So my 92 RS 3.1l is acting up. I gave it to my little sister and she said it's starting to backfire and lacks power. So I figure it needs a tuneup. We didn't change anything but the spark plugs which were all oily. We visually checked the wires, contacts in the distributor cap and rotor.

So anyway after we changed the spark plugs I fired it up and the engine is Vibrating left and right very violently. When I gave some gas, the engine was kind of choking but got the rpm's up. After which it backfired some when the rpms dropped back down to idle. The engine vibration was so bad, i turned off the car and told my sister not to drive it. I'm not sure if it could just be a very bad timing problem or what. Maybe timing chain is very stretched? Could that cause it? The car has 130k miles on it and I'm sure has never had that done. Any other suggestions on what could be the culprit?

Thanks a lot if you guys can help! Eric

 

I never change plugs without changing wires, rotor, and cap - replace those as well. There is no 'visual' inspection that can be done on ignition components - they either work or they don't. Unless you have a serious vacuum leak somewhere, chances are you have a bad plug wire, or a cracked cap, or the rotor is worn down too far.

AND - take a volt ohm meter, and test continuity on all the new wires BEFORE you install them - I've many times bought plug wires with shorts - the wiring manufacturers don't test them.

 

If the plugs are oily, I would suspect a leaky intake gasket. I believe that a 3.1 intake gasket can leak into the vee of the engine and suck oil into the cylinders.