My CDS truck has never done this before.

[gimmeagig]

Hi,
I thought I might have a day off but my dog had diarrhea and I had to clean up a big mess. Of course on top of that my truck is acting up.
Maybe you guys can help me trouble shoot?
My truck was cold and it didn't want to idle at first. Once it warmed up I had the right RPMs from the truck but when I started up my machine it wouldn't go past 1000RPM. I fiddled with the cabled on the vacuum bulbs a bit checked the lines and tried to coax the machine up to speed by closing the vac port to let the vaccuum build. No luck, so Ihad to use a stick and wedge it onto the gas pedal to hold the RPMs where they are supposed to be.
I have had that happen before and at the time my mechanic replaced a little block that is mounted to the firewall above the two bulbs. It is connected to those bulbs with a vacuum line and it has a couple of electrical connections too.
That fixed it . I don't know the function of that component. I wonder if it could be the problem again.
But here is the thing that is new. When I shut off my CDS the engine turns itself of too. That's weird.
Any ideas what the problem could be?
Thanks

 

[Doug Cox]

MAC Valve. It opens when you turn on the machine and allows the vacuum PODS to pull up the RPM's.
If your van engine won't maintain idle, that would be the idle air control valve which is on or around the throttle body.

 

[gimmeagig]

MAC Valve. It opens when you turn on the machine and allows the vacuum PODS to pull up the RPM's.
If your van engine won't maintain idle, that would be the idle air control valve which is on or around the throttle body.

Thanks Doug. So that block above the pods is called the MAC valve. Good to know. In the past few weeks I had to coax the RPMs up often by closing the vacuum port with my hand. The machine came up to speed every time. But because it was intermittent I didn't schedule an appointment with LPM who works on the machine.
I have adjusted the pods myself a few times and one thing that I notice to be different this time is that the screws are really easy to turn. I seem to remember that there was more resistance. Could the pods be defective?
I do have an appointment with my auto mechanic on Tuesday. Brakes, and a couple of other things. I will have him check the Idle air valve. When it is cold, the truck just doesn't want to idle until it is warmed up. Again that is another one of those pesky intermittent problems.
I guess I'll have the truck checked first , then the machine.

 

[Doug Cox]

Thanks Doug. So that block above the pods is called the MAC valve. Good to know. In the past few weeks I had to coax the RPMs up often by closing the vacuum port with my hand. The machine came up to speed every time. But because it was intermittent I didn't schedule an appointment with LPM who works on the machine.
I have adjusted the pods myself a few times and one thing that I notice to be different this time is that the screws are really easy to turn. I seem to remember that there was more resistance. Could the pods be defective?
I do have an appointment with my auto mechanic on Tuesday. Brakes, and a couple of other things. I will have him check the Idle air valve. When it is cold, the truck just doesn't want to idle until it is warmed up. Again that is another one of those pesky intermittent problems.
I guess I'll have the truck checked first , then the machine.

Pull the hose off the mac valve that goes to the pods. You will not have vacuum on that hose unless you turn the machine on. The pods could be defective and cause the same issue.

 

[Doug Cox]

This what a MAC valve looks like.

 

[gimmeagig]

Yes, that's the one. Mine looks slightly different but it has that diagram on it and it has the MAC inscription. I had it replaced a little more than a year ago. Probably too soon for it to go bad. So maybe the pods are the problem this time. When I pull on those cables that are connected to them , the idle will come up. But it won't stay when I release. Turning up the idle on the pod adjustment screws is counter clockwise, correct?
It is so strange that when I turn off the CDS that the truck engine is also turned off now. I'll try again tomorrow to see if it still does that.I'll also mess with the set screws in the morning It was too dark to see when I noticed I had a problem.

 

[bob vawter]

Pods...solenoids......high limit...low limits
Proprietary parts....
Mikey....if I buy this old Genie .....kin I sell it under yor very nose....
It'll be the best one yet...JUS LIK NEW!

 

[Doug Rice]

Are the newer pods proprietary? My older CDS uses vacuum choke pull offs I buy at the auto parts store.

 

[Doug Rice]

I'm probably not qualified to question Bob so I send my apologies out now.

 

[gimmeagig]

I'm sure the pods are the original ones. I hear that they are identical to some that I can get for a lot less at the auto parts store but I'm not trying to save money that bad. LPM who work on my machine need to make money to stay in business and I want them around. The mechanic is a great guy who always tries to help me over the phone whenever that's possible. I don't take that for granted. So if I pay extra for those pods I'm OK with that.
I just got my truck back from my regular auto mechanic and he replaced the idle air control valve. It seems to idle better now and tomorrow on my next job I'll see if that made any difference in the way the machine comes up to the correct RPMs.