EGR tuning $8D S_AUJP

[daleulan]

BLM is only giving you the difference between the airflow the ECM thinks is there (after subtracting out the EGR that it thinks is there) compared with what is actually happening on the engine, not the actual fuel economy. I think that generation of ECM had a BPC vs. EGR calibration in there somewhere and any error in that calibration would show up as a BLM shift. There will be an emissions benefit but you should see a slight mileage improvement when looking at the pulse width at the same vehicle speed - you'd need to log injector pulse width, RPM, vehicle speed and integrate pulse width * RPM and compare against miles (or kilometres) driven to get at least a semi-accurate reading. Also EGR is usually set up to allow more advanced ignition timing - maybe 5 to 8 crank degrees - which should help your efficiency numbers. I don't know if I've ever seen a calibrated EGR system make efficiency drop, but certainly if the timing isn't adjusted up that can happen. That being said, with EGR there is a peak efficiency point where you've lowered NOx as much as you can and advanced the timing as much as you can and if you increase the flow rate any more then you get an efficiency drop - if some is good, more is not necessarily better. Just like tequila. It also should help lower the exhaust temperatures at part-throttle.

[34blazer]

I know $42 has a scaler for EGR on/off, iirc $88 uses a modifier table, and $24 as well. There isnt any modifier I could find for spark or fuel in the S_AUJP xdf, and im not capable of finding something like that in the disassembly yet. I will make a note of the items to be logged and will record while on my way home from work. Even $24 has more modifiers that could be used. When I get home ill also look thru other $8D masks to see if there is more available items, if so ill put them in the S_AUJP xdf as long as the locations match up.

[RobertISaar]

That being said, with EGR there is a peak efficiency point where you've lowered NOx as much as you can and advanced the timing as much as you can and if you increase the flow rate any more then you get an efficiency drop - if some is good, more is not necessarily better. Just like tequila. It also should help lower the exhaust temperatures at part-throttle.

IIRC, that threshold is where the amount of exhaust gasses in the chamber make up so much of the air/fuel charge where misfires are inevitable. i would take a guess at saying that a stronger ignition system would allow higher concentrations.

[34blazer]

IIRC, that threshold is where the amount of exhaust gasses in the chamber make up so much of the air/fuel charge where misfires are inevitable. i would take a guess at saying that a stronger ignition system would allow higher concentrations.

well, I just set the DC at 60 in the 50-60 kpa MAP range, and 30-40% in the 40 kpa range, havent noticed a misfire yet. $8D has the DC set at 100% thru most of the range, I dont think the little 660 could handle that LOL.

[34blazer]

I managed to find a PDF copy of the ANHT hac(limited access at work), looks like $8D uses EGR partial pressure to adjust fuel requirments, the equation is there so Ill have to figure out which way to adjust that table so it doesnt skew my BLM counts too much. Not sure on the the spark yet....

[34blazer]

so using this calc....

VE CALC = ((MAP - EGR part press) * CYL VOL)/((MAT + 233) * 128))

increasing EGR part press value will reduce VE? trying to get the BLM's to not jump up 5-6 counts while EGR is active, already had some bogging this morning when the engine wast totally up to running temp.

[JP86SS]

The PDF of the ANHT is seriously flawed and has errors even though it helped to get the AUJP commented.
Download the AUJP files from Moates site (or here if EagleMark has them)
AUJP_JP2.zip is updated and commented as much as was known at the time it was posted.
ALL calibration values are in the S_AUJP there is nothing to add. All addresses in the calibration section of the bin are accounted for.
Verification of some of the uncommon items is still needed.
Nobody has all the info on them and I was hoping more people would investigate them and help solve them all.
If you find anything that could or should be clarified, post it up or something so it can be corrected.
Thanks,
John

[EagleMark]

John, Moates no longer has fileman, Craig gave us all the files for safe keeping when their site crashed and decided to leave it that way.There is a link on Moates site to here.

http://www.gearhead-efi.com/gearhead-efi/

[34blazer]

The PDF of the ANHT is seriously flawed and has errors even though it helped to get the AUJP commented.
Download the AUJP files from Moates site (or here if EagleMark has them)
AUJP_JP2.zip is updated and commented as much as was known at the time it was posted.
ALL calibration values are in the S_AUJP there is nothing to add. All addresses in the calibration section of the bin are accounted for.
Verification of some of the uncommon items is still needed.
Nobody has all the info on them and I was hoping more people would investigate them and help solve them all.
If you find anything that could or should be clarified, post it up or something so it can be corrected.
Thanks,
John

Thanks John!

I only used the ANHT due to it was the only doc I could use at work. Once I got home I verified everything I was looking at using the hac you posted. I wasnt sure if everything was there especially after looking at other definitions, seems really basic. I also wasnt sure if AUJP commanded additional spark advance while EGR is active like others defs do. Im just starting to understand very basic parts of a calibration so thats why I ask, before I blow something up.