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-   -   High Idle (http://www.jeepforum.com/forum/f12/high-idle-1526104/)

89WhyJ 05-20-2013 08:26 PM

High Idle
 
Alright, I started up the YJ for the first time today since replacing the exhaust manifold, gasket, and O2 sensor. For a bit of background, the engine would idle like crap, and really low. In the process of replacing the manifold I found the MAT sensor wasn't connected (the connector was melted in half). So, along with the stuff mentioned above, I re-wired the sensor. Today when I started it up, it still idled rough for a minute or two, but didn't require my foot on the pedal to keep it going. After a few minutes, I guess the ECU closed the loop, because the engine hummed right out, nice and smooth...but at about 1100 to 1200 RPM. This is the best the engine has sounded since I bought it 4 years ago. However, it seems like this is a bit high. Do these numbers sound high? Also, I went over the engine with carb cleaner and didn't find any leaks. If its the IAC or TPS, are the RPMs too high to drive before re-adjusting these sensors? Thanks for the help!

pete1991YJ 05-21-2013 11:41 AM

Yeah its a bit high, the idle should be right around 750. I know the IAC and TPS are adjustable in the TBI motors but I don't know the details of how to do it. Que is the expert on that I think, maybe try to find him of PM him.

Que89YJ 05-22-2013 06:43 AM

Hey 89WhyJ. Did you download the FSM? I know we discussed it before. The ISA and TPS both need to be set and play into your idle. The adjustemnts are in the FSM Ninja posted links for.

89WhyJ 05-22-2013 07:21 PM

Yeah Que, I got the FSM (thanks by the way). I was mainly curious if the RPMs were too high. I saw in another post where someone said that 1100 wasn't all that high. If it really is too high, then I'll go ahead and start the adjustments in the FSM.

Que89YJ 05-23-2013 06:20 AM

That is way too high. Follow the directions and you should be good. Do the adjustment for both the ISA and the TPS. The 9vdc battery trick works but you can do the same think by using the diagnostic on the passenger fender connector and jumpering power there with a small wire too. I was just going through the schematics and it looks like it would be easier. I started working at Chrysler after they went OBD1 in 91 so like you I am learning about my 89 every time I troubleshoot it too!

89WhyJ 05-28-2013 12:13 PM

So, I tried to get the jeep inspected, and got to pass safety...finally. However, they said that the timing chain was loose and slapping the cover. So, I got my shop to go ahead and replace the chain, tensioner, and cover (since the cover had been beaten to death by the chain slapping). After I got it back, the engine purred around 900 RPM. That's still a bit high, but nothing like it was before. They may have done some other adjustments, but didn't tell me.

That being said (to highjack my own thread), it still has a rough idle at startup. Also, it failed emission for NOX. I had an emissions guy look it over, and he's fairly confident its the EGR valve. I resurrected an old thread, where Que had pointed me to the test procedures for the EGR. I'm going to test that next. Some of the instructions say you can phyiscally manipulate the diaphram. How do you do that? Are there openings under top half of the valve where the diaphram is located? Also, under what conditions should the valve be open and allowing gases into the manifold...at startup, heavy load, and WOT? Also, where is the EGR solenoid physically located. Is it the object below and to the right of the battery (when looking at the engine from in front of the jeep)? Thanks for the help.

Que89YJ 05-28-2013 12:58 PM

Its all in the pipe. The egr valve gets crude in it from the exhaust. That tube from the egr to the intake is a BIT## to get off if it is corroded and impossible to find if it breaks so take your time getting it off. Definitely remove the drivers fender to get at it. Did you see where in the test the NOX were high and by how much? High nox is lean burn. The egr or the catalytic converter are usually the issues with high nox on the tbi. Dont worry about testing it. if you are getting to the point of testing it, replace it especially if you are dealling with an emissions test state. Consider it maintenance. It is a little expensive; I think it was just under $100. No solinoid it is vacuum controlled. glad to hear its running better.

89WhyJ 05-28-2013 07:35 PM

Quote:

Originally Posted by Que89YJ (Post 15490022)
Its all in the pipe. The egr valve gets crude in it from the exhaust. That tube from the egr to the intake is a BIT## to get off if it is corroded and impossible to find if it breaks so take your time getting it off. Definitely remove the drivers fender to get at it. Did you see where in the test the NOX were high and by how much? High nox is lean burn. The egr or the catalytic converter are usually the issues with high nox on the tbi. Dont worry about testing it. if you are getting to the point of testing it, replace it especially if you are dealling with an emissions test state. Consider it maintenance. It is a little expensive; I think it was just under $100. No solinoid it is vacuum controlled. glad to hear its running better.

So the only thing it failed was NOX...
15 mph (1828), Limit: 1273, Meas: 1655
25 mph (2926), Limit: 1163, Meas: 1316

I'm not sure if that is really bad, or just a little bad...regardless, it failed. The mechanic said he got no vacuum to the EGR, which is odd. But he also said he's pretty sure the diaphram was punctured. So, when I get back in town, I'll have to get ahold of an EGR and swap them. I wish I knew about cleaning the tube. I just had it off when I replaced the manifold last month. I'll still check it out.

89WhyJ 06-17-2013 06:46 AM

Ok, so I finally got time to start monkeying with the EGR system. I tested the EGR solenoid (that sends vacuum to the EGR valve) first, based on the service manuals that Que pointed me to...thanks again Que. At idle, I had about 15 inches vacuum going into the solenoid...check. On the outlet, I had 0 inches...check. Removed the electrical connector, checked the output, and had 0 inches...strike! From what I've read, the solenoid should pass vacuum when de-energized...by the computer or loss of connection. So, it appears my solenoid is shot. If the solenoid never passes vacuum, then the EGR valve never opens. That would be the cause of failing the emissions test for high NOX.

Of course, when I disconnected the vacuum line that ran from the solenoid to the EGR valve, I heard a hissing. I'm pretty sure (someone correct me if I'm wrong), that that line shouldn't have any vacuum on it when disconnected from the solenoid, since the solenoid should provide the vacuum input to the EGR valve. Now I could be wrong, but that would suggest that the diaphram in the EGR valve itself is leaking. When I put my finger over the hose, and then remove it, the engine definitely idles differently.

That brings me to my comments and questions. If I'm replacing the solenoid, do I have to use the OEM solenoid (~$100 through Chryler Factory Parts online), or can I use some other EGR solenoid? They should all work in the same manner, pass and restrict vacuum. Some are much cheaper than others. Second, am I correct in the assumption that the EGR diaphram is busted, meaning I'll have to replace the valve? The mechanic who did the emissions test said that it wouldn't hold vacuum. If that's the case, and it's leaking, that may also explain why I have a slightly rough idle...vacuum leak inside the EGR valve. I've already got the EGR valve ready to go, based on Que's recommendation. It doesn't seem that difficult to replace. Is there anything I need to know, or things I should look out for when replacing it? Thanks for all the help guys.

Que89YJ 06-17-2013 07:19 AM

Your assumption on the solenoid is correct. No vacuum is a bad solenoid. I am not sure about a substitute. Roll the dice but I think you are better off getting the OEM IMO. Remove the drivers fender to try and take off that pipe in one piece.

UZI4U 06-17-2013 07:36 AM

You can test the diaphragm on the EGR valve if you have a vacuum pump. Does the vacuum line go to the solenoind and then the EGR valve? If the solenoid if bad you will have to replace it. I don't know if there are cheaper ones that interchange. Check Rock Auto and shop some other internet sites.

89WhyJ 07-17-2013 05:13 PM

I replaced the EGR valve and the EGR solenoid. I picked up the valve from RockAuto, and the solenoid from one of those online Mopar Wholesalers. I am definitely getting a better response now. I've got a slightly stronger vacuum at the solenoid input, and i no longer have the smell of exhaust under the hood. The idle still isn't real smooth, but it settles around 800 RPM now. Also, when I remove the electrical connection from the solenoid, the engine just about dies. So, I'm fairly certain the solenoid is working now, as is the EGR valve.

Now, the question I have is regarding the solenoid. The replacement solenoid has two output ports (just like the original one). I have my EGR vacuum hose attached to the top solenoid output port, just like the original. At idle, the bottom port is pulling vacuum. Can anyone tell me if this is normal operation? I guess its possible that the solenoid just switches between the two ports. Can anyone verify what the other port is doing at idle?

89WhyJ 07-23-2013 07:51 AM

Bump...


The time now is 12:51 PM.

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