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90 Deville misfire


JDeville90

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Hey everybody. I have a 90 Deville with 116k miles. Been having a problem that i think may be electrical. The car idles a bit rough even when it is running "good". But when i drive at night with the headlights on it will idle extremely rough. Even at hi speed it will misfire, like it has bad plug wires etc. Another clue is when i turn on a blinker the engine will take a hit, again a misfire condition, even at high speeds. Sometimes when i am at a stop light the car idles rough, but when i let off of the brake it will smooth out somewhat. The car generally runs ok during the day as long as i dont use the AC or heat, which will also make it run poorly. But when i run it at night it just doesnt run the same and it seems to be related to headlights blinkers etc. Occasionally i will have a dead battery if i let it sit 5 or 6 days. Any help would be appreciated.

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The battery is about a year old, but it replaced another brand new battery i put in it trying to chase dow this problem. It does seem that when i turn the headlights on, maybe it is pulling too much from the battery and not allowing the ignition to work properly?

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With engine running, enter diagosdics mode by bepressing OFF and Warmer button and take note of the codes, if any are present. When all codes have been displayed, it should display (.7.0). Press (LO) button to enter the engine data parameters it should then display (.9.0). Cycle from (p.0.1) to (p.0.10) with the (HI) button for battery voltage. Voltage should be between 13 and 14 volts. At this point turn on lights hi beam, turn signal, wipers and radio to put load on the engine. Look at the voltage display as you switch on the accessories. If your battery is good condition and the voltage regulator (on the alternator) is functioning properly, voltage should drop to a little under 12 but then should go back up between 13-14v. If it does not you might have charging system fault (old alternator, faulty voltage regulator).

Before jumping to conclusions on the alternator, make sure that the belt is not slipping and that the alternator is spinning freely (engine off and with no belt pressure applied). Inspect the connections to the alternator. Also make sure that your battery terminals are secure and free of corrosion.

Hope this will help track down the problem or at least eliminate a possibilty.

-KIMO-

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adallak is right on it, have your battery checked out, I had a bad battery in a 91 Seville and it would not run above idle, as soon as I hit the gas the ignition voltage requirement exceeded the systems power and the engine died, replaced the battery and all was fine. If its not the battery, check battery terminals for corrosion or for bad grounds... Mike

Early on sailors navigated by the stars at night and the North star became the symbol for finding ones way home. Once you know where the Northstar is you can point your ship in the right direction to get home. So the star became a symbol for finding ones way home or more symbolically even finding ones path in life.

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  • 3 weeks later...

I ran the diagnostic procedure and came up with a code E41. Voltage seems fine staying around 13.5. Upon startup engine raced at very high idle and i could tell it was missing bad. It eventually cut off after maybe 30 seconds. Got it running again and ran the procedure. Also, now my service engine light is on. Please, any help. I dont want to do something stupid like trade it for an Intrepid.

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E41 - no cam sensor signal for 4.9 motor. Yours should be the same. You might want to check the connector of the cam sensor or just replace it in the worst case. I am not familiar with your engine so cannot say anything about the location.

The saddest thing in life is wasted talent

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Looks like you have some wiring problem, some short to the ground. Inspect carefulle wiring in distributor area. That's where the cam sensor is probably located. Is the code current?

The saddest thing in life is wasted talent

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C:\Documents and Settings\Armen\Desktop\112-1223_IMG.JPG

Mine (4.9 engine) looks like this, yours should look similar. It is in the distributor. I would first try to disconnect -reconnect connectors related to the distributor, if it does not help you probably have to get in the distributor.

post-3-1107713514_thumb.jpg

The saddest thing in life is wasted talent

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