DIY PROMDo It Yourself PROM chip burning help. No PROM begging. No PROMs for sale. No commercial exchange. Not a referral service.
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that's funny, this was SUPPOSED to be a stock bin file. would you happen to know what they should be or better yet happen to have a copy of a known true bin file for a 91 5.7 tpi with automatic tranny? i don't know what the other settings should be either.
that's funny, this was SUPPOSED to be a stock bin file. would you happen to know what they should be or better yet happen to have a copy of a known true bin file for a 91 5.7 tpi with automatic tranny? i don't know what the other settings should be either.
i'm running a modified ARAP on my 87 5.7 gta, i do alot of highway driving currently and i want to setup the the highway mode but i don't have wideband 02, just chip burning equipment and datalog capability.
the engine is stock, but has AIR removed, no catalytic converter, a modified y pipe, and a 3 inch cat back exhaust, pretty much stock.
what would you guys suggest for a starting place for highway mode settings? Obviously the first place to start is the qualifiers rbob stated, but what about the timing and fuel? i know tuning is very situational but seeing as this car is quite stock, i thought perhaps someone could give me a starting point and maybe some tips on the adjustment so that i can datalog and improve from there.
Most likely the EPA. NOx increases with lean cruise mode.
RBob.
RBob is correct. The EPA and CARB determined the "Highway Mode" to be a defeat device, so GM was forced to disable it.
Lucky for us the code still exists in the SW to use it.......
The general concensus is to take out all highway mode spark advance and stick to base timing. From what I've heard it doesn't improve mileage and ends up causing overheating problems.
You should set your enable parameters to just below whatever speed you cruise at on the highway and whaever you find as safe operating parameters. GM has enleanment set at .94 in ARAP ($6E), which should give about 16:1 AFR if I've got my math right. I'd like to try enabling this at lower speeds (35 maybe) to see how it would behave, but I'm stuck using $32B. No enleanment for me... unless someone is kind enough to come up with a patch.
From what I've heard it doesn't improve mileage and ends up causing overheating problems.
GM has enleanment set at .94 in ARAP ($6E), which should give about 16:1 AFR if I've got my math right.
Actually, it did make a difference for GM.
You have to remember these were the early days of the HWFET test for data fleet cars to establish that new EPA Highway versus City fleet number. So it does help.
As for the amount, if you take Lambda 1/0.94 = 1.064, and Stoich for gasoline of 14.67:1, so 14.67*1.064 = 15.6 for highway A/F ratio, its not that lean, but did provide some benefit for the testing numbers.
BUT, the EPA and CARB said "defeat device" since it blew the NOx numbers on the cars, so it was disabled by GM for compliance reasons......
Stoich is programmed as 14.73:1 in most stock bins that I've seen. I took another look at 6E and there's a table that specifies highway afr vs load. I was thinking of decel enleanment. D'oh!
