Gas Motor Experts Help Detonation with 87-93 Octane

[skammer1]

Ok Gas Motor Gurus, Our Ford needs some help, and I need some opinions from you gas experts for my research...Our 2001 Mustang GT 4.6L spark knocks bad, regardless of fuel grade 87-93. It is bone stock, and has done it since new. The 93 does detonate a little less than with 87 or 89, but it's still there especially on top of the power band. We had her dyno'd this weekend along with my PSD, and the difference in the quality of the dynograph was astounding. the Mustang looked like an EKG, where the diesel was smooth like buttah! I realize there are to be some differences , but surely the lack of continuity was alarming, even to the guys at the shop. They didn't have an immediate answer.

Also, the autotap software, detected a drastic drop in timing over the powerband, from 21-14 degs advance TDC, down to 7.5-9 in the band where the motor is supposed to be making mad power. Any ideas? I can email you dyno plots if you wish to see them, just email sean.kammer@wcom.com and I will ship them right off to ya.

[Manx]

Well,
The knock sensor is retarding the timing
But why it's knocking with 93 is a mystery to me
Bad gas would be the first guess
After that I'd look at the timing
maybe the timing belt was never put on right, and that's off
The car has to be under warranty

[Keith W]

Something is seriously out of whack there. I have a 2001 GT Bullitt and it ran fine on 87 octane 95% of the time when the timing was stock. With the timing adjuster, I run 93. I can't believe it's not pulling any codes with that kind of problem. Have you tried <a target="_blank" href=http://www.corral.net>www.corral.net</a> for help with it yet. If not, post it in the Modular section.

BTW, the 2V engine doesn't have a knock sensor, so it's picking up the problem elsewhere and pulling out timing. What did your A/F ratio look like on the dyno pull? The Autotap, didn't have any weird codes?

[skammer1]

DIdn't get a chance to look at the A/F ratios...Correct the 2V heads don't have a knock sensor..but the computer is pickig up something that is causing it to dial back timing drastically. no wacky codes on the autotap, but i have to say, we didn't get too much chance to really dig. I am thinking something mechanical to blame, as I am certain that the quality of gas isn't to blame, she will detonate on any gas.

[Keith W]

Yeah, I don't believe it is a "bad gas" issue. The worst 93 should keep you out of detonation. Seriously, if you haven't tried Corral, you should. I'm sure one of the thousands or members has run across this before.