Cadillac: 94 Cadillac STS, chevron gasoline, joe shmoe


Question
Carlos,

I have a 94 Cadillac STS with 110,000 miles on it. Just recently it has begun giving me problems starting.  The Code came up as P020. The mechanic replaced the battery and everything was working fine, but here a week later I`m having the problem again. A new alternator was put on in February and the fuel filter was changed as well.  He(mechanic) insists the fuel pressure was fine and that he doesn`t believe it is the fuel pump.  I use 93 rated Chevron gasoline, use only synthetic oils.  A tune-up was performed at 60,000 miles even though Cadillac states one isn`t needed until it reaches 100,000.  The car turns over, but it doesn`t catch.  Help!

Raquel

Answer
I assume from what you said at the end that the engine won't turn on but will crank.  If the fuel pressure is indeed OK, then this sounds like an ignition problem.  Maybe the ignition module is bad, or the ignition coil(s) are bad.  I haven't really had a chance to totally inspect a Northstar engine, I assume your STS has it.  Honestly I don't know if the Northstar uses a distributor type ignition or a DIS type ignition with several ignition coil PACKS with the ignition wires coming out of them to the spark plugs.  It is not unheard of that the coil packs go bad.  I assume the Northstar has this type of ignition as it is a pretty advanced engine when compared to the previous Cadillac V8's.  You would have to have the ignition coil packs checked to make sure they are OK, and also the ignition module should be checked.  I have had both of these things go bad in my 88 Fiero and when to ignition coil went bad the car had EXTREME trouble turning on, and I'd have to crank it many many times, and then the engine would run terrible and jerk on and off.

From previous experience, I'd say it's something with the ignition system, have it totally checked by someone who REALLY knows elctronics, no joe shmoe mechanice will do, the service manual for the Seville will clearly indicate what electronic devices to use to detect whether certain ignition parts are OK or not.
Hope this helps.