Surging Cruise Control
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New User
Joined: Jan 2003
Posts: 6
Likes: 0
Surging Cruise Control
I have an '89 F250 that I love, but it has a problem. When I set the cruise, the truck will speed up by about 5 MPH. Then, the cruise will back off and the truck will slow down by 5-8 MPH. The cruise then kicks in again and speeds the truck up by 5-8 MPH. It never does settle down. It just keeps cycling faster and slower like this. Where's a good place to start? Thanks.
Posting Guru
Joined: Dec 1999
Posts: 1,903
Likes: 2
From: Copley, OH
Surging Cruise Control
What mods have you done to the engine? It's not unusual for modded engines to hunt (although usually not that badly) in cruise since the computer still adds throttle for a stock engine.
Post Fiend
Joined: Nov 2002
Posts: 9,987
Likes: 7
From: Memphis, TN
Surging Cruise Control
That old vacuum-type servo is flaky even when new. It has 2 vacuum solenoid valves in it that can get blocked by debris or just sticky with age, and the TPS built into it isn't very good. You CAN take it all apart and clean it up, but you should start looking for a replacement. Either get a newer one from a junkyard (you can get them from Tauruses or anything and swap your cable onto it), or swap to the newer electronic servo like I did.
