87 TR rough idle and stalling/surging | FerrariChat

87 TR rough idle and stalling/surging

Discussion in 'Boxers/TR/M' started by ozziindaus, Aug 7, 2016.

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  1. ozziindaus

    ozziindaus F1 Veteran
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    Guy's, I need some help. The last time I drove it to test and bed the new brakes, it drove very well but stalled as soon as I was about to pull it into the garage. Today, it barely reached a stable idle. (video was taken last week before taking it out again).

    I let it reach temperature thinking it had something to do with the cold start relay but things only got worse. The engine periodically started stalling and surging as I limped back home carefully riding on the accelerator and clutch.

    I should also note that the Engine Temperature backlight went out. I'm only mentioning this because I remember reading that this light could share a common fuse or relay with something else that ties back to my engine issue, but I could be wrong.

    Any help would be very much appreciated.

    https://www.youtube.com/watch?v=BBMYtSt9yoA
     
  2. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    For the symptom you report (was good running to instantly poor/weak running whether cold or warm) on a US version TR, the primary suspect has to be the protection relay/protection relay fuse. Try a search using "red wire protection relay".
     
  3. ozziindaus

    ozziindaus F1 Veteran
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    OK, I have some reading ahead of me. BTW, does the engine temp back light have anything to do with this protection relay?
     
  4. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    No (if by "engine temp back light", you mean the bulb mounted in the engine coolant temperature gauge that comes "on" with the parking/headlights).
     
  5. Gialllo uno

    Gialllo uno Formula Junior

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    Love it. Going thru Ferrari chat and watching Olympics .
     
  6. Veedub00

    Veedub00 F1 Rookie
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    yeah, I had mine come loose after hitting some bad pot holes. I took out that triangular box over the right rear fender and cleaned out all of the connections and made sure that fuse is still good. Put it all together and it idled and drove normally.
     
  7. ozziindaus

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    #7 ozziindaus, Aug 12, 2016
    Last edited by a moderator: Sep 7, 2017
    Update,
    James came over last night to try and trouble shoot the issue. The passenger side coil to distributed cable was replaced due to lack of continuity but it did not solve the issue. James did however realize that the tachiometric relay connector was loose but no matter what we did, we couldn't get the car to idle normally.

    Questions:
    -Do these pins look ok?
    -Can the pins be tested without the engine running?
    -Could a bad ignition coil lead screw anything up?
    -What's the best way to eliminate bad fuel in the system? I don't want to drain the tanks. Is there an additive I can throw in that's safe?

    Further notes.
    I can touch on the throttle to prevent stalling but the engine would momentarily surge indicating that there is still something going on with one of the banks or both simultaneously. When I let go, it would sometimes remain stable but will eventually stall. Both exhaust pipes were hot. One of the test pipe lines (passenger side) was fractured but did not look like it was leaking.
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  8. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    #8 Steve Magnusson, Aug 12, 2016
    Last edited: Aug 12, 2016
    It's best to first make a functional measurement of voltage on the red wire at the water thermoswitch on the side of the water "Y" pipe at the top front of the engine (with that plug plugged in) -- it should be +12V whenever the engine is running or cranking. Were you unable to find the prior threads on the subject?

    Do you mean the "protection relay" in the triangular black box over the RH rear wheel well? If you were in that deep, you can also make the same "red wire" voltage measurement there (i.e., terminal 87 on the protection relay with the red wire connected should be +12V whenever the engine is running or cranking). If that was +12V, but there was 0V at the (same) red wire at the water thermoswitch = that would be a bad sign for the pins in that connector.
     
  9. ozziindaus

    ozziindaus F1 Veteran
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    Briefly but one link to a thread had an error. I'll spend some more time over the weekend but thanks for the tip so far
     
  10. Steve Magnusson

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  11. ozziindaus

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    #11 ozziindaus, Aug 13, 2016
    Last edited by a moderator: Sep 7, 2017
    Here are the KE ECU Connector resistance measurements for pins 2 and 21 and for both connectors. I have taken pics of each measurement with the corresponding connector since I'm not sure which one applies to which bank.

    Pic 1 is the connector closer to the front
    Pic 2 is the resistance between pins 2 and 21 for that connector (381 k Ohms)

    Pic 3 is the connector closer to the rear
    Pic 4 is the resistance between pins 2 and 21 for that connector (288 k Ohms)

    Pic 5 is the chart/graph of corresponding output resistance by temp from another thread Steve M. posted. Note that the ambient temperature was ~28 degrees C

    So if I'm measuring and interpreting the chart correctly, then I'm off by a factor of x100. Is that correct?
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  12. ozziindaus

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    Pulled the Protection Relay from the triangular box. 10Amp fuse is fine. I gave the relay a shake. There's a slight rattle which comes and goes. Not sure if that's a clue.

    So the only test I have not yet done is the 12V red wire off the water thermoswitch. It is so tight in there so I would rather try testing it out at the relay box but in the meantime, I would like to resolve the high resistance at the thermistor.
     
  13. Steve Magnusson

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    #13 Steve Magnusson, Aug 13, 2016
    Last edited: Aug 13, 2016
    Not sure if the moveable armature contact could be OK, but still "rattle" if shaken, but the functional measurement will tell all.

    Measuring either place is fine. I just like using the water thermoswitch, because it can be done without disassembling anything.

    Have to agree that your resistance measurements indicate something is wacko, but make sure that you are on the right terminals (can't really tell where the probes are in your photo). The connector diagram in the figure is as looking at the ECU - not looking at the harness connector end. Terminal 2 is in the longer row of contacts; terminal 21 is in the shorter row of contacts (and it looks like to me you've got the black probe on terminal 15, not terminal 2). If you measurements are correct, the next step would be to unplug the dual-channel thermister and make the same resistance measurements between each of the terminals of the thermister itself to the thermister body:

    If those measurements are still wacko = probably need to replace

    If that's OK = maybe a connection problem? But it's very unlikely both connections have the same flaw, but, IIRC, there is a ground wire that connects the "Y" pipe casting to ground so maybe that's got a problem that would affect both.

    Good hunting!
     
  14. ozziindaus

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    #14 ozziindaus, Aug 13, 2016
    Last edited by a moderator: Sep 7, 2017
    Red wire voltage measured at terminal 87 of the protection relay is fluctuating between ~12.5 and ~13.5V. I was using the engine as a ground so that may explain the fluctuations.

    I'll start measuring the resistance at the thermistor and report back
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  15. ozziindaus

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    #15 ozziindaus, Aug 13, 2016
    Last edited by a moderator: Sep 7, 2017
    Measured resistance at the top Thermo-Time Switch (the one you labeled 113980/118790). One lead has about 60 ohms, the other 0.

    Measured resistance at the 2 Channel Thermistor (the one you labeled 121720). Both leads to ground read ~1000 Ohms.
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  16. ozziindaus

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    Stupid me. I'll check again once the rain starts easing off. Man we have been in a drought around here up until yesterday :(
     
  17. carguy

    carguy F1 Rookie

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    Have you checked the electrical connectors under the expansion tank? Sometimes they can get loose and cause similar issues.
     
  18. ozziindaus

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    #18 ozziindaus, Aug 13, 2016
    Last edited by a moderator: Sep 7, 2017
    I think they are according to connector based on the pin outs aligning with the diagram (see pic).

    Anyway, I measured them again. Resistance is 1170 Ohms and 430 Ohms for each harness. So that may be about right since the engine has been running for a few minutes but doesn't explain why they're imbalanced.

    PS. Strong smell of unburnt fuel coming out of the exhaust I must add.

    These ones? They look OK to me but I'm afraid to disconnect them unless I'm told they are robust connections.
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  19. ozziindaus

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    #19 ozziindaus, Aug 13, 2016
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    Excuse the crappy graphics but I just wanted to emphasize that the connector pin out configuration matches the connector/harness side rather than the ECU module side. If we agree, is it still 2 and 21 that we test?
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  20. Steve Magnusson

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    #20 Steve Magnusson, Aug 13, 2016
    Last edited: Aug 13, 2016
    Yes, still 2 and 21 (and you've got the right idea -- match the asymmetric pattern of the contacts -- guess I mis-remembered)

    That's in a more reasonable ballpark, and could be related to a bad connection. Recommend same strategy as before -- get the engine warm and then measure at the dual-channel thermister itself:

    If similar imbalance as measured at the ECU connectors = think you could replace without regret

    If balanced at the thermister, but not balanced at the ECU connectors = has to be related to something in between.
     
  21. ozziindaus

    ozziindaus F1 Veteran
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    Will do. I will however have to keep my foot on the throttle since it's stalling quite regularly. Is it safe to say the Protective relay is OK? Just want to put it back together.
     
  22. carguy

    carguy F1 Rookie

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    Sam...yes those are the connectors I was referring to. I would try to disconnect & reconnect them. The larger square connector is fairly strong but the small round is delicate. The smell of unburned fuel usually indicates an ignition problem or an extremely rich fuel mixture. I just happen to have a couple of old relays in my tool box so I went out and shook them and they did not rattle....just an FYI. Sometimes the coil lead wires do slip downwards out of the coil and create issues, so if you are missing the retainer clips that keep the wires tight in the coils that could be a problem.
     
  23. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    Yes, your voltage measurement there confirms it is OK, but it doesn't guarentee that it is reaching the ECUs thru the big round C12 connector. One advantage to measuring at the water thermoswitch is that the wiring path is:

    +12V battery cable -to- starter solenoid -to- C12 round connector -to- protection relay -to- C12 round connector -to- 1-6 ECU -to- 7-12 ECU -to- water thermoswitch

    therefore, if the +12V is reaching the water thermoswitch, that confirms that the second pass thru the C12 connector is OK.
     
  24. ozziindaus

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    Resistance at the thermistor is ~330 Ohm each and about 350 Ohm at the connectors after running engine for a few minutes. Although temp gauge barely budged, pipes got too hot to touch.
     
  25. Steve Magnusson

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    No trouble there.

    Are you sure that you aren't have an ignition (spark) issue? Have you done any preliminary checks there?
     

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