Zeustopher

Well after lots and lots and lots of work my jeep is finally running correctly! Turns out that the distributor plate was loose and replaced the distributor and runs like a champ! Thanks for everyone's help and suggestions! You can see the old thread here:

https://www.cherokeeforum.com/f2/nee...limited-33292/
But thats not the topic of my post.


Now that it is running correctly we went and took it to get emissions done again. It passed the CO2 and HC very well but my Nox failed really bad. After searching I read that the cause is more than likely the EGR valve. Starting diagnosing it and figuring out why it isn't working. There was no vacuum getting sent to the Black part next to the EGR (not sure what this is but it says EGR Vacuum on top of it). Traced it back to this solenoid mounted on the side wall right next to the airbox. There is vacuum going in but none coming out. What makes this activate so that I can test to see if it is bad or not? I looked at another jeep's solenoid and it doesn't have any vacuum coming out either. What make the EGR valve open? Any suggestions on how to make my EGR valve work?

If I put a vacuum on my EGR valve it does open so I know the valve itself is good. Also if it is just idling and i put the vacuum on and the valve opens, the car nearly dies and barely fights to stay alive. i read this is what should happen if the valve is opened during idle.

Any help or suggestions would be appreciated!

89Laredo

The ECU opens the EGR solenoid and allows exhaust gas to come through only at certain times.
I think its mainly at a cruise, and it is disabled at idle and WOT

Maybe 5-90 or Blue will come in and correct me if im wrong

Abovetimberline

The part on the firewall is the egr solenoid,the black saucer is the back pressure transducer,you need vacuum to the egr,there is a diagram posted on the drivers side that shows your vacuum diagram,emissions sticker. If you want to check your egr just apply vacuum to the egr with engine running,it will cause a stumble or kill the engine.
There will be no vacuum at idle from the solenoid.
You must live in ca and so cal.
The egr is only used during cruise.

Zeustopher

I know the EGR valve works because when i put a vacuum on it, it opens. The engine then nearly dies. Is there a way to test it and see if the EGR valve will open or not at cruise?

Would there be a problem if the valve was just open part way all the time?

I actually live in Utah. We have a few similar things to California's smog laws but luckily just not as intense.

dieselgriff

The solenoid should be ground switched. Check for power and if it has power then take the opposite terminal and ground it with a jumper, the solenoid should open and the engine should sputter when the egr valve actuates. If the solenoid passes that test then there may be a problem between the ECU and the solenoid. Being an 89 makes life harder because we lack the ability to connect a scan tool to it.