OK all... I'm currently running :

'96 GSR
T3/4 custom install - 7-9 psi depending on what mood the d-gate is in
Starion intercooler
2.5" Comptech exhaust
stock cat
stock fuel pump
cartech FMU set for very little rise
450cc injectors
VAFC
J&S Ultra V2

I'm currently running into this situation where if I'm on the highway and accelerate gradually, the J&S starts bouncing around 1-5 lights, apparently on all cylinders since there are usually 3 or 4 lit at the same time. This usually occurs between 4 and 6k rpm right about the 0-1psi mark.

Do you think this is really detonation or is it just valve noise setting off the J&S? If I wanted to deal with tip-in detonation problems I would have just got a JRSC!!! I am leaning things out quite a bit with the VAFC but if I go much richer it REALLY bogs under part throttle acceleration. My fuel supply is plenty adequate under boost even up to 8-9 psi but I'm not convinced this is actual detonation going on. Any thoughts? I hate to just turn the sensitivity down if it's a real problem. My car makes a lot of valve and other mechanical noise when it's idling so I was wondering if the reappearance of this noise at speed is setting off the J&S.

 

Can the V-AFC really be accurate enough to know you are at 0-1 psi? It has no boost compensation... only throttle (as you know.) Maybe you should change the hi-lo throttle percentage setting, and up the rise on the cartech FMU. You need at least SOMETHING that is boost dependent.... You really should get a hondata....

Dustin

 

here is a point of interest for you. After my J@S being on for a year, it wiggled its way lose in the motor mount hole. (yea, it probably wasn't full tight in the first place...)

Also, have you ran high fuel pressure through those injectors? One might be locked up and not giving fuel to one cylinder.

here is the best bet though. Wait until you are almost out of gas, then go put a few gallons of 104+ octane in the tank. If it is still knocking at part throttle, it isn't knock. (unless its due to being lean, but even then race gas is pretty leanient)

Good luck!

 

Dustin - that's a good point; of course the VAFC has no freaking clue if I'm boosting or sucking air through a crazy-straw; but increasing the rise rate also wouldn't help if it's detonating at atmospheric pressure; generally at part throttle as soon as it hits atmospheric pressure I'm between 12.0-13.0:1 (according to my J&S AF gauge which is naturally only as accurate as an O2 sensor operating out of its range).

Miata - thanks for the suggestions; I've not run high pressure through those injectors so that shouldn't be an issue... and the knock sensor is the stock factory sensor which appears to be solidly in place. I'll consider trying higher octane to see if that narrows things down; oddly enough I was running like a 95 octane mix when I was noticing this though. I richened the fuel up a little bit at the 4000 range and it seemed to help so perhaps it was just leaning out in some odd way down there.

Thanks guys.

 

if u can afford it, go standalone, will probably save u money in the long run..

 

That's certainly in my plans for the future. I just want to make sure my engine lasts until then so I don't end up spending my savings on a new engine instead of the ECU.

 

ha! Unfortunatly, I DID end up spending the avings on a new engine instead of a standalone