Having problems with your 1994 Cadillac DeVille ?
My car is back firing when i change from 87 to 93 gas ?
You need to change the timing if you up the octane this much. get a garage to do it
Either your timing is off, your valves are sticking or the 93 in way too hot-burning for your engine. I would check the first two.
Repair Help & Product Troubleshooting for 1994 Cadillac DeVille
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