homestd

OK, I know I have a lot to learn. Could someone please clarify the CTO ports for me? The top port gets vacuum from the fuel pressure regulator (obviously). I need to understand which of the lower ports have vacuum and when. Normal operating temp/ 1500rpm what does what?



Should this line be plugged?



All the vacuum diagrams/service manuals I have researched have failed my meager intellect.

robsjeep

That port you have circled in red is for the vacuum operated thermostatic controlled warm air valve on the stock aircleaner. This is for supply of warm air for cold start operation.
Your air cleaner is not stock, so likely lacks the warm up air feature. thus if not used this hose should be capped closed.

You wont pass california smog inspection without it, but she can run ok without it too

the two ports with red "?" are for...
1. the aforementioned warm air valve, and...
2. for egr valve. from that "?" port the vacuum goes first to the egr solenoid valve ( next to fuel pump resister on driver side behind headlamp ) then it goes to the egr transducer ( the black round plastic "flying saucer" that rests above the egr) and from the transducer to the erg valve.

The function of the egr solenoid valve is to allow the ecu (the brain) to override the egr so it will turn off under certain conditions.

The egr transducer will interupt the erg operation based on exhaust manifold back pressure, hence the transducer has three ports, two are vacuum ports in and out, the third port is hooked to the base of egr where it recieve the backpressure of the exhaust, which controls if the transducer is open or closed to passing the egr vacuum signal to the egr. Note that many schematic do not show the transducer, if your egr valve has two ports, then you need the transducer, or you will to cap that port on the egr (NOT the vacuum port to cap, rather the exhaust port coming from the base of the egr, else you will have an exhaust leak there if no transducer)

hope this is helpful

treat your egr with care, new egrs are near impossible to find these days, You can still get new transducers, as of two years ago.

good luck

PS.... Transducer link.....
https://www.autozone.com/znetrgs/repair_guide_content/en_us/images/0900c152/80/0a/9b/af/medium/0900c152800a9baf.gif


Hose diagram..

https://www.cherokeeforum.com/f2/1988-renix-vacuum-lines-alt-question-252551/


note purple hose is for the warm air valve, it hooks to rear of aircleaner lid, not applicable in your case. green hose is egr vacuum, but transducer is not shown here at all. that green hose should go to the transducer transducer vacuum inlet, then from the transducer outlet into the egr valve vacuum port.

homestd

Thanks Rob, I couldn't get this link to open, Could you re-send it maybe? Or just the diagram?
Oh yes, I do have a transducer, how do I test it?

robsjeep

ok, try it now, I changed it, it be a thread on cherokee forum, second post of that thread has the diagram. I dont know why the other link didnt work, it was for the same diagram. let me know if this is still problematic.

homestd

It tries to, but no. Can you give me the name of the post?

cruiser54

robsjeep

Here is the thread, see 2nd post.....

thread title.....

1988 Renix vacuum lines & alt.question

the link does work, I tried it again. you need to copy and paste it. for some reason it is not turning into a blue colored direct link you may simply click on, so copy and paste, or search the forum for the thread listed above

Saudade

It appears to be missing the URL tags

https://www.cherokeeforum.com/f2/198...estion-252551/

robsjeep

how do you make an url tag?

it used to be i could copy and paste and direct link will work, now for what ever reason my copy and paste thing does not make a direct link anymore.

how do you do that url thing?

homestd

Thanks Rob, that's a clear diagram. Thanks all, I think I've got it now.

Saudade

Odd but that's what I did. I copy/pasted your link and got to the page, then copy/pasted the url into my post. It turned "blue" and the linked worked.

I always preview my post before submitting to make sure it looks OK.

robsjeep

I dont know what happened to my computer, it used to be Id copy and paste a internet address and it would be a direct blue link, now it simple gives me a black non link. If anyone knows how to fix this, please let me know. I know little of computers except frustration, but I can set timing, adjust valves, synchronize carbs, even rebuild transmission, but computer stuff, ugh it is so not logical
one day my telephone stopped ringing. I could not get it too ring, tried the volume buttons on the side, tried the "settings screen" and nothing. then friends son told me to touch the battery charge state icon, drag down and then touch the crescent moon icon (allah be praised!) now it rings again,. he tells me the telephone is loaded with what he called "hidden features" which is total bull stuff to have. He figures I might have accidentally touched some icon that shut off the ringing

so how do I make direct internet links work again? Id like to copy and paste and have it be a blue direct link again. and note this was not done on the telephone but a computer tablet.

Saudade

Not to turn this into a non-XJ "support call", but are you using a browser or some app like Tapatalk? Clear your cache.

You can also use the Test forum to try things out.

https://www.cherokeeforum.com/f23/

robsjeep

No apps, just a computer. Like I said, direct link pasting used to work for me, now it is just a non direct link text pasting.

5-Speed

Well good thing @cruiser54 posted a picture of it so no one has to get confused on how to open/create a link....