high idle after washing engine
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HT4100 4.1, 4.5, 4.9 Discussion, high idle after washing engine in Cadillac Engine Technical Discussion; After I washed my engine compartment (had distributor covered and battery cables off) on saturday . after starting up again ...
  1. #1
    red_ghost is offline Cadillac Owners Fanatic
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    high idle after washing engine

    After I washed my engine compartment (had distributor covered and battery cables off) on saturday . after starting up again my isc motor was rachetting like crazy and the car idling really high (I could bearly keep it still when on the brake). I changed my isc motor, pulled the batter cables and checked the tps. THe new isc also rachets and clicks. The idle has gone down some, and now the car doesn't race upon braking. It gains 1mph every 2 to 3 seconds.

    i received the codes 22, 70, 91 (unrelated),98

    I believe that may be the tps? However, the tps has the correct voltages (0.47v at throttle closed, and 5v at the Ref wire from the ECM). Otherwise could it be the little screw at the end of the isc? Even with the motor retracted fully there was no gap between the little hammer for the throttle and the screw (the screw is in as far as it goes). Should I try buying a shorter screw for it so the throttle isn't held open as much and then pull the battery cables so it has a chance to relearn?

    This morning I reset the codes and took it for a little drive. Only 91 came back on. It still idles high. I do not have a tachometer to hook up to tell the exact rpms.

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    the recluse is offline Cadillac Owners Connoisseur
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    Re: high idle after washing engine

    It sounds like you drowned your TPS and ISC. The voltage reading for the TPS should be -.2

    I know + or - .5 is good for spec, but I like a little on the negative side.

    All the codes were TPS except the trans switch. It just may need to dry out.

  4. #3
    steelybill is offline Cadillac Owners Enthusiast
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    Re: high idle after washing engine

    I've had the bat cables off multiple times with no re-learn issues. If you used a power washer, like in the quarter-type wash places, you may have disturbed some connectors etc (?) Or penetrated the stuff that the recluse mentioned, ISC, TPS etc, with high pressure water.

  5. #4
    red_ghost is offline Cadillac Owners Fanatic
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    Re: high idle after washing engine

    nope, it was just a regular garden hose. I put a smaller bolt on on the new isc and adjusted teh tps down as far as it goes. The idle is a little better. It acts like its on cruise at speeds between 0 and 35 (the speed never changes when i'm off teh accelerator). There also is a major power lag if I floor it. It will accelerate like expected from 0-22, then it lags really bad until it hits about 35. The engine is also running much hotter than normal. After letting it sit in park running in my garage for 20 mins, the radiator cap indicated it was at about 220F. The front wheels were hot to the touch (couldn't keep my hand on them for more than 2 seconds). So obviously its running lean. Could the timing have somehow gone retarded?

    Got a car show to go to on Saturday so hopefully I can fix it by then. Although lucky for me the car show is about a mile away.

  6. #5
    cadillac_al is offline Cadillac Owners Connoisseur
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    Re: high idle after washing engine

    I would think after everything got good and warm the moisture would leave. When i washed my engine the MAP sensor shorted out but I got a code for that. I swapped it with a used one that ran worse, put the wet one back in and it must have dried out because it worked fine after that. A high idle could be vacuum related and the MAP is vacuum related soooo..........it may be worth looking into since they are cheap and easy to replace.

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    red_ghost is offline Cadillac Owners Fanatic
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    Re: high idle after washing engine

    I will look into it. I just replaced that too... I will also recheck the lines. I didn't hear any hissing though that would indicate a vacuum leak. I think I need to replace teh purge valve too because there seems to be air build up in the gas tank (this has been going on the last few months, unrelated to the current condition).

  8. #7
    steelybill is offline Cadillac Owners Enthusiast
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    Re: high idle after washing engine

    Even with a quiet running engine, a vacuum leak may be hard to hear. WD-40 works fairly good to spray on suspected leak areas, making the rpm pick up if there a leak. In the old days I used gas, but of course it's a bit dangerous, and with old age I became a bit more cautious

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    the recluse is offline Cadillac Owners Connoisseur
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    Re: high idle after washing engine

    WD-40 works good, but ether works better. It doesn't leave the oily mess that WD-40 leaves.

    With the engine running lean and heating up, you prolly fried some sort of sensor. Did you run the entire TPS ISC procedure?

  10. #9
    red_ghost is offline Cadillac Owners Fanatic
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    Re: high idle after washing engine

    changed out my park nuetral saftey switch and everything seemed to be fine. Might be just a coincidence though... no more trouble codes.

    car ran fine today. Went to a car show and got rained out. Still took 1st in my catagory though. I'll have to see how it runs tomorrow.

  11. #10
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    83CADMAN is offline Cadillac Owners Fanatic
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    Re: high idle after washing engine

    The ratcheting you mention is an indication of TPS/ISC misadustment.
    I highly recondmend revisiting the TPS/ISC adjustments. There are plenty of threads covering the procedures.
    With the engine Prewarmed remove aircleaner and attach Tach, multi-meter . Start the engine. With the engine running move the throttle and hold slightly open while pushing on the ISC shaft (switch activated). Keep applying pressure till it fully retracts (you will feel it motor in). as soon as it bottoms out within the unit, QUICKLY unplug the wires to the ISC. Then gently lower the throttle arm. It should be barely running somewhere around 400 to 450 RPM. Then with a feeler gauge placed between the throttle arm and the ISC shaft, adjust the screw to get a .060 inch gap. Adjust the TPS to 0v. Shut off the engine reconnect the harness to the ISC. wait 10 seconds and restart the car.

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