2002 Deville Multiple codes, rough idle, surging at high RPM
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Northstar Engines and System Technical Discussion Discussion, 2002 Deville Multiple codes, rough idle, surging at high RPM in Cadillac Engine Technical Discussion; Hello All! I have been reading many discussions regarding these problems and much points to the plenum but I wanted ...
  1. #1
    Deltamaster is offline Cadillac Owners Member
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    2002 Deville Multiple codes, rough idle, surging at high RPM

    Hello All!

    I have been reading many discussions regarding these problems and much points to the plenum but I wanted to run it past to find out your thoughts.

    Vehicle = 2002 Deville
    Unknown maintenance history. Check Engine light on for last two (at least) years (appx 8000 miles). Driven by 80+ year old man that should not have been driving anyway. I inherited it after his death.


    I retrieved the codes thanks to the info found here.

    B0429 = Aux rear temp air door.
    I understand this is a common code and not worth messing with.

    B1004 = Keep alive memory.

    B1327 = Device Power Circuit low.
    May have been triggered by the battery??? Had to charge battery at one point when there was not enough power to turn over starter motor.

    I guess none of these really means much and likely has nothing to do with engine performance but I wanted you all to have all the data I have.

    __________________________________________________ __________

    Now the interesting codes:

    P0101 = Mass air flow sensor.
    From what I have read on these forums the sensor may be bad but is not as likely as if there is a vacuum leak after the sensor.

    P0171 = Fuel Trim Lean
    ?????

    P0174 = Fuel Trim Lean
    ?????

    P0300 = Engine misfire detected
    Bad spark plugs? Bad coil? Bad Wires?

    P0741 = TCC stuck off
    Torque converter problems? No problems shifting noted.

    P1189 = Engine oil pressure switch circuit.
    When I inherited the car I took it to Tire Kingdom for tires and they checked the oil and found it was very low. Maybe so low that the pressure was below spec at some point and left the code in the computer?

    P1860 = TCC PWM solenoid circuit electrical.
    ???????

    The vehicle seems to drive normally at highway speeds. The display on the dash shows average MPG as between 12 and 14 MPG.

    After I acquired the car I drove it from Florida to SC with no problems (approximately 6-700 miles).

    A couple months later the engine began to idle roughly.

    With the transmission in park and the throttle applied, when it gets over 3500 RPMs the engine surges.

    With the transmission in "D" and the vehicle stopped the engine idle falls to about 700 RPM and idles roughly... may stall occasionally.

    With the vehicle traveling at approximately 30 miles per hour no throttle pressure applied the RPMs and speed gradually increase. Vehicle will not hold low RPMs or stand still while in "D". Speed will not decrease normally when throttle is released.



    OK, Guys. I suspect from reading all the threads that I have found that the Intake Plenum may be the culprit. I did not have any carb cleaner to test it so I sprayed WD-40 on the plenum clamp screw with no change in RPM.

    What do you all think?

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    Ranger's Avatar
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    Re: 2002 Deville Multiple codes, rough idle, surging at high RPM

    I still think it's the plenum duct. Spray it again and this time try flexing the bottom while spraying it.

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    Deltamaster is offline Cadillac Owners Member
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    Re: 2002 Deville Multiple codes, rough idle, surging at high RPM

    Quote Originally Posted by Ranger View Post
    I still think it's the plenum duct. Spray it again and this time try flexing the bottom while spraying it.

    Thanks for the response.

    From everything I have read here I suspect you are right... Just wanted to make a confirmation before I consider the project. It does not look to be too bad but...

    Has anyone posted instructions on how to replace the plenum?

    Can it be done without removing the intake manifold?

    OH,

    This plenum must be a common flaw. Why has GM not addressed this as a flaw and developed a better solution for it?

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    Re: 2002 Deville Multiple codes, rough idle, surging at high RPM

    No, I think you're gonna have to lift the manifold, but that's not a bad job.

    Yeah, the plenum duct does seem to be a rather common problem. Not sure why GM has not addressed it. Then again, maybe they have. Hope I'm not jinxing myself, but mine is 7 yrs old with 80K on it.

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    Deltamaster is offline Cadillac Owners Member
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    Re: 2002 Deville Multiple codes, rough idle, surging at high RPM

    OK.

    I understand this is a dealer only part so I am off to find a local dealer and some instructions for removing the manifold.

    I will post back when the deed is done to let you know the results.

    Thanks

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    Deltamaster is offline Cadillac Owners Member
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    Re: 2002 Deville Multiple codes, rough idle, surging at high RPM

    Well...
    I just called the local Caddy Dealer and the parts guy told me they have PLENTY of the plenums in stock. He said they get about two requests (between their service department and outside customers) for them per week!

    Now to find instructions to replace the thing!

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    Re: 2002 Deville Multiple codes, rough idle, surging at high RPM

    The procedure and pictures are posted in this Forum, and maybe in Discussion, Tech Tips.

    There are several threads during April alone that have over 30 pictures and diagrams of the plenum, intake manifold, fuel rail, manifold seals (gaskets), and torque sequences.

    Look through past pages here and in Deville - stuff like Plenum, Intake Manifold, various P codes, rough idle, etc.

    All the job takes is simple hand tools and time. The plenum is held on by 3 long bolts through the throttlebody casting: the "nuts" on the Plenum are welded on. Manifold torque is only 7.5 ft/lb - 89 in/lb......be careful or you'll crack the composite plastic bolt bosses.

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    Re: 2002 Deville Multiple codes, rough idle, surging at high RPM

    Well...

    I bought the plenum... $35.00 at the local Caddy dealer. I wanted to replace the intake manifold gaskets but they wanted over $7.00 each for them so I opted not to spend the $58.00 for rubber gaskets. The original ones were in pretty good shape and still pliable so I should be OK there.

    I took everything apart which was not too bad (as you mentioned), only needed one socket and a flat screwdriver to do the job. Problem was when I was removing the injectors from the fuel rails one of the blue rubber "O" rings popped off and flew out in to neverland. Dealer did not have them in stock and wanted $75.00 for the kit which included the eight blue upper and the eight black lower "O" rings... WOW!

    Advance Auto parts was able to order the uppers for a little over eight bucks total (came in sets of four so I bought two sets).

    Am waiting for them to come in now... should be here in about two and a half hours.

    Sure enough, though... when I pulled the old plenum there was a tear on the bottom where the rubber meets the metal plate about one inch long.

    Sure hope this solves the problem!

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    Re: 2002 Deville Multiple codes, rough idle, surging at high RPM

    Quote Originally Posted by submariner409 View Post
    There are several threads during April alone that have over 30 pictures and diagrams of the plenum, intake manifold, fuel rail, manifold seals (gaskets), and torque sequences.
    Seems to me that if this is such a big problem General Motors needs to develop a solution (better engineered part) and replace them free of charge.

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    Re: 2002 Deville Multiple codes, rough idle, surging at high RPM

    That has about the same chances as restitution for '97-99 blown head gaskets from head bolt hole thread failure: slim and none.

    When you drop the fuel rail back in, oil the upper and lower fuel injector O-rings - use a smear of your engine oil around each - it will make your life much easier.

    When it's all buttoned up, before you try to start the engine, turn the key ON for 10 seconds, OFF for 30 seconds, twice. This will prime the fuel rail again. Start 'er up and use a flashlight to snoop for fuel leaks at the injector/rail connections.

    For future use, buy a cheap Walgreen stethoscope, remove the chest diaphragm, and substitute an 18" length of proper sized vacuum hose (Help ! rack). Use the rig to snoop for vacuum leaks and mechanical ticks and squeaks.

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    Re: 2002 Deville Multiple codes, rough idle, surging at high RPM

    I used WD 40 on the lower "O" rings and popped the injectors in to the manifold already. Figured I would do same for uppers when I got them.

    Good thing you told me about how to prime the fuel rails/system. I would likely not have done it that way.

    Right now I have everything back together except the fuel rails. I just need to pop them on and bolt them down. I figure another 15-20 minutes (after I get the new "O" rings and I will be up and running again.

    Thanks for all the info.

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    Deltamaster is offline Cadillac Owners Member
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    Re: 2002 Deville Multiple codes, rough idle, surging at high RPM

    Got the new "O" rings. They are not blue, they are black.

    Hooked everything up, checked it all out OK. I went for a drive and kept smelling fuel. Went home and checked it out and one of the injectors was spewing gas. Disconnected everything and reconnected to the fuel rails and then a different injector started leaking... Juggled and twisted the problem injectors and eventually the seals seated and the fuel stopped flowing.

    Now all is good, car runs fine and smooth!

    Still have the SES light on due to the P1860/0741 TCC issues. I have found on the forums that this is a problem that is (as noted) a $50.00 part buried in a $2000.00 repair! WOW... must drop the engine/tranny about 8-12 inches to get to the access cover and effect replacement of the solenoid.

    Fortunately from what I have read here the only disadvantage to not repairing this is a loss of about one mile per gallon of fuel economy since the torque converter will not lock up... SO... I guess this goes on the deferred list until my ambition level rises enough to try dropping the engine/tranny myself.


    Thanks for all the help and encouragement in replacing the plenum. Local dealer wanted $300.00 to do the job and total time involved for me was about one and one half hours... maybe two with cigarette breaks and all!

    Heck, I could charge half that much and make good money all day long on that job!

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    Re: 2002 Deville Multiple codes, rough idle, surging at high RPM

    Quote Originally Posted by submariner409 View Post

    For future use, buy a cheap Walgreen stethoscope, remove the chest diaphragm, and substitute an 18" length of proper sized vacuum hose (Help ! rack). Use the rig to snoop for vacuum leaks and mechanical ticks and squeaks.
    Great idea. I still have my Litman from my USAF EMT days that I could convert like that. If I save the parts I could use it for people and cars BOTH!


    Oh, BTW, what is this "casino cash" thing on the right side of each of my posts?

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    Re: 2002 Deville Multiple codes, rough idle, surging at high RPM

    When I converted my stethoscope I used a 12" length of copper tubing in place of the chest diaphragm, then added a rubber cap and drilled a hole through it to prevent noises when probing. It helps greatly when getting into tight or hard to reach places.

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    Re: 2002 Deville Multiple codes, rough idle, surging at high RPM

    Go up in the blue bar ^^^ and gamble.

    While you're at it, go further up to the black bar and read the entire Cadillac Technical Archive.

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