Cm870 throttle issue

[Chamberpains]

Or if you have the old speedo sensor that can be adjusted, it'll look like a very large threaded stud, it needs to be installed and adjusted correctly. Take it out and clean the tip of it. Make sure its perfectly clean this goes for all speedo sensors. Then check your speedo pick up ring for chips and garbage in the teeth. Yes, this will require you to jam your head in a very awkward place with a flashlight and turn the tail shaft while you look in. If all is good, reinstall the speedo sensor all the way in till it bottles out lightly. Then back it off half a turn and lock the jam nut down. Check all your wiring like Uni said. Its very common for OEM to twist the wires or zip tie them to tight to something and have them ground out and touch each other.

Also, its very common for this problem to only happen when the oil is cold. My 9400i stops fluttering the speedo on high idle once the truck warm up. So I've never dug real deep in to resolving that issue on mine because its not a problem. I don't need high idle for anything.