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Cold idle poor

Discussion in 'Boxers/TR/M' started by bpcurtis, Sep 16, 2022.

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  1. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    25,040
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    You have to sort out being able to get to the mixture screw -- and your post seems somewhat confusing as in post #21 you reported that you did access and turn that mixture screw -- no?
     
  2. bpcurtis

    bpcurtis Karting

    Nov 5, 2003
    79
    Dickinson, TX
    Full Name:
    Burnell P Curtis
    Sorry but i had my sides confused but now are straight. I can adjust the mixture screw of the drivers side and I get no response as it stays at 0.744 volts and wanders a bit but not much. The passenger side now has a new O2 sensor and I get the same results and it is the passenger side that I can not get the screw out. I will try a bit more but am out of options. Any thoughts as to why the drivers side is not responding?
    Burnell
     
  3. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    25,040
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    Can only say that your results seem strange (and very weird they are exactly the same) -- just to confirm, you have one of the voltmeter leads connected to the unplugged single wire coming from the O2 sensor of the bank you are measuring and the other lead of the voltmeter connected a good ground?
     
  4. bpcurtis

    bpcurtis Karting

    Nov 5, 2003
    79
    Dickinson, TX
    Full Name:
    Burnell P Curtis
    Yes, I have two voltmeters and both are connected as you described. We can assume that the passenger side is running lean and I can not adjust it. Do you know of any reason why I can not grind part of the covering around the protection screw so I can get to it better to remove it?
    Thanks,
    Burnell
     
  5. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    25,040
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    I've no information about that (but I'd be more inclined to mangle the screw and replace it).
     
  6. Veedub00

    Veedub00 F1 Rookie
    Owner Silver Subscribed

    Jun 30, 2006
    4,887
    Troy, Michigan
    Full Name:
    James
    Honestly I wouldn’t mess with the mixture at all until you follow the manuals instructions for setting the idle speed.

    you basically have to disconnect the e part of the ke jetronic, jump the plug going to the throttle position sensor so it’s out of the loop too.
    Disconnect each side from the throttle rod so you can sort each side independently.
     
  7. bpcurtis

    bpcurtis Karting

    Nov 5, 2003
    79
    Dickinson, TX
    Full Name:
    Burnell P Curtis
    More data. I am not as yet able to get the passenger side mixture cover screw out. However, just to see what happens I started the engine with the O2 sensors connected but I was still reading the voltage. The drivers side was at 0.744 volts until the engine got hot and then it ran 0.72 and changed in the third place. The passengers side was 0.04 volts until the engine was warmed up and then it cycles rapidly between 0.05 and 0.75 volts. By rapid I mean it changed each second. Obviously, something was trying to control it and could not.
    Thoughts?
    Burnell
     
  8. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    25,040
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    Not good -- either the O2 sensor has failed or that bank really isn't running or that bank ECU is dead or that bank EHA is dead, etc.

    Not a bad sign. Since you report that the unplugged O2 sensor value is way lean (very low O2 unplugged voltage at warm idle) just adding some enrichment at idle via the mixture screw might get this to swing from 0.1~0.2V to 0.8~0.9V as it should when running closed-loop at warm idle.
     
  9. bpcurtis

    bpcurtis Karting

    Nov 5, 2003
    79
    Dickinson, TX
    Full Name:
    Burnell P Curtis
    So, is it suppose to swing from 0.1 to 0.8 volts normally?
     
  10. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    25,040
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    Yes -- see the flowchart on page D90 where it describes how the system continuously "wanders" from the lean boundary (0.1~0.2 VDC from the O2 sensor) to rich boundary (0.8~0.9 VDC from the O2 sensor) and back again when running closed-loop -- i.e., after the water thermoswitch opens (warm-running), and you are not at large throttle opening (WOT switch not closed).

    "Probe" = O2 Sensor

    "ECU PROVIDES CURRENT RISE" = increases the current going to the EHA coil = increases the amount of fuel delivered for a given size slit opening

    "ECU DECREASES CURRENT TO PRESSURE ADJUSTER" = decreases the current going to the EHA coil = decreases the amount of fuel delivered for a given size slit opening
     
  11. bpcurtis

    bpcurtis Karting

    Nov 5, 2003
    79
    Dickinson, TX
    Full Name:
    Burnell P Curtis
    So, the passenger side is approximately correct but would be better if the mixture screw could be adjusted a bit rich so it would run better at open loop. The drivers side is definitely wrong as it is constant and rich. It is also rich at open loop and does not respond to mixture screw adjustments. Could it be getting fuel from somewhere else, say a bad injector or a bad cold start injector?
    Thanks,
    Burnell
    Ps - the engine runs at 17 inches of Hg on closed loop, 1000rpm, and sounds good but maybe has a small bit of hunt.
     
  12. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    25,040
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    The passenger side is "correct" for the system seeming to use the EHA to run closed-loop when warm, but the mixture screw is set too lean. Yes, if you add some richness by turning the mixture screw CW to the proper open-loop unplugged O2 sensor output value, it would probably improve your open-loop, cold-running behavior and bring the closed-loop, warm-running voltage swing to the more correct range.

    0.74V is not excessively rich, but not responding to the mixture adjustment (with the O2 sensor unplugged) is a very serious problem (as is the voltage not swinging during warm-running idle with the O2 sensor plugged in). Even if the electrical part of the system is completely dead, the unplugged O2 voltage output should change when you turn the mixture screw. I think I asked this before, but during the unplugged adjustment of the mixture screw, regardless of what the O2 sensor voltage is, you should be able to go too lean (CCW) to an obvious bad running condition, turn the screw CW some to better running, then keep turning the mixture screw too rich (CW) again to an obvious bad running condition. Do you get that result? If not, you have some very serious problem somewhere.
     
  13. bpcurtis

    bpcurtis Karting

    Nov 5, 2003
    79
    Dickinson, TX
    Full Name:
    Burnell P Curtis
    I did adjust the drivers side mixture screw CCW until the engine ran rough. I then adjusted it back CW about 1/16 and it ran smoothly. All of this time the O2 sensor ran 0.74 + or - the whole time. O2 sensor was unplugged at the time. Previously, I had turned the screw CW to see if the voltage changed (it did not) but did not turn it enough to cause the engine to run rough.
    Thoughts?
    Burnell
     
  14. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    25,040
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    That might just show that the O2 sensor is unresponsive (and would probably be the best possible outcome for you) -- have you tried a different O2 sensor in that position? Getting a (logical) change in the runability with the mixture screw adjustment is a very good thing.
     
  15. bpcurtis

    bpcurtis Karting

    Nov 5, 2003
    79
    Dickinson, TX
    Full Name:
    Burnell P Curtis
    I changed out the O2 sensor for the passenger side. The voltage moved from 0.744 to 0.54. I tried to adjust via the mixture screw with no success, in fact CW seemed to make it leaner but the results were mixed. I then went to closed circuit and after warming up to hot the passenger side started cycling from 0.1 to 0.7. The drivers side did not move. I let the car run and both sides went to very lean, about 0.06 and stayed there. BTW, CW is looking down from above.
    Thanks,
    Burnell
     
  16. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    25,040
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    You lost me here. Are you saying that on the Driver's (7-12) side that:

    1. You warm it up, unplug the 7-12 O2 sensor (using the O2 sensor that was previously on the 1-6 side where it seemed to work OK) forcing open-loop operation, and the (now) 7-12 O2 sensor still reads a near-fixed 0.54V value and adjusting the mixture screw has no or just weird effects,

    2. You plug in the 7-12 O2 sensor to run closed-loop, but the 7-12 O2 sensor value just stays about the same, but

    3. After a while running, you unplug the 7-12 O2 sensor (again forcing open-loop operation), but now the 7-12 O2 sensor reads a very lean value near 0V?

    (I'm going to assume that your Passenger 1-6 side is sort of working OK, and the only problem there is you can't access the 1-6 mixture screw to add a little richness).

    Please explain more clearly.
     
  17. bpcurtis

    bpcurtis Karting

    Nov 5, 2003
    79
    Dickinson, TX
    Full Name:
    Burnell P Curtis
    Sorry I was not clear.
    1. Yes but it was open or closed look and the value stayed the same, adjusting the screw or not (very little erratic movement of O2 voltage).
    2.yes
    3. No, with both sides running closed loop, 1-6 varying approximately correct, 7-12 at 0.54, after running a while both sides went to very lean (0.05volts)
    With these results, I quit and closed it all back up and decided not to work on it for a while.
    A friend suggested that I: a.close off all vacuum lines to see if there is a change, b. Check to see if O2 sensor wires go to correct computer, c. Screw the air bypass screws in and back out to see if they are about the same.
    Will do these later.
    Burnell
     
  18. Veedub00

    Veedub00 F1 Rookie
    Owner Silver Subscribed

    Jun 30, 2006
    4,887
    Troy, Michigan
    Full Name:
    James
    I bought and installed a Glowshift dual wide band sensor for my car. It’s great. It tells you the air fuel ratio on a digital gauge as you drive.

    bought it from glowshift on eBay.
     
  19. bpcurtis

    bpcurtis Karting

    Nov 5, 2003
    79
    Dickinson, TX
    Full Name:
    Burnell P Curtis
    I have an update on my car. I checked the temperature of the exhaust, 1 -3, 4-6, 7-9, and 10-12. I-3 was very cold, 4-6 was warmer, and the rest were hot when the car was up to temperature. Checking of the wires showed that 12 was not firing due to a rodent chewing the wire, and 9 was probably firing poorly due to a cracked spark plug extender. Fixing these problems caused the engine to idle cold quicker in the warm up cycle and the computer for 7-12 started working after the engine was hot. I am sure that plug 12 was fouled so I expect better results after doing an Italian tuneup. The engine does run nicer now.
    So, lesson learned is to check the basics first.
    Thanks everyone for your help. I will probably give one final report after the Italian tuneup and then following with a cold start.
    Burnell
     

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