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Thread: Emissions fail - high hydrocarbons in exhaust

  1. #101
    Stupid Newbie DaraSue's Avatar
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    Quote Originally Posted by opethmike View Post
    I wouldn't check the reading or change the mixture until the car has warmed up.
    I was following the steps in Dave S.'s article from an old DeLorean World that said to check it first with the engine off and the RPM relay jumped to engage the lambda system. It's supposed to read 45 like that. That was when it was reading 54 whether I had the WOT switch plugged in or not. The adjustments I made today were with it running hot enough to cycle the fans. I'm just wondering if whatever issue was causing the weird readings when it was cold is something I also have to factor in when it's hot?

  2. #102
    Senior Member Bitsyncmaster's Avatar
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    Quote Originally Posted by DaraSue View Post
    Just tried adjusting and had to turn it clockwise to get it down into the 45-55 range. Do I need to compensate in some way for it reading high cold?
    There is no adjustment for the cold engine dwell. Those values of cold and with WOT closed are preset values build into the lambda ECU.
    Dave M vin 03572
    http://dm-eng.weebly.com/

  3. #103
    Administrator Ron's Avatar
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    Quote Originally Posted by DaraSue View Post
    I was following the steps in Dave S.'s article from an old DeLorean World that said to check it first with the engine off and the RPM relay jumped to engage the lambda system. It's supposed to read 45 like that. That was when it was reading 54 whether I had the WOT switch plugged in or not. The adjustments I made today were with it running hot enough to cycle the fans. I'm just wondering if whatever issue was causing the weird readings when it was cold is something I also have to factor in when it's hot?
    No, you don't...It is like Dave M said...

    Check the chart out below:
    "E:" shows the dwell should be 50-60 steady, until it is warm (15C = 59F).
    So, 54 is OK, when cold.

    "A:" shows the dwell should be 35-45 pulsating, when everything is normal including engine temp.
    So, that's where 45 would be ~OK.
    As mentioned, if it is staying at 54 under these conditions too, the LightGreen (LG) wire shared by the WOT and the Thermal Throttle Enrichment sensor/switch (in the valley) is shorted to ground, or, one of the two switches are activated. You can disconnect the LG wire from the Lambda ECU's pin #7 to eliminate all three cases....And it could be the ECU (easy to swap out for a test).

    dwell.jpg

  4. #104
    Not a DeLorean Guru
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    I think we should all hug Ron now.
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    1981 DeLorean, Carb LS4 swap completed
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  5. #105
    Stupid Newbie DaraSue's Avatar
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    I drove it to work today and it seemed fine. I'll recheck the dwell next time I have a day shift and can do it when I get home. I noticed after I got home tonight that the engine didn't seem to be vibrating at idle as much as it was before. Hopefully that's a good thing.

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