TJ drive train in a YJ - After a Year of Work It lives! 4.2 to 4.0
- Thread starter mcguirjf
- Start date
GrEmLiN
New member
I actually agree with something Alan said... my first thought when I saw that picture was the movie "Canadian Bacon"... haha.
That's a cool timeline. Did you have any issues passing emissions with the 4.2?? I passed and then the DMV lost the results (seriously) and I had to do it again... passed the second time too! These old 4.2's are great engines!!
That's a cool timeline. Did you have any issues passing emissions with the 4.2?? I passed and then the DMV lost the results (seriously) and I had to do it again... passed the second time too! These old 4.2's are great engines!!
mcguirjf
New member
Passing emissions, :lol:. The first time I failed for high NOx. I found that my ERG vacuum stem was broken so I had no EGR. I ran a direct vacuum line from the intake and it just passed! When I pulled the old 4.2 exhaust system down the cat was empty!!! My 4.2 passed with an empty cat! WOW!
:rotflmao:
:rotflmao:
mcguirjf
New member
I just found out something very disturbing. It appears the TJ gas gauge sending unit works opposite to the YJ. In other words, if you have 0 Ohms at empty and 240 Ohms at full for the YJ, the TJ's sending unit sends the opposite signal, and the only cure is to install a YJ sending unit. Crap. I have to drop the tank again!
GrEmLiN
New member
You'll have to double check but I believe this to be accurate:
CJ's were 73 Ohms Empty / 8-12 Ohms Full
Early YJ's 87-92 were 0 Empty / 88-90 Full
and 92-Up Wranglers used the 240 Empty / 33 Full.
90-92 is what I'm not 100% sure about. I know what my 87 uses. I know what the 94+ uses.
You could go another route: Scrap those ridiculous PCB gauges that never ever work, and install Autometer gauges, then it's a matter of ordering the gauge for your sending unit.
I installed a Stewart-Warner mechanical oil pressure gauge before the last M&G, the only gauge that resembles "working" condition in my YJ is the gas gauge. I know, I'm as surprised as you are. lol
CJ's were 73 Ohms Empty / 8-12 Ohms Full
Early YJ's 87-92 were 0 Empty / 88-90 Full
and 92-Up Wranglers used the 240 Empty / 33 Full.
90-92 is what I'm not 100% sure about. I know what my 87 uses. I know what the 94+ uses.
You could go another route: Scrap those ridiculous PCB gauges that never ever work, and install Autometer gauges, then it's a matter of ordering the gauge for your sending unit.
I installed a Stewart-Warner mechanical oil pressure gauge before the last M&G, the only gauge that resembles "working" condition in my YJ is the gas gauge. I know, I'm as surprised as you are. lol
mcguirjf
New member
Hooking up the OBD2 Data Link
So there are 16 locations 1-8 are on the top and 9-16 on the bottom. The top of the data plug is larger than the bottom. Numbering is when you are facing the plug interface.
There are only 7 used locations.
You need to use Wiring harness interface C107 (Yellow) and C108 (Blue). The numbering of the C107 and C108 are more complex. They use the same numbering system as the data link, but the only difference between top and bottom is that the top is defined by two notches over the #1 and #7 locations in the wiring manual. I recommend that you use the numbering on the back side of the plug as this is a fail safe method to knowing what wire is what in the connector. See photos for clarification. In other words, "Don't cut the wiring harness connectors off!"
#3 C108 (D4)
#4 C107 (E6)
#5 C107 (E9)
#6 C107 (E13)
#7 C107 (E14)
#11 C108 (D5)
#16 C108 (D12)
Now once the data link connector is established you can use any scanner / programmer with the engine. More power, better fuel economy!!
I plan to use my Garmin Eco Route HD so I can see what the engine is doing and if I have any error codes unitl the rest of my gauges are connected.
So there are 16 locations 1-8 are on the top and 9-16 on the bottom. The top of the data plug is larger than the bottom. Numbering is when you are facing the plug interface.
There are only 7 used locations.
You need to use Wiring harness interface C107 (Yellow) and C108 (Blue). The numbering of the C107 and C108 are more complex. They use the same numbering system as the data link, but the only difference between top and bottom is that the top is defined by two notches over the #1 and #7 locations in the wiring manual. I recommend that you use the numbering on the back side of the plug as this is a fail safe method to knowing what wire is what in the connector. See photos for clarification. In other words, "Don't cut the wiring harness connectors off!"
#3 C108 (D4)
#4 C107 (E6)
#5 C107 (E9)
#6 C107 (E13)
#7 C107 (E14)
#11 C108 (D5)
#16 C108 (D12)
Now once the data link connector is established you can use any scanner / programmer with the engine. More power, better fuel economy!!
I plan to use my Garmin Eco Route HD so I can see what the engine is doing and if I have any error codes unitl the rest of my gauges are connected.
mcguirjf
New member
The one mistake I made when I purchased the new engine was that I missed grabing the wiring harness for the headlights. I thought I didn't need it, but the Duty Cycle Evap/Purge Solenoid is run inside that harness. So $50 dollars later at a local junkyard that was resolved. Crap! :swear_mad:
mcguirjf
New member
So just an update...
With my Garmin linked to the Jeep's computer I've been averaging 19-21 MPG per fill up. I've been driving every where with no issues. Well to be honest the starter is on its way out. Other than that its a blast!
One item to note...
I used the TJ throttle cable and appeared to work fine. Using the Garmin readout my throttle open percentage was 14% idle to 64% floored. I tried pulling up on the throttle cable with the gas pedal floored and noticed the percentage jumped up to 77%. So I need to modify my gas pedal linkage.
Here's my to do list...
Install Gas Gauge to work with TJ sending unit
Install speed sensor that has both mechanical and electrical sensor
Weld two holes in the rear floor by front seat belt interface
Find a place to install water temp sensor.
Hook up reverse lights
Install Front Drive shaft
Hook up Vaccum lines for 4WD control
Finish 4wd select lever between floor and transfer case
Improve throttle travel to gas pedal linkage
fix the intermitent wiper module
With my Garmin linked to the Jeep's computer I've been averaging 19-21 MPG per fill up. I've been driving every where with no issues. Well to be honest the starter is on its way out. Other than that its a blast!
One item to note...
I used the TJ throttle cable and appeared to work fine. Using the Garmin readout my throttle open percentage was 14% idle to 64% floored. I tried pulling up on the throttle cable with the gas pedal floored and noticed the percentage jumped up to 77%. So I need to modify my gas pedal linkage.
Here's my to do list...
Install Gas Gauge to work with TJ sending unit
Install speed sensor that has both mechanical and electrical sensor
Weld two holes in the rear floor by front seat belt interface
Find a place to install water temp sensor.
Hook up reverse lights
Install Front Drive shaft
Hook up Vaccum lines for 4WD control
Finish 4wd select lever between floor and transfer case
Improve throttle travel to gas pedal linkage
fix the intermitent wiper module
What a project!
Are you using Eco Route HD with a bluetooth Garmin?
Are you using Eco Route HD with a bluetooth Garmin?
mcguirjf
New member
Yes I am! The Garmin is a blue tooth capable devise model Nuvi 2460. I just swapped the speedometer gears and now my speedometer works (mechanical). It appears to be 3MPH too fast. I purchased the 1991 VSS and should have it installed today. Driving in to work today I noticed when reading my gauges that I had no speedometer readout! The Garmin takes the VSS signal to calculate the fuel economy and output for the gauge. So when I install the 1991 VSS I can see what it actually is telling the computer. If you perform an internet search there is a lot of discussion on if the 1991 VSS being a difference between a Hall Effect verses a Reed Effect sensor and if it really works. My Garmin will provide me the true VSS output and how the computer will interpret it. If this does not work, I guess I'll have to go with advance adapters. With the TJ VSS I was getting 20-21 MPG. With the mechanical speedometer I'm getting 16.7MPG, and thats with it reading 3MPH too fast! I have to believe that the VSS not only controls drivability, but also fuel map usage. Currently the engine thinks I'm just sitting in my driveway gunning the engine.
I also picked up a new fuel gauge from summit for $50. Should be able to install this weekend.
I also obtained the final piece of the tailpipe bracket assembly from dealership. $40 for a stamped piece of sheet metal. AHAHAHHAAH!!
I am still trying to find a solution on how to install the temperature gauge sending unit from the 4.2 engine. HMMMMMM!!!
It appears that others have had difficulty running a remote temperature sensors for an electric fan.
Update soon.
I also picked up a new fuel gauge from summit for $50. Should be able to install this weekend.
I also obtained the final piece of the tailpipe bracket assembly from dealership. $40 for a stamped piece of sheet metal. AHAHAHHAAH!!
I am still trying to find a solution on how to install the temperature gauge sending unit from the 4.2 engine. HMMMMMM!!!
It appears that others have had difficulty running a remote temperature sensors for an electric fan.
Update soon.
