Can't lean out the PE

[RRRocketMan]

The Camaro has always run ridiculously rich from the factory and after I installed my wideband I got to see exactly how rich... down into the high 10s for a completely N/A car. So today I had enough and went through my tune to try to lean it out.

Re-wrote my PE table - Nothing happened
Went to the "Open Loop" section and cut all the multipliers by 50% or more - Very little effect
Even went so far as to lean out the boost enrich table - still nothin

WTF?!

I'm sure others have gone through this process themselves so can anyone please tell me which key tables need to be changed in order to get rid of the killer enrichment? I've managed to get up to low 11's but this is still unacceptable. I want 12 - 13.5 until I'm boosted.

Thanks.

[5FDP]

Post tune.

The power enrichment EQ ratio is what you would adjust for your WOT afr target. If your target AFR differs from the actual AFR you have to tune the VVE and MAF to fix the issue. Remove from them to lean it out or add to them to bring in more fuel.

[RRRocketMan]

But does not the PE multiply the current fuel dosage being commanded by the VE table? If I cut the PE table in half should I still not see a difference?

[5FDP]

Your boost enrichment table is richer than your EQ ratio table.

Could be very likely that no matter what you change your EQ ratio to, it never gets leaner.

Make all 3 the same. EQ ratio, Boost EQ and alcohol EQ, make them all 1.175.



Then if that doesn't work, start removing 3-5% at a time from the VVE to see if it gets leaner.

[RRRocketMan]

Your boost enrichment table is richer than your EQ ratio table.

Could be very likely that no matter what you change your EQ ratio to, it never gets leaner.

Make all 3 the same. EQ ratio, Boost EQ and alcohol EQ, make them all 1.175.



Then if that doesn't work, start removing 3-5% at a time from the VVE to see if it gets leaner.

Ok I'll give that a shot and get back to you.

[luciddeath]

Just a quick thought.. Did you multiply your maf by 2? Seem's pretty high to me.

[RRRocketMan]

I'm running MAFless but I still update the MAF when I do a roadscan for some paranoid reason. I have no idea how far off it is from stock but it's based on my histograms and whatever they spit out.

[RRRocketMan]

So a little update... I've cut down the top end of my VE table a good amount and reduced ALL PE entries to 1.04, which is nothing. I'm still still running at low 11.somethings according to my wideband despite the commanded AFR being quite a bit higher than that. I don't know what could be causing this except the injectors. I did upgrade them to DW 650cc injectors but I imported all the data as I was told to do it. Granted my trims were immediately off by about 30% and I had to dial that back in, which I thought was odd but at least my closed loop operation is pretty much tuned in now... but this PE. Nothing I do seems to touch it. I'm tempted to just null out the entire PE table to 1.0 and keep doing that with the rest of the tables until I see a change in my WB.

Has anyone ever experienced this before? It's really pissing me off not being able to change my AFR at all.

[RRRocketMan]

BTW, does anyone happen to know what the actual formula is for AFR calculation?

AFR = ________ ?

[5FDP]

Well I guess it equals whatever you want/need it to be. Or 14.70 parts air to 1 part fuel.

Like stoich in AFR from regular non ethanol fuel is 14.70, E10 would be 14.10ish

You based the AFR you want to run off of what the stoich value is. So if you wanted to run 12.5 AFR under WOT with a stoich of 14.68 your EQ ratio would be 1.175.

[roastin300]

Actual AFR is calculated by measured lambda/equivalence ratio and an assumed stoichiometric AFR which is an input in your tune. You should be calculating equivalence ratio error instead of AFR error. If you do use AFR error then make sure the output from your wideband is using the same stoichiometric AFR as your tune. If you change this then the wideband voltage output slope will change!

Just eliminate these issues and have the wideband output the voltage based on lambda or equivalence ratio. Remember lambda and equivalence ratio are inversely proportional.

[RRRocketMan]

I misworded my question. What I meant was, in every ECM, the computer figures out AFR by doing a calculation to determine what the IPW needs to be, which is the only thing the computer cares about... how many mS to energize the injector solenoid per cycle. This number, whatever it is, is determined by a complex interplay of variables; Some sort of base value (VE or MAF), which is then augmented by a ton of scaling factors (temperature, PE, TPS, TQ managment, bleh bleh bleh) until you finally get something out that can be converted to IPW via the injector calibration tables. So I was wondering what the big-ass equation was that is used to calculate the final air fuel ratio. Back when I tuned my old grand am, the equation was available. Not sure how but somebody knew what it was because I found it in a tuning guide. For the Camaro, I'm not sure such info exists but my end goal is to figure out how many tables the ECM looks at and pulls values from to come up with AFR because so far, nothing I've touched has had any effect on it. The trial and error system has failed so now I'm shifting gears to the theoretical model behind it.

[roastin300]

The computer does it the other way around. It looks at the measured/estimated air mass and the Target AFR and then calculates a pulsewidth and sends it. Your question sounded like you are thinking the opposite

the computer figures out AFR by doing a calculation to determine what the IPW needs to be

I dont know the exact equation, but maybe this will help? The parameters used to calculate the commanded injector pulsewidth for it, I would assume based on other more "open source" engine calibration systems I have used, would include the following:

Measured Airflow if MAF is being used (i.e mass/time)
VE %
IAT and Coolant Temp to estimate/calculate charge density
IAT/Coolant Temp charge density influence/bias
Calculated Cylinder Air Mass from the above
Cylinder Displacement
Number of Cylinders
RPM
Target AFR
Stoichiometric AFR value
Injector flow rate
Fuel Pressure and Manifold Pressure (both influence flow rate)
Engine Cycle (4-stroke)

[RRRocketMan]

The computer does it the other way around. It looks at the measured/estimated air mass and the Target AFR and then calculates a pulsewidth and sends it. Your question sounded like you are thinking the opposite



I dont know the exact equation, but maybe this will help? The parameters used to calculate the commanded injector pulsewidth for it, I would assume based on other more "open source" engine calibration systems I have used, would include the following:

Measured Airflow if MAF is being used (i.e mass/time)
VE %
IAT and Coolant Temp to estimate/calculate charge density
IAT/Coolant Temp charge density influence/bias
Calculated Cylinder Air Mass from the above
Cylinder Displacement
Number of Cylinders
RPM
Target AFR
Stoichiometric AFR value
Injector flow rate
Fuel Pressure and Manifold Pressure (both influence flow rate)
Engine Cycle (4-stroke)

I've scoured the tables in HPT and changed everything I can and still no effect. My last resort is to change all tables to 1.0 and see what that does. If it's still rich, I have to conclude that the injectors are way out of calibration and that the only thing maintaining stoich in closed loop is the fuel trims... but even that doesn't make sense because I tune my VE table to get rid of the trims. Maybe something is wrong and the computer is going into some sort of limp mode and enriching the fuel? I have no MIL lights so this is very bizarre. Still pegged to low 11s every time I go WOT.

[reubone]

can you post a data log please