I'm starting to use my car a great deal on the freeway for commuting and need all the milage I can get.

Can someone with $8D and 3.42's please share with me all of their Highway Mode parameters that seems to work best?

Thanks!

 

I don't know if you'll get any define numbers on that. The best bet would be to lean it out and watch your WB. Then play with the HW SA table and keep watching for the best running.
the total fuel output maybe a good way to judge the performance per distance traveled if you go the same route all the time.

 

Hmmm, then my next question would be who can post info on how to add a mpg filed to the ads file that I can monitor while datalogging that's based on the injector flow rate and the injector pulse width taking into account the 8 injectors and the distance travled etc...

 

I can't tell you how to get an approximate mpg but I can give you an idea of how to estimate for better or worse. Kind of like a narrowband o2 sensor, sure it's good at 14.7 but other than that it only tells me higher or lower . So here's how to do it. Look at the pulse width, RPM, and MPH. For a commute you will probably be holding a steady RPM so the frequency of the fuel delivery is constant, same with MPH... this leaves pulse width. Lower = better MPG . Nothing more too it. I take an emulator on a non-busy time of the day and cruise with a driver that isn't "digital" (can hold a steady MPH not on/off the throttle and brakes) and sneak up on the timing and leaning of the AFR. I don't lean out the AFR more than 16:1. I haven't seen any mpg gain by going higher on anything I've tuned, and for a heavy vehicle or high specific output motor that number goes down. Same with gears. With a high reving almost no throttle needed to cruise thirdgen you can get away with the 16:1 almost every time. This is because the specific output of the engine is very low during cruising so it doesn't build up much heat in the oil as would a smaller motor. By running only as much timing as you need (not on the brink of pre-ignition or detonation) the oil temps should stay well within range. Does this all make sense?

 

Thanks. I'll do some more reading up and start on it as soon as I tweak my TCC & IAC issues that remain that I made another topic about.

Then my PROM should be right where I want it For this week that is, lol.

Thanks!

 

Prego!, Its in there
From the $8D Datastream A100. Haven't done much with this myself but know it can be helpful.
Any logger will be able to display the values.
Will take a little calculating to get it into the units you want but will give results that can show increase/decrease with your changes.
HTH

 

Or, you can increase the spark to increase throttle response (which is needed as you lean things out) and install an oil cooler.

92 GTA - I found 17.4:1 and 47* total spark gave me my best fuel economy with a stock L98 TPI car. Play with your AF & spark and take some LONG highway trips. The best I ever I ever got was 385 miles on 12.9 US gallons using the combo above.

 

My TBI 305 VAN will tolerate 16.7:1 and about 44* total spark on 93 octane in OD w/3.73 gears and P295/50/R17s. That just tells you that you can get pretty aggressive at part throttle cruise without hurting anything. Just watch for the warning signs of detonation and high EGTs and you will be fine. The engine will let you know when you push it too hard, before it blows up, usually in the form of a lean surge.

My best ever tank was 721 miles on 31.3 gallons, or 23.05 MPG.

 

Thanks for the suggestions guys!

I'm first going to try 16.0 AFR and 41* of timing and work from there.

 

I'm not doubting your gains but did you get a good before and after measurment of the oil temps? If not, what was your mpg with a richer AFR?

The other thing I'd like to note as important is the strength of the ignition system. No big gaps unless you've got the power to jump it. The CDI's would work well in a lean burn if only to lower the emissions .

 

Jon, I was the first person to REALLY experiment with Highway Mode a number of years ago (on TGO anyways - check some of the old posts). Before people found certain switches to invoke the HMSA, I had to physically alter the code to make the Highway Spark work properly. This is REALLY old stuff for me and I have since moved on to "bigger & better" things.

I tried a gazillion combos and drove 100,000 miles testing it. The AFR & spark that I mention above gave me the BEST mpg. Oil temps were never a problem. I never burnt out my cat.

I'm only stating my experiences - nothing more.

 

can u show me what u changed to get HW mode to function please?

 

Are you using TP? If so you can search TP for hyway or highway. I believe a bit needs to be checked.