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Discussion Starter · #1 ·
What exactly is the purpose of the CTO valve (the one with 5 vaccuum hoses off of the manifold)? I pulled it off today and it was doing nothing. Would this be the cause of my bad idling? Any helpful tips for an 82 cj would be much appreciated. Nobody I know really knows what is supposed to be going on with each vaccuum hose.
Thank ya kindly,
the chase

 

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/wwwthreads_images/icons/smile.gif Chase, are you saying the CTO has FIVE ports??? Not possible/wwwthreads_images/icons/crazy.gif

CJDave
I never believe any statistics unless my moonguys /wwwthreads_images/icons/crazy.gif/wwwthreads_images/icons/wink.gif made 'em up themselves.
 

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The coolant temp overide valve usually has 3 ports. The lower one goes to manifold vacuum, the middle one goes to the dist., and the upper one goes to ported vacuum. When the engine is cold, it will apply full manifold vacuum to the dist. for faster warm ups. After the engine comes up to normal operating temp., it uses the ported signal. And if the engine becomes too hot, it will switch back to manifold vacuum, to bring the idle up a little and try to cool the engine off some.

If the one that you are talking about has five lines, I don't know, and would have to look at the vacuum scematic. Off road.com has a link someplace that shows all of the diagrams.

 
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Discussion Starter · #5 ·
"It was doing nothing"? So, no hoses were attached to it? Then, yea, it was doing nothing. It's a valve that opens when the coolant reaches a certain temp. I believe the vacuum lines for the EGR and evap canister on my 85 CJ7 were routed through the CTO. Hence, they were inoperative until the engine warmed up and the CTO opened.
I doubt that it would have anything to do with rough idle if no hoses were attached to it. But I would imagine that antifreeze would come flowing out the opening if you simply took it out. I don't use mine either, but I left it in.

BTW, I have the 5-port version as well and the AMC manual and every other manual I've found is very ambiguous about exactly what ports are supposed to go where.

Ciao

'85 CJ7/258
 
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Discussion Starter · #6 ·
cant help you on your cto valve, but maybe I can on your rough idle. Do you have a large plug in the back of the carb. If so, I know my 84 had it. It is called the stepper motor, when you are idling, it should be moving back and forth it you look down in the carb. Make sure all vacuum lines are hooked up, that can cause a rough idle also. Give us some details on how it is running. Rough, only when cold? what does it do when you rev the motor? The more info you give the board, the more likely we can diagnose your probs.

 
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Discussion Starter · #7 ·
This is late in coming--the answer to your 5 port CTO dilemma : based upon days of struggling with a 5 port CTO on my 88 Wrangler , here's my understanding . The Coolant Temp Overide valve is a switch for both the EGR and the Evap charcoal cannister . At the proper time , the CTO permits ported vac from the carb to pass through the CTO valve . Of the 3 ports facing closest to the radiator , the port at the bottom of the CTO valve ( near the threads into the engine block ) should be closed off / sealed / blocked . The middle port hose feeds ported vac "signal " to the evap cannister . This permits the opening of the evap cann " purge main port" , allowing vacuum from the carb (manifold vacuum) . The third outer CTO port is teed into the CTO port which is on opposite side of CTO ( 2 port side ) and closest to engine block . Together , the conjoined hoses lead back to the air cleaner thermo vacuum switch TVS . Not until both engine coolant temp and TVS have hit their respective critical temps will the ported vacuum source ( originating from carb half way up the side facing the valve cover )hooked into the outer CTO port ( on the two port side )be permitted to flow through the CTO and TVS . When this occurs , ported vac is allowed to turn on the evap cannister "Signal valve" . Also , ported vac is permitted to flow to the air cleaner's TVS , through the TVS ,and then on toward the EGR .

 
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