The cruise control on my 1982 Corvette has been working well until last weekend. The engine increases by approx. 200 RPM and then decreases when the cruise control is on. Any ideas on what would cause this and then fix it.
I am not sure which system you have.1.If you have a cable driven C/C see if there is any way you can check the cable for fretting (or the cable showing the strands that are unwrapping or broken) You can sometime undo the connector from the unit under the hood. Then easily pull the cable out. It's like the cable driven tachs. When they act up could hear them clicking, and/or the tach resond slow. That same cable also is used on your cable driven speedometer. When it acts up it bounces. 2.Have the engine running,you can simply move the vacuum hoses and if the engine changes idle quality check that hose out for a leak. (PLEASE NOTE) some lines will not have a vacuum in them until the C/C is programmed.Most vacuum operated C/C will not operate will the wheel speed is above 35MPH. In that case you will need an OBD1 testing unit, that has C/C or speed control capabilities to test the system. 2.A.The vacuum type C/C for this you need the engine running. Sometime if you spray brake clean or carb clean around the vacuum hoses. Be carefull not to spray too much that the engine ingest's it,and makes the engine idle high Just get a service manual for your car. Most have flow charts to follow.Just visually check the vacuum hose for cracks. You may have to wiggle them or move them. (NOTE) If you have to replace any vacuum hoses, make sure you use VACUUM HOSE....Good LuckBob
Thanks Bob for your assistance with this scenario.I will have a look at it at the weekend and see if anything comes to light. Hopefully smooth cruising.Cheers
bob is completely correct...Just visually check the vacuum hose for cracks. You may have to wiggle them or move them. (NOTE) If you have to replace any vacuum hoses, make sure you use VACUUM HOSE....Good LuckBob bad vacuum hoses is a probable issue...the cruise control vacuum is run all over the engine compartment and includes the AC and heater control system.. there is a vacuum reservoir ball stashed someplace on that car... that car probably also has vacuum operated headlight doors and perhaps a vacuum operated wiper door.. you will probably want to if you have a bunch of cracked vacuum hoses... if your car is really clean and original... there are precut kits with factory markings.. or you can buy rolls of vacuum hose.. you will need probably a roll of 5/32 vacuum hose.. and 10 or 12 feet of 7/32 and 4 feet of 7/64 find a section to replace.. cut the side from the hose at the hose barb.. so you don't have to twist... take the removed piece... cut a matching piece and install it... not longer.. not shorter... move to the next piece... one piece at a time.. work your way around the engine compartment.. there is a check valve somewhere around the engine.. probably near the firewall.. it has a single fitting on one side.. a pair on the other.. engine vacuum is hooked to the single side.. the cruise control vacuum hoses have at least one that goes all the way to one of the brake switches at the pedal...
Wayne: Thanks for the ATTA BOY. I was going on memory.Bob