Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here XJ (84-01)
All OEM related XJ specific tech. Examples, no start, general maintenance or anything that's stock.

PLEASE help me PASS SMOG!

Thread Tools
 
Search this Thread
 
Old 02-12-2021, 01:24 AM
  #16  
Junior Member
Thread Starter
 
Homerlasvegas's Avatar
 
Join Date: Dec 2020
Location: Las Vegas
Posts: 80
Received 7 Likes on 7 Posts
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0 L
Default

I just put in a brand new exhaust manifold. Rechecked the tightness of the bolts/nuts..

The tach is fine. The engine idles at around 650 rpm. Reasonably steady with slight fluctauations.

I have sprayed carb cleaner checking For leaks...

This is. 1990 so no c101..
Old 02-12-2021, 06:47 AM
  #17  
CF Veteran
 
Dave51's Avatar
 
Join Date: Jan 2017
Location: Connecticut
Posts: 3,283
Received 371 Likes on 331 Posts
Year: 2000
Model: Cherokee (XJ)
Engine: 4.0
Default

Originally Posted by Homerlasvegas
BIG PROBLEM.. Will not pass smog. got a:
Idle Speed CO 5.46% (must be less than 1.2%)
High Speed CO 7.07% (Must less than 1.2%)
Idle SPeed HC 382 parts Per million (must be lower than 220)
When was this analysis done in relation to the work you did?

Is the oxygen sensor heater working correctly?

Do you have the old sensor?

Last edited by Dave51; 02-12-2021 at 06:50 AM.
Old 02-12-2021, 07:16 AM
  #18  
CF Veteran
 
Dave51's Avatar
 
Join Date: Jan 2017
Location: Connecticut
Posts: 3,283
Received 371 Likes on 331 Posts
Year: 2000
Model: Cherokee (XJ)
Engine: 4.0
Default

Originally Posted by Dave51
Is the oxygen sensor heater working correctly?
Cause you gotta heat that thing to about 1500 degrees for it to work correctly.
Old 02-12-2021, 07:19 AM
  #19  
Junior Member
Thread Starter
 
Homerlasvegas's Avatar
 
Join Date: Dec 2020
Location: Las Vegas
Posts: 80
Received 7 Likes on 7 Posts
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0 L
Default

The readings from smog were before I tightened the manifold bolts and before the CTS. I am considering rechecking. Ths 02 readings at the time of smog were mid 2's.

I plugged the old 02 in deadlined at 4.98.

The videos are current.
I will recheck the 02 heater readings. The REM. Says yes.

One other caveat. I have a severe power steering leak. The bottom of the engine is covered in power steering fluid. Any probability that power steering fluid could cause a problem with the 02 sensor conbection. I get readings. But the connector has a liberal coating of power steering fluid.

Will be replscing the power steering unit tomorrow.

Last edited by Homerlasvegas; 02-12-2021 at 07:59 AM.
Old 02-12-2021, 09:42 AM
  #20  
CF Veteran
 
RocketMouse's Avatar
 
Join Date: Nov 2017
Location: Southern Texas (former AZ & Aus)
Posts: 2,415
Received 249 Likes on 199 Posts
Year: 1999
Model: Cherokee(XJ)
Engine: I6 4.0L
Default

thats a laundry list things checked/replaced at the top there.... maybe I'm smoking crack.... but that fuel pressure stuck out to me. how does this thing run? I think I remember getting close to 50 when primed and then at standing idle dropped to 40-45.
31 seems low to me, but maybe it's because yours is a '90...mine's a 99
Old 02-12-2021, 03:34 PM
  #21  
Junior Member
Thread Starter
 
Homerlasvegas's Avatar
 
Join Date: Dec 2020
Location: Las Vegas
Posts: 80
Received 7 Likes on 7 Posts
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0 L
Default

I just picked up 2 used EGR valves at the pick a part.

Someone said.. go by used parts and try them. I said none available then i looked and they had just put out 3 Cherokees on Wed. Showed up this morning at 8 am.

Probably over bought.. but ..

I have:
MAP
2 - IAC
2 - EGR
Complete Throttle Body. With TPS
front Skid plate
02 Sensor
ECU
TCU
Wiring Harness
Air box
Water Bottle
Water bottle Strap
Battery Tray.

So.. If someone needs something I don't have...

On the comment for the Fuel Pressure. RENIX experts correct me If I am wrong.. But I think 31 is correct for a RENIX.

-H
Old 02-12-2021, 03:52 PM
  #22  
CF Veteran
 
Dave51's Avatar
 
Join Date: Jan 2017
Location: Connecticut
Posts: 3,283
Received 371 Likes on 331 Posts
Year: 2000
Model: Cherokee (XJ)
Engine: 4.0
Default


Old 02-12-2021, 04:06 PM
  #23  
Junior Member
Thread Starter
 
Homerlasvegas's Avatar
 
Join Date: Dec 2020
Location: Las Vegas
Posts: 80
Received 7 Likes on 7 Posts
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0 L
Default

Thanks Dave...

I got a rock solid 31 while idling.. I think thats good.

I did screw up though . the 89 Cherokee I stole most of my parts off of today.. had a practically brand new fuel regulator . and I forgot to grab it ..
Old 02-12-2021, 05:57 PM
  #24  
CF Veteran
 
RocketMouse's Avatar
 
Join Date: Nov 2017
Location: Southern Texas (former AZ & Aus)
Posts: 2,415
Received 249 Likes on 199 Posts
Year: 1999
Model: Cherokee(XJ)
Engine: I6 4.0L
Default

Originally Posted by Dave51
well learned a new one today.... that's different than mine... thanks for posting it
Old 02-12-2021, 10:27 PM
  #25  
Junior Member
Thread Starter
 
Homerlasvegas's Avatar
 
Join Date: Dec 2020
Location: Las Vegas
Posts: 80
Received 7 Likes on 7 Posts
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0 L
Default

Originally Posted by Dave51
Cause you gotta heat that thing to about 1500 degrees for it to work correctly.
OK.. Now I'm stumped... The REM says . the heat circuit is working. I don't think I am getting anything on the heat circuit.. I get 5 volts with key on. I thought the other side was supposed to give me battery voltage.. I'm getting NOTHING.

Where do I go?

Is there a fuse?? A relay???

-H
Old 02-12-2021, 11:13 PM
  #26  
CF Veteran
 
lawsoncl's Avatar
 
Join Date: Dec 2017
Posts: 3,953
Received 1,097 Likes on 880 Posts
Year: 1989
Model: Comanche (MJ)
Engine: 4.0
Default

Originally Posted by Homerlasvegas
OK.. Now I'm stumped... The REM says . the heat circuit is working. I don't think I am getting anything on the heat circuit.. I get 5 volts with key on. I thought the other side was supposed to give me battery voltage.. I'm getting NOTHING.

Where do I go?

Is there a fuse?? A relay???

-H
Have a good look at the wiring to the sensor near the exhaust manifold. Check that it didn't get too closed and melted.
Old 02-12-2021, 11:15 PM
  #27  
CF Veteran
 
lawsoncl's Avatar
 
Join Date: Dec 2017
Posts: 3,953
Received 1,097 Likes on 880 Posts
Year: 1989
Model: Comanche (MJ)
Engine: 4.0
Default

Originally Posted by Homerlasvegas
OK.. Now I'm stumped... The REM says . the heat circuit is working. I don't think I am getting anything on the heat circuit.. I get 5 volts with key on. I thought the other side was supposed to give me battery voltage.. I'm getting NOTHING.

Where do I go?

Is there a fuse?? A relay???

-H
Not sure without checking the diagram but I think the wire in the diag connector that the rem is looking at is connected to the realy output?

Have a good look at the wiring to the sensor near the exhaust manifold. Check that it didn't get too closed and melted.
Old 02-12-2021, 11:25 PM
  #28  
Junior Member
Thread Starter
 
Homerlasvegas's Avatar
 
Join Date: Dec 2020
Location: Las Vegas
Posts: 80
Received 7 Likes on 7 Posts
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0 L
Default

ok so I rechecked.. disconnected the connector ..Started the Jeep and I am getting 14 volts.. at least disconnected. Unless . the 02 sensor short circuited and is causing a problem when plugged in.

Apparently you can not tested that circuit engine off.. I tried "back probing" with no luck.. So I am not sure if I am a numb skull.. or if the 02 could be shorted. Any ideas on how to check??

Again it starts at 4.98 on the REM and bleeds down. settles around 3++ now..

-H
Old 02-12-2021, 11:27 PM
  #29  
Junior Member
Thread Starter
 
Homerlasvegas's Avatar
 
Join Date: Dec 2020
Location: Las Vegas
Posts: 80
Received 7 Likes on 7 Posts
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0 L
Default

I should add.. I have now tried a different IAC.. A different Coil.. I do think it sounds just a touch better on this coil (and the "BOX" it sits in)...

I picked up a 89 ECU.. should I plug that in??

I think I may try this JY 02 sensor first and see if there is any kind of change.

Old 02-12-2021, 11:49 PM
  #30  
CF Veteran
 
lawsoncl's Avatar
 
Join Date: Dec 2017
Posts: 3,953
Received 1,097 Likes on 880 Posts
Year: 1989
Model: Comanche (MJ)
Engine: 4.0
Default

I pulled up the wiring diagram. The computer controls the positive to the O2 heater relay. So I'm not sure if the REM is telling you what the computer is commanding or sensing the output of the O2 relay which is also present in the second yellow diagnostic connector (pin D2-9). If you see voltage at the O2 connector with it disconnected and it immediately goes away when you connect it, I would suspect a bad relay or high resistance in the wiring somewhere.





Quick Reply: PLEASE help me PASS SMOG!



All times are GMT -5. The time now is 07:46 AM.