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Exhaust system high temperature warning light (cyl 1-6 )

Discussion in 'Boxers/TR/M' started by Triton, Aug 9, 2009.

  1. Triton

    Triton Karting

    May 17, 2009
    182
    Boston - Metro West
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    Paul M
    #1 Triton, Aug 9, 2009
    Last edited: Aug 9, 2009
    Ok Testarossa guy's -

    Beautiful clear summer day here yesterday just west of Boston, not real hot or humid...just perfect, so me and my daughter took our 91 Teastarossa for about an hour long ride.
    Much of the ride was through the country backroads of Sudbury, Concord Acton and out on to Rt 495 for the short 10 mile run down the highway back home.
    The first half of the ride was a very leisurely 40-50 miles an hour at best and then a run down 495, at 75 - 85 miles an hour...nothing crazy with my kid in the car.
    The car ran great! However, after about 5 minutes, and lets say it was 80 miles and hour, the Slow Down warning light came on for Cyl 1-6.
    The warning light came on twice in a row for about 3-4 seconds, went out and never came back on???
    The car has about 2,400 miles on it, and just had a 30,000 mile major in May this year.

    Thought?
     
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  3. Mr.Chairman

    Mr.Chairman F1 Rookie

    Mar 21, 2008
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    Robbie
    you may have a clogged cat converter...

    R
     
  4. Shamile

    Shamile F1 Veteran

    Dec 31, 2002
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    #3 Shamile, Aug 9, 2009
    Last edited: Aug 9, 2009
    Dear Ferraristi,

    Ummm.....no help till you can spell the name on your own car. :D

    Before you jump to a clogged cat....which is what that warning light would indicate.....

    The Thermocoupler ECU's are flakey....at best.

    Most people just disconnect them. I still have mine connected and they work fine. Look closely at the wire ( stainless steel shield over wire ) going to the main plugs at the passenger side of the engine bay...right next to the dist. cap (1/6) The wire as it comes out of the stainless steel wrap rubs the shielding and shorts the contact....giving you the warning light.

    Also, did you just wash the car? I find water gets into those wires and make the warning lights go on. On the Testarossa, the cat temp warning system is passive. It won't shut down a bank like on the 512 TR. If your light comes on and STAYS on....check the cats just behind and below the muffler. If one or both are red....you can say it's the cat. :) If it just comes on and goes off....once in a while...just do some visual checks on the wires.

    BTW, the ECU's are in the passenger side foot well...under an aluminum kick plate.


    Shamile

    Freeze....Miami Vice !
     
  5. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    You should try to determine if it is giving an unreliable, or reliable, signal -- i.e.,

    1. Is the self-test working perfectly every time? -- if not, it really destroys any confidence in the signal (you do know that there is a self-test to observe, right?),

    2. Does the light ever stay "on" after cold start-up? -- that is, does it ever give a high temperature signal when it would really be impossible for things to heat up that quickly.

    3. Does it go thru the two display modes? -- for the situation you described (constant speed at moderate load and no obvious loss in power), if you had a missing cylinder, or the cams were incorrectly timed, the temperature should've increased in a linear fashion -- so the light should first blink repeatedly at 900 deg C, and then stay "on" constantly when it reached 940 deg C. Since you didn't report that the "flashing" mode occurred before being constantly "on", that's a sign that you are getting a false signal rather than a real over-temperature situation.

    If the odd (bad) behavior persists, the easiest thing to do is to swap the two warning light ECUs (they are mounted behind the cover over the RH rear wheel) and see if the bad behavior changes sides -- if so, you can be fairly sure that the ECU itself is getting flaky. Of course, don't drive like a madman if the light does come on -- and, if you note a big drop in power (dead bank), don't limp home on the one good bank unless you remove the fuel pump relay for the bank showing the light; however, if the power seems good, but the light is "on", the light should really go out if you drive gently (and the indicated over-temp is real).
     
  6. Triton

    Triton Karting

    May 17, 2009
    182
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    Paul M
    I deserved that shot!

    I didn't wash the car - but by the way the warning light was flickering, the possible short scenario might just be the problem.
    I will investigate that today.
    Hope to get the TESTAROSSA out again today before the weather turns.

    Thanks for the advice.

    Paul
     
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  8. Triton

    Triton Karting

    May 17, 2009
    182
    Boston - Metro West
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    Paul M
    Steve,

    Shamile has proven I can't spell and it looks like there is something else I should be embarrassed about.

    1. Besides the the initial display of the warning light operation, when you first turn the key on, what is the specific self-test you are refering to?

    2. The light has never stayed on after a cold start.

    3. The light has never come on and stayed on, and I really didn't experience a flashing either. Although it's tough to be certain, these light are not in the best place to monitor from my driving position. The light came on for 3-4 seconds, went off, then came back on for 3-4 seconds, went off and never came back on.

    The car was running great, with no signs of lost power at all. My first instinct was to slow down and get in the right lane, but the light went out and stayed, and we enjoyed the rest of our trip home without incedent.
     
  9. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    #7 Steve Magnusson, Aug 9, 2009
    Last edited: Aug 9, 2009
    That initial display (both lights come "on" for a second or two and then both lights go "off") EVERYTIME you first turn the key "on" is the self-test. When a light (wrongly) stays "on" at the end of the self-test, it gets easily noticed, but if the light never comes "on" that is just as bad (but is more easily not noticed). Many times people have thought that nothing was wrong if the light never comes "on" when the key is first turned "on", but really this is just as bad a failure -- and a clear sign of ECU flakiness (so I suggest you watch each self-test sequence carefully).

    That's good. I just mention it as another thing to watch for -- i.e., if the light usually is "on" for only 1 second, but, occasionally, it stays "on" for 5~10 seconds, that would be a another sign of ill-health IMO.

    Same here. I'm tall enough that I actually have to tilt my head to one side to be able to watch both lights during the self-test. There is a buzzer that is supposed to sound if the over-temp warning lights or the oil pressure warning light comes "on", but it's so annoying that usually it gets disconnected (so it wouldn't surprise me if yours was disconnected).

    This alone, IMO, is an indication that there's a 95% probabilty that it was a false signal, rather than a real over-temperature event, as the temperature really can't vary in that way that quickly due to the thermal inertia of the parts.

    You did rightly. If the light stays "on", even though the power seems OK and you've backed off to driving gently, then you should stop and have a visual look at the precats/cats, as Shamile suggested, just to confirm that one of them isn't really glowing red hot and starting to burn things nearby. Normally, if a precat or cat is really over-heated it's fairly obvious from the smoking/crackling.

    If it happens again, I suggest you swap the ECUs, and see if the indication moves to the other side, or not (if it happens a third time).
     
  10. Triton

    Triton Karting

    May 17, 2009
    182
    Boston - Metro West
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    Paul M
    Steve,

    As always, I appreciate your very detailed and educational repsonses.

    There was definately no buzzer when this warning light came on. But with only 1,700 miles of use in 18 years prior to my acquiring the car this May, seems strange that the prior owner could have found anything annoying enough to start disconnecting things. The car now has about 2,400 miles on it, meaning I have put almost 30% of the miles on the car, in only 2 months.

    Although the car is 18 years old, one would excpect cats to fail from use not age - correct?

    If this happens again I will certainly try swapping the ECU's.

    Thanks
    Again
    Paul
     
  11. fastradio

    fastradio F1 Rookie
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    Apr 26, 2006
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    Paul.

    A quick test to verify if indeed you have a "hot cat", although I suspect not...is to shoot the cats (both sides) with an IR pyrometer when the problem occurs. Considering the "history" of the factory thermocouples and ECU, I be more inclined to go down that route as Steve described.

    However, I never, ever discount the slow down lights, as a "hot cat" can cause a fire. With the actual cat readings (or comparisons from left to right, pre-cat and post-cat) from a pyrometer, you'll know for certain if there's anything to be concerned about.

    If you need to use one...PM me and I can let you use mine.

    Best,
    David
     
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  13. Triton

    Triton Karting

    May 17, 2009
    182
    Boston - Metro West
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    Paul M
    Dave,

    How have you been since Tutto?

    Thanks for weighing in. I certainly don't ingor any type of warnings with the Ferrari...probably just electrical gremlins, but you never know.

    I will keep a close eye on things out back there for a while, thanks for the offer to use your pyrometer.

    How's you car running?

    Hope to see you again soon.

    Regards,
    Paul
     
  14. Triton

    Triton Karting

    May 17, 2009
    182
    Boston - Metro West
    Full Name:
    Paul M
    Well - just got home from work, had to move the "TESTAROSSA" out of the garage, so a contractor working on the house didn't have to come within twenty feet of the car with his tools, turned the key on...the warning light for Cyl. 1-6 didn't even come on!

    Started the car and shut if off several times, still no slow down light for Cyl. 1-6. Wires look like new, no chafing anywhere to be found, looks good from the sensors on the cats, right into the modular plugs they run in to.

    Going to be too busy for the next few days to start the diagnosis, but the process of elimination begins.
     
  15. fastradio

    fastradio F1 Rookie
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    Paul,

    Electric gremlins in a Ferrari...surely you jest? It's time, not miles that gets to these cars.

    We had a nice trip back from Tutto...and had a bit of fun "nudging" those 328s I was travelling with along. Much to my total disbelief, we made it home dry!

    If you have a chance, come by the show in Merrimack on the 22nd.
    http://www.northeastexotic.com/

    Best,
    David
     
  16. Triton

    Triton Karting

    May 17, 2009
    182
    Boston - Metro West
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    Paul M
    David,

    Looks like the electrical engineering background is going to come in - huh!

    I am going to try to come on the 22nd, I should be able to sort this out by then.

    Regards,

    Paul
     
  17. fastradio

    fastradio F1 Rookie
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    Italian style, no less...
     
  18. Triton

    Triton Karting

    May 17, 2009
    182
    Boston - Metro West
    Full Name:
    Paul M
    Ok Guys,
    Thanks for all the support.
    Through the simple process of elimination and swapping the connectors between the cyl 1-6 and cyl 7-12 - it appears that as Steve Magnusson suggested, the ECU for cyl 1-6 is acting flaking. When I swapped them, the Slow Down light for Cyl 1-6 works fine and Cyl 7-12 is out.
    Just checked out Ricambi, and if was not shaking to much to read this correctly, part # 141037 (141037 Control/Cat 2.5) is $895.00!!!!!!!!!!!!!
    It looks like a $20 radio shack part.
    Steve is there any way to do CPR on this little black box - or do you have a spare in your treasure chest for about $200 bucks?
    Anyone ever open up one of these sealed babies to see whats inside?
     
  19. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    Jan 11, 2001
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    Unfortunately, I'm in the same boat that you are -- so I'm thinking about trying to autopsy my 1st pair myself (and see if the internals could be duplicated) since my 2nd pair are now both flaky (no light during the self-test sometimes for both of them, and one of them has the annoying habit of turning the light "on" steady occasionally for no reason). You can do a little better on price at www.allferrariparts.com or www.eurospares.co.uk, but it's still pretty painful -- especially if you need 2!

    I would love it if someone could supply these at ~$300 each (which was what I paid for my second pair in 2000) -- so I wouldn't have to do another science project! ;)
     
  20. Triton

    Triton Karting

    May 17, 2009
    182
    Boston - Metro West
    Full Name:
    Paul M
    Well - after reporting earlier this week that I had determined that I have a bad Thermocoupler ECU, the saga continues.

    While putting things back together last night, I decided to completely pull everthing associated with both ECU's apart again. The only thing I did different this time, was while I was holding the plate in my hand that both ECU's are mounted to, out of frustration, I lightly tapped both with the handle of a small screwdriver.

    I am sure someone in Maranello is going to be laughing their ass off when they read this...but the damn thing is working fine again!

    I am still going to continue searching for a spare set at a fair price and put them away, as well as any other quirky items worth having on hand.

    so long for now...
     

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