The only check-engine code is "knock sensor", but it's the only thing I actually trust, because I can definitely hear the knock, too. The sputtering happens only on acceleration or going up a hill...where the intake vacuum would be greatest, so I think it is caused by a feedback sensor or something related to vacuum. It happens at any range, low rpm to high rpm, when the engine is cold or after it has been running for hours on the road. It sounds like this: "rrrrrrcoughrrcoughrrrrrrrrrcoughrrrrr" with rrr as normal operation. I can duplicate it in the shop only at about 4000 rpm. Otherwise, it runs great. Gas mileage is normal. Vacuum tubes and vacuum-operated diaphragms are okay. Intake maifold and gasket seem to be okay. It doesn't seem to be a fuel injector or fuel pump problem.
I've put in new spark plugs and spark-plug wires (the hardest spark plug change EVER), ignition coils, accelerator-position sensor, mass air-flow sensor, oxygen sensor. I am thinking that the main power control module has a problem and will replace that next.
I've put in new spark plugs and spark-plug wires (the hardest spark plug change EVER), ignition coils, accelerator-position sensor, mass air-flow sensor, oxygen sensor. I am thinking that the main power control module has a problem and will replace that next.