Hi All,

I'm new to the Cadillac family, and I love them! We purchased a 1989 Cadillac about three months ago. It's a beauty, but has it's problems. Our mechnic had it in the shop for almost four days, and couldn't find the problem. Every once in awhile, it hesitates, almost to the point of stalling. It appears worse when it's warmed up a bit. The shop even called around to other shops & GM to see if there was any clues. So... has anyone out there had a similar problem???

I assume that the DTC's have been pulled?

http://www.cadillacforums.com/forums/cadillac-tech-tips/55172-how-pull-codes-got-codes-warning.html

sounds a lot like the idle air control (IAC). But its a caddy so there are 1000292341 other things it could be.

No IAC valve on the '89.

I had a simlar problem with my 91 sedan deville 4.9l. Turn out that their was a problem with the injector wires. Do you have a hard time starting it in the morning, or when it's hot? It might be your fuel pressure regulator, but I'm not for sure if your car has it or not.

I've got a 4.1l with the same problem. Starts up fine in the morning, it usually (sometimes) drives fine, but others I have really poor acceleration (to the point of stalling the car, which proceeds to immediately restart itself), surging during idle (lights dim while RPM goes down, then engine picks up), have no acceleration during a fair amount of pedal (maybe first 60%). I've done a ton to get it running - replaced spark plugs, thermostat, O2 sensor, fuel filter, MAP sensor, spark plugs, wires, timing chain/gears, battery, even ran Sea Foam through it (direct to engine, gas, and oil - need to change the oil again soon, get it all out). Still runs like crap.

I have new spark plugs to put in (fourth set, keep getting fouled for various reasons) - just don't want to do it, number 1 is a real PITA, and the rear ones look hard too.

fuel pump, or ignition coil, could also be a loose/dirty module connector although that would probably show up as codes

Not sure about topic starter, but I'm not throwing any codes (except ISC motor - had to disconnect it, it was revving the engine too much and making it overheat). Also had the distributor/cap/rotor all checked out.

Alice - check the wiring to the 2 fuel injectors on top of the TB, I had a problem where one injector would stop firing, which would cause a loss of power.. turned out to be a bad ECM, didn't give me any codes either. take off the air cover and observe the spray of fuel into the TB... when your car acts up see if they are both spraying

Brent- have you checked your fuel injectors? the 4.9L are notorious for bad injectors... check the resistence in them (there are 8)
with a meter.. it sould be about 16 ohms. at each injector.
i bet the cylinders with the fouled plugs have the bad injectors

I have a 4.1L, but I've been thinking about checking the injectors. Pump should be fine, but in-tank filter may be bad, or exhaust could be clogged.

Check for a plugged CAT.