the oil to drain out of my car when I drove it hard, and over time it would get low enough and cause that noise. You may not be experiencing this at all, and it may be timing but I figured I'd just throw this out there.