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Deville misfire. Maybe.


rockfangd

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Hi all. I dont want to think about it but my Deville has developed a stumble. Or miss. I will elaborate. It will only do it on cold startup.

about 6 months ago I thought I felt a miss on startup. was gone in seconds.

About 3 months ago same thing

Last week started to feel it almost daily. When the car sat for 3 days it stumbled for 1.5 blocks. I got right on it and it definately stumbled.

The stumble only lasts a very short time. No codes. no other problems at all.

I would like to not think about it but the dreaded HG beginning stages comes to mind. I really hope not as this car is my main 4 season vehicle. and with winter coming I need it.

Anyone have any insight on this. Thanks. I only run premium fuel. Chevron treatment every 6 months. I drive it hard. Coolant temps are perfect.

I use WOT generously and it takes every bit of it with no spikes in temperature. Everything is well maintained. fuel filter is about 1 year old

miles are 197000

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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Check the ignition wires, morning condensation/dew can cause the same symptom. Check the tops of the coil towers for corrosion and rust.

The NAPA block test kit works terrific, for 49 dollars you will have a definitive answer

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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if it was very early stages would it even fail the test?

Wires are possible. As far as I know they are original. Maybe it is time for a tuneup. I will say that in the rain it runs great and thats why I didnt think wires.

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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I 2nd the notion of wires and early morning condensation.

I had that happen to me on my old 427 Chevy...

When started for the first time of the day... it had a miss.

It ran fine after it warmed up.

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  • 2 weeks later...

Ok to update this. It has been dry here for the past week or so and the car sat since thursday night. I started it saturday morning and it had a definate miss. Same today. Sunday.

I just ordered plugs and wires for it and pray it solves the problem.

I need my Deville for the winter. The transmission went out out of nowhere on my boyfriends car this week and he is going to be using the Deville until we can find him a car, so that means I will be using my Seville until fall, then my truck will have to take over. The seville is strictly seasonal., NO questions asked. So I need to rely on my Deville.

I will update once I verify whether the plugs and wires helps. I hope so

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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  • 2 weeks later...

Update. 9/13/12

Great news. The car sat since tuesday and I put the plugs and wires in this morning. All were perfect. May have been originals but not sure. old plugs and wires were ac delco but the wires were 7mm. I think the originals were 8mm.

Anyway cylinder 2 plug had gap of 0.800 due to part of the inner tip being gone. All plugs burned clean. I found no oil in the holes.

I started the car and no misfire at all. The engine runs even smoother. Amazing how a v8 can run so smooth. so doing this was definately worth it. I am pretty sure this has solved my misfire issue. I will update in a week.

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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Glad to hear that you found the problem, you lost a platinum pad it seems

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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Well A week later and no misfire at all. The engine runs flawless. I am so happy because I was a tiny bit worried.

I love this car and it has been absolutely the most reliable car I have ever had. All I ever do is drive it and it asks for nothing but to be driven hard.

I am thinking the computer was compensating for the plugs and thats why the miss only lasted briefly.

This car still blows me away. I have almost 198000 miles and it runs and drives fantastic. It kills me because I have alot of money into my Seville and it rides nothing like my Deville.

This forum is wonderful as we all work together to help each other out. Even the simplest thing can be missed.

Thank you all

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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This IS a great resource, I couldn't be without it

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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