Greetings Folks - Apologies if this has been covered prior but haven't driven my Stealth much in the last several years so it's been awhile since I've visited this site. Hopefully you guys can help me once again.
1991 N/A Stealth MTX FWD: Owned since 2008. It is my Bonneville 150 Club vehicle: The ECU has been rebuilt before me - at least the caps have been replaced. Unfortunately, it is an OBD I car and my OBD II diagnostic tool does not apply here.
Anyway, the high RPM fuel cut off has always been a little low - as I remember, the nominal spec is supposed to be 7300 RPM. Years ago, the ECU used to interrupt the fuel at around 6900 RPM but now it activates at about 6400. These readings are from the stock dash mounted tachometer. Engine load seemingly has nothing to do with this - it happens at the identical 6400 RPM, regardless if it is at WOT on the road or in my shop in neutral. The engine doesn't miss fire at any other time - it runs great - but once it's at 6400, the engine speed will not increase. The cutoff is abrupt - the critter runs perfectly at 6300. LOL!
So the question is - does the RPM limiter in the ECU degrade over time? If so, what is the procedure to fix it?
I have a fuel pressure gauge taped to the outside of the windshield and it remains pretty constant at about 48 PSI, which is right at service manual spec. The ignition seems to be fine - my spark plug timing light at fuel cut off RPM is still flashing normally. That's one of my, "old school" ignition testing tricks - been using it for decades. LOL!
Thanks - - Any guidance is appreciated -