Removing Smog pump, AIR: $8D 730 modifications
12-20-2008, 09:07 PM
#51
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Re: Removing Smog pump, AIR: $8D 730 modifications
i see all of yall talkin about all these codes and stuff tryin to tune yur computer n stuff right if u take off the A.I.R system, i kno it makes it run leaner but couldnt you just get a fuel pressure regulator and turn it up a little to make it run a bit richer. Maybe to factory standards or maybe even richer, i dont know much about the computer tuning and stuff but couldnt this work??????
12-21-2008, 07:30 AM
#52
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Re: Removing Smog pump, AIR: $8D 730 modifications
You might want to read some more. If you change the fuel pressure it changes it everywhere, so how do you correct the times when the air pump isn't calling for air?
Tuning an engine is like stacking bricks, it can all be balanced but not very stable (think of a kids teeter totter or see saw).
It takes a good foundation, good bricks, and good mortar to build a strong house, same with the engine, good mechanical basics and smart tuning (knowledge) will give you a good strong engine.
Tuning an engine is like stacking bricks, it can all be balanced but not very stable (think of a kids teeter totter or see saw).
It takes a good foundation, good bricks, and good mortar to build a strong house, same with the engine, good mechanical basics and smart tuning (knowledge) will give you a good strong engine.
12-21-2008, 06:58 PM
#53
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Re: Removing Smog pump, AIR: $8D 730 modifications
This smog removal sounds very complicated. Who sells a tuner and how much are they? Would like to simplify my engine compartment. But for now I guess I will keep it. Running lean would not be good. Any simple ways to remedy or must change computer settings? Sorry I am not up to speed with you guys in computer controlled engines. 
You might want to read some more. If you change the fuel pressure it changes it everywhere, so how do you correct the times when the air pump isn't calling for air?
Tuning an engine is like stacking bricks, it can all be balanced but not very stable (think of a kids teeter totter or see saw).
It takes a good foundation, good bricks, and good mortar to build a strong house, same with the engine, good mechanical basics and smart tuning (knowledge) will give you a good strong engine.
Tuning an engine is like stacking bricks, it can all be balanced but not very stable (think of a kids teeter totter or see saw).
It takes a good foundation, good bricks, and good mortar to build a strong house, same with the engine, good mechanical basics and smart tuning (knowledge) will give you a good strong engine.
08-06-2009, 04:28 PM
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Re: 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
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
is this the same for CC Carb motors also or just for the FI motors?
12-07-2010, 05:16 PM
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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.
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.
1. In various parts of this thread, it looks like the default minimum AIR enable temp is above 58.5F.
2. However, the above quote is indicating that AIR is enabled below 58.8F. This does not make sense.
If you wanted to disable AIR you would set the minimum enable temp. to 303F. "Divert" in this case means to the exhaust manifold, I would presume, as indicated in earlier parts of the thread.
12-07-2010, 06:30 PM
#56
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Re: Removing Smog pump, AIR: $8D 730 modifications
There are three directions that the air can go (w/a two valve set up):
1) Divert, which is to the atmosphere (dumped)
2) Port, which is to the exhaust manifold(s)
3) Converter, which is to the catalytic converter
Note that is is only one of the three, never a mix of them.
While in divert the ECM subtracts the O2 offset from the O2 window. Thereby targeting a leaner AFR. However, the O2 window is richer then stoich by about the same amount that is sub'd off. So when not in divert the ECM is targeting a richer then stoich AFR.
The ECM always diverts when the CTS is below the enable threshold.
The ECM, above the CTS enable and not in closed loop sends air to port.
The ECM, once it has gone into closed loop, never again sends air to port.
In normal mode, and in closed loop, the ECM sends air to the converter.
In PE mode the ECM can send air to the converter, but usually diverts so not to melt the cat. There is a calibration parameter for "time to cat while in PE mode."
During decel the air is diverted. This is done to prevent backfires in the exhaust.
RBob.
1) Divert, which is to the atmosphere (dumped)
2) Port, which is to the exhaust manifold(s)
3) Converter, which is to the catalytic converter
Note that is is only one of the three, never a mix of them.
While in divert the ECM subtracts the O2 offset from the O2 window. Thereby targeting a leaner AFR. However, the O2 window is richer then stoich by about the same amount that is sub'd off. So when not in divert the ECM is targeting a richer then stoich AFR.
The ECM always diverts when the CTS is below the enable threshold.
The ECM, above the CTS enable and not in closed loop sends air to port.
The ECM, once it has gone into closed loop, never again sends air to port.
In normal mode, and in closed loop, the ECM sends air to the converter.
In PE mode the ECM can send air to the converter, but usually diverts so not to melt the cat. There is a calibration parameter for "time to cat while in PE mode."
During decel the air is diverted. This is done to prevent backfires in the exhaust.
RBob.
12-07-2010, 09:47 PM
#57
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Re: Removing Smog pump, AIR: $8D 730 modifications
Thx RBob, I got it now.
When the correct terms (and items are defined) it is easier to understand. Early in the thread, it was mentioned that "diverted" air was sent to the "manifolds", then air was "injected" to the manifolds.
When trying to learn, you sometimes take the meaning and use of words / phrases literally. After reading your post and re-reading the entire thread it makes more sense now.
Thanks for the clarification.
CG
When the correct terms (and items are defined) it is easier to understand. Early in the thread, it was mentioned that "diverted" air was sent to the "manifolds", then air was "injected" to the manifolds.
When trying to learn, you sometimes take the meaning and use of words / phrases literally. After reading your post and re-reading the entire thread it makes more sense now.
Thanks for the clarification.
CG
03-29-2012, 01:04 AM
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Re: Removing Smog pump, AIR: $8D 730 modifications
this is helpful to see- since i pulled the AIR stuff off my car, i get a check engine light when cruising at highway speeds for more than a few mins.. i also have non-stock 2.72 gears, and the speedo was never re-calibrated. so the speedo reads 40-50 mph on the highway. i do have some correct 3.73s to put in, but i think i will also disable air as outlined here. this site is very very helpful. indeed-o.
03-29-2012, 07:20 AM
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Re: Removing Smog pump, AIR: $8D 730 modifications
this is helpful to see- since i pulled the AIR stuff off my car, i get a check engine light when cruising at highway speeds for more than a few mins.. i also have non-stock 2.72 gears, and the speedo was never re-calibrated. so the speedo reads 40-50 mph on the highway. i do have some correct 3.73s to put in, but i think i will also disable air as outlined here. this site is very very helpful. indeed-o.
Blink out the code, likely it is EGR.
RBob.
03-30-2012, 10:17 AM
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Re: Removing Smog pump, AIR: $8D 730 modifications
dont mean to hijack a thread, but ive never messed or read or know how to read anything pre-OBDII. i was actually looking at some of the prom burning threads yesterday for the first time, but i'll look up how to read and delete codes etc. thanks for the info!
04-29-2012, 06:47 PM
#62
Re: Removing Smog pump, AIR: $8D 730 modifications
Originally Posted by TRAXION
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...
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