Newbie looking for ground(s)
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HT4100 4.1, 4.5, 4.9 Discussion, Newbie looking for ground(s) in Cadillac Engine Technical Discussion; Evening, everyone- My first Cadillac ever, a 1990 DeVille with 48k miles on her. One owner, it's a beauty and ...
  1. #1
    charco68 is offline Cadillac Owners Member
    Automobile(s): 1990 Cadillac Deville
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    Newbie looking for ground(s)

    Evening, everyone-

    My first Cadillac ever, a 1990 DeVille with 48k miles on her. One owner, it's a beauty and does everything well. I have two things to address, one underway and the other a mystery.

    Underway: Bouncy, boing-y, spring-y ride, been told during a wellness visit to Capital Cadillac here in Atlanta that all four struts are gone, they can replace them for $1800. I'm going the Strutmaster route and will have a passive system installed elsewhere.

    Mystery: Doesn't have a smooth idle, and chugs during acceleration at any speed. Can especially feel it in the steering wheel. Sometimes it's smoother than others. The dealer found one dead injector, replaced that ($$$) and it's better, but warned me two other injectors are on their way out. No CEL. I'll go another route for the other injectors, but here's my question before I go any further:

    I've read a lot about proper ground for these engines, and I've had my head under the hood several times looking for it (them.) Does anyone have pics, or can point me to a link with some? I've looked over a wiring diagram (fail) searched the cr*p out of this on YouTube and here, but I just need some visual.

    Many thanks!
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  3. #2
    carnut is offline Cadillac Owners Master
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    Re: Newbie looking for ground(s)

    Most are at the Alternator bracket and on a stud just in front of the starter. Another I believe is at the driver side strut tower.

  4. #3
    HUF's Avatar
    HUF
    HUF is offline Cadillac Owners Connoisseur
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    Re: Newbie looking for ground(s)

    Yup, one on the engine near starter is very important and not much visible. By the way, you better forget the dealer if you do not want to spend several thousand dollars a year for pretty much nothing. A set of refurbished injectors should be less than $250. Check out ebay. Some Ford injectors might be good for you .

  5. #4
    cadillac_al is offline Cadillac Owners Connoisseur
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    Re: Newbie looking for ground(s)

    In the meantime try some Techron in the gas. A bad MAP sensor makes them run bad and seems to take a while to activate the ses light. It's nice to see an older Caddy so well cared for.

  6. #5
    HUF's Avatar
    HUF
    HUF is offline Cadillac Owners Connoisseur
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    Re: Newbie looking for ground(s)

    Run onboard diagnostics (ignition ON press Warmer and OFF simultaneously for a few seconds) and write down the trouble codes.

  7. #6
    carnut is offline Cadillac Owners Master
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    Re: Newbie looking for ground(s)

    I think you just have remaining dirty injectors, some better than others. Looking for grounds at this point is not, IMO, the next step. I would unplug each injector harness connector one at a time while the engine runs. The ones that barely affect how the engine runs are suspect. An unplugged good injector will cause a fairly drastic roughness.

  8. #7
    charco68 is offline Cadillac Owners Member
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    Re: Newbie looking for ground(s)

    Evening, all-

    Thanks for all the feedback! Just had the injectors replaced with refurbished Bosch III's, found them on eBay for less than $200. DRASTIC performance change--quiet, strong and smooth, like a Cadillac should be. Noticed a bit elevated RPM at startup and coming to a stop, so I reset the computer via the manual, just to cover my bases. Still have an intermittent miss at idle now and then, but who cares?? I'm still going to make sure those grounds are tight though...appreciate the help.

    PS: Ran OBD before and after injector replacement. No codes.

  9. #8
    carnut is offline Cadillac Owners Master
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    Re: Newbie looking for ground(s)

    Remove the ground wires, clean them and then tighten.

  10. #9
    drewsdeville is offline Cadillac Owners Master
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    Re: Newbie looking for ground(s)

    be careful with the online injectors. Many retailers mark the same injectors to be compatible with both the 4.5 and 4.9, 90-95. However. the 1 year 1990 4.5 took 16 lb/hr injectors where the 4.9 took 19 lb/hr. Many times the 4.5 will have a slight rough idle and stumble with the larger injectors. The ECM fuel trim range isn't quite wide enough to compensate...

    Do a search. Another member ad I uncovered this a few years ago when both our 4.5s werent quite right with the Bosch IIIs

  11. #10
    charco68 is offline Cadillac Owners Member
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    Re: Newbie looking for ground(s)

    Hey, ya'll! Thanks for all the great advice. Drewsdeville, you are correct, it's not a perfect idle, and the fuel center is reading all kinds of nutty stuff. After I get a handle on a few more things (sail-on; stereo suddenly silent) I'm going to turn my attention back to the injectors.

    Also: Got the suspension conversion done, Strutmasters all around. Soooo much better. Found a small leak in the exhaust on the back of the engine, had a gasket replaced for peanuts and now it's quiet like my stereo.

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