I drove myEVO to work today. This was the first time I was able to drive it after getting the EMS. I noticed my gas consumption sucked!!!. While at 5th (3000 rpm gear my A/F was at 11.2 - 11.5. I really don't need this at cruise. I will probably tune it myself. What is the best cruise A/F and how do I tune it. I want to make a separate map for daily driving. Bear in mind my car is still completely stock with the exception of the EMS.
TIA
John

 

15.5-16 works pretty good. Ultimately you get the fuel map set up so the AFR is 14.7-15 in the cruising range and then set up the O2 Feedback control and set that to lean things out to 15.5.

 

15.5? .. Aint that a little too Lean? .. I was thinking more of like 15

 

Can you explain to me how to read the Load Psi .. Basically what does it mean .. I know it means the engine load. But what Im particularly concerned about is .. what is it when its in negative numbers? around where should the load PSI be when at cruise?

 

The Load value can be expressed in several different units like KPA or PSI. PSI is the most common amongst EMS users from what I've seen.

The value is reading the amount of pressure in the intake manifold. 0 would be the same pressure as outside air. A negative value means there is "engine vacuum", and a positive value means the turbo is making boost and pressurizing the intake. Don't let the term "load" fool you, it is just a boost gauge.

If you compare it to your standalone boost gauge, like say you have an Autometer, which reads positive pressure in PSI, and it reads vacuum in inches of Mercury, so when you compare that to the all PSI measurement of the EMS it is confusing. The EMS uses the same unit of measurement for both positive and negative manifold pressure for simplicity.

With that said, -14.7PSI would be absolute vacuum (think outerspace), 0PSI is 1 atmosphere of pressure at sea-level, and +14.7PSI is boost pressure from the turbo 1 Atmosphere of boost. The AEM 3.5BAR MAP sensor reads 1 atmosphere of vacuum and 2.5 atmospheres of boost, so -14.7PSI to +35.31PSI

At idle the load should read in the -11 to -9 range depending on if you have cams or not. Stock cams will read closer to -11 since they create more vacuum.

In the cruising range it will be around -7 to -2 PSI.

You want the AFR to be 14.7 at idle (or as lean as you can get it with a stable idle, may have to be richer than that), 15.5 everywhere from 0 PSI down, except at idle, and you want the AFR to be 12.5 or richer from 0 up.

 

Thanks for your help in making things a little more clearer. I will post the chart after i make adjustments. If you can verify that would be great.

 

i have found the best way to get a good afr for cruise is to find a nice long flat stretch of road, get going a good speed, turn on the cruise control and while monitoring the throttle % slowly lean it out untill the cruise has to add more throttle to maintain speed, then richen it up a tad. some cars will cruise a bit leaner than others, it just depends on the car. i have done some that are perfectly happy at 16.5-17:1 and others that wont run unless they are richer than 15:1

 

Sounds like it would work great but unfortunately EVO's don't have cruise

You think this can be done just maintaining speed on your own?

 

After hooking my laptop up to the serial cable and turning the car on but not igniting it i went to fuel>fuel map>table and this is what I got. This can't be right can it. What is the proper way to get a fuel map. Sorry for all the dumb questions Im new to this.

 

evo's dont have cruise??? wtf, god damn 30g's for a car it better have some damn cruise........

but anyway, you can but you just have to be carefull to hold the gas steady.

 

30G race car, not limousine

The AFR at cruise speed really depends on the turbo size and injector size. Big turbos and big njectors donot really like anything leaner than 15AFR. Especially on cars with no ignition boxes

George