Found these due to rough idle/stalling today. Dont know how it happened. These are stock heat range and I'm going to go colder, but dont know that it would cause this.

Help.

Setup

FMAX (no mf2 or intake injectors)
4:1 FMU
Walbro 255 hp pump
500 cc RC's
VAFC
Accel 300+ Ignition & magnecore 8mm
Dyno a/f 12.5 to 13

[Modified by niedejb, 9:53 PM 6/28/2002]


[Modified by niedejb, 10:18 PM 6/28/2002]

 

detonation...dude

 

Could be. Never heard a thing on the dyno. Had good fuel the whole time. Stock compression is 8.8 to 1. Timing is 15 degree advance at 550 rpm.

 

yes,i have seen that.when i saw it it was from detonation.what heat range are you using on what horsepower level?that could be your problem.i would guess not enough fuel.

 

Heres the 10 psi run. Fuel never got out of control under boost.

 

If this is detonation causing this, how do I cure it? Dont hear anything so how do I know its gone? The spark plugs stop breaking their insulators?

 

is it just on those two? that is really strange that you only have detonation on 2 cylanders.....check your injectors for those two....

 

Yep just the two. I think I may have damaged the insulator somehow when gapping them. I'm clueless.

 

Sure, you can have detonation on only two cylinders and even one cylinder. Also, you CAN'T always hear detonation. That's the beauty of a J&S safeguard, which tells you how many cylinder has detonation and how many degrees of timing is removed ONLY for those cylinders. In fact, I've never heard any detonation on my car. However, I know it's there and J&S took care of it, and let me know via the knock monitor.

 

I guess I'm the only one that seesthe f/a ratio go lean after 5500 rpm... Dude, anything over 6 psi needs 1 or 2 heat range colder plugs. It's not a "I'm running fine on the a/f ratio, I don't need it thing." It's a proven fact. All factory cars running turbo or superchargers run colder plugs. Get 1 heat range colder and see how it does... Also, look at why it leans out at 5500-up. If I'm reading the graph correctly it goes as lean as 13.0 or 13.5. You should be sitting at 12.5. I bet the detonation happened that high in the rpm, that's why you couldn't hear it... Too much engine noise...

Hope this helps...