How far can I safely bump the base timing?
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Car: 1986 W69 Special Edition
Engine: 2.8/ECM/Int/Exh
Transmission: T5
Axle/Gears: 3.42 posi
How far can I safely bump the base timing?
Haven't tried bumping the base timing yet... Was wondering if there is an ECM provision for knock retard? I don't want to pop anything, but maybe try and squeeze a little but more out of the 1986 2.8 motor. Current relevant mods are: 3" custom intake pipe w/ custom K&N filter adapter, 2.75" cat-back exhaust (no cat), Hypertech Thermo-Master chip w/ 180° thermostat and cooling fan mod and matching silver pinstriping... I assume since the timing is computer controlled, a curve kit will not work here, right?
Thanks!
EDIT: Forgot to mention that the smog pump and things associated with it are sitting in a tote in the garage as well...
Thanks!
EDIT: Forgot to mention that the smog pump and things associated with it are sitting in a tote in the garage as well...
Last edited by BackInBlackGP; 05-19-2005 at 08:54 PM.
#2
There are too many variable to quote a definite number. It will depend on head temperature, combustion chamber contamination, fuel grade, actual compression pressure, RPM range of operation, detonation sensor reliability, valve condition, air charge temperature, and probably several other things I'm overlooking.
The ECM does retard timing on a detected knock. You can monitor the ECM detonation sensor crosscounts for excessive activity, then experiment with the base timing setting. Once you get excessive counts and sustained spark retard steps, you'll know you have too much initial timing for the conditions the engine is operating in. If the system is working properly, you should never hear an audible knock, so don't rely on that for determining the correct initial timing. It's not a '72 Olds, after all.
The ECM does retard timing on a detected knock. You can monitor the ECM detonation sensor crosscounts for excessive activity, then experiment with the base timing setting. Once you get excessive counts and sustained spark retard steps, you'll know you have too much initial timing for the conditions the engine is operating in. If the system is working properly, you should never hear an audible knock, so don't rely on that for determining the correct initial timing. It's not a '72 Olds, after all.
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Car: 1986 W69 Special Edition
Engine: 2.8/ECM/Int/Exh
Transmission: T5
Axle/Gears: 3.42 posi
Without a scanner, is there another way to monitor knock counts?
I ran the vin on the car, and it is reported to be a "Pontiac Firebird Trans AM Special Edition". It has the T/A tails and front bumper and the upgraded interior and suspension package as far as I can tell.
The "SE" designator on my Grand Prixs should stand for "Stripped Edition", since they came with no fun features...
I ran the vin on the car, and it is reported to be a "Pontiac Firebird Trans AM Special Edition". It has the T/A tails and front bumper and the upgraded interior and suspension package as far as I can tell.
The "SE" designator on my Grand Prixs should stand for "Stripped Edition", since they came with no fun features...
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