1990 Fleetwood fwd 4.5L Surges and looses power when warm
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HT4100 4.1, 4.5, 4.9 Discussion, 1990 Fleetwood fwd 4.5L Surges and looses power when warm in Cadillac Engine Technical Discussion; Hi I just was given a 1990 Fleetwood 4.5L Fwd sedan I picked it up in Washington state where I ...
  1. #1
    martinthereal6 is offline Cadillac Owners Member
    Automobile(s): 1990 Fleetwood
    Join Date
    Jul 2010
    Location
    texas
    Posts
    3

    Exclamation 1990 Fleetwood fwd 4.5L Surges and looses power when warm

    Hi I just was given a 1990 Fleetwood 4.5L Fwd sedan I picked it up in Washington state where I had to cut the catilatic converter off before the trip (to Texas) cause it was clogged I put in a straight pipe but did route the air hose from the emission system back into the straight pipe that had previously gone to the cat. Also did a fuel pressure test where it did fine. The car ran fine untill i got to some 100 degree weather were it started to surge at freeway speed and lose power. I then put octane booster in the car and it ran fine for another two full tanks then it did it again and the octane booster did not help anymore but it did help to drive the car below 90 degree weather (drove at night when cooler) but now I made it to Texas and the car now surges and loses power alot more but again only in the heat of the day at its worse I could not go above 35mph and at 35 it surged ALOT. I've since replaced the TPS unit, I replaced the fuel filter twice the second seemed clean but replaced anyway, dropped the fuel tank to find no loose baffles or debris, replaced the thermistat and flushed the radiator, I've also listened to all 8 injectors with a long screwdriver and they all seem to be clicking fine at idle, I've also taken the throttle body off and cleaned it, the power steering resivour does seem to push fluide out the cap sometimes while running but when i check it cold it is between the recomended cold lines on the dip stick, the only codes it displays is E40 and E49 I clear the pcm but they come back quickly. any help would be greatly appreciated Im running out of ideas! Thanks

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  3. #2
    daniel58 is offline Cadillac Owners Fanatic
    Automobile(s): 58 Coupe Deville, 77 Coupe deville, 90 Deville
    Join Date
    Sep 2009
    Posts
    183

    Re: 1990 Fleetwood fwd 4.5L Surges and looses power when warm

    I have a 90 deville with a 4.5, I just put $2500 in parts into the dang thing. Just about everything has been replaced or checked and it is hardly drivable due to missing and a lack of power. I would advise you to junk it before you waste anymore money on it. I have had cadillacs all of my life, my first car was a 56 Coupe Deville and I am to the point now where I have given up on FWD cads. Good Luck... you will need it!

  4. #3
    caddynewby's Avatar
    caddynewby is offline Cadillac Owners Member
    Automobile(s): 1990 Fleetwood
    Join Date
    Mar 2010
    Location
    Montreal, Canada
    Posts
    65

    Re: 1990 Fleetwood fwd 4.5L Surges and looses power when warm

    A similar discussion is happening on the main forum, some are suggesting checking for cat back pressure: http://www.cadillacforums.com/forums...ccelerate.html

  5. #4
    carnut is offline Cadillac Owners Master
    Automobile(s): 1988 Allante' (sold), 1984 Eldorado, 84 Sedan DeVille
    Join Date
    Feb 2003
    Location
    california
    Age
    67
    Posts
    5,942

    Re: 1990 Fleetwood fwd 4.5L Surges and looses power when warm

    The pieces that broke up and plugged the cat are now in the muffler. Take a rubber mallet and hit the muffler. If you hear things rattling around das it!!

  6. #5
    justin4yu is offline Cadillac Owners Member
    Automobile(s): 1992 Cadillac Fleetwood 2door sedan
    Join Date
    Jun 2010
    Location
    Yelm, Washington, United State
    Age
    28
    Posts
    31

    Re: 1990 Fleetwood fwd 4.5L Surges and looses power when warm

    i would buy a new napa premium vented gas cap sounds like your geting vapor lock in hot weather.

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