Engine Idle and "almost" stalling problems
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HT4100 4.1, 4.5, 4.9 Discussion, Engine Idle and "almost" stalling problems in Cadillac Engine Technical Discussion; I've read a lot here about cleaning the EGR tubes in regards to symptoms with rough idle and the car ...
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    rmonyer is offline Cadillac Owners Member
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    Engine Idle and "almost" stalling problems

    I've read a lot here about cleaning the EGR tubes in regards to symptoms with rough idle and the car almost shutting off when slowing down. I have a '93 Sedan Deville and I wanted to know: Do I have these EGR tubes? I see one tube connected to the EGR valve, but the mechanic told me that was a vacuum line. If my '93 has EGR tubes, where are they?

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    Re: Engine Idle and "almost" stalling problems

    If you have a 4.9 you have the "EGR tubes"....

    Take the air cleaner off, hold the throttle blades wide open (engine off) and look down the throttle bores. The tubes that are sticking up at you down below the blades are the EGR tubes. They are not supposed to be full of carbon and crud...rod them out thoroughly with a piece of still wire all the way thru to the passage in the manifold below.

    The EGR tubes will likely not cure any idle problems, however.

    While you are in there, spray the throttle bores and the throttle blades with carb cleaner and scrub with an old toothbrush to clean the throttle bores down below the blades and the backside of the throttle blades thoroughly. The deposits that build up will restrict air flow past the blades at idle and cuase idle speed control problems. After cleaning all the deposits off of the bores and the blades and putting everything back together, disconnect the negative battery cable for 60 seconds to reset the idle learn offset values in the PCM to the default "clean throttle body" values.

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    rmonyer is offline Cadillac Owners Member
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    Re: Engine Idle and "almost" stalling problems

    Thanks for the help and location pointers. I had the throttle body cleaned on Friday with "Run Rite" fuel system cleaner. I looked at the throttle body today and the butterfly valves look good (no black crud or build up). Today, I asked my mechanic to replace my fuel filter since they didn't when the did the run rite treatment. Now they are about to install a new EGR valve. I might try to clean the EGR tubes once I get the car back. Can I use a wire hangar? If not what kind of wire will fit these tubes?

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    Re: Engine Idle and "almost" stalling problems

    Quote Originally Posted by rmonyer
    Thanks for the help and location pointers. I had the throttle body cleaned on Friday with "Run Rite" fuel system cleaner. I looked at the throttle body today and the butterfly valves look good (no black crud or build up). Today, I asked my mechanic to replace my fuel filter since they didn't when the did the run rite treatment. Now they are about to install a new EGR valve. I might try to clean the EGR tubes once I get the car back. Can I use a wire hangar? If not what kind of wire will fit these tubes?

    Likely you just need to clean the EGR tubes out....not replace the EGR valve.

    The tubes are fairly large in diameter. You just need to use any sort of stiff piece of wire to clean the carbon out. When you look at them you will see.

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    Re: Engine Idle and "almost" stalling problems

    Quote Originally Posted by rmonyer
    Can I use a wire hangar? If not what kind of wire will fit these tubes?
    Get a gun barrel cleaning kit.
    One that comes with different diameter brushes and an extension handle to attach them to.
    I purchased one a while back and 2 of the brushes were a perfect fit.

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    rmonyer is offline Cadillac Owners Member
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    Re: Engine Idle and "almost" stalling problems

    You guys are great! Thanks for all the help. I haven't gotten the car back yet, but I should have it tomorrow. There was a delay in getting the new EGR part. I know you said I probably didn't need it, but after my emissions failures (prior and during the rough idle) I feel that it can't hurt. I failed for NOx if you're curious. Passing was 800 or less, I was at 1100-1300 during 3 different tests. I read a lot on NOx failures, and the EGR valve was in question. So this new one won't hurt me (except for the $70 cost and labor to put it in ). Once I get my car back I will drive it for awile WITHOUT cleaning the EGR tubes just to see if we have any improvement with the work that was done. I will then update this post with my results to help out someone else. Thanks again and stay tuned.

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    Re: Engine Idle and "almost" stalling problems

    Quote Originally Posted by rmonyer
    You guys are great! Thanks for all the help. I haven't gotten the car back yet, but I should have it tomorrow. There was a delay in getting the new EGR part. I know you said I probably didn't need it, but after my emissions failures (prior and during the rough idle) I feel that it can't hurt. I failed for NOx if you're curious. Passing was 800 or less, I was at 1100-1300 during 3 different tests. I read a lot on NOx failures, and the EGR valve was in question. So this new one won't hurt me (except for the $70 cost and labor to put it in ). Once I get my car back I will drive it for awile WITHOUT cleaning the EGR tubes just to see if we have any improvement with the work that was done. I will then update this post with my results to help out someone else. Thanks again and stay tuned.
    Why create more problems for yourself? You received instructions from a GM engineer and you choose to disregard them? Maybe I missed something?

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    rmonyer is offline Cadillac Owners Member
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    Re: Engine Idle and "almost" stalling problems

    Quote Originally Posted by 91TexasSeville
    Why create more problems for yourself? You received instructions from a GM engineer and you choose to disregard them? Maybe I missed something?
    Not "disregarding" suggestions/advice. I am just trying to ISOLATE the problem. I was already failing emissions tests (high NOx) so replacing the EGR Valve was next anyway. Rather than replace the EGR, have my fuel filter changed AND clean out the EGR tubes, I felt I would like to test the car BEFORE cleaning out the EGR tubes......just to see what results I would get.

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    rmonyer is offline Cadillac Owners Member
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    Re: Engine Idle and "almost" stalling problems

    New update 2/25/05. The car has the "rough idle" and "engine stumble" again. I have narrowed it down to: It only happens when the heater or defroster is on. It seems as if when the fan for the heater is blowing, the engine starts having trouble idling smooth. Anyone ever heard of this?

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    Re: Engine Idle and "almost" stalling problems

    Sounds like low voltage? The heater motor may have enough load to pull the volts down to a level the engine doesnt like. Do turning all the lights on make it worse also? What are the voltage readings with everything off as opposed to everything on?

    BTW I like your method of doing one thing at a time and documenting the results. Scientific Method..

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    rmonyer is offline Cadillac Owners Member
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    Re: Engine Idle and "almost" stalling problems

    Thanks. There is a method to my madness. I like to specifically identify a problem if I can. Thank years of electronic troubleshooting for this habit. Anyway, I will have to check into the voltages and report back. I will post the info as soon as I get it. As far as checking the voltage, are you suggestion checking it right on the battery or at another location? Thanks.

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    Re: Engine Idle and "almost" stalling problems

    I would check at the main fuse block.

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    Re: Engine Idle and "almost" stalling problems

    Am now confused to this one
    Quote Originally Posted by rmonyer
    Thanks. There is a method to my madness. I like to specifically identify a problem if I can. Thank years of electronic troubleshooting for this habit. Anyway, I will have to check into the voltages and report back. I will post the info as soon as I get it. As far as checking the voltage, are you suggestion checking it right on the battery or at another location? Thanks.
    Years of electronic trouble shooting ?
    What kind of madness method are you describing ??
    Do you mean replace it and if it doesnt fix it then replace something else ???

    Checking the votage as CharBroiled stated and having years of experience trouble shooting elec should in my mind be self explanitory
    Quote Originally Posted by rmonyer
    Not "disregarding" suggestions/advice. I am just trying to ISOLATE the problem. I was already failing emissions tests (high NOx) so replacing the EGR Valve was next anyway. Rather than replace the EGR, have my fuel filter changed AND clean out the EGR tubes, I felt I would like to test the car BEFORE cleaning out the EGR tubes......just to see what results I would get..
    I would have to say you did disregard the suggestions/advice."...so replacing the EGR Valve was next anyway.". Dont know why you would say it was next ? Replace ? For what reason ?
    Quote Originally Posted by bbob
    Likely you just need to clean the EGR tubes out....not replace the EGR valve.
    Sounds like you have it backwards.
    Replacing items does not "specifically identify a problem".

    I can understand what you meant when saying you felt it couldnt hurt.
    But besides the price of the part..the labour that is charged as well...what was that ?
    50 maybe 60 bucks that resuted in nothing ???

    According to your logic and method to madness:
    If I sit down on the couch, grab the remote, hit the power button, TV doesnt come on ??
    Should I change the batteries in the remote or should I open up the TV and start replacing circuit boards ?

    Of course change the batteries !
    But if that doesnt work then it must be the TV ?
    Right ??
    No matter what anyone else says. "Need A New Remote".
    Hang on Im going to change this circuit board first..............

    Good thing you replaced the EGR Valve though.

    BTW:
    Did you
    Quote Originally Posted by bbob
    ...... clean the EGR tubes out.....
    .

    You can change as many EGR valves as you want.
    But if the tubes are still plugged..................

    Not saying that you should take what you read here or anywhere else as written in stone, (As bbob has personally informed me of. BTW Thanx boss).
    But the info here is free.
    Informative.
    Educational.

    Sorry for the rambling...
    What was your problem again

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    rmonyer is offline Cadillac Owners Member
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    Re: Engine Idle and "almost" stalling problems

    Murphy G.....Thanks for your HELP.

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    Re: Engine Idle and "almost" stalling problems

    Quote Originally Posted by rmonyer
    Murphy G.....Thanks for your HELP.
    Did you or did you not resolve the problem?
    Have you had the vehicle retested for emissions yet?

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