She rufuses to be fixed
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HT4100 4.1, 4.5, 4.9 Discussion, She rufuses to be fixed in Cadillac Engine Technical Discussion; I have a 91 Eldorado tc 4.9 that has had idleing issues for almost three years.On start up the idle ...
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    91 Eldo TC's Avatar
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    Question She rufuses to be fixed

    I have a 91 Eldorado tc 4.9 that has had idleing issues for almost three years.On start up the idle will stay around 1100 rpm and drop slowly,when I rev it up the engine boggs down.It has never stalled.It runs slightly rough until the car warms up then the idle will go up and down 700-900 But after 15 minutes of driving the engine is shaky and the idle seems to be unstable and I lose power.When i speed up the idle jumps from 1200-2300 and takes forever to get up to speed.It doesn't happen all the time and shutting off the car for a few minutes will make the idle more stable.Disconnecting the battery seems to smooth out my car for a few hours but it goes back to running rough.I have had it to many shops including Cadillac and no one can fix my car. So far I have replaced two fuel injectors,main bearing,fuel filter,k&n air filter,plugs(platnium bosch)wires(delco),egr cleaning,tps sensor adjustment,grounds cleaned,idle relearn,torgue convertor,muffler,starter,oil coolant line,three water pumps,timing(retarded),timing chain cover,battery,compression tests ok,fuel system ok,transmission ok,exhuast clear,many many engine diagnostics(never showed a problem).There is a whinning noise coming from the altenator area with a low ticking sound,should I have the altenator rebuilt?Change pulley's?
    Could I have a problem with my ecm?It never shows codes when there present,i always have history codes but nothing to do with the engine.I had ran out of oil and water(different times)no check engine light came on.If I had the computer reprogramed by Cadillac would it make a difference?What could be causing the engine to run so bad,but not all the time.Another problem is the heater,if I drive on the freeway with the temp at 90 it will come through the dash vents and not shut off until I turn off the car.Recently it started with the temp on 85,blows through the vents and won't shut off..it doesn't happen all the time,why is it doing that?Vaccum problems?I can't say if the repairs have been done right and is causing a problem so what i'm asking is a list to run down and see if I'm forgetting something that should be checked or repaired,any help will keep this car from falling off a cliff

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    BUILDINGCTSAMG is offline Cadillac Owners Connoisseur
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    Re: She rufuses to be fixed

    My suggestion for all problems that cant be fixed is a nice bottle of bg44k

  4. #3
    91 Eldo TC's Avatar
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    Re: She rufuses to be fixed

    I have found people love this stuff but were can I get a bottle?I called a few dealers and no one seems to know what I am talking about.

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    Re: She rufuses to be fixed

    Quote Originally Posted by 91 Eldo TC
    I have a 91 Eldorado tc 4.9 that has had idleing issues for almost three years.On start up the idle will stay around 1100 rpm and drop slowly,when I rev it up the engine boggs down.It has never stalled.It runs slightly rough until the car warms up then the idle will go up and down 700-900 But after 15 minutes of driving the engine is shaky and the idle seems to be unstable and I lose power.When i speed up the idle jumps from 1200-2300 and takes forever to get up to speed.It doesn't happen all the time and shutting off the car for a few minutes will make the idle more stable.Disconnecting the battery seems to smooth out my car for a few hours but it goes back to running rough.I have had it to many shops including Cadillac and no one can fix my car. So far I have replaced two fuel injectors,main bearing,fuel filter,k&n air filter,plugs(platnium bosch)wires(delco),egr cleaning,tps sensor adjustment,grounds cleaned,idle relearn,torgue convertor,muffler,starter,oil coolant line,three water pumps,timing(retarded),timing chain cover,battery,compression tests ok,fuel system ok,transmission ok,exhuast clear,many many engine diagnostics(never showed a problem).There is a whinning noise coming from the altenator area with a low ticking sound,should I have the altenator rebuilt?Change pulley's?
    Could I have a problem with my ecm?It never shows codes when there present,i always have history codes but nothing to do with the engine.I had ran out of oil and water(different times)no check engine light came on.If I had the computer reprogramed by Cadillac would it make a difference?What could be causing the engine to run so bad,but not all the time.Another problem is the heater,if I drive on the freeway with the temp at 90 it will come through the dash vents and not shut off until I turn off the car.Recently it started with the temp on 85,blows through the vents and won't shut off..it doesn't happen all the time,why is it doing that?Vaccum problems?I can't say if the repairs have been done right and is causing a problem so what i'm asking is a list to run down and see if I'm forgetting something that should be checked or repaired,any help will keep this car from falling off a cliff

    Forget the snake oil fuel additive. That will not fix your problem.

    Why was the timing retarded..??? That is only recommended if the owner insists on running regular fuel to prevent detonation/spark knock. It is not a cure for a rough idle... I would generally recommend advancing the timing 3-4 degrees beyond the factory setting and running premium all the time to ensure the best idle and best performance.

    Has anyone checked the fuel pressure regulator?? With the engine idling, pull the vacuum line off the FPR and watch the vacuum nipple on the FPR for several minutes for any sign of fuel leakage. Even if it is OK I would consider replacing the FPR as a preventive maintenance item....

    Checked fuel pressure when the rough running occurs??? Get a fuel pressure gauge and screw it onto the schraeder valve fitting on the fuel rail and watch the pressure when the rough idle/running occurs.

    Check the vacuum supply to the HVAC system. There is a check valve and a vacuum reservoir for the HVAC system to make sure it always has consistent vacuum and if there is a leak, failing check valve or leaking reservoir it could cause the air delivery door to malfunction as it is vaccum controlled as I remember.

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    Re: She rufuses to be fixed

    BTW....anyone clean out the EGR tubes under the throttle body. The EGR valve itself rarely if ever screws up on that car or needs cleaning....the EGR tubes, however, do need service occasionally. Hold the throttle body blades wide open and look down the bores. See the two tubes sticking up at you...???...they are NOT supposed to be full of carbon. Rod them out good with a stiff piece of coathanger wire.

  7. #6
    captainkirk is offline Cadillac Owners Member
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    Re: She rufuses to be fixed

    Quote Originally Posted by bbob
    BTW....anyone clean out the EGR tubes under the throttle body. The EGR valve itself rarely if ever screws up on that car or needs cleaning....the EGR tubes, however, do need service occasionally. Hold the throttle body blades wide open and look down the bores. See the two tubes sticking up at you...???...they are NOT supposed to be full of carbon. Rod them out good with a stiff piece of coathanger wire.

    Great tip. I've been wonderin is it ok to clean those tubes out ever since I cleaned my throtle plates. Don't know if it will improve the ride but just cleaning off the plates made a BIG difference. They looked like they haven't been cleaned since the car rolled off the showroom floor.

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