mileage till empty
09-30-2008, 11:43 AM
#26
Factory tunes are so general that the ecm will pull timing (even if its only a fraction of a degree) no matter what pump gas you run. Factory tunes are designed to work in alomost all climate conditions. For example: Lets take the wonderful climate here in northern Indiana. 95 Degrees on a hot summer day, - 10 degrees on a clod winter night winter. The factory tune has to work in both situations. The computer adds/subtracts timing wherever it feels is needed to maintain low/no knock condition while achieving driveable performance. It uses the good spark timing table as a guide. If your wondering how I know this, I did my own tuning in my Grand Prix for almost 3 years. I'm not a professional but I know how an ecm works and I've done a lot of research.
If I had only ever seen -1's, I wouldnt be concerned, the ECM will go -1 while your floating down the highway, My point is that I am not talking about -1, or -2 degrees of timing, I am talking -3, -4, -5, consistently and and on several occasions and with several vehicles even as much as a -9 adjustment on properly running cars.
Reducing the timing advance by 5 degrees under full load is unacceptable, and this is what happens when you run 87 in a 2.2L.
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You know, what? I fold, you guys are right, I dont know what the hell I am talking about. I am gonna fill my car with some fresh 87 octane fuel and head over to get it fixed at the dealer, theres gotto be someone there who could fix it.
Last edited by Maven; 09-30-2008 at 11:51 AM. Reason: Automerged Doublepost
09-30-2008, 04:05 PM
#27
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I was agreeing with you Maven 
But I had no idea an ecotech pulled 5 degrees going down the road. wow. it wasn't that way with my 3800; of course I tuned it so many times that i forget what the factory number were 
But I had no idea an ecotech pulled 5 degrees going down the road. wow. it wasn't that way with my 3800; of course I tuned it so many times that i forget what the factory number were
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