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Thread: Best AFR values for emissions?

  1. #11

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    Hmm...I'm thinking it's still in Closed Loop, even with Learn off, isn't it? Your 3.6% CO would indicate that's the case because if it was really at 14.7:1, your CO would be almost zero. Can you plumb the air pump into the downstream exhaust where it won't do anything? Either that or turn both Learn and Closed Loop off.

  2. #12

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    Quote Originally Posted by 351C Sniper View Post
    You might want to read this: http://www.idahovip.org/faq.html
    And especially "This program was established based on EPA standards, which state that a visual inspection shall be conducted on all applicable model years. The purpose of the visual inspection is to ensure the vehicle has all the emissions control devices originally required by the manufacturer pursuant to the requirements of the Clean Air Act and they appear to be in good working order. To remove or render inoperative any emissions control device or element of design installed on or in a motor vehicle or its engine in compliance with federal regulations is prohibited and constitutes “tampering.” “Tampering” is defined by the Clean Air Act of 1970 (revised in 1977) to be the removal or rendering inoperative of any emissions control device or element of design installed on or in a motor vehicle or its engine in compliance with federal regulations prior to its sale and delivery to the ultimate purchaser, or for any person knowingly to remove or render inoperative any emissions control device or element of design after such sale and delivery to the ultimate purchaser (Clean Air Act Section 203(a)(3)(A)). For the purposes of the Canyon County and City of Kuna I/M vehicle emissions testing program, vehicles that are found without emissions control devices will fail the emissions test until the vehicle is brought back into compliance with manufacturer emissions control device specifications. Consumers should be aware that if the emissions control device is not working properly and is still intact on the vehicle and the vehicle is under eight (8) years old and under 80,000 miles, they may qualify for a manufacturer warranty for emissions control devices. Waivers and extensions will not be granted for vehicles with tampering-related emissions test failures in accordance with federal guidelines (40 CFR 51.360
    Thanks for that information. Yeah, this is why I'm installing a smog pump. The engine is out of my '81 Bronco that was totaled. It didn't have a visual inspection. But now that I've put the engine into an '85 body, it requires them to be present. I've restored them, and I'm passing the visual inspection just fine. The air/smog pump is installed and working.

    Quote Originally Posted by zwede View Post
    Hmm...I'm thinking it's still in Closed Loop, even with Learn off, isn't it? Your 3.6% CO would indicate that's the case because if it was really at 14.7:1, your CO would be almost zero. Can you plumb the air pump into the downstream exhaust where it won't do anything? Either that or turn both Learn and Closed Loop off.
    As far as I know, Closed Loop IS Learning. Open Loop turns Learning off. They're a 1:1 relationship. Either way, basically, I removed the belt to the smog pump, let it learn properly, put it into Open Loop, and put the belt back on. That made it so that it didn't re-correct itself once the extra air was introduced. The idea worked, it just wasn't close enough.

    As for switching them, I could, but it's not that simple. The threaded holes for the WBO2 sensor and the smog pump valve are totally different. Also, the smog pump goes into 1 of 2 manifolds, whereas the O2 is after the Y collector. It'd put the O2 about 8" away from the head, which seems really close. Doable, but at this point, it's a bit of a project to switch them.

    I almost passed last night. Unfortunately, as I got my idle to pass - my high speed got thrown off, so it failed. Foolishly, I didn't save the fuel map for the passing high speed, so now I have to figure it out again. Not having the computer relearn on its own is a bit of a pain. However, now I'm going to just tweak it by hand until it passes. That way, I can make subtle changes and see what they do. I leaned both out very slightly, and will see how they do again this evening.

    Idle
    CO%
    Result Standard Test
    PASS 1.20 1.13
    HC (PPM)
    PASS 220 179

    2500 RPM
    CO%
    Result Standard Test
    FAIL 1.20 2.08
    HC (PPM)
    PASS 220 86
    1985 Ford Bronco. 300 (305) ci inline 6. 9.1:1 compression, P&P head with enlarged valves, high flow exhaust. 32" BFG A/T tires. 5 speed ZF5 manual transmission with 3.55 rear end. Holley 550-850 2300 Sniper EFI.

  3. #13

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    Maybe it's different on the Sniper, but my HP has a separate setting for Closed Loop on/off and Learn on/off.

    Considering you'll have to do this every year going forward, have you considered gutting the AIR pump? It just needs to be present and look OK, it doesn't actually have to do anything.

  4. #14

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    I'm strongly considering it, considering I've passed many times without it. It can help with HC, but I don't think that's a problem I'm facing.

    The other thought I had is I have a diverter valve that goes with it. If I install it and then connect it to constant vacuum, it'll continually vent the air pump to atmosphere, instead of into the exhaust stream. This would allow me to let the computer do its job. I might try that.
    1985 Ford Bronco. 300 (305) ci inline 6. 9.1:1 compression, P&P head with enlarged valves, high flow exhaust. 32" BFG A/T tires. 5 speed ZF5 manual transmission with 3.55 rear end. Holley 550-850 2300 Sniper EFI.

  5. #15

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    Quote Originally Posted by zwede View Post
    Maybe it's different on the Sniper, but my HP has a separate setting for Closed Loop on/off and Learn on/off.
    Considering you'll have to do this every year going forward, have you considered gutting the AIR pump? It just needs to be present and look OK, it doesn't actually have to do anything.
    Looks like you are right. When I went back, there was both the option to disable Closed Loop & Learn, separately. Probably should have turned off Learn, instead of Closed Loop, but it seemed to closely accomplish the same thing. Either way, the air pump is "bypassed", so now it's not pumping in fresh air. I can turn Learning back on, and have the computer handle it while I'm running the test. The only issue I'm having is that with the idle AFR turned up to 14.7, I can't seem to get the IAC lower than 20% at idle, so it likes to "dance" and waver between 13.5 and 16.0 AFR while the RPMs waver between 650 and 850 RPM. That seems like it'll throw my test values off by going back and forth between rich/lean, instead of sitting at stoichiometric. Not sure how to fix it.
    1985 Ford Bronco. 300 (305) ci inline 6. 9.1:1 compression, P&P head with enlarged valves, high flow exhaust. 32" BFG A/T tires. 5 speed ZF5 manual transmission with 3.55 rear end. Holley 550-850 2300 Sniper EFI.

  6. #16

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    They allow up to 1.2% CO at idle, so you can set your idle target a bit richer than 14.7 and still pass. A true 14.7 mix will be just about 0% CO. Try 14.2 at idle, that should still be well below 1.2%

  7. #17

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    Quote Originally Posted by 85 Phoenix View Post
    Looks like you are right. When I went back, there was both the option to disable Closed Loop & Learn, separately. Probably should have turned off Learn, instead of Closed Loop, but it seemed to closely accomplish the same thing. Either way, the air pump is "bypassed", so now it's not pumping in fresh air. I can turn Learning back on, and have the computer handle it while I'm running the test. The only issue I'm having is that with the idle AFR turned up to 14.7, I can't seem to get the IAC lower than 20% at idle, so it likes to "dance" and waver between 13.5 and 16.0 AFR while the RPMs waver between 650 and 850 RPM. That seems like it'll throw my test values off by going back and forth between rich/lean, instead of sitting at stoichiometric. Not sure how to fix it.
    To, in effect, disable the IAC. You can set the idle speed very low using the handheld, say 400 RPM. Then use the adjustment screw to set the idle speed. This will cause the IAC to stay closed (trying to lower the idle down to 400). Also set the IAC hold position to 0, to eliminate it from the equation at all RPM. Without re-reading this thread, I think I'd let the ECU Learn best it can 1st. Then turn off Closed Loop & Learn. Then enable the air pump. Then adjust the "Target Air/Fuel Ratio" to give you the best results at the smog machine. Can set the idle A/F Ratio and cruise A/F Ratio separately to help emissions in each part of the test.

  8. #18

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    Thanks for the tips. What I ended up doing was a culmination of a lot of the above. I ended up bypassing the smog pump, so that it just blew the air out to atmosphere and I could leave the ECU in Learn mode. For the idle, I found that if I put the RPM down to around 550 - 600, it would get the IAC where it needed to be. Also, I found that putting the Closed Loop Speed up to 1 kept it from "surging" at idle, and it held the lean AFR much tighter.

    This is with a 14.7 AFR set for both idle and 2500 RPM. The idle still wavered a small amount, but the 2500 RPM was pretty rock solid. Still...I barely passed. Still, a pass is a pass and I don't have to worry about it for 2 more years. With both set at 14.7, and holding pretty steady, I'm not sure why it passed so poorly. It did pass a lot better in other tests (just not at the same time), so I know it's not something like the cat, at least. Thanks for all the help everyone.

    Idle
    CO%
    Result Standard Test
    PASS 1.20 1.07
    HC (PPM)
    PASS 220 155

    2500 RPM
    CO%
    Result Standard Test
    PASS 1.20 1.19
    HC (PPM)
    PASS 220 80
    1985 Ford Bronco. 300 (305) ci inline 6. 9.1:1 compression, P&P head with enlarged valves, high flow exhaust. 32" BFG A/T tires. 5 speed ZF5 manual transmission with 3.55 rear end. Holley 550-850 2300 Sniper EFI.

  9. #19

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    Even if you only ran it super rich for a little bit you probably gunked up the cat (carbon). Hopefully it will burn off over time and start working better again. An hour on the highway should help greatly. Also, idle emissions get worse the lower the idle speed. An old trick for passing idle tests is to set the idle speed to the max they allow (usually 1,000 - 1,100 RPM). You should adjust your throttle stop so the IAC is around 5% at idle.

  10. #20

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    I suppose that's possible, and entirely probable. It passed two years ago with the carburetor at much lower levels at both idle and 2500 RPM. I'm wondering if the cat is just getting old as it is (about 10 years). Running it too rich for the bit that I did might have sped up its demise. Good to know at the higher RPM at idle. I'll try for 1100-1200 next time. We get 775 +/- 425. So, 350 to 1200. Does the same go for high speed? We are allowed 2200-2800.
    1985 Ford Bronco. 300 (305) ci inline 6. 9.1:1 compression, P&P head with enlarged valves, high flow exhaust. 32" BFG A/T tires. 5 speed ZF5 manual transmission with 3.55 rear end. Holley 550-850 2300 Sniper EFI.

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