Question about 2005 Cadillac STS

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Engine problem Randome misfire, misfire on number 7 cylinder. I beleave I am loosing coolant but there is no external leak.I have changed spark plugs, number 1 coil bank. engine runs ruff when first started like it is getting to much will run this way until I drive for about 15 miles then I will pull off the road turn the engine off and set for aprox. 20 to 30 min. and thin start the car and it will run wright some times. if I give it to much gas it will run ruff again. there is a strong oder coming from the exhaust. I have changed the spark plugs and the number one coil bank

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More than likely you have a v8 cylinder or v6 most likely you have a bad head gasketl pulled the plug out you will see that it is very white clean and look like new compair to other plans and you should see a small cloud of white smoke when you get up as well as going to be the problem most common, with the GM Motors

Posted on Jan 13, 2015

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Sounds like you might need to do a compression test. did you check to see if the code was the same? if you keep running it like that it can clog you catalytic converter. Might have a bad injector also.

Posted on Jan 13, 2015


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Posted on Jan 02, 2017

SOURCE: 92 deville car does not stay running after 1-2minutes

i know this sounds stupid but did you check the oil some caddys have a fuel pump shut off if the oil gets to low

Posted on Nov 21, 2008

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SOURCE: 2003 cadillac deville rough idle with blinking ses

have the head gasket checked,pretty common on these

Posted on May 07, 2010

  • 46 Answers

SOURCE: 1991 deville idling very ruff

Hi you should change the coolant temp sensor this is a white sensor on top of the intake and is part ot the computer system.

Posted on May 19, 2010

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SOURCE: 1997 cadillac deville- misfires on cylinder #1

It sure is. If a plug is truly wet, the energy for the spark will travel through the moisture, rather than across the gap. The fuel air mixture flowing into and out of the cylinder serves to ventilate the cylinder, drying the plug.

Plus, that air is preheated, so that would accelerate the drying once warming up got underway.

You really need to have that head gasket replaced. If this questionable repair gives way (and it almost certainly will), you can get enough water in the cylinder to start breaking things on startup without any warning.

Posted on Jun 29, 2010

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SOURCE: My 04 cadillac srx v6

i would check for obd codes and see if it still is misfiring and what cylinder

Posted on Dec 05, 2010

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