Over my last weekend I was able to finally fix the EGR tube on the fiero. Last night I spent some time patching DC values and qualifiers from $24(fiero bin) and other $8D bins. The EGR DC table was propagated using values from $24, along with TPS threshold values. I cant open TP at work but iirc, $24 uses engine load in kpa for its qualifiers to enable EGR DC, also uses a qualifier for MAX threshold(higher loads). $8D uses TPS. On my way into work this morning the EGR looked like it was functioning normally, which is good. I did spot a possible issue, though. Let me start with the 3D EGR DC table, $24 uses a higher resolution table, but doesnt command and EGR DC above 50kpa, and max DC is ~44%. $8D commands 100% DC(which I didnt use those values) upto 80-90kpa, which I didnt use either just zeroed the table above 50kpa. Now in theory there wouldnt be any EGR DC commanded above 50kpa(in my mind) but I noticed EGR DC was 44%(at times) in the 60-90kpa areas. Thats weird to me because the table is zeroed out in those cells? If I dont want any EGR DC above 50kpa, theres nothing in the XDF to disable that. Or am I not understanding that right? There is only the TPS qualifiers, oh and the coolant temp V. EGR DC multiplier table. Im also going to assume that since the EGR DC table only reaches to 2000rpm that the values are interpolated above that? I didnt see a max rpm for EGR DC in the XDF either, possibly not found in hac? Or does it continue to operate no matter what RPM?

I will try to remind myself to get a datalog on the way home today.
Thanks!

 

The EGR DC% versus KPa is KPa in vacuum, not MAP. The ECM calculates vacuum by subtracting the current MAP value from the current barometric pressure reading.

> If I don't want any EGR DC above 50kpa

You will want to zero out the DC% table from 50 KPa to 0 KPa.

RBob.

 

so are you saying that the table is backwards? 100kpa being no load and 0 being WOT condition? if I zero'd out everything from 50-0 kpa then the whole table would be zero'd.

attached is the $24 EGR DC table, AUJP is slightly different but for all intensive purposes ill use this on. you can see that there is only values from 50 to zero.

 

What I am saying is that in $8D the EGR DC% table is RPM & vacuum. Which is why it goes from 80 KPa (lots of vacuum) to 0 Kpa (no vacuum). I have no idea about the $24 mask.

RBob.

 

So it is inverted from something like the spark or VE tables, gotcha. Maybe $24 is the opposite, I will ask the fiero crowd to confirm.

Ok so looking at the table in AUJP, I have zero'd out the values from 50 to 0 as you recommended. I will move those to the left and observe. Ive also built another history table and now notice the pattern, since there is a vacuum displayed in the datastream ill change the history table from MAP to Vac.

Will report back with results probably tomorrow, wife is in the hospital right now and Im home with the kid.


Thanks Bob!

 

Scratch that. EGR is functioning properly and my questions have been answered. This morning I observed effects of the EGR and found that it provides no increase in fuel milage. Depending on the duty cycle, the impact negatively affected fuel milage. As soon as DC rose above 30% I noticed an increase in BLM counts. Not satisfied with that observation I toggled EGR on and off while highway mode was active, watching NBO2 readings similtaneously. With EGR DC at or above 30%, the A/F mixture would lean out, ~30-50mV. While it helps with emissions, it doesnt help fuel milage at all, at least in my case. Toggled off, the BLM counts fell back down to where im used to observing them, some cells fell by 6 counts. So I have no use for EGR anymore.

Thanks again for your help, Bob.

 

Not necessarily. When EGR is active the ECM reduces the volume of fuel injected. You need to use the accumulated fuel pulses and accumulated VSS pulses to calculate the MPG. The increasing BLM is just from the EGR tune being a tad off.

RBob.

 

I thought S_AUJP was fully disassembled and commented? There isnt anything I can adjust to modify EGR fueling, nothing for EGR spark either iirc. I just looked at a couple of other masks last night and found that they have a modifier while EGR is open. That would explain why the mixture seems to lean out, I ASSumed there was no other way to adjust for it other than the main VE table.

 

Along with the source being released. That would be helpful, and was supposed to be that way. But without that, I can only go by the real $8D code. And just use my imagination as to what did or didn't change...

Maybe if the purveyors of S_AUJP would support their code it would be better.

RBob.

 

I looked at a PDF copy of ANHT at work today and found EGR partial pressure is included in the equation for final PW. So im going to ASSume that adjusting that 2D table will help correct BLM while EGR is active. OTOH, I counldnt find anything for added spark, except for maybe part of the highway spark logic but Im still pretty new and cannot understand much yet.

 

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.

 

That should be called the "AIR MASS CALC = " calculation.

What is being done is to subtract off the manifold pressure that is due to the EGR gases, which is the air/mass that didn't entered via the TB.

Looks like this table: "; EGR PARTIAL PRESSURE vs VACUUM", which is right before the VE table is the one to adjust.

RBob.

 

Yep, thats the table. I was also thinking that since AUJP, or any $8D bin(?), has the EGR DC set to 100%(most of the table), and im only using up to 60% in some areas. So the EGR part press table was calculated for more EGR DC, if I reduce the values in the part press table, the BLM should go down. Correct?


In the original AUJP or ANHT hac that you have, is there any kind of spark added when EGR active?

 

And if I had a question about an EBL I could get source code?

My 2 + years of effort on it is free.
All the changes have been documented. No functional changes have been made to the emmissions or EGR operation.
Only the values were changed for those who don't have it.
Instructions to restore the values is there as well as the full stock code files updated with all info known at the time that can be modified and reassembled if desired.
I don't make a dime from any of this nor do I intend to.
Sorry the support is not better. I do not know it all.
Jp

 

Big difference between a commercial product where the support is excellent, and some add-on code to an existing mask that many people contributed to. Including myself.

RBob.

 

So I am to understand that there isn't source that is able to be assembled? That it is just a bunch of patch files?

This stuff is along the same lines as $59. Help us, we want to improve it and will release everything... Haven't seen that happen either.

I've released a ton of stuff that I too haven't made a dime off of. Nor did I intend too.

RBob.