False knock or fuel problem?

[alvin87gn]

I have an 87 gn Fact turbo 15 lbs boost (sometimes spikes to 18 but thats another problem) i have a 23 row bgc stretch IC, joe lubrant chip, 93 octane 18 deg, 50# msd inj, 44 psi line off at idle and a walbro 340(at least thats what i was told when i bought the car a few weeks ago) pump and racetronix hotwireand when i get to about 10 lb boost i get all kinds of timing retard on the scanmaster(2.1) my crappy postons downpipe is about 1/8 away form the manifold and i know it hits it, but i cant really hear it hit when im pulling boost cause the crappy flowmaster exhaust is plenty loud. any ideas?

 

[scottyb]

What are your O2's during the retard?

 

[alvin87gn]

well obviously too low, usually .5 or .6 ish
occasional .7

 

[alvin87gn]

my static fuel pressure is about right isnt it?
i mean thats bout avg for a chipped ecm, and what fuel pressure can i run up to, just to see if it helps, without dmg to my fuel system?

 

[scottyb]

I'd start by cranking up the fuel pressure a bit. It won't hurt it to raise the pressure. If you go too rich, it'll just run like a pig, but not harm anything. Bump it to 46 and go from there.

Do you have proof of the fuel pump age?
I'd also go ahead and replace the fuel filter. What kind of FPR?

 

[alvin87gn]

i have an accufab billet regulator and i dont even know for sure what the fuel pump is but i hooked up a guage today and the pump puts out 60 psi @ 15 lbs boost with 9.6 KR @ .375 o2 millivolt, i just installed a new wix fuel filter before the test

 

[scottyb]

yikes. I was going to point the finger at the Accufab, but you ruled that out with the gauge. My guess next would be injectors/chip since you know you've got pressure. What about MAF reading at WOT?

 

[alvin87gn]

hmm i havent ever checked the ol maf reading @wot what should it be abouts?
im gonna try this chip that came with the car that says "50# 1100 idle street" on it and see if it works any better. that idle seems high to me but if it works i know to buy a new chip at least.

 

[alvin87gn]

the AF was up to 181 at one point, i didnt do very much wot though cause of KR i only made two runs. that 1100 idle sucks, the car will go almost 20 mph with no throttle, it even shifted into second before the end of my street. that chip will come right outta there,oh yeah and it didnt help the knock either. i wanna flush the ole inj asap and maybe replace em all if that dont help.
I have to baby the car so much that right now when i drive the car the turbo is just there for moral support i guess, i really am gettin annoyed at this prob, lol.

 

[azgn]

how about good old lack of octane...where is it written one should be able to run 15 lbs on today's crap gas....you sure can't here in Az with our oxygenated "91"

turn the boost down and see what happens

 

[alvin87gn]

93 octane no ethanol or methanol
it doesnt just knock it runs lean

 

[azgn]

ok, don't turn the boost down........turn the fuel pressure up

unless you have a wideband you have no way of knowing it is "running lean"

 

[Lee_Burough]

When I asked Ken Mosher a similar question, he suggested a very high octane fuel to test whether the knock retard remained or went away with the increased octane.

If it went away, it was fuel related. If it remained, it was something other than fuel, maybe even mechanical (false) knock.

I took his advice, with a mild to moderate level of boost. Too much boost with all the wrong conditions will light the 'Change Engine light' Razor frequently warns about

lee

 

[alvin87gn]

hey sorry azgn, didnt mean to insult you chill yer beans, its just that i always use the same gas from the same place as well as my buddy who has a t-type. he has no prob with it and i didnt in my wrx. but that's not a bad question to throw out there. Could my maf maybe be reading to low? ive read that other people see like 256 out of their maf at wot and i never saw more than 180. im gonna swap in my buddy's maf and see what happens.