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I'll check Posted by Ari [Email]  (#2847) [Profile/Gallery]
(more from Ari) on Mon, 30 Jul 2001 14:22:25
In Reply to: Re: Cruise control, Michael Kaiser, Mon, 30 Jul 2001 12:51:31 Members do not see ads below this line. - Help Keep This Site Online - Signup |
This is the first time I've heard of a 4200 rpm 'enable' of full boost for the CC. The switch on the fender is plumbed into the CC vacuum line. The CC controls throttle position by an actuator controlled by vacuum. More vacuum, the more throttle it commands. The fender-mounted switch interrupts power to the APC solenoid (base boost) if it senses pressure in the line.
I've got two thoughts on this - first, your explaination makes sense, that the CC could get full boost under max conditions, EXCEPT that it would present a safety issue - if the CC 'ran away' you'd get full boost exactly when you didn't want it.
Here is why it might work as you say - the pressure switch commands base boost when it sees vacuum from the CC pump. The CC pump uses vacuum to command throttle position - more vacuum means comanding more throttle.
If you set the CC speed for say 60 mph, then mash the heck out of the throttle, the car will speed up. The CC will say, 'whoa, too fast' and cut back on throttle, or at least try. It does this by reducing the vacuum to the throttle actuator. If you're going much faster than the CC set point, the vacuum in the pump line will be very little (near atmospheric), and the pressure switch may switch off, allowing full boost.
That scenario depends only on vehicle speed versus CC set speed, and has nothing to do with RPM. But you say you can get full boost with CC engaged in all gears.
If you set the CC for 60 mph, then coast down to 25 mph and hit resume, do you get full boost?
Either way, I'm going to check my schematics this evening. What year car do you have?
, Mon, 30 Jul 2001 11:39:43, Mon, 30 Jul 2001 14:22:25 <-- Viewing This Message, Mon, 30 Jul 2001 11:16:10
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