: PC0300 with troubleshoot. Coil Resistance?

02-20-06, 04:26 PM
My '96SLS started misfiring yesterday - under low/rpm loading and during acceleration. The SES came on as well. I checked the codes and got the PC0300. I checked the resistance between the terminals on the coils. With the resistance set to 20k on the multi-meter, I read 5.83 on all coils except the 5-2 coil, which read 5.98. Should I replace this coil or is it still good?

I plan on replacing the plug wires. 82,000 miles on car.

Also, my wife filled up the entire tank with 87 octane right before this happened. I didn't find out until half the tank was gone (and I asked her), which I then immediately pulled over and filled up with 93 octane. Could this also be the culprit, and a possible temporary one?

Any input would be greatly appreciated!
Easy Mac

02-20-06, 06:14 PM
She (the car, not your wife) will run fine on 87. I ran my '97 on it for years. That is not your problem.

Have you had the fuel rail recall done recently? That is a very common problem after the recall. Been there, done that. Apparently, disturbing old wires tends to make them break down internaly. I would bet that after you change wires (and plugs while your at it), it will be fine. Worked for me. Stick with OEM (A/C Delco) plugs and wires.

02-20-06, 06:21 PM
I bought the car used last October. I took it to the Caddy dealership nearby for the "before buying a used car" inspection. They told me according to their computer that checks the VIN, all recalls have been done.

I'll look into the wires and plugs tonight. Thanks!

02-20-06, 08:36 PM
The fuel rail is easy to verify. Just lift the silver beauty cover and make sure that the fuel rail is stainless steel vs black plastic.

02-21-06, 09:04 PM
Is my 96 included in that recall? im not to sure if its been done im pretty sure it hasnt. i have a pic of it for one of you to confirm if its been done or not. if it hasnt what does it cost and can any dealer do it?

02-21-06, 09:13 PM
Yours has not been done, any dealer can do it, it's free, take it in now.

02-21-06, 10:30 PM
ok that will be the next place it goes too.

02-24-06, 08:45 PM
I swapped out the spark plugs with new ACDeclo platinums, and replaced the wires with Autolite Prefessional Series 7mm. Car runs like brand new. I cleared the PCM code and took it for a spin. I could not duplicate the code, nor did I feel the engine miss a single lick. It even seems to run smoother than before I got the code. Thanks for the replies!

FWIW- I did find somewhere on the web that the resistance between the posts on the coil should be between 4000-6000 ohms. Therefore, they all don't need to be exactly the same.

BTW- I do have the stainless fuel rail.