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Smog pump

Discussion in 'The Garage' started by Ledzoso, Mar 2, 2005.

  1. Ledzoso

    Ledzoso Registered Member

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    I have a while before my next inspection and want to remove smog pump. I know I will have to plug the hole on my exhaust manifolds. Is the smog pump connected to the computer? Will it affect anything if I remove it?:ears:
     
  2. Fierospeeder

    Fierospeeder Banned

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    if it is an old truck, then no.

    You will be polluting a lot more.
     
  3. Thunder

    Thunder 3/4 ton status

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    Why do you want to go thru all that work just to reinstall it when inspection time comes around again? Smog pumps really dont hurt performance espically in a truck. Unles there is something wrong with it, with it takeing it off will make no diference in the way your truck runs. Also many times when you remove them and they set around a while the smog pump freezes up and you end up haveing to buy a new one when you need it for inspection.

    If you have TBI You can remove it without the ECM throwing codes. The ECM does not look for smog pump operation. All the smog pump does is add air when the engine is cold to help clean up the exhaust till the cat starts working. After the engine warms up it just vents to the atmosphere. I have seen no diference in ECM operation between having a smog pump on and taking it off.
     
  4. dyeager535

    dyeager535 1 ton status Premium Member

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    Smog pumps do not like to be disconnected and let sit, then run again. They seem to fail quite often after trying to be reused after sitting.

    I'm not saying yay or nay, these guys are much more in tune with this stuff than I.

    "[font=Verdana, Arial] Removing Smog pump, AIR: $8D 730 modifications[/font] [font=Verdana, Arial]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"
    [/font]

    [font=Verdana, Arial]The ECM code could easily be different based on application, so that may not apply, who here knows? In any case, removing AIR won't throw a code, but it MAY cause problems you may not notice.
    [/font]
     
  5. K5MONSTERCHEV

    K5MONSTERCHEV 1/2 ton status

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    You could just take the belt off too. Id leave it.
     
  6. dirtwarrior17

    dirtwarrior17 Banned

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    unless your putting headers on i say leave it... like thunder said the power difference would be tiny. Probably won't be able to feel anything. maybe 2 or 3 hp. if you want to get some headers then i see the point but plugging up manifolds and pulling the pump just because doesn't make too much sense.

    that being said just pull the smog pump hose off of the air injection pipe and let it blow air wherever it wants... this way it won't seize from sitting and you can leave it in without actually running the air system. you can also just plug the air pipe and the end where the pump is supposed to pump air into it and leave it hooked up to the manifolds.
     
    Last edited: Mar 4, 2005
  7. chevy_addict

    chevy_addict 1/2 ton status

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    Dorian, do you have access to the source code or are you looking at the hex code? Pretty impressive if you're going through the hex :bow:

    Dave
     
  8. Fierospeeder

    Fierospeeder Banned

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    he is just quoting someone elses website that did all the work
     
  9. dyeager535

    dyeager535 1 ton status Premium Member

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    You know, you can keep your snide comments to yourself. If I wanted to take credit for it, I would. Amazing what you can find with search.

    And for the record, I would have gladly said where I got this without your prompting. If you can't keep your attitude to yourself, take it elsewhere.
     
  10. nemesis_pyros

    nemesis_pyros 1/2 ton status

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    Stupid question, but what does BLM mean? I removed the AIR system off my truck when I rebuilt my motor it seems to run good but it does seem to run a little rich, I think it may need a new O2 sensor.
     
  11. dyeager535

    dyeager535 1 ton status Premium Member

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    BLM=Block Learn Mode

    I'm fairly certain that the 7747 (truck TBI ECM) does not care nor know if the AIR pump is still there or not.
     

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