What its this lean cruise mode tht i have read about? An how could I tell my tuner to do it. Using hpt . 04 a4 .

 

I would really like to know more about this as well. I also have an 04' A4.

 

HP Tuner has a section in there for this.
From my understanding it works for going 30mph+ only. What it does is once over that speed and you hold a constant speed for 8sec, it will lean out using less fuel which betters your fuel economy. It's pretty much for highway situations.

Someone correct me if I'm wrong on this.

 

You can set to come on at any speed or length of time. It works at light load, light throttle, as in cruising down the highway. Hence the name, lean cruise.

There are a few tables to play with to get it to work. Not too difficult to get it turned on. Easiest way to see what to do is look at a stock Holden file and use that as template.

 

This, we were kind of scared about it at first, thinking if we are cruising on the highway for extended time then jumped into boost, but the logs showed perfection.

normal fueling took over instantly.

 

So on hpt you will see the tables to adjust it ? I have someone else do my tuning.

 

What year is your goat?

 

04' a4

 

Good, yes, you will see the tables, not hard to find, its in the fueling IIRC, ill check tonight, unless someone else chimes in.

 

Engine>fuel control> COT,Lean cruise

 

how do you adjust it to help with mpg?

 

Im not a tuner, lol.

I just tinker with the program a little here and their, i leave all that to my tuner, i know enough about it to be able to look at what hes doing and somewhat understand it.

your tuner should be able to figure it out without issue.

sorry i couldnt be of further help. Im sure someone will chime in.

 

Ok thanks for the input.

 

Shoot over to LS1GTO.com and do a search for "lean cruise". You'll find everything you need from posts over the years.

 

This shows some of the tables and their settings. To make it work right the air fuel ratio as well as some timing is adjusted. I get about 12% better mileage with it enabled. It's main benefit is driving on the freeway. It's one of the benefits of the '04 as it's the only year with it. Because they brought it over fairly quickly they left the Australian computer in the car and just zeroed out the tables. An engine can run very well under very lean conditions (greater than 16 to 1) with no harm to the engine. As soon as a load is placed on it (monitored thru MAPs) it reverts to normal. The reason we don't have it here on other cars is the EPA. Lean conditions use less fuel but make more NO emissions which are a concern for smog in some places but frankly out in the country don't mean squat.

 

This is a cool perk to the car. Iv had mine almost 3 yrs now and never knew anything about this. I will surely have this enabled next time i go out and get some tuning done.

 

Can lean cruise be manipulated with a diablo?

 

No. Basically HPT or EFILive.

 

Can it be manipulated with a fast tuner?