93 STS with 4.6 sounds runs like crap, dies constantly!
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Northstar Engines and System Technical Discussion Discussion, 93 STS with 4.6 sounds runs like crap, dies constantly! in Cadillac Engine Technical Discussion; I was drivin to work last night and my 93 STS started stuttering. I pulled off the road, and by ...
  1. #1
    lonnieh is offline Cadillac Owners Member
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    Unhappy 93 STS with 4.6 sounds runs like crap, dies constantly!

    I was drivin to work last night and my 93 STS started stuttering. I pulled off the road, and by the time I stopped, my RPM gauge was jumping from 0 to 2200. I forgot to check the error codes, and had to leave the car off the road (I hate leaving my baby anywhere) until I can find a way to get it home. Does anybody have a clue of whats going on here? Any information would be appreciated.

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    dloch is offline Cadillac Owners Fanatic
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    Re: 93 STS with 4.6 sounds runs like crap, dies constantly!

    Quote Originally Posted by lonnieh
    I was drivin to work last night and my 93 STS started stuttering. I pulled off the road, and by the time I stopped, my RPM gauge was jumping from 0 to 2200. I forgot to check the error codes, and had to leave the car off the road (I hate leaving my baby anywhere) until I can find a way to get it home. Does anybody have a clue of whats going on here? Any information would be appreciated.
    You need to get any codes. Did it turn on the check engine light?

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    lonnieh is offline Cadillac Owners Member
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    Re: 93 STS with 4.6 sounds runs like crap, dies constantly!

    No, the check engine light didn't come on, although, now that shes back in my driveway, I have the following codes...

    A047 - Yes sir its the "4 window" AC for me....
    T073
    T083
    S021
    S051
    S044
    S055
    S060
    S044
    S055

    It started right up, ran fine for a few minutes, and then started choking again. Could this possibly be a fuel pump?

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    dloch is offline Cadillac Owners Fanatic
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    Re: 93 STS with 4.6 sounds runs like crap, dies constantly!

    Quote Originally Posted by lonnieh
    No, the check engine light didn't come on, although, now that shes back in my driveway, I have the following codes...

    A047 - Yes sir its the "4 window" AC for me....
    T073-
    T083
    S021
    S051
    S044
    S055
    S060
    S044
    S055

    It started right up, ran fine for a few minutes, and then started choking again. Could this possibly be a fuel pump?
    T073 .......................... PCM - EBTCM/EBCM Pulse Width Modulation Signal Fault
    T083 .................................................. ....... Brake Fluid Level Low
    S021 .......................... Left Rear Damper Solenoid Valve Short to Ground/Open
    SO51 ??
    S044 .................................................. ... Lift or Dive Signal Fault
    S055 .......................................... Resistor Module Short to Ground/Open
    S060 .............................................. Left Front Position Sensor Fault

    Looks like a bunch of suspension faults but nothing that woulo make the car just quit. It could be the fuel pump or a clogged fuel filter.

    Can you hear the pump run when you first turn on the car? You may need to get a gage so you can read the fuel pressure.

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    lonnieh is offline Cadillac Owners Member
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    Re: 93 STS with 4.6 sounds runs like crap, dies constantly!

    I'm really not sure what to listen for, so I'd probably give you inaccurate info on that. I'll definately go get a pressure guage, but its off to work for now, in a Sunfire (urg)...

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    lonnieh is offline Cadillac Owners Member
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    Re: 93 STS with 4.6 sounds runs like crap, dies constantly!

    OK, now the car starts, runs rougher than normal, throws a P030. Almost choked myself standing by the exhaust (LOL, I think I'll have to get that fixed also) Hopefully its a little warmer this weekend, I'll get out the new pressure guage :-) BTW, I didn't hear anything after the ignition was turned on, not even the slightest squeak from the compressor...

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    Re: 93 STS with 4.6 sounds runs like crap, dies constantly!

    Sounds like the old fuel pressure regulator leaking. Take the silver top cover off (remove the perimeter row of screws....leave the 4 inner, recessed screws in place) and look inside the intake manifold. Have someone turn on the key to energize the fuel pump and watch the vacuum nipple on the fuel pressure regulator (that canister shaped device on the rail near the throttle body end). Fuel should NOT come out of the vacuum nipple on the FPR...nor from anywhere else. Do NOT crank or start the engine with the top cover off the manifold...just turn the key to on to energize the fuel pump to pressurize the system to look for the leak.

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    lonnieh is offline Cadillac Owners Member
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    Re: 93 STS with 4.6 sounds runs like crap, dies constantly!

    I popped the silver cover off, didn't see any leakage when the ignition was turned on. I reassembled, hoped for the best, expected the worse, and ofcourse, it died. I really don't know what to look for, especially in this type of engine, so I think I'll take it in to a dealer for further diagnostics, thanks for all the help!

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    lonnieh is offline Cadillac Owners Member
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    Re: 93 STS with 4.6 sounds runs like crap, dies constantly!

    Running through your post bbobinsky, seems I've failed to mention a few things! I do see some white smoke, not to much, but noticable. Over the past months I've started the car, and sometimes it runs fine for a few minutes and then goes to hell, and sometimes it goes to hell right after I start it. I've changed the plugs and wires last week, and the coil packs about 10k miles ago.

    I've decided not to take it to the dealer, and just attempt to fix it myself. I popped the silver cover off again today. I looked again for leaks, and didn't see much, I'm hoping to find one of those 'pin-hole' leaks, but nothing so far. I can't really lift that plate up to high, because all of those wires are connected, so its sort of difficult to check out the injectors.

    Does anybody know how much injectors run? I'd hate to be one of those guys who just guesses and slaps a few bills down, but I'm almost sure that the problem is coming from up there around the fuel rail because of its spuratic behavior. The plugs were wet when I pulled them out, and it even gave me a backfire a few times.

    BTW I keep forgetting to introduce myself! Hi I'm Lonnie from Marion, Indiana. I work at Red Gold, and I like Cadillacs. Previously owned an 89 Sedan Deville (loved the tails) and now I'm driving a 84 RAM VAN until my 93 STS is fixed. :drinker LOL

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    Re: 93 STS with 4.6 sounds runs like crap, dies constantly!

    With the rough running and white smoke it definitely sounds like an injector or possibly the fuel pressure regulator.

    Pull the plugs and look at them. If an injector is sticking it should leave that plug wet/fouled/black with carbon. By comparing all the spark plugs it should give you a clue as to which cylinder has the bad injector(s).

    You can lift the fuel rail up out of the intake manifold with the silver top cover off. Lift it up until the injector tips are visible and turn on the key (do not start....just turn on the key to energize the fuel pump) to see which injector drips fuel.

    I would replace the fuel pressure regulator regardless. Consider it preventative maintenance at this point. They seem to be good for 100K or 10 years....whichever comes first....and then they start failing here and there. Just replace it as along as the top cover is off.

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    Re: 93 STS with 4.6 sounds runs like crap, dies constantly!

    bbob, could you elaborate a little more on the fuel pressure regulator. I have a 94 4.6 with 156,000 miles, bought it was 86k. I have yet to change the regulator, but I get bad gas mileage. I recently got the car running really good and haven't even really opened it up on the interstate or what not to get a good look at the fuel economy, but it's been 11-12 mpg in the city. I guess my question is, can the regulator or injectors have anything to do with the economy? It's not running or idling rough at all, and I also wonder about the high mileage fuel pump. Hope the OP finds his problem. Kudos on taking it on for yourself, even if it ends up at the dealership, you can't blame yourself for trying! Good luck.

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    Re: 93 STS with 4.6 sounds runs like crap, dies constantly!

    Yes, a leaky injetor(s) and/or FPR will have an adverse effect on milage as it will dump extra unmetered fuel into the intake.

  14. #13
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    CadiJeff is offline Cadillac Owners Connoisseur
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    Re: 93 STS with 4.6 sounds runs like crap, dies constantly!

    I would also check the coil packs as they will cause this problem (Has happened twice to my 94 eldo) also check egr and pcv valve

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    eldorado1 is offline Cadillac Owners Connoisseur
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    Re: 93 STS with 4.6 sounds runs like crap, dies constantly!

    If your tach is dropping to 0 while your engine is still putting along, wouldn't that point to the crank sensor(s)? Or possibly the ignition module?

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    lonnieh is offline Cadillac Owners Member
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    Re: 93 STS with 4.6 sounds runs like crap, dies constantly!

    As far as I can remember, there would be times where the tach came close to 0, but it was bouncing around so much it was hard to tell.

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