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1997 Cadillac Seville SLS
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11 Posts
Discussion Starter #1
First, I have zero history on this car as I just bought it. It was running a little rough, missing.

I installed new AC Delco plugs and wire set. Cleared all codes. After starting it up and letting it come to temp, I got check engine light. Pulled codes: p0300, p0141, p0603.

I tested the ignition coils and got the following results:

Primary - Secondary Resistance
.2ohm - 5k ohm
.2ohm - 5k ohm
.3ohm - 5k ohm
.4ohm - 5k ohm

From the reading I've done, I'm getting that it should be .5 to .6ohms and 8k ohms on the secondary. Is that correct? If so, then is it a valid deduction that all of my coils are going out on me?

Lastly, is it a fair to say that it is possible that the random misfire could be causing the O2 code p0141 because fuel is not being burned correctly?

Thanks in advance for your input/help! cal
 

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Super Moderator
White Diamond '03 DHS (with DTS floor shift)
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86,781 Posts
Might try a good TB cleaning before doing anything else.
 

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98 DeVille, 97 DeVille d'Elegance
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7,345 Posts
use a hand held scanner and see what cylinder specific code is showing. the onboard scanner will not show cylinder...
The other is an O2 sensor code is it not? please post definitions with all codes and if history or current. And yea clean the TB
 

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2001 STS
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313 Posts
Also try checking your intake plenum. When mine had a leak, the same misfire code showed. I used a little cleaner to spray around the plenum. It's worth a shot.

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P0300 is multiple misfire, correct?

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From what I've experienced, one code will trip other codes. If you're having a random or multiple misfire code, I would start with fixing that and see if the other codes clear.
 

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2001 Seville STS, 1990 Seville (RIP), 1972 Sedan Deville
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26,323 Posts
No plenum duct pre '00.

Codes can not set other codes. Codes are set when certain criteria are met, and detected by whatever module is monitoring the component/system.
 

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1997 Cadillac Seville SLS
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11 Posts
Discussion Starter #6
The p0300 was pulled with hand held scanner. There are no history codes since I put a new battery in it.

The two possible causes I think I could be facing are ignition coil(s) or I had moister in the fuel lines as it sat in my shop for the last 4 months. When I started it after setting 4mo, it stuttered just a bit then idled fine.

Today I'm going to drive it to town put in some high octane fuel and some Lucas fuel treatment, clear the codes and take it for an hour drive and see what I get. I'll post the results when I return.
 

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Super Moderator
White Diamond '03 DHS (with DTS floor shift)
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86,781 Posts
The fuel nor additives are going to help. You are probably running 10% ethanol and that will absorb any moisture in the fuel lines.
Try swapping out the coils one at a time with a known good one. If that doesn't help, you may be looking at a new ICM.
 

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1997 Cadillac Seville SLS
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11 Posts
Discussion Starter #9
Cleared the codes, added fuel injector cleaner and a full tank of premium fuel. Drove it and after 30min of driving, check engine came on. Pulled codes and I'm no longer getting the misfire code but just an O2 code. So I'm thinking that the original misfire p0300 I was getting was due to some moisture in the fuel line from setting 4 months.
 
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