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Flat running at 4K

Discussion in 'Technical Q&A' started by modena001, Aug 26, 2004.

  1. modena001

    modena001 Rookie

    Mar 21, 2004
    32
    Seattle
    Hi guys, any help would be much appreciated. I have a 97 550. I had a slow down light going on everytime I drove the car. I replaced the Thermocouple ECU's and have fixed the slow down light problem. However, the car still is not running correctly. I hammer the throttle at 4k rpms and the car revs but very slow and without much power.

    I was having this problem before I replaced the ECU's. I thought the replaced ECU's would fix the problem. Any ideas what else could be causing this. I have no CEL, slow down or any other lights going on.

    Thanks in advance for the help.

    Regards
     
  2. jimangle

    jimangle Formula 3

    Nov 5, 2003
    2,438
    Haverford
    Full Name:
    James
    Maybe your catalytic coverter is plugged up. You probably got the slow down light because the cat was heating up. Now it's possibly plugged up.
    Just my thought.
    Jim
     
  3. modena001

    modena001 Rookie

    Mar 21, 2004
    32
    Seattle
    How do I know if I have a plugged cat. And how would I unplug it.
    thanks
     
  4. davehelms

    davehelms F1 Rookie

    Jan 3, 2004
    4,629
    Full Name:
    Dave Helms
    Remove one of the fuel filters and drain it out backwards. Inspect the fuel that comes out. Just had a 550 in this spring that had all of the rubber components in the fuel tanks decomposed and plugged the filters. Look for a "fuel injection cleaners" post from a few months ago. I posted pictures of the results, and the symthoms were identical.
    Dave
     
  5. jimangle

    jimangle Formula 3

    Nov 5, 2003
    2,438
    Haverford
    Full Name:
    James
    The only way to unblock a plugged catalytic converter is to hollow it out, but that's not really legal. To checked a plugged cat, you could check the difference in exhaust flow between both sides at 4-5k rpm. I'm not sure how that exhaust is set up. You may want to check the fuel filters first like Dave said.
     
  6. modena001

    modena001 Rookie

    Mar 21, 2004
    32
    Seattle
    thanks guys. I will try tonight.
    Regards,
     

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