GMTech

I tried searching through the archives, but the Q&A about actually enabling highway mode has been slim pickin's.

I want to enable it, and I'm pretty sure I know how. The Min. Vehicle Speed for Highway Mode Fuel parameter is set at 255 MPH. Obviously I need to move it down to, say, 60?

My .bin file is so heavily moddified, I don't even remember what it started as (AUJP???) I'm running the ARAP spark table, 93 Octane and NO spark counts at WOT. With about 30 minutes of driving, I might get 4-5 counts on the entire drive.

I'm running a 357, ported TFS G1 heads, LT4 Hot Cam w/ 1.5 RR, Accel TPI base, AS&M runners and all the other "typical" TPI mods. I want to know if highway mode is a good idea and how much change do I need to make and what do I need to watch out for?

3.8TransAM

Got to do a search...several great threads on them... If i get a chance later I'll pull the files ive printed most of them out. Glenn even goes into detail on what he changed/had to change to make it work properly and included the approprite modified source code(if i ever fiogure out how to do it i will)
LAter
Jeremy

Grim Reaper

Bernard, what's youir e-mail?

poncho@home

Glenn will your stuff apply to '89 MAF? I know that you run SD.

I want to enable Highway mode as well, so I would be interested in exactly what needs to be done.

RedIrocZ-28

I can get better than 24 mpg highway!?!

Send me info too!

Grim Reaper

I had posted a LONG explanation, but my computer froze and I lost my reply. So I will give a "short" version of my original reply.

The $6E MAF (using the ARAP as a base) worked just fine in Highway Mode. No code modifications needed whatsoever (though I prefer to have the RPM work as a "max limit disabling" parameter instead of a "min limit invoking" parameter. When you have the MPH as a "min limit invoking" parameter, you don't need the RPM limit to be another "invoker". So having it behave as a "disabler" makes more sense.

Later, when I am not quite so ticked off at my computer, I'll explain the various parameters that control the Highway Mode for MAF (which are very similar to SD - except they work as is), as well as my own personal experiences. T

There are "warnings" that need to be stated such as possible decrease in cat life (though I personally have had good luck with no ill effects). But if you don't have any emissions testing to worry about, then the warning is of less consequence.

GTA91

iTrader: (1)

I am also very intersted in this, but I'm not sure exactly what highway mode consists of and what you have to do to engage it and also what to watch for? Any help greatly appreciated Glenn!

Vader

I vote for 54 MPH. It works for me, but I'm running a MAF, so my opinion doesn't count.

JPrevost

Since I replaced the motor and have 3.73 gears I found no ill effects from enabling highway mode just after the tcc locks (36mph). It rarely enters highway mode unless I'm on the highway but ever once in a while I'll be going down a long residential road and it will turn on.
I believe stock the setting in the TBI cars was 54mph, not certain on that. Also none of the 7747 (TBI trucks) had highway mode enabled from the factory. Lean burn = high emissions, I guess back then the TBI cars were fine with it....although it makes you wonder when all the info on the web says trucks have lower tolerances.