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Thread: Lambda problem?

  1. #21
    Junior Member
    Join Date:  Aug 2011

    Posts:    27

    On the right track

    Thank you for the tip on using the diagnostic plug to get a reading from. That worked great. FV tested out at 44.3. Replaced the o2 sensor and started the car, reading was 44.2 until it warmed up and then it went to 10. Seemed to run really smooth at 10, when I could hear the FV kick in the meter went 44 and ran rough. Then back to 10 after FV kicked off. Seems to me the car is running rich and needs to be adjusted up to get a consistent 44 or so before the FV kicks in. I'm I in understanding the correctly? It gets kinda to wrap your head around sometimes.

  2. #22
    Senior Member Bitsyncmaster's Avatar
    Join Date:  May 2011

    Location:  Leonardtown, MD

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    My VIN:    03572

    Quote Originally Posted by delorean82 View Post
    Thank you for the tip on using the diagnostic plug to get a reading from. That worked great. FV tested out at 44.3. Replaced the o2 sensor and started the car, reading was 44.2 until it warmed up and then it went to 10. Seemed to run really smooth at 10, when I could hear the FV kick in the meter went 44 and ran rough. Then back to 10 after FV kicked off. Seems to me the car is running rich and needs to be adjusted up to get a consistent 44 or so before the FV kicks in. I'm I in understanding the correctly? It gets kinda to wrap your head around sometimes.
    You looking to adjust it to read about 30 to 35 degrees (average) after it is warmed up.
    Dave M vin 03572
    http://dm-eng.weebly.com/

  3. #23
    Junior Member
    Join Date:  Aug 2011

    Posts:    27

    Ok

    Ok so I was able to get the car dialed in to 44 - 32.
    But still getting the hot cat only near the muffler end of it, then the car just died. Wouldn't restart.

    Does this sound like when I finally get it dialed in the cat was on it's way out and fianally went plugging the exhaust and casting the car to run poorly?

  4. #24
    Senior Member Bitsyncmaster's Avatar
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    Quote Originally Posted by delorean82 View Post
    Ok so I was able to get the car dialed in to 44 - 32.
    But still getting the hot cat only near the muffler end of it, then the car just died. Wouldn't restart.

    Does this sound like when I finally get it dialed in the cat was on it's way out and fianally went plugging the exhaust and casting the car to run poorly?
    My guess would be yes, your cat is plugged. You really need to pull it and look inside to know for sure. The honeycomb will melt when it gets that hot.

    It's also very hard to set the mixture with a plugged cat. It will be changing every few minutes.
    Dave M vin 03572
    http://dm-eng.weebly.com/

  5. #25
    Junior Member
    Join Date:  Aug 2011

    Posts:    27

    Thanks

    That's what I thought, thanks for all the help. The car was Also sputtering like it was backfiring but wasn't . Tells me that it was just backed up with back pressure

  6. #26
    Junior Member
    Join Date:  Aug 2011

    Posts:    27

    Fixed! Almost...

    Ok so I took a break from this problem to read the book closely and found that I had actually mixed up number 3 with number 1 plug wires.

    So car runs better, no hot cat. But now I have a new problem I still can't dial the fuel in with the dwell meter and I have a high idell. Rpm is about 900 to 950 when it used to be 750 consistently. I checked for vacuum leaks and only find a slight one at the w pipe where the o rings are but I replaced those.

    As for the fuel I closed the mixture screw all the way, full lean, then opened it up until I got a decent fuel injector spray. Still cannot get the dwell meter to get off 84. It fluctuates between 84.3 and 84.7. When I push the WOT switch it goes down to 53.4.

    Any ideas?

  7. #27
    DMC Midwest - 815.459.6439 DMCMW Dave's Avatar
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    Quote Originally Posted by delorean82 View Post
    Ok so I took a break from this problem to read the book closely and found that I had actually mixed up number 3 with number 1 plug wires.

    So car runs better, no hot cat. But now I have a new problem I still can't dial the fuel in with the dwell meter and I have a high idell. Rpm is about 900 to 950 when it used to be 750 consistently. I checked for vacuum leaks and only find a slight one at the w pipe where the o rings are but I replaced those.

    As for the fuel I closed the mixture screw all the way, full lean, then opened it up until I got a decent fuel injector spray. Still cannot get the dwell meter to get off 84. It fluctuates between 84.3 and 84.7. When I push the WOT switch it goes down to 53.4.

    Any ideas?
    You're still apparently running way too lean. What happens if you keep going richer? Does the idle speed up more or does the car sputter and slow down?

    If you richen and now the idle is way too high, but it otherwise seems to run OK, you are compensating a vacuum leak. If you try and accerate but the car backfires or lacks power, you are more likely dealing with unmetered air leaks.

    Your WOT switch test proves the ECU is working. You could do the service manual battery/ground O2 sensor test to verify that the ECU is working completely. Disconnecting the O2 sensor should get you to 45 degrees all the time, if that's not the case you are chasing other issues.

    Common issues:
    Unmetered Air Leaks (usually can be adjusted to idle OK but will lean misfire on acceleration and CO setting will seem erratic/lazy):
    Idle Air pipe aka "the pipe of agony" not inserted all the way in;
    Torn rubber gasket between the air metering assembly and the throttle;
    Missing o-ring under the fuel distributor

    Vacuum Leaks:
    Disconnected brake booster or auto trans modulator hose;
    Missing intake O-rings.

    Sneak Air Path (internal air leak):
    Stuck idle motor or disconnected idle thermistor (usually more like 2000 RPM idle)
    Stuck/bad decel valve springs
    Idle stop screws too far in
    Brass idle screws open
    Dave S
    DMC Midwest - retired but helping
    [email protected]

  8. #28
    Senior Member Bitsyncmaster's Avatar
    Join Date:  May 2011

    Location:  Leonardtown, MD

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    My VIN:    03572

    I agree with Dave S. Your way to lean because the lambda is trying to make the mixture richer.

    You idle speed just may be your curb idle is set to high. When the plugs were wrong it kept the idle speed down into the idle ECU control range. Make sure your three bypass screws are fully seated and then back out the lower screw on the idle arm.
    Dave M vin 03572
    http://dm-eng.weebly.com/

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