Spark knock?

[gallotte]

I've always put premium fuel in my 00 seville sls. I left for a business trip this morning and filled up with mid grade. About 2 hours into my journey the car started acting funny on cruise control. It seemed to hesitate and miss, like it suddenly lost power for a split second. It only did this when the speed was stable. If the car was speeding up, there was no miss at all. Does anyone know if the gas might be to blame for this? All help is appreciated. Thanks.

[JimD]

I would not suspect a fuel octane problem. Your year/model should perform well on 87 octane fuel.

Read this and tell us if you have any trouble codes (DTCs) showing up; specifically "P" codes:

http://www.caddyinfo.com/readingcodes.html

[gallotte]

Thanks. I'm pulling 3 codes.

C1246 - Level Control Exhaust Value Circuit

P0172 and P0175 - Fuel Trim System Rich

I would not suspect a fuel octane problem. Your year/model should perform well on 87 octane fuel.

Read this and tell us if you have any trouble codes (DTCs) showing up; specifically "P" codes:

http://www.caddyinfo.com/readingcodes.html

[JimD]

.... Does anyone know if the gas might be to blame for this? All help is appreciated. Thanks.

The answer is yes, fuel contaminated with water or alcohol will affect the long term fuel trim resulting in P0172 and /or P0175.

Another possible cause is faulty Mass Air Flow (MAF) sensor.

I would fill the tank with fresh fuel from a different source, clear the codes, and take a test drive.