Great Lakes 4x4. The largest offroad forum in the Midwest banner
1 - 20 of 70 Posts

·
Premium Member
Joined
·
8,920 Posts
Discussion Starter · #1 · (Edited)
97 TJ 4.0 5 speed

The Jeep started to chug and missfire or cut out once it got hot. It won't do it cold, but as it warms up it gets worse. Had it scanned and the downstream O2 sensor was dead. The guy who scanned it also said that the coil MAY be bad, fairly common problem.
Replaced the downstream O2 sensor, coil, plugs, wires, cap and rotor. While we were in there we noticed that the air snorkel was loose at the throttle body. When we took it off and the inside of the throttle body was trashed. Black sooty dirt, so we took it off and took the sensors off of it and cleaned it.
Reassembled it all and took it for a ride and it seemed like it was actually worse. Not a more drastic chugging, but more frequent.
Had a guy come over yesterday with his scanner, he says the crank sensor is bad and he leaves. We replaced the crank sensor and no change at all.
It seems to happen when you are in a certain RPM range. When you are in different gears at different speeds it seems to require a different throttle input to make it happen. Again, it only happens once it is warmed up and gets worse the warmer it gets. Once it happens, if you let off the throttle it goes away, and if you downshift it goes away and you can stand on it and it'll go like hell.
Anyone experience this before? Thoughts? TPS? Maybe?
 

·
Premium Member
Joined
·
8,920 Posts
Discussion Starter · #3 ·
I will check it as soon as I get home. Does that sound right or am I way off?
 

·
Premium Member
Joined
·
8,920 Posts
Discussion Starter · #4 ·
Tested it, and it looks like it reading 164.6...
 

·
Premium Member
Joined
·
8,920 Posts
Discussion Starter · #5 · (Edited)
Well, I may have screwed up. I guess the Crank Sensor I threw on this thing is for an automatic trans and this Jeep has a manual. I tested the original taken off the Jeep to see how many ohms I could get and can't get a reading. Does anyone know what the difference is between the Crank Sensor for a manual and an automatic aside from the $50 price difference?
 

·
Registered
Joined
·
1,120 Posts
They should be the same for that part. Did it just show up a cps being bad?? There are two sensor that are called the same letters crank postion and cam postion??
 

·
Premium Member
Joined
·
8,920 Posts
Discussion Starter · #8 ·
If they are the same, why is there a $50 difference from an automatic to a manual?
 

·
Premium Member
Joined
·
8,920 Posts
Discussion Starter · #10 ·
The one I just bolted in is for an auto, the Jeep is a manual, it bolted right in.
 

·
Registered
Joined
·
838 Posts
my 98 xj doing same thang try unpluging front o2 senser when runing cleared mine rite up old o2 was only 1 1/2 years old put new one no more prob. for me worth a try
 

·
Premium Member
Joined
·
8,920 Posts
Discussion Starter · #12 ·
Thanks. I'll give it a shot tonight.
 

·
Registered
Joined
·
4,335 Posts
Tested it, and it looks like it reading 164.6...
I missed used the terms ohm and volts, here is the proper way to check a tps: make sure your meter set to dcv. Find the 5 volt reference and return and then monitor the signal line for actual voltage output from the throttle position sensor. You can monitor this by back probing the circuit at the TPS. Voltage should steadily increase as throttle is opened. This should be checked with the key on and engine off. Any erratic dropping or spiking voltage indicates a concern. You should also check while tapping and heating the sensor if you have a possible intermittent.
 

·
Premium Member
Joined
·
8,920 Posts
Discussion Starter · #14 ·
I missed used the terms ohm and volts, here is the proper way to check a tps: make sure your meter set to dcv. Find the 5 volt reference and return and then monitor the signal line for actual voltage output from the throttle position sensor. You can monitor this by back probing the circuit at the TPS. Voltage should steadily increase as throttle is opened. This should be checked with the key on and engine off. Any erratic dropping or spiking voltage indicates a concern. You should also check while tapping and heating the sensor if you have a possible intermittent.
Makes sense, thanks. I'll try it tomorrow.
 

·
white trash
Joined
·
120 Posts
my 03 was doing that, only required a little "seafoam" run through it. cleared it up.
 

·
Premium Member
Joined
·
8,920 Posts
Discussion Starter · #16 ·
my 98 xj doing same thang try unpluging front o2 senser when runing cleared mine rite up old o2 was only 1 1/2 years old put new one no more prob. for me worth a try
Tried that, ran terrible and the problem was still there.
 

·
Premium Member
Joined
·
8,920 Posts
Discussion Starter · #17 ·
I missed used the terms ohm and volts, here is the proper way to check a tps: make sure your meter set to dcv. Find the 5 volt reference and return and then monitor the signal line for actual voltage output from the throttle position sensor. You can monitor this by back probing the circuit at the TPS. Voltage should steadily increase as throttle is opened. This should be checked with the key on and engine off. Any erratic dropping or spiking voltage indicates a concern. You should also check while tapping and heating the sensor if you have a possible intermittent.
Tried this, the TPS is working fine. We threw the meter on another TJ 4.0 manual Crank Sensor and wrote down the readings. Then we did the same on this one and wrote them down. Very different numbers. Gonna throw a CPS in it today and see what happens.
 

·
Pokerob is my B*tch!
Joined
·
11,515 Posts
Tried this, the TPS is working fine. We threw the meter on another TJ 4.0 manual Crank Sensor and wrote down the readings. Then we did the same on this one and wrote them down. Very different numbers. Gonna throw a CPS in it today and see what happens.
Hopefully that cures it. You have lots of problems with things chugging and missfiring. I'm glad you got it straightened out with your truck . . . hopefully this will be a quick fix for you. :beer:
 

·
Premium Member
Joined
·
8,920 Posts
Discussion Starter · #19 ·
Hopefully that cures it. You have lots of problems with things chugging and missfiring. I'm glad you got it straightened out with your truck . . . hopefully this will be a quick fix for you. :beer:
You sir are correct! This one isn't mine though this time. Most of the time when I have a misfire it's because I had too much fun the night before:sonicjay:
 

·
Registered
Joined
·
5,173 Posts
You sir are correct! This one isn't mine though this time. Most of the time when I have a misfire it's because I had too much fun the night before:sonicjay:

well at lest you still fired :sonicjay::sonicjay:


Are you getting any codes??
 
1 - 20 of 70 Posts
Top