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Thread: 89 Deville engine pinging under load when warm

  1. #1
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    89 Deville engine pinging under load when warm

    Folks,
    I have an 89 Cadillac Deville with the 4.5. Ever since i bought the car, the motor pings under load after it has warmed up. When i first got it, i had the intake off and it was badly carboned up. I cleaned the intake out and also the EGR. It still does this. It is worse if i run 89 or 87 octane fuel. I suspected it might be the egr, but i am getting no egr codes and no engine idle/drivability problems whatsoever. I don't think i could ask for a motor that runs better. This has been going on for almost 30k miles now :O and i have been running 93 octane the entire time. It has had regular tune-ups, etc. Timing is fine. If i retard the timing, it gets better, but i have to retard it to the point where it has NO power whatsoever and DRINKS the gas before the pinging goes away. This has been a problem that has plagued me for quite some time. Any help would be appreciated.


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  3. #2
    Ranger's Avatar
    Ranger is offline Cadillac Owners Member
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    Re: 89 Deville engine pinging under load when warm

    I don't believe the EGR will set a DTC on an 89 as it is vacuum as opposed to electrically operated. I would look closely at the EGR valve. Stick your finger under the "top hat" or "mushroom top". There are slots in there as I recall that should allow you to feel the diaphram. Push up on it at idle and the engine shut run rough and maybe die. Then run the RPM up and hold it. I believe you should feel the diaphram lift (open the valve). The vacuum that operates the diaphram is controlled by a solenoid. or control valve. That could be malfunctioning and may or may not set a DTC, I am not sure. Ewill3rd can probably shed more light on it and/or correct me if I am wrong.

  4. #3
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    Re: 89 Deville engine pinging under load when warm

    It is typical "lack of EGR" problem. Badly plugged EGR tubes would set a code and SES light. But not operational EGR valve for some reason does not set the code. Do not waste your time trying to clean it up. You have to remove TB and a lot of other hoses, parts to get access to EGR valve's bolts. The only cure might be replacing the EGR valve and gasket. They are around $55 incl. shipping at gmpartsdirect. com or autopartsgiant.com. Good luck! Use only ACDELCO part.

  5. #4
    100 is offline Cadillac Owners Enthusiast
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    Re: 89 Deville engine pinging under load when warm

    My 4.9 (95 Sedan De Ville) was pinging when it warmed up. The EGR valve was not working properly. It did open under load, but it was not opening as much as it should. The diaphragm was deteriorated and it leaked a bit, so it didn't hold vacuum as tight as it should have been.

    Anyway, replacing it solved my problem. But I spent a lot of time checking other components were OK including the EGR solenoid.

    Good luck!

  6. #5
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    Re: 89 Deville engine pinging under load when warm

    i messed with it a little today. after warming it up to operating temperature, i did lift up on the diaphragm and the motor did bog down and almost die. I removed the vacuum line from the egr valve and there was no vacuum on it. I removed it from the solenoid side and there was no vacuum there either, but there was vacuum going to the solenoid. there was no vacuum at idle and also when i ran the rpms up a bit. how far should i have to rev it up and for how long before it starts applying vacuum? i am wondering now if it's my solenoid, or my solenoid and egr valve both. also, anybody have gm part numbers for the egr solenoid and valve? i will check prices on gmpartsdirect.com.

    thanks!

  7. #6
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    Re: 89 Deville engine pinging under load when warm

    Quote Originally Posted by pjunod
    i messed with it a little today. after warming it up to operating temperature, i did lift up on the diaphragm and the motor did bog down and almost die. I removed the vacuum line from the egr valve and there was no vacuum on it. I removed it from the solenoid side and there was no vacuum there either, but there was vacuum going to the solenoid. there was no vacuum at idle and also when i ran the rpms up a bit. how far should i have to rev it up and for how long before it starts applying vacuum? i am wondering now if it's my solenoid, or my solenoid and egr valve both. also, anybody have gm part numbers for the egr solenoid and valve? i will check prices on gmpartsdirect.com.

    thanks!
    Everything is correct. ECM disables vacuum supply to EGR valve in idle. If you bypass the solenid and connect the vacuum hose from TB directly to EGR valve it will open in idle because of extra vacuum and the engine will stall. But you can start the car and drive like that around the block and most likely will be surprized there will be no ping. It will confirm your ping is because of EGR malfunction. The problem with older EGR valves is not that they do not operate at all. They do open and close, but their threshold changes so that they do not open at slight throttle. My guess is once again- do not waste time and money get EGR valve from the online stores I mentioned. The EGR solenoid is most likely fine. If it is not replacing it is a five minut work.

    EGR valve ACDELCO 214-5539 (GM#17089071) YOu can buy any aftermarket gasket. Replacing the gasket is a must.
    Last edited by adalla; 11-26-05 at 04:06 PM.

  8. #7
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    Re: 89 Deville engine pinging under load when warm

    hey. thanks for the info. i will order an egr valve this week.

    btw -- i checked gmpartsdirect and they have 17113460 for an 89 deville egr valve part #. guess i'll do the front struts, right halfshaft, and egr valve all next weekend.

  9. #8
    snoopy321 is offline Cadillac Owners Member
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    Re: 89 Deville engine pinging under load when warm

    I have a similar problem, just started. 2 things changed before it started, 1. I put fuel injector cleaner in a full tank of 91 octane non ethanol gas, 2. my mechanic turned off my automatic idler.

  10. #9
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    Ranger is offline Cadillac Owners Member
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    Re: 89 Deville engine pinging under load when warm

    Have you checked the two EGR tubes down in the TB?


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