1990 YJ 4.2L Gross Polluter Running Rich

[BigJman]

I have a 1990 Jeep Wrangler 4.2L manual that I have been trying to pass smog in CA. The Jeep has been running pretty good for an old vehicle and my mechanical experience has been growing vastly since I have had her. She is running 33's w/ stock gears and has 130,000 miles.

Here are the Max and Gross polluter limits
15mph (HC-124(MAX)311(GP),CO-0.75(MAX)2.05(GP),NO-1020(MAX)1807(GP))
25mph (HC-104(MAX)261(GP),CO-0.95(MAX)2.25(GP),NO-880(MAX)1607(GP)).

Here are the results of my first test.
15 mph (RPM-1984, %CO2-13.9, %O2-1.0,HC-102, CO-0.53,NO-1965)GP
25mph(RPM-1902,%CO2-14.0, %O2-0.9,HC-105,CO-0.52,NO-1870)GP.

They said the high NO had to do with my EGR system. So I looked at it and the plastic nipple from the EGR temp switch was broken off, so the EGR had no vacuum. I fixed that w/ super glue and EGR gets vacuum and diaphragm moves when revved.

Test2
15 MPH(RPM-1952,%CO2-12.3,%O2-0.6,HC-198,CO-3.44,NO-114)Gross P
25mph(RPM-1905,%CO2-11.9,%02-0.6,HC-201,C0-4.02,NO-99).

Now its running super rich. I looked at my vacuum line and one that was supposed to go to my carb had a plug on it. I went through all the vacuum hoses and replaced an re-routed them per the vacuum schematic in my chiltons. Boy, whoever did it before really messed it up; now she is idling super high, like 1300 RPM. I'm stuck, does anyone have any idea of what to do?

 

[BigJman]

Update 1

I adjusted my idle, so now she is purring like a kitten. Not really, but compared to how she was it is definitely an improvement. I went through and adjusted the fast idle and curb idle and even the sol-vac idle for start up. She runs about 1100rpm for 15 seconds then down to 900 for 45 sec to a min. then purrs at around 650 at curb idle. I think I am going raise it up a 100 rpm or so. When I have to stop fast she bogs down.

I was ****ed because I got her running right, put the air cleaner assembly back on drove around the block and the idle stayed at around 1000rpm. I thought my wiring to my sol-vac was screwed up. Then I noticed the backside of the plunger toward the front of the vehicle could not release because it was hitting the air cleaner assembly. After a little nudge she went right back to 650.

Now I have to see if i can figure why she is running rich. The stepper motor pushes the metering pin back and forth but it looks like she tends to go rich. When i let her idle the pin seems too far forward, but I dont know where the middle point is. When I hit the gas the pin pulls in and leans it out and then slowly goes out and stays out.

I tried the test when you get the rpms up and close the choke plate the metering pin moved forward to rich it up. I also did the test when you create a vacuum leak and the pin pulls in and leans it out. So I know the O2 sensor, stepper motor, and computer are working for the most part. I need to see if there could be an electrical issue making it run rich or mechanical.

I spoke with a buddy of mine that used to be a mechanic,and he said the timing could be the thing that is making it run a little rich. He said if I adjusted the timing a little to make it burn a little quicker. Also he said that if its running rich that could cool the exhaust and cat down enough to not burn the rest of the gas off. Or if it's way too rich it could build up in the cat and ignite and super heat the cat. So checking the timing is what i'm going to tackle tonight, and I think I'll replace the spark plugs too. I need to remove the distributor anyway to change that little gasket, its leaking oil right there. I just bought a timing light, update tomorrow.

 

[BigJman]

Update 2


The vacuum lines are now at factory spec. I adjusted the idle on the carb sol-vac, fast idle and curb idle. It is now idling better than ever. I also ran some seafoam in my tank, down my carb, and some in the oil. I changed my spark plugs, pcv valve, air filter, changed oil 3 weeks ago, and I checked my timing and it is at 9 deg. I took another test yesterday and it did much better, but still not good enough. Here are the results of my third smog test.

Test RPM CO2 O2 HC CO NO
15 mph 1964 14.0 1.0 124 0.46 219 Pass
25 mph 1929 14.2 1.0 133 0.39 210 Fail

I don't really know what to do now. It is weird that at higher speeds the CO and NO went down, but the HC went up. Now I just need to see what to do to get the HC down.

 

[BigJman]

Another question. My PVC air in hose was disconnected from my air cleaner housing. Would that affect my PCV system? Is there vacuum in that hose, does it make a difference other than being hooked up to a filter? Does the air cleaner regulate how much air is drawn in? If the vacuum is affected with that hose could the computer think there is a vacuum leak and possibly make it run richer to compensate for vacuum leak?

 

[88YJ6]

hey the carb-sol vac is that funny plunger assembly on the side of the carb, how do you adjust it and what does it do

 

[BigJman]

It regulates the Idle when you start the jeep. It is vacuum actuated when you start the jeep to give a high idle at start. It holds it at 1100 rpm for the first 10 to 15 seconds, the the vacuum is released and an electronic solenoid takes over and keeps the idle at about 900 rpm for another 30 seconds or so until the jeep is warmed up a little bit. When the jeep is warm it deactivates.

And check out this site it has all the info you need on how to adjust it and pretty much anything else you need to know for the carbed yj's.

http://home.sprynet.com/~dale02/list.htm

 

[BigJman]

By the way I got it to pass! It needed a new cat. The old one was broken up inside. The new NO reading was at 1 and 2 ppm. This thing is probably cleaner now than when it rolled off the lot.