Internment Rough idle

[Mel]

I just wanted to share my experience on my rough idle, hopefully it will save someone the headaches I went through.

I have a 1988 Comanche with the 4.0.

 

For months I have tried to figure out what was causing my rough idle, it was never consistent, sometimes it would run great and the next minute it would idle rough causing the engine to shake, it always ran great while driving, it was only at idle that I had any problems. I had checked and rechecked sensors, I had done almost all of Cruisers tips including the C101 delete. I never just threw a bunch of parts at it at once, but went through all possible causes, I checked for vacuum leaks many times, checked EGR valve operation several times and it always worked.

 

On top of everything else I read as many different forum discussion on anything close to my problem with no avail. 

The other day I was  working on it again, changed the coil and then since it had been a couple of years I changed out the TPS and Map sensor still did nothing. I resorted back to the internet and came up on a thread about the IAC and in the comments someone mentioned check the EGR solenoid to see if it was working. I had checked it at one point but never went back to it, so to make a short story longer, I pulled the vacuum line going to the EGR off while it was idling rough and walla I found vacuum when there I shouldn't have been, I pulled the electrical connector off and put it back on and the idle immediately smoothed out. On further inspection I found a broken tab of the connector that was keeping the terminal from making a full connection. I don't think I need to really express what a glorious moment that was but I do think I heard angels singing 😂... Sorry for the long post but I hope this might help someone out at some point. 

[Tex06]

Awesome, love it when people post a good fix to their problems and not just the problem itself! Is this Papa Mel from 3rd Coast Comanches by chance?

[Mel]

1 hour ago, Tex06 said:

Awesome, love it when people post a good fix to their problems and not just the problem itself! Is this Papa Mel from 3rd Coast Comanches by chance?

No sir I'm not, I'm in New Mexico...

 

That's why I wanted to share, I know how valuable that kind of info is.

[Mel]

Just an update, drove it around all day and one time it went back to its old ways then all was good, so I believe the solenoid is acting up. I just placed an order for one, but there's no doubt that it is the culprit.