hustler

iTrader: (6)

The problems I had on his car with Adaptronic defied logic.

JasonC SBB

Because nobody has tried to tune the part throttle timing maps by looking for MBT?

THe Adap had a great feature, its "MBT finder", which nobody used... so it was taken out.

18psi

iTrader: (76)

I messed with it using your suggested technique of staying under 100kpa and all that, but you're right: I don't think any of us REALLY used it.

What makes you think the OEM mapping is tuned to MBT?

JasonC SBB

It'll have to be pretty close, in order to improve MPG.

Savington

iTrader: (31)

Am I the only person who is entirely uninterested in what the stock ECU does? I tuned a fairly stock '94 last week and found nearly 20ft.lbs of torque at 3000rpm by switching from the stock ECU to an AEM EMS.

If the stock ECU is that far off the mark, then I prefer to just ignore it entirely and build my own maps.

18psi

iTrader: (76)

that's what I've been saying in basically every post

JasonC SBB

And Sav is saying the factory WOT maps aren't good.

Has anyone shown that the factory part-throttle maps are similarly lame?

JasonC SBB

Has anyone attempted to tune part throttle on the dyno?

I mean, what's the point of having a load holding dyno? If you are just doing WOT RPM sweeps then a Dynojet will be almost as good.

Techsalvager

I will be doing driveability tuning on the local dynojet once I deem my car ready.
part throttle and traistition tuning.
and a dynojet can do it if it has a load cell

JasonC SBB

Are you going to attempt finding MBT at part-throttle?

Techsalvager

ah forgot to post, but yeah that is the goal.

hustler

iTrader: (6)

Only on my turbo car. I've added a ton of spark to my daily everywhere and not confirmed MBT on a dyno, but it's significantly faster and easier to drive. I can't imagine not tuning part throttle. I did this to maximize fuel economy...then promptly destroy that fuel economy with enrichment tuning.

ThunderFox

Well mine is also running pretty advanced compared to stock, about 6 degrees advance on the whole map taking into account the fact that the car is pre-tuned for 91 RON, and we can only get 95 RON over here. But even though the drive is awesome, I'm worried that there could be detonation... Anyway to figure it out without buying some det cans?

Martin Y

Bump to say: yes, that's one of the things i found in the '94 BPF3 ECU code. The lookup table is between addresses EE1C and EF02 in the ROM and it occurred to me you could run a different model of AFM on the stock ECU just by editing that table.

A solution looking for a problem, I guess. It would be some use on a 1.6 where you could fit an RX7 AFM instead, but not much use on a 1.8.

Anyway,the law of the lookup table looks like this:


(X-axis is input value, Y-axis is output)

Techsalvager

hmm need to compare with obd 2 data output on a newer car
X is voltage\adc
Y is airflow
Don't know off hand what airflow units those are because 640g\s is way to much for this maf and 64g\s is way too little

Martin Y

It's only the shape of the chart that's meaningful; the actual numbers are arbitrary. It's not reading airflow in any particular units. It just takes a voltage reading from a 10 bit A-D input and uses that to interpolate a value from a 7 bit lookup table to produce a 16 bit output.

Whatever it does next with that value (divide it by rpm?) will rescale it again.

Techsalvager

ok, appericate the feedback.

ThunderFox

I reckon the AFR target table on the first page makes no sense at all. While on open loop the ECU won't cycle the fuel mixture according to the narrowband sensor, thus that table makes no sense for open loop. And on closed loop it always fluctuates between 14.5 and 15.3 (that, I tested myself) independent of load or speed. Of course, if you go near WOT, or into high revs, the ECU steps back to open loop, therefore that map does not have any meaning in practice. I reckon, if that map was stimmed, then it serves only as a very rough readout of AFRs on a mix of open loop and closed loop...

Techsalvager

it very well has meaning. it is the commanded AFR map the ecu uses for fuel calucations

ThunderFox

How so? It can either go one of two ways...

Either that map was read out of the original memory, and it only makes sense at a purely theoretical level (such as, the ECU calculating the fuel to match this AFR from the AFM data and the injector capacity), and it will not correspond with the actual value because there are always slight variations

or

this map was read from the ECU by stimming it and/or driving around and logging results, in which case it's a mix of open and closed loop driving. I know someone said some posts before this one, that the ECU can't read anything other than rich or lean from a narrowband (which is true) but it can use these values to modify the turnpoint of the lean/rich wave signal, which would work in theory, but like I said there is no change to the AFR targets in closed loop mode in practice.

So, I have no idea what to make of that. Would be nice to be able to set up a Megasquirt to run just the same as the factory ECU, and tune from there, though!