I have a good friend w/ an '94 Olds 88 Royale 3.8 that is getting an intermittent MIL (Service Engine Soon).
It sets when decelerating from 65mph or more (but NOT from 64mph or less), then disappears later, but certainly when the engine is shut off and re-started.
I understand it may have a 12 PIN OBD I or a 16 Pin OBD 1, ("OBD 1.5"?), or even a complete 16 Pin OBD II depending upon the VIN.
I am trying to help him long-distance (I am not where the car is).
Anyone know for sure what type OBD and DLC connectors '94 Olds 88 (3. have?
My "guess" is an EGR code from the symptoms.
The car runs perfectly w/ or w/out the MIL illuminated except for the typical reluctance for the torque-converter to unlock in OD with light/moderate throttle application, causing a bit of shudder due to the low RPM. I had a '96 Bonneville that did the same thing. The shudder thing was present well before the MIL illumination that just started, plus the shudder only happens on acceleration, while the MIL illuminates briefly only during deceleration, and then ONLY if he was at 65mph or above when letting off the accelerator on downhill sections of Interstates.