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Old 07-20-2000, 05:51 AM
irbob's Avatar
irbob irbob is offline
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Join Date: Apr 11, 2000
Location: Huachuca City, AZ 85616
Posts: 2,788
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I noticed that the CTO was taken out of the loop on my grandfathers 78 Chero. The vacuum hose should come from the EGR to the CTO and then to the carb. Well his goes straight to the carb from the EGR. He had just taken it to a mechanic who had done this. It runs great (better than mine, sniffle).

My curious self went and talked to the mechanic (Jim) about this. He said that he suspected the CTO was bad and at this altitude and temp in AZ the CTO wasn't really needed. He put the vacuum line above the throttle plate so no vacuum at idle and a gradual increase in vacuum when the plate opens during acceleration.

Any comments on this situation?

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  #2  
Old 07-20-2000, 06:38 AM
BobBarry
 
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<BLOCKQUOTE>quote:</font><HR>Originally posted by irbob:
I noticed that the CTO was taken out of the loop on my grandfathers 78 Chero. The vacuum hose should come from the EGR to the CTO and then to the carb. Well his goes straight to the carb from the EGR. He had just taken it to a mechanic who had done this. It runs great (better than mine, sniffle).

My curious self went and talked to the mechanic (Jim) about this. He said that he suspected the CTO was bad and at this altitude and temp in AZ the CTO wasn't really needed. He put the vacuum line above the throttle plate so no vacuum at idle and a gradual increase in vacuum when the plate opens during acceleration.
<HR></BLOCKQUOTE>

All the CTO does is prevent the EGR from opening before the engine is warmed up. If the EGR kicks in when the engine is cold, it can run rougher.

Since the CTO is only a $10-$20 part, it's really not all that much of a sacrifice to replace it. Heck, though, if your uncle doesn't notice the engine stumble when it's still cold, then more power to him; leave it off and be happy. Of course, the EGR valve itself could be non-functional, in which case he may as well just plug the vacuum port entirely.

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Bob Barry<UL TYPE=SQUARE>* '78 Cherokee 4-door
* '88 Grand Wagoneer[/list]http://studentweb.providence.edu/~rbarry/wheels/
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  #3  
Old 07-20-2000, 06:43 AM
Veepster Veepster is offline
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Join Date: May 14, 2000
Location: State College, PA USA
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I would have connected the vacuum advance to full ported vacuum.

it seems from my unfortunate in depth study of this the CTO limits vacuum advance during warmup for emmissions reasons only.

after warmup it runs off full port vacuum......attempting to guess how much vacuum it needs and where to put the port would be totally guessing...

kinda seems like reinventing the wheel


Peace..................BartG
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