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94 Deville Car choking and backfiring?


povich444

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Have a 94 sedan deville that chokes looses power and backfires once in a while? Car if shut of and restarted again runs good for days until it happens again..Looses all acceleration and smells of gas badly when this happens.Recently had to mechanic and had cat hollowed out as well as fuel rail cleaned new fuel pump installed and filter installed, to come to realize must be some kind of ignition problem!Other day wife was driving and it backfired louder than ever she says and exaust was even louder than the throaty hollow cat! I crawled under rear to find the backfire split the seams of the muffler clean open :o Someone had suggested maybe an Ignition switch problem? Any one with any suggestions would be greatly appreciated!!! Goin broke and tired of trial and error on this darn thing! :angry: Thx for any help!

going broke :(

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Smelling gas sounds like a fuel leak. Take the intake manifold cover off and turn the key on to pressurize the fuel system, but DO NOT start the car as it will run away unthrottled. Now look for leaks on the fuel rail and at the FPR (fuel pressure regulator) nipple.

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94 Deville has a 4.9. The FPR is under the plastic cover. If you had the fuel rail cleaned you might have a leaky injector. Have you checked your codes? If it resets itself when you turn the car off, it could be the PCM or a bad ground. We seem to be having a lot of this lately.

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  • 3 weeks later...
Have a 94 sedan deville that chokes looses power and backfires once in a while? Car if shut of and restarted again runs good for days until it happens again..Looses all acceleration and smells of gas badly when this happens.Recently had to mechanic and had cat hollowed out as well as fuel rail cleaned new fuel pump installed and filter installed, to come to realize must be some kind of ignition problem!Other day wife was driving and it backfired louder than ever she says and exaust was even louder than the throaty hollow cat! I crawled under rear to find the backfire split the seams of the muffler clean open ohmy.gif Someone had suggested maybe an Ignition switch problem? Any one with any suggestions would be greatly appreciated!!! Goin broke and tired of trial and error on this darn thing! mad.gif Thx for any help!

going broke sad.gif

checked codes and only got IPC history codes Io39 and Io52? Question about readings on o2 sensors though? Front o2 cross counts 11 and rear cross counts 0? what exactly does this mean?any help appreciated! sad.gif

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The first ground to check out is on the engine block next to the starter. It may look good... Disconnect, clean, reconnect. Replacing the stud (8mm) and star washers is a good idea.

The saddest thing in life is wasted talent

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Yeah....check the ground near the starter. Very common Cadillac electrical issue on the 4.x engines. They can look 'ok.' Also check the insides of the battery cables.

4.9 engines....no big issues.

Maybe....

Bad ECM/PCM.

Green terminals on the igniton module connections inside the distributor.

Green AC pick up coil.

Rare...but maybe a bad connection it the ignition switch.

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checked codes and only got IPC history codes Io39 and Io52? Question about readings on o2 sensors though? Front o2 cross counts 11 and rear cross counts 0? what exactly does this mean?any help appreciated! sad.gif

http://caddyinfo.ipbhost.com/index.php?showtopic=1008&hl=

http://caddyinfo.ipbhost.com/index.php?sho...hl=cross+counts

http://caddyinfo.ipbhost.com/index.php?sho...hl=cross+counts

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hey guys appreciate all the suggestions and knowledge given,this car is driving me nuts and broke! goin to check all above mentioned and probably replace o2 sensors seeing that Im at 88,000 or so and never replaced! any ideas why Im getting the IPC codes and what they mean? but really appreciate all the help already for sure and will tear this thing apart this weekend in MY GARAGE instead of lettin someone else throw parts at it! Im thinkin after runnin diag. on highway and watchin rear o2 sens. stay around zero that hes gotta lot to do with it but will check everything!!! Big THX again! Will keep informed on outcome!! wink.gif

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IPC history codes Io39 and Io52?

I039 .......................................... Loss of Road Sensing Suspension Data

I052 ....................................................... Keep Alive Memory Error

The I052 occurred because the battery must have been disconnected recently. If it has NOT been disconnected recently, you may have dirty battery cable connections which may explain your intemittant problem.

You have a 4.9, bad grounds were mentioned. The PCM has been known to act up, you might want to drop the PCM down and tap on it to see if you can induce some of your symptoms. There are a few that had problems similar to yours that needed a new PCM. I will search later and post the links.

The backfire concerns me, look for carbon tracking and cracks in your distributor cap. Has your gas mileage dropped? Check the FPR, and I would check to see if you have a leaky injector. Try a small bottle of Techron on a full tank of gas to see if it helps.

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  • 1 year later...

The first ground to check out is on the engine block next to the starter. It may look good... Disconnect, clean, reconnect. Replacing the stud (8mm) and star washers is a good idea.

Why didnt I listen to ya in oct of 05??? Been messin with this car for ever and finally attached a jumper from neg batt. terminal to ground on block and solved all problems!! After about 600$ worth of replacement parts!! Gotta few new parts anyway! LOL! :blink:

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Good job Adallak! Have we figured out why this is happening to the 4.9? Is this an engine mount ground problem?

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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The first ground to check out is on the engine block next to the starter. It may look good... Disconnect, clean, reconnect. Replacing the stud (8mm) and star washers is a good idea.

Why didnt I listen to ya in oct of 05??? Been messin with this car for ever and finally attached a jumper from neg batt. terminal to ground on block and solved all problems!! After about 600$ worth of replacement parts!! Gotta few new parts anyway! LOL! :blink:

There are things money can buy, caddyinfo.com - priceless! :)

Good job Adallak! Have we figured out why this is happening to the 4.9? Is this an engine mount ground problem?

I really do not know, Mike. At least five people followed this advice and fixed problems they could not fix otherwise.

The saddest thing in life is wasted talent

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Didn't Marika have an engine mount problem that created electrical problems?

See this link:

http://caddyinfo.ipbhost.com/index.php?sho...hl=engine+mount

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Pretty sure mine is a ground strap problem but havent lifted it to check yet!! I just ran a new 8 gauge from block to chassis to cancel prob for now! Could maybe be an engine mount Im sure ! Will check and report back with findings! Any way fixed Mny thx to all of You and these wonderful forums! Just wish I wouldve listened 1.5 yrs ago LOL! Thx again All!

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I am pretty sure Matt did after he got the new engine.

Yes Matt did, but he had a distributor problem also. But I vaguely recall him having a PCM or ground problem, will have to research that

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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I am pretty sure Matt did after he got the new engine.

Yes Matt did, but he had a distributor problem also. But I vaguely recall him having a PCM or ground problem, will have to research that

I remember Matt fixing the ground as well.

The saddest thing in life is wasted talent

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