Half my engine shuts down..

Discussion in 'Boxers/TR/M' started by Soundguy, Jul 4, 2005.

  1. Soundguy

    Soundguy Rookie

    Aug 6, 2004
    Ok, here's the deal.
    While driving my 512TR randomly, at any time the light for CYL 7-12 and the Warning "SLOW DOWN" light will come on, at which point the car starts to buck, backfire, wheezing, etc...
    Usually it will only last a few minutes then I can get it going again.
    Till the next incident!

    Now, I've noticed two things:
    It ususally (but not always) occurs when I down shift coming into a stop light.
    That can bring it on.
    And I've also noticed that when this happens if I put the car in neutral and rev it, it's fine, no bucking, coughing, etc...
    So it seems to happen only under load?
    What can cause this???

    Tomorrow I'm going to switch the Motronics computer modules to see if it the problem follows that?
    Cause I've already tried switching the O2 sensors, the ignition coils, the thermo couplers, with no change, still 7-12 cylinder lights come on.
    The cats are on my car although there is nothing left in them, so I've been told by my mechanic?
    Does this make a difference?

    Any ideas....
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  3. wax

    wax Four Time F1 World Champ
    Advising Moderator

    Jul 20, 2003
    Full Name:
    Dirty Harry

    WILLIAM H Three Time F1 World Champ

    Nov 1, 2003
    Victory Circle
    Full Name:
    I had the same problem on my 93 512TR. It would go away if I turned the car off & restarted it. Mine was occuring when the engine was cold.

    Could be tired spark plug wires, these are very hard to find & very expensive. I've heard you can make new ones for a lot less $ using magnecor or equivalent wire
  5. Birdman

    Birdman F1 Veteran

    Jun 20, 2003
    North shore, MA
    Full Name:
    THE Birdman
    Whatever it is, do not ignore it. When half the ignition shuts down, raw fuel is being pumped into the exhaust system and this can cause a toasted car rather quickly. This is not something to put up with!
  6. No Doubt

    No Doubt Six Time F1 World Champ

    May 21, 2005
    Full Name:
    Mr. Sideways
    Happy 4th! I can't speak for TR's, but 348's commonly get this problem. The first thing that 348 owners do is to swap the exhaust ECU's (you've got two, one one each side of your engine).

    Typically, you'll get the *other* SLOW DOWN light when you swap the exhaust ECU's (it's just one bolt/cable), meaning that the problem followed the exhaust ECU (i.e. the problem *is* the exhaust ECU).

    Fixing the exhaust ECU "failure" (if that's what you've determined is the problem) typically revolves around trying a couple of things. Sometimes, simply adding an *additional* ground wire from the "bad" exhaust ECU to a known "good" frame or battery Ground will fix everything.

    Other times, adding an additional ground wire from your O2 sensor to a known good ground will fix your problem, or changing out the O2 sensor on your "bad" exhaust ECU side might work.

    If none of the above works, then replacing your "bad" exhaust ECU can often fix your problem.

    Barring all of the above, you may have to replace your cats themselves (especially if you can see them glowing red at night or "rattling" when you first start your car when cold).

    Good luck! I don't know how much of the above will apply to TR's, but it works wonders time and again for that very problem on 348's.
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  8. Soundguy

    Soundguy Rookie

    Aug 6, 2004
    Hey Guys;
    First let me thank all of you responding, especially on this holiday weekend~!
    I myself just got back from Lime Rock Park, the New England Grand Prix.
    What a beautiful day, great cars at the track.
    Lots of fun, can't wait to for weekend, (Ferrari Challenge) although I did not take my car because of the problem I've been having.
    Didn't want to chance getting stuck in Ct.
    I'm gonna swap the Ecu's tomorrow and see if the other warning light comes on?
    I'll start with that, and see what happens...

    Any other info, or ideas are welcome, cause at this point I'm lost.
    I'm not sure if this is a coincidence or what, but I had the same probelm last year, and for lack of any other info, I switched the Motronic Computers modules behind the seats, and the problem "SEEMED" to go away!
    At least for about 8 weeks, then the car was put away for the winter.
    But when I took it out again this spring, it all started once again?

  9. No Doubt

    No Doubt Six Time F1 World Champ

    May 21, 2005
    Full Name:
    Mr. Sideways
    Hey, just be sure that you are swapping *exhaust* ECU's, not your motronic fuel/air mapping computers.
  10. yookdan

    yookdan Rookie

    Jan 14, 2004
    Denver, CO
    Full Name:
    Robert Stevens
    You folks are incredibly well versed - so pardon the amateur vernacular - but my 348 went through a week of cold starts at Suderia Rampante (Dave Helms, or should I say Nikki Helms ROCK!) - and they found the cables to my spark plugs needed replacing - car has been amazing ever since.
  11. burriana

    burriana Formula 3

    Jul 8, 2004
    North Yorkshire UK
    Full Name:
    Alternatively, if your cats have nothing in them then they won't get hot. In which case do as we 348 drivers do (when we get test pipes on). Simply disconnect the Lambda sensor to emission ECU connection.

    My 348 had exactly your problem (as did a few of my mates 348s) and this solution has worked. Just make sure that your cats are not in any danger of over heating though, which without any internals i don't think they will.

    It will cost nothing to try. If you swap the ECUs you may upset the other one too!
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  13. bazzis

    bazzis Karting

    Nov 5, 2003
    Sarratt, Herts
    I had a similar problem with my 512tr, get some electrical contact lube,not WD40!!, pull all the electrical connectors and lubricate, including the ECU's just behind the seats, and the relays in the front trunk, especially the connectors from the oxy sensor and cat thermocouple that are located on either side of the clutch housing, this cured my car, hope it helps...........
  14. Soundguy

    Soundguy Rookie

    Aug 6, 2004
    Ok as an update to the story,
    I attempted to switch the Thermo Couplers by just switching the cables, but the cables were too short.
    So instead I switched the actual Coupler themselves. Taking the 1-6 out and switching it with the 7-12 and vica/versa...

    Anyhow, the problem happened again (almost immediatley) on the same bank 7-12 as before. All the same symptoms.
    Half the engine shutting down, the 7-12 Cyl light and the Slow down light, followed by a loud chattering coming from the rear engine bay in time with the flickering lights?

    Ok, so then I decided to switch the modules that the Termo Couplers are plugged in to??? (Why Not?) I had to try something.
    So I switched them, and in a matter of minutes the same stuff all over again?

    So what does this mean?
    The Thermo Couplers are good, they had the same response in either "Cat"?
    And then the Modules themselves reacted the same when they were switched? Still bank 7-12 ???
    What gives?
    Any Ideas, cause I'm totally confused.
  15. Soundguy

    Soundguy Rookie

    Aug 6, 2004
    As an aside...
    I just tried unplugging the Thermo Couplers from the ECU box on both sides of the engine...
    And it wouldn't run at all, just coughing spitting, all dashboards lights flashing?

    I thought it was supposed to run without the connection?
    What does this suggest?
  16. Soundguy

    Soundguy Rookie

    Aug 6, 2004
    So now that the car is totally screwed up, not one to quit that easily,
    I take the Motronics Computer modules out behind the seats, and clean all connectors, and switch them also...
    Once again, I'm drawing straws here, but had to try something.
    After I did that, I went to the battery and dissconnected the Pos and Neg cables and touched them together. Someone told me this is a good way to
    re set the computers, and have them learn all over again.
    So I re-connected everything, and started her up.
    (well starting the car is a whole other issue) After a few trys I got her started.
    Let the car warm up for a few minutes and took her out for a ride.
    Well, I just got back, rode around town for approx. 30 minutes, fast, slow, stops, starts, etc, etc, etc...
    And not a hiccup?
    At least for now...
    Go figure...
    Which one of the things I did made the difference?
    The funny part is that now the Thermo Coupler, ECU units, and the Motronics Computers are all back where they were when I got the car last year. And after a few days of receiveing the car last year these problems all started. So I swapped everything last year, and finally got the car to work, until this spring, when it all started over again?
    So now everything is back to the way it was when I received the car a year ago, and now it's working?
    Is it me?

    Anyhow, I thank everybody for all their insight and help.
    Keep posted, cause I'm not sure that this saga is over....

    PS...if the car is still working on Saturday, I'm headed over to Lime Rock for the Ferrari Challenge, anyone going.
  17. Standig

    Standig Karting

    May 13, 2002
    Spring Hill, Fl
    Full Name:
    Stan DiGuiseppi
    first you need to determine if you are losing fuel or spark
    I had a 87 Tr that would run on only one side of the engine / after many hours of adjusting and changing componets / It was suggested I uplug each side of the engine's ecu to determine for sure which side was off. Then do a fuel volume test / it turned out i was dropping a fuel pump / however along with all the other guesses, the fuel pump was also replaced which in its self was not the problem. It was a burnt wire coming out of the fuse block. I repaired wire and problem went away.

    Moral of the story? Investigate to determine / internal engine problem? probabably not / fuel? good posibility / last look at electrical..

    If one complete side of the motor is off then it has to be something common to the running of all the cylinders of that back / so its fuel, primary ignition or some fluecky thing with an ecu.

    It should be easier to figure out if the car is acting up as you work on it.

    F-cars are just like any other car in most ways ... you have to narrow down the exact area of the problem.

    You will feel great when you find it...
    Dont' give up...investigating helps you to understand how your car will get a better appreciation for the design.
  18. f355b

    f355b Formula Junior

    Jan 23, 2004
    Little Silver,NJ
    i would say you are going to need a new ECU, i just changed one of mine cost!!! $2,300.00 got to love ferrari's
  19. genesseo

    genesseo Rookie

    May 22, 2006
    I was having the same problem with my 1992 TR 512. I just bought some new Ignition ECU's (2) of them.
    Let's see what happens.
  20. Mike C

    Mike C F1 Veteran
    Lifetime Rossa Owner

    Aug 3, 2002
    Southeast USA
    Full Name:
    Mike Charness
    That could also be caused by a bad TDC/cam sensor (and thankfully they're not very expensive to replace)
  21. Birdman

    Birdman F1 Veteran

    Jun 20, 2003
    North shore, MA
    Full Name:
    THE Birdman
    It sounds like when you swap all the components around, it heals itself, for a while at least. So it may be a dirty connector somewhere. I would start with electrical contact cleaner (get it at Radio Shack) on all electrical connectors, and then I would also add ground straps to all ECUs. (Costs nothing, might help, can't hurt). The magnetic crank sensors DEFINITELY can cause this, and they are known to be "flaky"--meaning that they can work one minute and then not work the next.

  22. RP

    RP F1 World Champ

    Feb 9, 2005
    Bocahuahua, Florxico
    Full Name:
    Tone Def
    I don't know TR's, but on a Boxer when this has happened the first place to look is the fuel pumps. There are two, so if one of them blows a fuse, it affects the entire engine operation.
  23. Soundguy

    Soundguy Rookie

    Aug 6, 2004
    Hey Guys....
    Well, let's see a year later and the problem is back worse then ever....
    But the funny thing sometimes I drive for hours and hours without a hiccup..
    And then yesterday from 2 minutes after I started the car for over an hour the lights would flash, the car would backfire, etc, etc...
    Back to the drawing board...
    Today I'm going to swap and clean all the connectors on the motronic computers once again?
    And see if the problem follows them?
    But it's so random....I'm never quite sure what's what?

  24. MYMC

    MYMC Formula Junior

    Mar 10, 2006
    Full Name:
    Mine is doing the same thing and I have been advised to replace the two round connectors (one large and one small) under the passenger rear 1/4. I'll keep you posted.
  25. Jeff Pintler

    Jeff Pintler Formula Junior

    Jul 20, 2005
    Full Name:
    Jeff Pintler
    There is a water temp sensor on the top, front of the motor that the connector points up that goes bad and causes the bank to die. Is about $67. The posting I read was frome someone at a dealer that replaced the spark plug wires ($1.5k), the computer ($5k) and finally the sensor. Do some searching on this site....there's a bunch of stuff like this. My car also had a completely burnt wire from the coil to the distributor (solid core wire and put the red silicone sleeve back over it.....problem was the sensor.....get an extra. Geed luck!

    Jeff Pintler
    89 348, 86TR
  26. No Doubt

    No Doubt Six Time F1 World Champ

    May 21, 2005
    Full Name:
    Mr. Sideways
  27. RP

    RP F1 World Champ

    Feb 9, 2005
    Bocahuahua, Florxico
    Full Name:
    Tone Def
    I just had this happen the other night on the Boxer. Suddenly, running on 6 cylinders, some back firing. I turned around to head home, as I approached an intersection, the engine died. I started it up again, and the problem disappeared.

    About six months ago, with a warm engine this happened, running on 6 cylinders, backfiring. When I got home, I shut the car off. I restarted the car, and it seemed fine. I even posted a question here on FChat. The next day, started the car, no problem. No problem until six months later, this week.

    Both cases the fuses for the fuel pumps were fine and only very slightly warm.

    Took the car to Tim Stanford's yesterday, long story short, sediment appears to build up in the gas tank, clogging the flow to the fuel pump(s). Thus causing one of the pumps to "starve". When you shut off the car, there is no pressure, so the sediment settles, and the flow is once again OK. Interesting enough, I also filled a quarter full gas tank the day before this happened. That may have caused the sediment to move around.

    Cleaning this out may correct your problem.

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