linuxman51

iTrader: (7)

How does running in open loop equate to pollution if the car is properly tuned? decel fuel cut still occurs, ostensibly one would tune for correct AFRs if for no other reason than to get fuel economy back up from say a stock fuel map run in open loop.

Anyway..

What is the correlation between the two maf tables? there's a MAF Compensation table, and a AF/Hz Raw scaling table-- both with the same X/Y axis, same reference hz values. I presume this references something that has since changed names, I'm trying to get the scaling nailed down since I de-screened my maf and I'm about 95% there I think (I suspect I'll still have to futz with the fuel map a bit, but thats alright). Right now I'm messing with the MAF comp table to get things in line, should I be applying changes to both at the same rate?

shadow1

iTrader: (38)

No way a 30 x 15 fuel table can replicate infinitely variable feedback control of closed loop fueling. Even a 500 x 500 table would not be as good. That is what I meant.

linuxman51

iTrader: (7)

Linear interpolation when applied correctly is more than enough to get things 'in spec' given similar/same inputs (fuel quality, ethanol content, etc), map size doesn't have as much of an impact on that as you would think. Besides, you are giving too much credence to the accuracy of a narrow band 02 sensor, in closed loop op, you have in effect, a 'swing' between rich and lean, something like a sine shaped wave going above and below the spots on the map.

closed loop op where the ecu can take averages and generate trims based on what its getting as input is there to ensure that Joe Random Buyer can purchase any type of gasoline from anywhere and the car can still reasonably adapt for both performance reasons and emissions reasons. The closer your map is tailored to whatever grade/brand/mix of fuel you prefer, the less those trims come into play (what is the eventual goal? +- 2% or something? basically the variance you can expect even from the same gas station on different weeks) and the less 'closed loop' operation matters. From a pure fuel economy stand point you actually do better to run slightly above stoich , but as you run the engine leaner, NOx emissions start going WAAAY up (as do other less desireable things). Most cars will "feel" the best cruising around town running richer than stoich, but then you're wasting gas.

Anyway, I'm running way off topic here, the bottom line is you can tune a car to pass emissions and get good fuel economy without any kind of closed loop operation, over in the volvo world people have been doing it for years with megasquirts on cars with cams bigger turbos etc, and the MS 'closed loop' routine is garbage, it stays off on 95% of the installs. And there you're looking at a fuel map thats 12x12 unless they have the latest and greatest.

fostytou

iTrader: (15)

It is described better above, but so far as it has been explained MAF Scaling was used to provide the expected model for how the MAF would respond. MAF Compensation was used to modify that expectation where it did not fit into the real world.

So far changes seem to be similar across tables, but it seems easier (don't have to account for boost adder) and possibly better (since thats why it appears it was there) to apply your corrections to the MAF Compensation table scaled as percent128.

linuxman51

iTrader: (7)

Ok, thats kind of what I figured, I just wanted to make sure. The scaling, meh I don't really care about that, I'll get the numbers down to where they're close enough and massage the fuel map the rest of the way for the affected areas. In other spots on the map the numbers are really close to what the map calls for (this was reached almost purely by accident after looking at what the approximate afr differences across the board were before and after removing the screens and adjusting accordingly). Now it seems I've got it down to non-a/c idle and a stumble when lifting off and clutching.

napolean

Where would I need to start from the attached info for scaling my maf? From what I gather I could start out by decreasing my fuel trims by 12.4%? But it seems that the airflow hertz at idle is 37.5 which is exactly halfway between the 25 and 50 hertz cells in ecuflash. Would this mean decreasing both the 25 and 50 cells by 12.4%? Does this sound correct?

Cheers


RPM AirFlow FuelTrim_L FuelTrim_MFuelTrim_H O2FeedbackTrim
1000 37.5 -12.4496 0.1008 0.1008 2.454
1000 37.5 -12.4496 0.1008 0.1008 2.2579
1000 37.5 -12.4496 0.1008 0.1008 2.6501
1000 37.5 -12.4496 0.1008 0.1008 2.8462
1000 37.5 -12.4496 0.1008 0.1008 3.2384
1000 37.5 -12.4496 0.1008 0.1008 3.4345
1000 37.5 -12.4496 0.1008 0.1008 3.4345
1031.25 37.5 -12.4496 0.1008 0.1008 3.2384
1000 37.5 -12.4496 0.1008 0.1008 3.0423
1000 37.5 -12.4496 0.1008 0.1008 3.0423
1000 37.5 -12.4496 0.1008 0.1008 2.8462
1000 37.5 -12.4496 0.1008 0.1008 2.6501
968.75 37.5 -12.4496 0.1008 0.1008 2.6501
1000 37.5 -12.4496 0.1008 0.1008 2.454
968.75 37.5 -12.4496 0.1008 0.1008 2.454
1000 37.5 -12.4496 0.1008 0.1008 2.8462
1000 37.5 -12.4496 0.1008 0.1008 3.4345
1000 37.5 -12.4496 0.1008 0.1008 3.6306
1000 37.5 -12.4496 0.1008 0.1008 3.4345

Werd

iTrader: (2)

I don't have a MAF Scaling table in my ECUflash but I do have an IAT Scaling table that looks similar to the pics of the MAF Scaling. Is it the same thing?

shadow1

iTrader: (38)

What car do you have and what ROM ID?

Werd

iTrader: (2)

It's an IX with a 0015

shadow1

iTrader: (38)

On the 88590015 ROM, the MAF scaling table is labelled "Airflow/Hz Raw Scaling".

Werd

iTrader: (2)

Aight cool, thank you.

Werd

iTrader: (2)

Are the newer versions of Ecuflash already scaled like this?

shadow1

iTrader: (38)

I don't understand the question

fostytou

iTrader: (15)

I think I get what you are asking... but why don't you just look?

Current versions of ecuflash should have the left column scaling set to hz. Right column is still the bit value.

EvoMike

iTrader: (3)

Ok, so I've been reading a lot and need to get some clarification... I just installed the evored turbo, fp 3" recirc inlet pipe, and PTE injectors all at one time. I scaled the injectors so the trims are really close to 0 but sometimes the car wants to surge at idle (1000rpm up to 2200rpm and repeat then eventually settle at 2200 rpm) could this be because my MAF scalling is way off. My high fuel trims are 0 but my map has 11 afrs in it while actual AFR is below 8AFR.

Should I put the stock injectors back in with stock injector scaling, tune the maf for idle and cruise, then install the PTE880s, scale the low and mid fuel trims, then go back to adjusting the upper range of the maf till my actual afr equals what is in ecuflash?