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.

Crank sensor? Was idling then died...

Old Feb 14, 2024 | 02:00 PM
  #16  
4x4jeepmanthing's Avatar
Thread Starter
CF Veteran
 
Joined: Jun 2016
Posts: 1,011
Likes: 20
From: CO
Year: 99
Model: Cherokee (XJ)
Engine: 4.0
Default

Originally Posted by Dave51
Nah. If there's a problem it'll be massive. And whatever it is it's there now.


Looking that up now. Yours is


Mine is


and I use the HT-25 cable which has


I also have a 20:1 external attenuator. I don't think you have enough stuff to attenuate that down.
I am guessing not because my scope on came with the two probes. They only have 1x,10x attenuation ability.
Reply
Old Feb 14, 2024 | 02:53 PM
  #17  
Dave51's Avatar
CF Veteran
5 Year Member
Liked
 
Joined: Jan 2017
Posts: 3,438
Likes: 417
From: Connecticut
Year: 2000
Model: Cherokee (XJ)
Engine: 4.0
Default

Originally Posted by 4x4jeepmanthing
I am guessing not because my scope on came with the two probes. They only have 1x,10x attenuation ability.
Correct. See your gain in the specifications:

200mV~50V/div@x10 probe
So you can do 50V on 10x but without 10x you can only do 5V (fortunately CKS and CPS power). Anything higher make sure you use 10x (like the 12 volt stuff).
Reply
Old Feb 14, 2024 | 03:09 PM
  #18  
4x4jeepmanthing's Avatar
Thread Starter
CF Veteran
 
Joined: Jun 2016
Posts: 1,011
Likes: 20
From: CO
Year: 99
Model: Cherokee (XJ)
Engine: 4.0
Default


Ok, here is where I'm at currently. I see that "negative" spike in the cam sensors wave, on the last pulse of the Crank sensor. Does this mean the cam sensor signal is dropping out on that last wave of the crank signal? I'm very interested in understanding what we are seeing here, please do explain if you would be so kind?


Last edited by 4x4jeepmanthing; Feb 14, 2024 at 03:12 PM.
Reply
Old Feb 14, 2024 | 03:14 PM
  #19  
Dave51's Avatar
CF Veteran
5 Year Member
Liked
 
Joined: Jan 2017
Posts: 3,438
Likes: 417
From: Connecticut
Year: 2000
Model: Cherokee (XJ)
Engine: 4.0
Default

Originally Posted by 4x4jeepmanthing
I'm at currently.
LOL!! That's electricity humor, right?
Reply
Old Feb 14, 2024 | 03:20 PM
  #20  
4x4jeepmanthing's Avatar
Thread Starter
CF Veteran
 
Joined: Jun 2016
Posts: 1,011
Likes: 20
From: CO
Year: 99
Model: Cherokee (XJ)
Engine: 4.0
Default

Hahaha what's a little pun for a learning thread.
Here is how I had hooked up our test to the PCM:


The ground is just some new wire that I tightened into the battery ground.
Reply
Old Feb 14, 2024 | 03:27 PM
  #21  
Dave51's Avatar
CF Veteran
5 Year Member
Liked
 
Joined: Jan 2017
Posts: 3,438
Likes: 417
From: Connecticut
Year: 2000
Model: Cherokee (XJ)
Engine: 4.0
Default

IDK what that is. It was actually occurring the last time you analyzed this:



but I think the location in this image shows that it's somewhat independent of CKS signal. Yet, also in this image there's extra activity in the CKS at the same spot.

What are you grounded to?
Reply
Old Feb 14, 2024 | 03:41 PM
  #22  
4x4jeepmanthing's Avatar
Thread Starter
CF Veteran
 
Joined: Jun 2016
Posts: 1,011
Likes: 20
From: CO
Year: 99
Model: Cherokee (XJ)
Engine: 4.0
Default

I am grounded directly to the battery on todays reading. IIRC the previous test on the old thread, I replaced the Cam sensor and that "fixed" the issue, or allowed the jeep to start just fine until now. Even when I took the Jeep in to a shop for diagnostic, the previous thread, they were unable to find what the issue was.

On the scope reading you posted for the older thread, I believe I grounded with pins for both signal and ground on the plugs.

Last edited by 4x4jeepmanthing; Feb 14, 2024 at 03:43 PM.
Reply
Old Feb 14, 2024 | 03:46 PM
  #23  
Dave51's Avatar
CF Veteran
5 Year Member
Liked
 
Joined: Jan 2017
Posts: 3,438
Likes: 417
From: Connecticut
Year: 2000
Model: Cherokee (XJ)
Engine: 4.0
Default

What's the sample rate? Can't see, it's cut off.

You're gonna love this. Another poster:

Reply
Old Feb 14, 2024 | 04:11 PM
  #24  
4x4jeepmanthing's Avatar
Thread Starter
CF Veteran
 
Joined: Jun 2016
Posts: 1,011
Likes: 20
From: CO
Year: 99
Model: Cherokee (XJ)
Engine: 4.0
Default

Originally Posted by Dave51
What's the sample rate? Can't see, it's cut off.

You're gonna love this. Another poster:

I switched to 100ms to fit the camshaft wave on the screen.

Hahaha apparently I've finally learned how to adjust the reading into a visible square wave.
Reply
Old Feb 14, 2024 | 04:13 PM
  #25  
Dave51's Avatar
CF Veteran
5 Year Member
Liked
 
Joined: Jan 2017
Posts: 3,438
Likes: 417
From: Connecticut
Year: 2000
Model: Cherokee (XJ)
Engine: 4.0
Default

Sample rate = lower right hand corner.
Reply
Old Feb 14, 2024 | 04:18 PM
  #26  
Dave51's Avatar
CF Veteran
5 Year Member
Liked
 
Joined: Jan 2017
Posts: 3,438
Likes: 417
From: Connecticut
Year: 2000
Model: Cherokee (XJ)
Engine: 4.0
Default

NM I see it 1 MHz. Any chance you can turn that down to at least 240K Hz?
Reply
Old Feb 14, 2024 | 04:42 PM
  #27  
Dave51's Avatar
CF Veteran
5 Year Member
Liked
 
Joined: Jan 2017
Posts: 3,438
Likes: 417
From: Connecticut
Year: 2000
Model: Cherokee (XJ)
Engine: 4.0
Default

Originally Posted by 4x4jeepmanthing
...the previous test on the old thread, I replaced the Cam sensor and that "fixed" the issue, or allowed the jeep to start just fine until now.
I think there's 2 choices:

Those extra spikes are artifact and the problem is somewhere else; or

Those extra spikes are real and ECU REALLY doesn't like seeing -0- volts where there shouldn't be. If we can't clean up the signals by reducing the sample rate, including those spikes, and given the history of solving the issue before (would've been nice to get waveforms when it was running, but oh well), IIWM I'd shoot the Parts Cannon at another camshaft sensor.
Reply
Old Feb 14, 2024 | 04:45 PM
  #28  
Dave51's Avatar
CF Veteran
5 Year Member
Liked
 
Joined: Jan 2017
Posts: 3,438
Likes: 417
From: Connecticut
Year: 2000
Model: Cherokee (XJ)
Engine: 4.0
Default

New idea!

Use the sensor ground instead of the battery ground.

Better new idea!

Watch this (18:00):


Last edited by Dave51; Feb 14, 2024 at 04:51 PM.
Reply
Old Feb 14, 2024 | 05:39 PM
  #29  
4x4jeepmanthing's Avatar
Thread Starter
CF Veteran
 
Joined: Jun 2016
Posts: 1,011
Likes: 20
From: CO
Year: 99
Model: Cherokee (XJ)
Engine: 4.0
Default

Ok, hooking up now. Was trying compression, but everything is low and I'm not sure the rental tester is valid.
Reply
Old Feb 14, 2024 | 06:07 PM
  #30  
4x4jeepmanthing's Avatar
Thread Starter
CF Veteran
 
Joined: Jun 2016
Posts: 1,011
Likes: 20
From: CO
Year: 99
Model: Cherokee (XJ)
Engine: 4.0
Default









Reply

Thread Tools
Search this Thread

All times are GMT -5. The time now is 02:09 PM.