94 Buick RoadMaster Estate Wagon LT 1 issues

[Bentwings]

Thanks. Thats the exact information I needed. I’m not sure if this is how he reset using his SnspOn scanner. I’ll ask when I pick the car up.

[1project2many]

three cylinders are dead rich one is very near

Please tell us (again if necessary) how you are determining this? There is a level of detail here that seems impossible. It's like reporting measurements to the hundredth of an inch using only a carpenter's measuring tape. The most likely way to determine this is to measure unfiltered O2 output with a scope concurrently with injector or ignition pulses for a cylinder based reference. If you are relying on individual cylinder injector trims to determine rich/lean operation you will be led astray.

[vilefly]

When the catalysts were replaced, was either one broken up or missing a honeycomb element? If so, a piece might be left inside the muffler to clog up one side, and lower engine vacuum. Cut off the exhaust (or drill a 1/2 or larger hole) on the straight run prior to the muffler, but after the converter, and then look at your readings to see if they improve.

Just cut in a spot you know you can weld it back together.

Spoken from experience.

[vilefly]

Please tell us (again if necessary) how you are determining this? There is a level of detail here that seems impossible. It's like reporting measurements to the hundredth of an inch using only a carpenter's measuring tape. The most likely way to determine this is to measure unfiltered O2 output with a scope concurrently with injector or ignition pulses for a cylinder based reference. If you are relying on individual cylinder injector trims to determine rich/lean operation you will be led astray.

I think they are doing the old fashioned "read the spark plugs" method. This is my guess. Whomsoever wields the answer, wields the power of one can of pop.