News

348 1-4 cylinder bank shut down. Ideas?

Discussion in '348/355' started by Husker, May 1, 2004.

  1. Husker

    Husker F1 Veteran
    Silver Subscribed

    Dec 31, 2003
    7,894
    western hemisphere
    My 1990 348 ts has a strange problem. Runs fine part of the time. Just drove it 400 miles home from Dallas with no problems. Drove it this a.m. with no problems. Then, later this afternoon, I started the car and it was hesitant in starting, then when I drove the car after starting it the power was reduced by half. Then, the "check engine 1/4" light came on, went off, and kept coming on and going off. The car never resumed full power. I am guessing that cylinder bank 1/4 is shut down. Any ideas on where to start on this one?

    A month ago, the same thing was occuring except this time it was the "Check Engine 5/8" light was on. Same circumstances, same loss of power issue.

    When I sent the car to Dallas for another, unrelated repair, the mechanic could not find a stored code in the ECU, nor could he get the "Check Engine" light(s) to come back on. So, here I am at! I'm just glad it didn't happen during my 400 mile trek home!!

    Any ideas or suggestions would be greatly appreciated. Also, does anyone know how to interpret the codes, and how to get them? Thanks!
     
  2. henryk

    henryk Formula Junior

    Dec 9, 2003
    479
    Door County, WI
    It is either one of 2 problems: Fuel pump, or coil wire to that bank. Since it appears intermittent, I would check for a loose wire on the coil side, or a loose ground to the fuel pump.
     
  3. WILLIAM H

    WILLIAM H Three Time F1 World Champ

    Nov 1, 2003
    34,891
    Victory Circle
    Full Name:
    HUBBSTER
    My 512TR did that once, when I restarted her she ran fine
     
  4. kenyon

    kenyon F1 Rookie

    Oct 7, 2002
    2,836
    East Yorkshire
    Full Name:
    Justin Kenyon
    Its the CAT ecu's not - The temperature probes. The CAT are getting to hot and shutting down the cylinder bank. Its nearly 99% of the time a ECU/thermo probe fault.

    Disconnect battery fully, postive and negative terminals.
    Reconnect,
    then start engine,
    let engine idle for 10-15 mins with no reving only on tick over.
    This resets the ecus.
    Switch off engine,
    start again and go for a drive, should be OK.
     
  5. ernie

    ernie Two Time F1 World Champ
    Lifetime Rossa Owner

    Nov 19, 2001
    22,022
    The Brickyard
    Full Name:
    The Bad Guy
    Are you sure it wasn't the SLOW DOWN 1/4 and 5/8, and not the check engine? I'm willing to bet it is. It is one of two things. Either your cats are on the way out and you are getting a true reading, or the exhaust ecu's are on the blink. What the exhuast ecu's do is monitor the temperature of the cat's if the affected cat gets above a certain temperature they give you a warning to slow down. They will show you the bank of cylinders that the cat is getting hot on, 1/4 or 5/8. If the cat's continue to give the ecu a high temperature reading, the exhaust ecu will shut the bank of cyinders down to prevent damage to the cat. So that is what you are experiencing when you had the power loss. It also is audable that you have lost a bank, as the engine note changes. Quite often the exhaust ecu's go bad, but it usually is only one ecu that is giving the false reading. Since you had both come on, it would be worth you while to have the condition of the cat's looked at. You could have one, or both, of the internals of the catalytic converters coming appart, resulting in a blockage of the exhaust flow causing the cat to get hot.
     
  6. Husker

    Husker F1 Veteran
    Silver Subscribed

    Dec 31, 2003
    7,894
    western hemisphere
    Kenyon, thank you. I will try these items tonight. Ernie, it definitely IS the "check engine 1/4" light, NOT the "slow down" light. Any other thoughts Ernie?

    Also, it seems this is no longer "intermittent". The right bank of cylinders are "no go" now every time I start the car. I've driven it around the block a few times and it's just running on the left cylinder bank.

    Any more help is very much appreciated. Thaks everyone.
     
  7. Miltonian

    Miltonian F1 Veteran

    Dec 11, 2002
    5,959
    Milton, Wash.
    Full Name:
    Jeff B.
    There should be something stored in the memory of the Motronic ECU for the 1/4 bank. From your first post, it appears that you do not know how to download and interpret the code - is this correct? It isn't difficult, no special tools needed. It's just a series of blinking lights. Described in detail in the Workshop Manual.
     
  8. ernie

    ernie Two Time F1 World Champ
    Lifetime Rossa Owner

    Nov 19, 2001
    22,022
    The Brickyard
    Full Name:
    The Bad Guy
    Have a look at the crank position sensors. They are located at the bottom and side of the pully for the alternator, and air conditioning belts. You could have one that is bad, or not connected properly. However if you got a check engine light, the computer should have a code stored. Especially since the car is only running on one bank at start up.

    If you want you can just unplug the cat ecu's altogether, and see if that solves the problem. If it is a bad cat ecu, the car can run with them unplugged. You can also try switching the ecu from one side to the other and see if you get the problem on the other side.
     
  9. ShanB

    ShanB Formula Junior

    Jul 9, 2003
    547
    Tejas/Europe/Desert
    Full Name:
    shanb
    I would start by going over the wiring diagram to see what circuits "check engine 1-4" monitors and work backwards. There are something like four or five things that could make that light go on. (RPM sensor at intake crankshaft cyl 1-4 for example) However for a quick check I would agree with Ernie that the crank position sensor is a typical suspect. FYI - the cylinder 1-4 crank sensor is the one at the six o'clock position in the picture.
    Good luck!
     
  10. airbarton

    airbarton Formula 3

    Nov 11, 2002
    1,462
    Kennesaw, Ga.
    Full Name:
    Chuck Barton
    Ernie's right, crank sensor is most likely the problem. I had the same thing once. Turned out to be a loose connection on the sensor.
     
  11. Ricambi America

    Ricambi America F1 World Champ
    Sponsor Owner

  12. Husker

    Husker F1 Veteran
    Silver Subscribed

    Dec 31, 2003
    7,894
    western hemisphere

    Ernie, if I were to unplug that "cat ecu's" where are they to unplug? If this fixes the problem, would you keep them unplugged indefinitely? Long term problems associated with this?
     
  13. ernie

    ernie Two Time F1 World Champ
    Lifetime Rossa Owner

    Nov 19, 2001
    22,022
    The Brickyard
    Full Name:
    The Bad Guy
    I posted in your other thread how to find the exhaust ecu. I ran my car for over six months with the exhaust ecu unplugged. All it does is tell the motronic ecu if the cats are getting hot. I knew mine was bad because after the car sat all night, as soon as I started the car in the morning the light came on. Just to make sure I switched it from one side to the other, and sure enough I had the slow down light on on the other bank now. So I just left it unplugged. I did this because I had brand new cats, and knew they were good. The problem comes when you leave it unplugged and then you really do have a cat that is bad. If the cat gets to hot it will destroy the insides, and your emissions will be screwed. The other bad thing is that the cat wil get cherry red hot and could cause a fire. So just check to make sure you don't have a bad exhaust ecu. But don't forget to check the crank position senors.
     
  14. jkuk

    jkuk Formula Junior

    Nov 3, 2003
    259
    Wirral, UK
    Full Name:
    John K

    I note of warning with the crank sensor connectors.

    My 348 would not start - no spark on 5-8 bank. The crank connector was the source, but only when I removed the rubber shroud did I find the true problem.

    The centre wire and power wire were both shorting together. The insulation had worn through over time giving a resultant intermittent fault.

    So just cleaning them may fix a crank sensor problem, but whenever checking this area I would also check the integrity of the wiring.

    John
     
  15. ants2au

    ants2au Formula Junior

    Nov 19, 2003
    690
    Sydney Australia
    Full Name:
    Anthony
    I may have this wrong, but on the 512TR WSM (wich runs Bosch 2.7), the crank sensors (this is from memory now) are used to provide TDC and injector firing pulse.

    The ignition firing is handled by another set of sensors on the back of one of the cams.

    Someone correct me.



     
  16. Husker

    Husker F1 Veteran
    Silver Subscribed

    Dec 31, 2003
    7,894
    western hemisphere
    It was the oxygen sensor gone bad. Anyone know how much $ I should expect to pay for an O2 sensor?
     
  17. ernie

    ernie Two Time F1 World Champ
    Lifetime Rossa Owner

    Nov 19, 2001
    22,022
    The Brickyard
    Full Name:
    The Bad Guy
    The O2 senors should only be about $100 - $120. You can find them online.
     
  18. fatbillybob

    fatbillybob F1 World Champ
    Consultant Owner

    Aug 10, 2002
    19,018
    socal
    Actually, this is about the best part in the car. Most of these cars don't even have 50k miles on them and more 02 sensors are replaced than need to be replaced. Cehck the wiring to the sensors. You can also switch left to right and get the car really hot and sometimes burn off all the crap that you now have fouled on the 02 sensor from running on 4 lungs. More often than not the problem is the connection of the 02 sensor to the car wiring.
     
  19. likeyoudontknow

    likeyoudontknow Karting
    BANNED

    May 6, 2004
    50
  20. ernie

    ernie Two Time F1 World Champ
    Lifetime Rossa Owner

    Nov 19, 2001
    22,022
    The Brickyard
    Full Name:
    The Bad Guy

    Yes you still need the O2 sensors. They measure the amount of unburnt fuel coming out of the engine, before the catalytic converters. If the exhaust is rich, then the ECU will lean out the fuel supply. If the exhaust is too lean, based on the signal coming from the O2 sensors, then the ECU will richen up the fuel supply. What the ECU is trying to accomplish is getting the air fuel ratio of 14/1. That is 14 parts air to one part fuel. If you don't have the O2 senors, there is no way for the ECU to know what the engine is doing, and the engine won't run right. Also this is why the car doesn't wanna run right if one or both of the O2 sensors aren't working. What happens is that the tips get clogged over time with build up, and thus can't read the exhuast gasses properly.
     
  21. likeyoudontknow

    likeyoudontknow Karting
    BANNED

    May 6, 2004
    50
    I was looking at the cats last evening after reading this post and knowing that my 5/8-bank light is constantly on.

    It looks like it will be a tough job to get the cats out? Does anyone here have any experience in minimizing the work required to remove the cats on a 1990 348 ts and replace them with test pipes?

    Thanks!

    likeyoudontknow@hotmail.com
     
  22. RickDay246

    RickDay246 Karting

    Sep 10, 2004
    224
    San Diego
    Full Name:
    Rick Day
    Could someone please re-post either the link or the instructions on resetting and reading error codes on the ECU's? I may be developing a problem on my 348 Spider. Thanks, in advance. (There was a word doc on an old 2002 post, but I think it got wiped out when we had the server crash about a month ago.)
     
  23. Kevallino

    Kevallino Formula 3

    Feb 10, 2004
    2,248
    Los Angeles
    Full Name:
    Kevin
    Rick, my WSM is at home, so if someone doesn't get to it before I will scan the relevant pages for you tomorrow.

    I know how to do it, but if I try to describe it to you here I will for sure leave out something important!!!

    Cheers
    Kevin
     
  24. RickDay246

    RickDay246 Karting

    Sep 10, 2004
    224
    San Diego
    Full Name:
    Rick Day
    OK, I did the exercise of pushing the little buttons on the ECU's. Driver's side connected to 5-8; passenger side to 1-4. Mine are Motronic units with Bosch stickers w/# 0 261 203 327 over the bar code, and then # 0 000 156 536 0 over the lower bar code - same both sides.

    So I push the button down for about 10 seconds, and I get the following pattern on the dash lights:

    Long, 4 short blinks, 1 short blink, 1 short blink, 4 short blinks. Repeats. Both ECU's.

    Any worldly advice or translation? It's appreciated!

    (Kevin, thanks for your quick reply!)
     
  25. RickDay246

    RickDay246 Karting

    Sep 10, 2004
    224
    San Diego
    Full Name:
    Rick Day
    Kevin, thanks. PM'd you my fax # if it's convenient for you to do that!
    Rick
     

Share This Page