knock knock goes the jeep....

[Mark Romans]

If you have Terry Kelly's GMe Pro you can print the actual spark map and
plot where on it you were with rpm and load and plot the actual advance that
the ecm should be putting out.  If it is different then you could be
experiencing PE spark advance, or HWY spark advance or HWY fuel problem.
>From what little experience I have with a friends 89 TPI with Vortech, we
pulled the boost retard out and allowed the ecm to take out up to 14 deg of
timing when in pe and with only about 5 psi of boost the ecm rarely pulled
out more than 5 deg of timing when on the throttle and the car ran much
better without the boost retard.

I graph (Using diacom) rpm, LV8 and spark knock, 02 sensor voltage,
commanded afr and tune the spark map from there.  I have also noticed that
the 02 sensor still reads high (Over 850mv)  but the car just seems to lay
down if it's not rich enough.

Took me a while to find PE spark advance (Now all zero'd out) and I have
been playing with hwy spark and hwy fuel.  I only put in about 4 deg of hwy
spark and have hwy fuel set at  16.0 to one.  It seems to surge a slight
amount on very slight decel, but other than that, no detonation.

Hope this helps.

Mark
-----Original Message-----
From: Peter Fenske <Peter_Fenske at bcit.ca>
To: gmecm at efi332.eng.ohio-state.edu <gmecm at efi332.eng.ohio-state.edu>
Date: Thursday, December 30, 1999 9:25 AM
Subject: Re: knock knock goes the jeep....


>
>
>Hi John
>
>Been a while but I think you gotta disable the hwy spark..
>What happens GM tries to eak out the best CAFE MPG by advancing
>the timing at steady state.. Also there is a hwy fuel enleanment
>function which can give you AFRS of 17 to 1. all for MPG.
>
>I am not sure if these functions are enabled in your cal.. check em out
>
>:peter
>
>