I've got a general mapping question and I really need help from the mapping experts. Is acceleration fueling only used to maintain optimum power AFR when the car switches over from closed loop (stoichiometric AFR14.7) to open loop (AFR for optimum power, say AFR 13:1)?

At every upshift then WOT on the track, the acc fueling kicks in. Should I set the acc fueling such that it maintains around 12:5.1 to 13:1 throughout? Or should I run richer?

Please advice

 

If you dont mind me asking, what are you using to edit your maps?

 

It's called "Acceleration Enrichment", and it's to compensate for transients in operating behavior, like a gear shift or sudden stab of the throttle pedal. The whole point of it is to keep the engine running at a consistent AFR and keep from blowing the engine up from a lean spike.

You only want to run 12.5 to 13:1 if you're running a naturally aspirated car, or trying to push the ragged edge of destruction your super/turbocharged car. Stick to about 11.8:1 on a boosted car under max load. For what it's worth, 12.8 to 13.2:1 is generally referred to as "Max Torque", however the reason us boosted cars run richer is to curb detonation and keep the combustion events within a reasonable temp.

It's easier to add fuel than to add money [for a rebuild] *wink*

Cheers,
Ryan
P.S. I'd also like to know what system you're using.

 

I'd run mid 11s for A/F, especially on the track. If you're going to run 100+ octane you could go to 12:1 but anything leaner is just asking for trouble and you won't get much power in return.

Are you talking about acceleration enrichment from the throttle movement of just being in open loop?

 

The answer to this is really who knows? Maybe the ones that are hacking the maps and not sharing.... but the MCS run very rich so that they keep combustion temps down. Even with that, there's timing retard at 100% load....

You may want to ask those using the Apexi, as they've been tuning the A/F ratios. PM John (jlm) and ask him. I think his WOT map is set for 12.5:1..... For throttle blips to match revs, there isn't nearly as much load, and I doubt (but really have no clue) that the WOT map is invoked.

But if you're editing the maps you self, please share how, as you will instantly be one of the most popular guys on the boards!

Matt

 

I wonder if the "acceleration fueling" he is refering to is the same as "transition/throttle tip-in" enrichment. I've seen it expressed as a percentage multiplier in other ecu/ems map editors.

 

An electric acceleration pump! But we're still guessing......

I really wish someone would release ECU hacking SW! I'd just play and play and play, and try not to cook the motor!

Matt

 

Thanks guys for your quick replies. Yes, I heard that turbo and supercharged cars run much richer than naturally aspirated ones.

My question is related to my naturally aspirated Elise running a standalone ECU called the Emerald M3DK. I'm sorry that it's not really a MCS related question, so I had to rephrase it in more general terms

 

Matt

 

Yup, it's the same thing!

 

Playing with the map is fun, and there's a lot to learn. I guess it's safe to fiddle with the MCS map as the car is fitted with a knock sensor that will dial back the ignition timing if knocking occurs. Mapping is best done on the dyno, but I took a step further by logging speed, rpm, throttle position and AFR (signal from a PLXM300) and mapping my car on the track to allow for the ram air effect, realistic oil/coolant temps and different ambient temp and humidity.

Ideally, each car should be mapped on the dyno for the best results, because each car is different, and runs with the different fuel in different environments. It does surprise me that the MCS community generally takes a std map from MTH etc. and then live with it, rather than fine-tuning it further. This might explain why some cars ended up losing power after ecu mods.

 

The "MCS community" takes a standard map/flash from third parties (mth comes to mind) because we dont really have the ability to edit our own maps. For some people this is fine, but people with extensive mods or any experience with tuning any efi system, it is very frustrating. I used freeware applications called crome and uberdata to street tune (the equivalent of your "track mapping") my retired honda. We can only wish one day our MINIs will be tunable without having to go through the piggy-back (apex-i, unichip), standalone (hydra), or third party flash (mth, giac) BS.