Official OpenFlash Tablet FA20 Tuning Tech Discussion Thread

[Kodename47]

Originally Posted by steve99

Even if the sensor was inaccurate the ecu would not know so why doesn't it try to get AFR to 12.5 ?

It seems that the stock sensor loses accuracy richer than 12.5-13. As you're N/A you could create a map to run safely at 12.6/12.7 to dial in the MAF before running desirable ratios, just dial back some advance while doing so.

You seem to be missing how open loop fuelling works mate. It doesn't look to see how the end result compares to the O2 sensor, as far as the ECU is concerned it doesn't exist in open loop. It does a calculation based on the air intake in g/s and calculates the fuel needed to hit the AFR in the fuel table. The LTFT is set by consistent STFTs occurring and those only happens in CL operation.

Here's an OL example:
At 5000rpm the MAF is outputting 3.6v, the MAF scale shows this as 90g/s. The ECU then looks at the target AFR and calculates that x amount of fuel is required to hit the target AFR basedon 90g/s of air and then adds the LTFT on top.
If you now change 3.6v to 100g/s the ECU will now assume more air is entering the engine and to continue to make the target AFR more fuel is required, so the resultant AFR will become richer. If the ECU still has a similar LTFT due to the CL operation it will still add this on top, potentially making it even richer.

This is why ensuring that areas of CL to OL operation are scasled well on the MAF. The car I've done recently has 0 LTFT everywhere and I haven't disabled them or moved the WOT area out of the area of correction learning, although I probably will in the long term.

[steve99]

Originally Posted by Kodename47

It seems that the stock sensor loses accuracy richer than 12.5-13. As you're N/A you could create a map to run safely at 12.6/12.7 to dial in the MAF before running desirable ratios, just dial back some advance while doing so.

You seem to be missing how open loop fuelling works mate. It doesn't look to see how the end result compares to the O2 sensor, as far as the ECU is concerned it doesn't exist in open loop. It does a calculation based on the air intake in g/s and calculates the fuel needed to hit the AFR in the fuel table. The LTFT is set by consistent STFTs occurring and those only happens in CL operation.

Here's an OL example:
At 5000rpm the MAF is outputting 3.6v, the MAF scale shows this as 90g/s. The ECU then looks at the target AFR and calculates that x amount of fuel is required to hit the target AFR basedon 90g/s of air and then adds the LTFT on top.
If you now change 3.6v to 100g/s the ECU will now assume more air is entering the engine and to continue to make the target AFR more fuel is required, so the resultant AFR will become richer. If the ECU still has a similar LTFT due to the CL operation it will still add this on top, potentially making it even richer.

This is why ensuring that areas of CL to OL operation are scasled well on the MAF. The car I've done recently has 0 LTFT everywhere and I haven't disabled them or moved the WOT area out of the area of correction learning, although I probably will in the long term.

Thanks, that makes more sense. There is heaps on info on maf scaling but all seem to be "tools" that do it for you and not much on how its actually achieves it.

Its starting to sink in now

[troek]

This is some great reading, thanks guys!

[nelsmar]

I'll just place this here... Mind you my LM2 has an extra latency over AFR which has latency over equivalence ratio...



It is not always this consistent but it is more often than people seem to be suggesting.

[Lytheum]

new log with modified snorkel! got bored today and hacked it up lol.

http://www.datazap.me/u/lytheum/3281...ata=1-5-6-7-11

i think im done tinkering stuff on the car so now its time to start tinkering with the tune. any thoughts on how the OTS tune is looking? @shiv@vishnu ?

[nelsmar]

Originally Posted by Lytheum

new log with modified snorkel! got bored today and hacked it up lol.

http://www.datazap.me/u/lytheum/3281...ata=1-5-6-7-11

i think im done tinkering stuff on the car so now its time to start tinkering with the tune. any thoughts on how the OTS tune is looking? @shiv@vishnu ?

Just at quick glance I would start with adjusting your maf. after 2.9v you seem 3-5% too rich across the board. I would drop the g/s on the maf chart a few % and taper it closer to 1% off near 3.2v to start. Best to make minor changes rather than drastic. Just take out a calculator and do the math based off of how much your AFR is off from current vs your fuel trim compensation. Just adjust slightly short of your math as to not over shoot.

[stevo585]

To temporarily change subject:

Do you guys think the stage II EL flash could be ran with a gutted cat stock header? Anyone tried this yet? I'm still not convinced the stock header design is all that bad but rather restricted by the cat.

[AdrianG]

Originally Posted by stevo585

To temporarily change subject:

Do you guys think the stage II EL flash could be ran with a gutted cat stock header? Anyone tried this yet? I'm still not convinced the stock header design is all that bad but rather restricted by the cat.

That's the tune I would use.

- AdrianG

[phrosty]

I modified 1.58 Stage 1 700D with the MAF table for my Perrin 2.75" CAI. Also have a P&L catback. Here's a 3rd gear pull — how does it look?

http://datazap.me/u/phrosty/oft-stag...=0&data=1-9-11

[Kodename47]

Originally Posted by phrosty

I modified 1.58 Stage 1 700D with the MAF table for my Perrin 2.75" CAI. Also have a P&L catback. Here's a 3rd gear pull — how does it look?

http://datazap.me/u/phrosty/oft-stag...=0&data=1-9-11

Why didn't you use the A01D or B01D ROM? IMO try and use the latest ROM available that's compatible.

[phrosty]

Originally Posted by Kodename47

Why didn't you use the A01D or B01D ROM? IMO try and use the latest ROM available that's compatible.

My base ROM is 700D. OFT only lets you upload the same as your base.

[uncivilised]

ive been logging my e85 tune on my stock 86 using the latest OFT stg2 EL e85 tune.

so far it has stable afr between low 12s and mid 11 through out the rev range, IAM pegged at 1 and stable kc learned value.

my question is that i have a 4-1 catless EL header going on, will the tune re-learn for the header or will i need to reflash again?


my last log http://www.datazap.me/u/uncivilised/lol2-0

[2point0]

Originally Posted by uncivilised

my question is that i have a 4-1 catless EL header going on, will the tune re-learn for the header or will i need to reflash again?

I don't think you'll need to reflash necessarily, but with any big change like that, it's good to reset the ECU. This can be done by pulling the negative battery cable for a few minutes.

[Kodename47]

Originally Posted by 2point0

I don't think you'll need to reflash necessarily, but with any big change like that, it's good to reset the ECU. This can be done by pulling the negative battery cable for a few minutes.

Does the OFT not have qan ECU reset function?