4.5 liter misfiring on acceleration, rough idle
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HT4100 4.1, 4.5, 4.9 Discussion, 4.5 liter misfiring on acceleration, rough idle in Cadillac Engine Technical Discussion; need help!every since I installed an new stereo car started running rough. got an error code e49. disconnected and plugged ...
  1. #1
    ashunte23 is offline Cadillac Owners Member
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    Apr 2005
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    Question 4.5 liter misfiring on acceleration, rough idle

    need help!every since I installed an new stereo car started running rough. got an error code e49. disconnected and plugged up air management valve. still ran rough checked and cleaned egr pipes in throttle body. still runs bad. could the alternator have gone bad and might be causing low voltage if so, how do you check? any ideas would be helpful. also, disconnected stereo still running bad!also, if I cut off car quickly and back on runs fine for 5 min or so then back to misfiring.

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  3. #2
    DrDave is offline Cadillac Owners Fanatic
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    Re: 4.5 liter misfiring on acceleration, rough idle

    Did you splice into one of the main ignition/power wires for the "Ignition On" setting? If so, and you used the lower quality "splicers", you may be messing up the voltage to the ECM and/or coil etc.

  4. #3
    CharBroiled's Avatar
    CharBroiled is offline Cadillac Owners Fanatic
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    Re: 4.5 liter misfiring on acceleration, rough idle

    Low voltage will not cause the engine to run rough, my alt failed and about the only thing running after a 45 minute run at night in the rain with headlights and wipers going on just the battery was the engine, nice and smooth. Barely any lights, got a free lightshow from the dash warning lights blinking on and off randomly, no blinkers, no start on shutdown. But the engine ran fine. So I dont think thats it. Plus your battery idiot light should come on I would think. You can always measure it with a voltmeter.

    I would check the wireing as DrDave suggests, maybe you loosened a connector or ungrounded something.

  5. #4
    ashunte23 is offline Cadillac Owners Member
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    Re: 4.5 liter misfiring on acceleration, rough idle

    could my fuel pump be going bad, a couple of months ago turned corner with like 4g of gas and car kinda died then took off. maybe the vibration has hastened it's failure?didn't splice into any wires ran all new ones.

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