Here is the thread.
http://www.corvetteforum.com/ubb/For...ML/004013.html
thanks
bowtye8

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85 vette,383,miniram,ZF6,4.10's..best ET 11.66@119.00 60' 1.62
w/100HP nirous 11.05@127
http://geocities.com/bowtie8

 

I didn't read all tthe stuff but:

1) Vac leak causing the preignition
2) Pregnition is BAD for hp, causes retard function to activate and/or lsses of power...
3) most preignition will trigger retard function, bad for hp
4) if retard function disabled, you;re gonna hurt your motor and you need SPARK WORK BAD on your PROM or you have too much initial advance.
5) if retard function still enabled with generous amounts of retard degrees and you are STILL getting the knock, you have your initial timing advanced WAAAAAY TOOOO FAR or you NEED SEROIUS TIMING work on the PROM.

If the dyno operator said you had knock, you probably did. Check to see if the retard function is enabled and working, especially on the PROM ITSELF. If it is working with retard and you have knock, too much PROM advance and/or too much initial advance. redundant, huh. sorry. I think you get what I mean

Vac leaks can cause knock, too, so, of course, go that route first. Check intake gasket-to-o=port area, especially "under" the manifold, into the lifter valley area. you will see oil wetted plugs if vac leak there. have fun.

EDIT: If you post the actual spark curve in tabular form here, i will try to help.



[This message has been edited by FastBroker (edited April 06, 2001).]

 

I also had an Ed Wright chip and unless you have your car there he is only guessing. You should try have someone with access to a scanner and knowledge of gm efi burn a custom chip for you.
Also I read that people think that a MAF car cant make power after the MAF sensor maxes out at 255. That is false. At this point you have to go into the WOT%change air/fuel ratio vs RPM table and tweak it from there. It can be done but it does take time and the proper tools.

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355 10:1 , AFR 190 heads, LT4 HOT cam w/ 1.6 roller rockers, complete Superram intake, 58mm BBK TB, 24# injectors, screens out of MAF, MAT relocated, March underdrive pulleys, Streetdampner, Crane HI-6 ignition, 160 thermostat, K&Ns, TES headers(Jet hot coated), Mufflex 4' cat back, B&M shift Kit, 2500 converter, and 3.27s.

 

Please help. I'm one of the guys who posted and needs help. Just cam back from the track yesterday, and even my friend's 88 IROC with a ZZ4 crate motor and miniram could only turn a 13.50 @ 106. Our mph's are always consistent, and we both have about a 100-200 rpm drop around 4000 rpm in high gear. I taped my fuel pressure gauge to the windshield, and the pressure never dropped thru the run.

Is there a horsepower/airflow limit to the stock MAF at 255g/sec?

 

89GTA the 255gm/s limit doesn't really come into play when you are under WOT because you will be in Power Enrichment mode where the 255 limit doesn't really matter, the 255 "limit" is only a limit if your car requires over 255gm/s of air while in regular driving (not WOT), so you're probably OK.

 

That rpm drop in high gear is probably the torque converter clutch (TCC) locking up. I and several others have noticed the same thing, and it sometimes ends up hurting your e.t. and mph. I have a lock-out harness that keeps the TCC from locking up in any gear but 4th, partly due to this problem at WOT, partly because I like the way my car drives around town w/out having the TCC locking and unlocking. You can change this lock-up point (stock is around 76 mph) in GMEPro.

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Greg Westphal
'87 IROC 305TPI/A4

 

Canadian,

Are you sure about the 255 limit? If so, then why are some cars with the same combination but different custome chips going faster than others?