Hi all,

I am having a very cautious play with the maps on my car.

I have been examining the ignition and fuel maps in my Apexi Power FC and have also put the Commander into map trace mode and have just been learning the parts of the map my car uses in various driving conditions.

I have made quite a few mods to my car since it was last mapped(by previous owner in Japan) and I know the map is a bit all over the place and so i have been driving cautiously and looking at ways to tweek it.

Now, working out how much fuel to remove or add from the fuel map for it to register a change on the Lambdalink has just had to be trial an error on my part as the MAF load values seem to be just an abritrary scaling.

I was just wondering, how accurate is a Lambdalink, I know its rather crude in comparison to a wide-band lambda sensor and meter but I was just wondering how usefull is the information they provide to actually help me in improving performance, are they so crude that I could easily be way off the ideal for good power, or can the fueling be slightly say on the rich side of ideal, and decent power can still be made.

Also, what effect does ignition timing have on power, is this even more potent way of extracting performance. How much of an adjustment to say advance or retard of the timing would be considered a good starting point ?, Has anyone got any actual data on the effects of increasing ignition advance by X number of degrees and/or of richening leaning off of a map on power ?

THanks in advance

 

You're right to be very cautious, if the car was setup in Japan, it will be setup for 100+ octane fuel and will det badly even on optimax. I would keep the boost below 10psi until you can get someone to map it properly to uk fuel. I'd be wary about trying to remap it yourself if you aren't sure what you're doing. That is unless you can readily afford an engine rebuild.

In general an AFR of 12:1 gives best power but may push EGTs up too high, due to the loss of cooling effect of the extra fuel, and more advance gives more power up to a point but increases the risk of detonation.

I'm sure someone on here will point you in the direction of a reputable tuner who could remap it for you.

Cheers

Simon

 

Si, I think you're being a little alarmist, my MY93 doesn't det on Optimax despite not being mapped to UK fuel, it just doesn't run as much advance as it could. I assume the Power FC has the ability to adjust itself for lower quality fuel, just like the standard ECU?

 

93 wrx is very similar to Uk map of similar vintage. Not until 95/96 do the wrx maps differ considerably.

The standard Apexi PFC map is rather advanced ignition wise so you have every right to be cautious.

Fuelling wise, turbo engines seem to like about 12:1 AFR for best power, but it can go 0.5 AFR points either way. That said, the leaner you go the higher the temps and likelyhood of det is, so you may have to retard the ignition to compensate. THe exact mix of advance and AFR is often the subject of argument and there is no clear winner.

An 11.5 AFR target is probably wise to start with if you using the normal factory narrowband (unaccurate) lambda sensor.

Timing wise I would have to look at some maps, but at 1 bar of boost I would say 17-20degrees at high rpm (6000ish) and about 15 at lower RPM is BALLPARK. Knocklink is a very wise idea, det cans better, or at least knocklink calibrated with det cans.

nough typing for now

Paul

 

John Banks, have you got any data