Questions and Answers
Sick Old Oldsmobile Cutlass
Q. Vince, I'm a fairly good shade tree mechanic, but this one has got me stymied.
1981 Oldsmobile Cutlass with a 231 Buick V6 engine, automatic transmission, carbureted, with 270,000 miles on it. I've rebuilt the engine once myself at 120,000 mi. I've done everything it's ever needed except alignment, transmission and upholstery and paint. That's for others. Here's the deal:
It abruptly started running rough, idling slow enough to die, unable to keep it accelerating from a stop without constantly pumping the accelerator. It backfires often through the carb. The timing is horrible. There is sometimes not enough vacuum to for the power brakes assist without hitting Neutral and goosing the gas to pull some more vacuum. The only new diagnostic code is 44-lean mixture which is consistent with insufficient vacuum if its gulping air somewhere. I've checked the EGR valve, even capped off the mount with a flat steel plate with matching mounting holes and the gasket, so I'm not leaking exhaust or vacuum from the EGR valve or mount. I've replaced the O2 sensor, plugs, wires, distributor cap and rotor, No avail.
I'm wondering if I slipped a notch on the timing chain, but it will start right up and idle OK (most of the time) when it abruptly dies. Is that possible on this model? So far, I've checked the other obvious things like vacuum hoses and I can't find any leaks. I've checked continuity (OK) on the EST distributor wiring back to the computer. The is the first one without a vacuum advance.
The Idle Speed Control Unit on the carb hasn't worked for years and gives me a code-35 which I've ignored. It's never been a problem. That was the only code I've had for 10-12 yrs. 44 is new.
Bill
A. Well Bill, you've done a pretty good job eliminating everything else. It's not fuel injected so that makes things easier. It's possible that the chain jumped. The way you can check that is to get the engine to base timing. Get the piston on TDC on the compression stroke, then line up the timing mark on zero, going in the normal direction of engine rotation. Then pop off the distributor cap and see where the rotor is pointing. It should be at the number one tower. If it's not, the chain jumped. If it is, slowly rotate the engine backwards and see how many degrees it goes before the rotor starts to turn. That will give you an idea of how much slack is in the chain.
The other possibility is the Mixture Control solenoid in the carburetor. This will throw the code 44 you are getting. There is a test for it and you can look it up in the Chilton manual. It explains how to perfom the test it step by step.
