87 allante with a stumble miss and tries to correct itself
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Cadillac Allante Forum Discussion, 87 allante with a stumble miss and tries to correct itself in Past Cadillac Vehicle Discussion; Hi guys I know this is from left field but I have a problem with this car and my scan ...
  1. #1
    vinndiesel is offline Cadillac Owners Member
    Automobile(s): 2001 STS
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    87 allante with a stumble miss and tries to correct itself

    Hi guys I know this is from left field but I have a problem with this car and my scan tool won't hook into it and it has engine control system fault light on ... It will start up fine sometimes and then idle real rough ... Try to correct itself them stall ... Start up and same thing ... Then it will crank but won't start ... Is the any way to pull codes from this car ... Or can seone shade some light on tiu's thanks

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  3. #2
    carnut is offline Cadillac Owners Master
    Automobile(s): 1988 Allante' (sold), 1984 Eldorado, 84 Sedan DeVille
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    Re: 87 allante with a stumble miss and tries to correct itself

    This post is why a service manual is a must to purchase, especially on an Allante. This car has its own "scan" tool. Turn the key to run, then hold the OFF and the red warmer button in at the same time. Within 10 seconds the display will read out codes. Be prepared to write them down and re post. My 1st thought is a weak fuel pump.

  4. #3
    vinndiesel is offline Cadillac Owners Member
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    Thread Starter
    Ok carnut ... Have good fuel pressure 40 at idle 50 at wot ... Hence the lost of vacuum to regulator ... Cannot pull codes thru dic because the tower has gone out .. Can't make out what it says ... Replaced map sensor for the hell of it ... Had one laying around ... No change ... Years back I had a cadillac tech who is a friend come to shop and he replaced ECM and did something with the prom chip ... Car ran fine ever since he did that ... Symptoms back then were run and then no start for many key cycles then run again ... That's not the case here ... This it starts and it might run perfect then all of a sudden starts to run erratic and stalls ... After a couple if key cycles it will run fine again ... Then mess up ... The engine control malfunction light comes on when it starts to run messed up again ... When no light on the car runs great ... I'm lost here any info would help ... Maybe tps sensor ... I hate guessing ... But I have my ohm meter to check that today

  5. #4
    carnut is offline Cadillac Owners Master
    Automobile(s): 1988 Allante' (sold), 1984 Eldorado, 84 Sedan DeVille
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    Re: 87 allante with a stumble miss and tries to correct itself

    If it were mine, I'd pull the boot off the air intake and clean the throttle body first. Do not clean the larger bore, just the smaller one. Chance of shorting out the TPS. Then perform the idle relearn procedure. The idle relearn requires the car to be started with A/C off and put in gear and let idle for 10 minutes, then A/C engaged and repeat. If it still acts up, I would suspect a sticking injector, IE sticking open not closed. Without the ability to read codes with a faulty tower, you're guessing at best!

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    The TPS modifies the fuel delivery from idle to WOT so I doubt that's it.

  6. #5
    vinndiesel is offline Cadillac Owners Member
    Automobile(s): 2001 STS
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    Thread Starter
    Thank you so much Carnut for the info ..., I was able to get my hands on a snap on versus scan tool ... And do you know when the car was hooked up yesterday it didn't code out or run rough .... The one thing I did notice was there were two temp readings one for gauge or dash the other ECM ... Gauge was reading 216F and the ECM was at 176F at operating temp (after 10 mins run time ) when the car was cold or first started the gauge temp was reading about or close to ambient temp 87F and the other was 40F ... The o2 sensors weren't toggling or moving. Showed a rich loop ... It wasn't til the lower of two temps came up to about 160-170 F that the 02 sensor showed anything on the graph ... Now that being said this morning I start the car and it starts to stumble and run rough but no engine light ... I had to give scan tool Back to my buddy so I couldn't read parameters ... But it's got me thinking it has something to do with injectors like you said ... But why does it correct itself and run great when no codes present or light off

  7. #6
    carnut is offline Cadillac Owners Master
    Automobile(s): 1988 Allante' (sold), 1984 Eldorado, 84 Sedan DeVille
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    Re: 87 allante with a stumble miss and tries to correct itself

    Possibly a connector to one injector is loose? Try pushing on all the injector wire connectors. Look closely at all the connectors (little wire locks) that snap onto the top of the injector. Try pulling the connector off. It should not allow the wires to come off unless the wire retainer is removed. With a working DIC tower, you can isolate each injector and shut it off from the dash to pin point a cylinder. Regarding the coolant temp readings; it will stay in open loop (rich) until coolant temp is above about 170 degrees F. Then there should be a rapid switching reading as it toggles rich/lean, rich/ lean meaning closed loop. Getting to temp quickly is the function of the thermostat. If by chance there's a 180 degree thermostat installed, it will take longer to cause the OXY. sensor to toggle. Should be a 195 DELCO thermostat. The quicker it gets into closed loop, the better the fuel mileage and over all driveability will be. The proper thermostat will have a smaller disc at it's bottom to block circulation and then lift as warmed up. Should also have a small hole in the rim of the thermostat with a little pin to allow purging of air

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