Commanded timing does not match actual timing PLEASE HELP!

Z28LT1ROCKET · Apr 27, 2010

Hey im definitately famailar with tuning especially LT1s im own a 1994 z28 and its manual 6 speed so what Im expieriencing is I for example In my main spark timing and extended timing table I specifically set every single value above 68 degrees celcius at 30 degrees timing at every map value from 20kpa to 105 kpa and my "constants" at main spark bias and minimum spark value is 0 and minimum spark value at 4000 is 10 4500 is 15 and 5000-7000 is a MINIMUM of 23 degrees of timing and so what im getting at is everything is set at 30 degrees no matter what happens and i have power enrichment set to go into power enrichment at 0% throttle position so i have all variables ruled out! using a snap-on solius scanner and used datamaster for data logging and both scanning tools read 36-39 degrees of timing WHEN IM COMMANDING 30 !!! WTF! i ask other LT1 tuners and its happens to them but other times it will actually read 30 degrees of timing so whats the thing im missing or what already built into the pcm that i cant control

P L E A S E HELP

by the way im using tuner cats and data master

THANKS!!!

JSK333 · Apr 27, 2010

People have found the opti is hard-coded to progressively add more timing over certain RPMs, I think the most is 4* in the upper RPMs.

The other possibility is it could be the timing vs. coolant temp table adding timing if you are doing it with a cool engine.

Z28LT1ROCKET · Apr 28, 2010

cool atleast that same answer i got from 5 other people who professionally tune these this and you so idk i find it wierd though but thanks for the input and no im always running at 195 degrees farenheit with stock fan on times and stock 195 thermostat thanks

JSK333 · Apr 28, 2010

Oh, one more possibility is the EGR system, as it adds up to 5* in some areas when it's operating.

Z28LT1ROCKET · Apr 28, 2010

ill check that thanks

95Z · Apr 28, 2010

I've noticed it quite a bit in the upper rpm range, I find it rather annoying and would rather it just do what I tell it to in the tables :lol:

I wish it had a modifier for gear vs timing too, but oh well.

Z28LT1ROCKET · Apr 29, 2010

lol yah it is rather annoying but that egr correction table was not it because it does add 5 degrees in certian areas but under WOT theres no vacuum so it doesnt even operate under that circumstance because under my constant on my factory setting it say:

[ map(KPA) disable EGR thres- 70kpa ] soi it doesnt even look at the map(kpa) verse rpm table above 3/4 throttle

but i will go with that 3- 4 degrees are built into the opti circuit

opcorn:

Commanded timing does not match actual timing PLEASE HELP!

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