XJ 4.0 1989: Open-Closed loop with strange O2 signal
01-25-2017, 04:08 PM
#1
Junior Member
Thread Starter
Join Date: Dec 2016
Location: Italy
Posts: 49
Likes: 0
Received 0 Likes
on
0 Posts
Year: 1989
Model: Cherokee
Engine: 6L 4.0
XJ 4.0 1989: Open-Closed loop with strange O2 signal
Hello Guys,
I was able (thank you so much for the scheme interface and the software!!!)
to connect my laptop to D2 Diagnostic Connector.
Signals are crazy.
O2 voltage is fixed to 0.7V (RICH) also in closed loop (when the ECU is able to go in closed loop, 5% of the time).
Attached you can find two screenshot coming from my Renix Jeep Cherokee XJ 4.0 1989.
Could be the O2 sensor bad?
The O2 sensor resistance is OK (14 ohm).
Could be the cracked exhaust manifold?
Regards,
Lucio.
I was able (thank you so much for the scheme interface and the software!!!)
to connect my laptop to D2 Diagnostic Connector.
Signals are crazy.
O2 voltage is fixed to 0.7V (RICH) also in closed loop (when the ECU is able to go in closed loop, 5% of the time).
Attached you can find two screenshot coming from my Renix Jeep Cherokee XJ 4.0 1989.
Could be the O2 sensor bad?
The O2 sensor resistance is OK (14 ohm).
Could be the cracked exhaust manifold?
Regards,
Lucio.
01-25-2017, 05:49 PM
#2
Banned
Join Date: Oct 2016
Posts: 1,553
Likes: 0
Received 4 Likes
on
4 Posts
Year: 2000 and 1998
Model: Cherokee
Engine: 4.0
is that 14 ohms the heater?
seems like dead sensor with no change in volts. mine is always changing between 0 and 1 volt as i recall.
unplugged it does what?
seems like dead sensor with no change in volts. mine is always changing between 0 and 1 volt as i recall.
unplugged it does what?
Last edited by nujeepguy; 01-25-2017 at 05:55 PM.
01-26-2017, 02:22 AM
#3
CF Veteran
if that is fully warmed up running, then that is a bad o2 signal, typical to go bad that way, they should swing from about .1 to about .9vdc.
01-26-2017, 06:29 AM
#4
::CF Moderator::
Join Date: Aug 2011
Location: Prescott, Az
Posts: 43,875
Received 1,526 Likes
on
1,238 Posts
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
.1 to 4.9 volts switching quite rapidly is correct output.
01-26-2017, 07:10 AM
#5
CF Veteran
01-26-2017, 07:19 AM
#6
::CF Moderator::
Join Date: Aug 2011
Location: Prescott, Az
Posts: 43,875
Received 1,526 Likes
on
1,238 Posts
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
It's important that these O2 sensors have power and ground for their heater element.
Only use NTK/NGK replacements.
Only use NTK/NGK replacements.
01-26-2017, 07:21 AM
#7
CF Veteran
Did they really switch from .1 to almost 5v in 1989?
Trending Topics
01-26-2017, 07:25 AM
#8
::CF Moderator::
Join Date: Aug 2011
Location: Prescott, Az
Posts: 43,875
Received 1,526 Likes
on
1,238 Posts
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
01-26-2017, 07:33 AM
#9
CF Veteran
01-26-2017, 07:35 AM
#10
::CF Moderator::
Join Date: Aug 2011
Location: Prescott, Az
Posts: 43,875
Received 1,526 Likes
on
1,238 Posts
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
01-26-2017, 07:46 AM
#11
CF Veteran
01-26-2017, 07:48 AM
#12
::CF Moderator::
Join Date: Aug 2011
Location: Prescott, Az
Posts: 43,875
Received 1,526 Likes
on
1,238 Posts
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
01-28-2017, 10:27 AM
#13
Junior Member
Thread Starter
Join Date: Dec 2016
Location: Italy
Posts: 49
Likes: 0
Received 0 Likes
on
0 Posts
Year: 1989
Model: Cherokee
Engine: 6L 4.0
Probably the O2 sensor is wrong, but crazy...
And, at idle, should remain in closed loop and the O2 voltage should raise to 5V then drop to 0V, again 5V and drop 0V, instead.... nothing.
At idle, about 0.7V fixed.
It's rare that the O2 oscillates.
And, at idle, should remain in closed loop and the O2 voltage should raise to 5V then drop to 0V, again 5V and drop 0V, instead.... nothing.
At idle, about 0.7V fixed.
It's rare that the O2 oscillates.
01-28-2017, 09:27 PM
#14
::CF Moderator::
Join Date: Aug 2011
Location: Prescott, Az
Posts: 43,875
Received 1,526 Likes
on
1,238 Posts
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
You either have a bad O2 sensor or no power and/or ground to it's heating element.
01-30-2017, 11:30 AM
#15
Junior Member
Thread Starter
Join Date: Dec 2016
Location: Italy
Posts: 49
Likes: 0
Received 0 Likes
on
0 Posts
Year: 1989
Model: Cherokee
Engine: 6L 4.0
I am monitoring the O2 signal using an LM3914 (Led driver) during
the cruise.
I checked also the heating element, the voltage is present (+12V) also at idle.
Probably the O2 is bad or not for the right model.
Next O2 sensor will be the right Crown model.
the cruise.
I checked also the heating element, the voltage is present (+12V) also at idle.
Probably the O2 is bad or not for the right model.
Next O2 sensor will be the right Crown model.