Removing Smog pump, AIR: $8D 730 modifications
 

Found some cool stuff while looking through the code today. It seems that whenever the AIR management system diverts air then the ECM changes the O2 sensor thresholds by 100mV. This, logically, makes a lot of sense. If the ECM is basing INTegrator updates off of the O2mV then it needs to account for the extra oxygen in the exhaust. This is done by subtracting 100mV from the R/L threshold. Thus, the INTegrator will not change even though the O2 sensor is registering more oxygen in the exhaust.

What does this mean?

Well, if you removed the AIR pump then you are going to be running leaner than 14.7 whenever the ECM is commanding for AIR to be diverted to the exhaust manifolds. This is because the O2mV threshold has been reduced ... but you don't have the extra O2 in the exhaust that would require this change in threshold. So, the INT will subtract fuel to get the O2 voltage within the proper range (which is now 100mV lower).

To rectify this situation there are a couple choices:

1) Change the mV that is subtracted from the Rich/Lean Threshold. Change the constant at 849D (DIFF R/L WHEN AIR DIVERTED) from 100mV to 0mV.

Or, the better way,

2) Disable AIR completely. As far as I can tell, change the minimum temperature for AIR at 839A from 14.75 deg C to 254 degrees C.

My guess is that if you have removed AIR from your car and have not disabled AIR then the BLMs will be a little more erratic than if the system was disabled. Why? Because AIR is not always diverted. Thus, sometimes the INT will be based off of the O2 threshold and sometimes it will be based off of the O2 threshold minus 100mV.

Sweet.

Tim

intresting.. would that be enough of a diff to see a increase in hwy miliage?

because after i removed the air pump, my MPG went up.... not a whole lot, but def up...

Yes, I think this is possible. During normal driving the AIR system will route air to the exhaust manifolds if the load is between 20-60kPa AND the mph is less than 60. This is called "Low Load mode" in the hac.

Tim

Probably a dumb question, but where or what table in Tunercat do you change to disable AIR ? Or can you even do that in tunercat?

Sorry, but I looked in Tunercat and cant find it !

:confused:

Constants, Tables, etc are predefined in the definition file. It's not that TunerCat doesn't have it. It's that the definition file has not been configured to show it. I use TunerEditor (made by TunerCat) to modify the definition files (TDFs). TunerEditor allows you to add, delete, and modify anything you want with regard to constants, flags, and tables. In short, if using TunerCat, you need to use their TunerEditor to add a new constant to the TDF. This constant is located at 39A.

Tim

Offline question: Trax, you have mail! ;)

Tim,

Ive posted before in here if the 02 takes in account what the pump is pumping into the exhaust, but everyone was like "no".. Glad you found out..

...but...

Does the mv change by .100 only when AIR is directed to the manifolds? Or when its directed to the cat? Or Both?

It would seem to not make sense to mess with 02 voltage when air is diverted to the cat.

Also remember, in PE AIR goes to divert to atmosphere (filtered)

If I remember correctly when I was messing with it for emissions, after closed loop air never goes to the manifolds.

-- Joe

Technically, 100mV (102mv for ARAP) gets subtracted from the rich/lean threshold ... not from the A/D O2 sensor voltage. This basically yields a threshold that is leaner during AIR Management ... which is what we would expect now that more O2 is in the exhaust.

As far as I can tell, this is only done when air is injected into the manifolds, not at the cat. There are three sections where this happens. They all access #2 of L003F which is I believe just the manifold bit. Bit 1 is '1' when air is being injected to the manifolds and not diverted to the atmosphere. Bit 2 is '1' when air is injected at the cat and not diverted to the atmosphere. I believe that #2 of L003F is Bit 1? Can anyone clarify this?

XXXX X00X for everything diverted
XXXX X11X for Air at the manifolds and Cat
XXXX X01X for Air at the manifolds and NOT at the Cat
XXXX X10X for Air at the cat and NOT at the manifolds

Notice that bit 1 doesn't mean the first bit. It's actually the second bit because the first bit is bit 0.

Example code

As far as I can tell, from the code and from previous scanned logs, Air does go to the manifolds during closed loop as specified in the previous post about low load situations...

Tim

Tdf edited. Thanks Tim.

-- Joe

I have always wondered how that was handled, The same thing I was worried about with my crankcase evacuators. If you have a bad leaking valve cover or such it will let you know quick by sending BLM to 160 and burning your eyes out.
But long as your engine is decently sealed it works great. But I also found if you get a little blowby then it reads slightly richer

Do you know where and/or if it can be disabled in the $6E 165 ECM?

Try setting address 324 to 254.

Tim

What do you mean by crankcase evacuator? Do you mean a breather? If so, then I don't think that makes sense? I'm running a breather on each valve cover with no problems at all. Furthermore, more importantly, the stock setup pulls fresh air from the throttle body (basically just a routed breather AFTER the MAF).

Tim

i think hes refering to what happens if you let un metered air into the crankcase.... like if you have a leaking valve cover gasket or somthing...

NO TIM,
Not a breather.... A crankcase evacuator!
It uses vacuum from a venturi if you will, welded approx 1" after the primaries tubes in the header creating vacuum from the exhaust stream.
How a venturi workes is: air being passed over an opening (even though subject to preasure) causes a vacuum in the venturi. You then route that to your valve covers allowing you to have negative pressure in your crankcase. Much more effective than a breather - because pressure spikes in the bottom end causes oil to be splashed about all of the rotating assembly.
Also with breathers, oil leaks drips are common arount the front and rear seals and much less likely with negative pressure .
You would be surprised how much vacuum they can pull even with exhaust on.
So I hope it makes perfect sense to you now if you have a bad oil leak that would introduce fresh air into the crankcase which is then pulled into my header will and has caused o2 to falsely read
a/f.
I have unhooked them to see how bad it would effect 02, is does so very bad, just like a bad collector gasket does.:)
:)

here ya go..
Moroso Crankcase Evac System
A great way to clean out your crankcase.
These Moroso crankcase evac systems reduce crankcase pressure throughout the entire rpm range for increased piston ring seal, reduced intake charge contamination, and fewer oil leaks. They've been track and dyno tested to produce significant increases in engine performance. Includes two of each of o...

Trax where can I find the hack for the $6e if that is what you are looking at or is that a $32 one.

Another question. When it refers to divert in the comment does that mean to atmosphere or to manifold??????:confused: :confused:

I am running a heated O2 and I have removed the smog setup. The control for the heater is run off pin A3 on the ECM (Vader’s diagram). Would setting the minimum temperature for AIR at 839A from 14.75 deg C to 254 degrees C make the O2 heater never to come on? An ECM test bench would really come in handy right about now.

I emailed tunercat and they added "AIR Divert Enable Coolant Temp." and "AIR Divert O2 mV Rich/Lean Thresh Reduc." constants to the Constants table in the $8D calibration.

Edit: Ignore this, i pin A3 is not the smog solenoid

Of course he did :D I asked him to over the weekend. TC is always really good about adding stuff. Kudos to TC!!!

Tim

Is the CCP % added to the new TDF as well? (forced idle cell 4)

It's been in there for months.

Tim

It would help if you mentioned what pin A3 is in your post. Most of us wouldn't remember off hand, and would have to take the time to look at the schematic.

-- Joe

Real World experience: FWIW, I disabled AIR by setting the Min Temp enable to 151d C. This worked like a charm. Both AIR to Manifolds and AIR to Cats was never demanded by the ECM as verified via Datamaster and a 20min drive in both City Traffic and Highway, and open and closed loop.

Tim

I was asking this myself. Since I know in real world degrees celcius the highest it goes is 151.25 which is FF in hex. That make sense?

Hey Tim I made the change to the TDF at the location you specified and it looks great. I will test it tomorrow in car. How would I check to make sure everything is corresponding well without testing in car or on the bench if any?

I guess I'm not understanding the big deal here. I thought the only time you get AIR to the manifolds is in warm-up "mode", therefore, the time that you would be getting the added O2 before the O2 sensor would only be 2 minutes at most (Should only take 2 mins for an unheated O2 to get to sufficient operating temp, around 600-800 degrees F, and about 30 secs for a heated one).

I may be missing the point, because I haven't studied the code, but I'm going by what I've been taught in the general repair field.

This may be one of those many things that REALLY deviates from the stock type programming that I deal with day in and day out!

I use Datamaster and in Datamaster you can view the on/off status of many bits (highway mode, Decel Lean, TCC, etc.). Among these on / off bits is the AIR Dvtd and the AIR Port. When set to '0' in datamaster then everything is being diverted to the atmosphere. When something is '1' then AIR is being injected. Mine is '0' all the time now.

Tim

That's the problem. That statement is not entirely true. I have tons of datalogs with AIR being injected during normal driving. This is AIR being injected at the manifolds ... which DOES affect the O2 sensor. Furthermore, this happens A LOT. This is not just a simple inject at the manifolds every now and then. It happens a lot. On the other hand, I think your statement is true for AIR being injected at the Catalytic Converter. None of my scans show AIR being injected at the converter during normal driving after warmup.

Tim

Just when I think I'm starting to figure some stuff out.....

I guess I just never realized that! I'm glad to know it though, since I most likely will not have AIR on my car. I know it doesn't need to, but it just doesn't make much sense to me to inject AIR into the manifolds after warm-up. Gotta love some of the crazy stuff GM does! From what I have learned in the auto repair aspect of things, the AIR to the manifolds was just used to help heat the O2. Although, now that I think about it, the LT1's have AIR, and heated O2's. I suppose that answers my next question, about whether they do it on newer vehicles.....

Looks like I need to spend a whole lot more time in the code, learning it, so that I MIGHT one day know what's going on! :)

I definately understand the basics of how it all works, and even some of the semi-advanced stuff, but this one is in a new monster, and I don't think I'm really gonna have to deal with it. Maybe I can just get rid of a few lines of code that will no longer be needed? It will take some time before I know the code that well, but that's the direction I want to go!

Thanks for all the time you put into all of this stuff Trax, it really helps the guys like me that are just learning!

I am not aware of any ecu/tdfs that have the constant to disable air. I don't know how to manually edit hex(or whatever)..

The AIR injection has nothing to do with heating the O2 it is used purely for emotions; in fact it is actually cooling the exhaust gas. The reason DIFF R/L WHEN AIR DIVERTED is in the code is to account for the biased O2 reading that will occur from dumping air into the manifolds.

As stated above tunercat updated their definition file. Just email them and ask them for the latest version.

I'm coming in one this subject three years later with essentially the same lack of understanding as when I started reading this.

I have a TBI to TPI conversion controlled with a 730 ECM and am using the latest version Tunerpro RT To reprogram for the fact that I've removed the AIR system seems like a good thing to consider, but I still can't find the chart, map table etc in Tunerpro Rt to modify disable the AIR system aspects of the computer. I don't know code. If I can turn it off or disable it from a flag or map, Ii can propably handle that.

Go to the TP site and get the super_8dm2 ecu file from the bin definition section of the downloads. Then import it via the xdf "tab" at the top of TP.
The very first constant should be Air enable minimum Temp.

You can thank 69 Ghost for the ecu file......

Apparently I had an earlier version of the definition which does not show that entry as the first constant. I went to the Tunerpro site and found the "super" definition.

I had some trouble downloading it until I dragged it screaming and kicking onto my desktop. Prior to that, if I clicked on it. I could see the entry, but was not able to capture the information in a manner which I could download into my computer . I just saw it as a worksheet.

The new listing has all the constants flags and tables in alphabetical order whereas the old one was not. So if anyone is reading this meassage take a look at your Super-8dm file. If the entries are not alphabetical, then you have an older copy of the file. You might want to update it as well.


Thanks to Z69 and Ghost for the help! Another mystery has been solved.

So If i get the rest of this message correctly, I need to crank the enable temperature way up to "disable" the A.I.R. system. It is showing up as 140C before I start playing with it. Seems like 151.25 is as high as it will go in the program.


This also answers why I couldn't find the VATS turn off field as well.... old definition file,. Thanks boys!

Anyone have the def. for $6E code? I saw it above but cant do it myself. I downloaded TDFEditor from tunercats site but it needs a password to be unlocked. Any help is welcome.

The above related to Tuner Pro only.
And the included 6E definition for TP doesn't include the min. air temp constant. I'm not real familiar with the 6E and there may be another way to do it.

I'm going to bump this to the top to see if anyone else has any idea where the info is on the '165 ecm. I have deleted all my air crap and I would like to tune this out.

the purpose of the air injection is to speed the heating of the oxygen sensor, then to speed the 3way cat lighting up

check this out then put on a twoway cat
https://www.thirdgen.org/forums/elec...ghlight=heated

In the APYP 165 relocatable hac,
Could disable it by the coolant temp.
The main offset for divert is here.

Code:

---

LC454: .db 0x17  ; 23d = 100 mv, Diff R/L when air diverted

---

Re: Removing Smog pump, AIR: $8D 730 modifications
 

Does anyone know how to disable AIR from the 165ecm with $32B code? I'm using tunerpro.

Re: Removing Smog pump, AIR: $8D 730 modifications
 

Re: Removing Smog pump, AIR: $8D 730 modifications
 

Exactly what are we supposed to do with that? I remember a while back there was an extended .ecu or .xdf that I ran in Tunerpro that allowed me to modify alot more parameters, whatever happened to this? I don't understand what the text you're giving us here is good for.

Re: Removing Smog pump, AIR: $8D 730 modifications
 

He is showing you the memory addresses of what needs to be changed. He figures you could edit your .ecu file.

-- Joe

Re: Removing Smog pump, AIR: $8D 730 modifications
 

Yeah problem is alot of us can't, I added to my .xdf using Tunerpro at address 324 (what it shows in the hac for the ARAP.bin). Now I can turn it from 0 to 255, what's the conversion for this? Can I just set it to 255 and being at the max, it work? It would seem to me that this will be just the same as setting it to 304 degrees or whatever the top end of the CTS is.

Re: Removing Smog pump, AIR: $8D 730 modifications
 

If you have a $32B chip then all that "Exactly what are we supposed to do with that?" relates to all the previous posts for the $8D, it just gives the exact locations for $32B chips only.

The Arap chips ($6E) are similar in type of code but are located at different locations.

Loc31E Air Injection Management Divert if cont > 4000 RPM & time >
Loc320 Air Injection Management If LV8 < 25 then Divert
Loc321 Air Injection Management If LV8 > 100 & MPH > Divert Air
Loc322 Air Injection Management If > 60 MPH & LV8 > then divert

Loc454 Diff Value to Make up Rich/Lean Window When Air div.(VDC *
226) subtracted.

The rest of the $6E code is before or after, what is shown just above.

If you change the $6E bin using $32B information the results will be unpredictable, some loc's are the same some are different.

The $32B code/bin has the "BASE PULSE INJECTION vs LOAD" Tables the $6E does not, so from Loc434 to Loc557 ($32B fuel table is 17 rows times 17 columns) everything is different, those locations and beyond.

Re: Removing Smog pump, AIR: $8D 730 modifications
 

Oh no, I didn't use the 32B stuff, I was reading another post regarding the $6e and the arap bin, that's where I got the address from. I just didn't understand the multiplier at the time, I think I've got it now because when I run the numbers I end up with something like 303.8 which would be the upper limit of the ECM on temprature readings. All I did with this .bin was change the enable temp to the maximum allowable, this should keep the air injection stuff from coming on yet still allow closed loop correct? I was amazed how easy it was to go into Tunerpro and modify the XDF to show me the table I wanted, I've read alot of prom tuning stuff and never heard about this until last night. Is there a guide somewhere on how to do this?

Re: Removing Smog pump, AIR: $8D 730 modifications
 

XDF conversion
1.350000 * X + -40.000000
1.350000 * [X] + -40.000000 (the Conversion to Degrees F)
1.350000 * [73 (dec)] or [49 (hex)] + -40.000000 = 58.5 F

1.35 * 255 (dec) -40 = 304.25 F

255 (dec) = FF (hex)

(deg c + 40) * (256/192)
(14 + 40) * 256/192 = 72 (dec)
73 (dec) * 192/256 - 40 = 14.75 c

The bin hack "If Cool T < 14c, (58.5f) then divert"

The Air Pump valve will divert at any temp under the set point of 58.5 F

If you set $6E Loc324 X to 255 (dec) or FF (hex) then the air pump will divert all the time under 303 F.

Re: Removing Smog pump, AIR: $8D 730 modifications
 

hello everyone. i have taken most of my air management hoses off. i was wondering what i could use to plug up the two pipes that go to my dash and the one that is on my radiator. also i was wondering how to change your computer so that when the air is removed it doesn't make your car run leaner.