OBD Reader Fixes Stalling and No Start
04-22-2015, 01:02 AM
#1
Newbie
Thread Starter
Join Date: Mar 2012
Location: Port Alberni
Posts: 10
Likes: 0
Received 0 Likes
on
0 Posts
Year: 1996
Model: Cherokee
Engine: 1997 4.0l
OBD Reader Fixes Stalling and No Start
1996 Jeep Cherokee Sport 4dr with a 1997 4.0l (not HO) engine. Original motor threw a rod.
I've had this problem for a little while now.
Very high voltage, tach bouncing wildly, GEN light coming on, stalling when coming to a stop, no start, etc. After reading a bunch on here (best Jeep advice ever!), I sprayed half a can of throttle body cleaner into it and pulled off and cleaned up the Idle Air Control Valve, and it seemed to handle much of the problem, but it started happening again, eventually dying by the side of the road, and not starting. Cranking fine, no gas smell, but won't start.
To make a long story short (too late), I plugged in my little bluetooth OBD reader, and fired up my laptop. Using ScanMaster ELM but saw no errors. I turned it over and it fired up awesome. Voltage was at 14V and rock solid. No bouncing tach, no sputtering under load. It ran better than it had in a months.
I figured the software did something so I unplugged the scan tool. Immediately the voltage went wild.
Plugged the scan tool back in and it runs great, not a blip.
WTF? Could this be a bad PCM?
I've had this problem for a little while now.
Very high voltage, tach bouncing wildly, GEN light coming on, stalling when coming to a stop, no start, etc. After reading a bunch on here (best Jeep advice ever!), I sprayed half a can of throttle body cleaner into it and pulled off and cleaned up the Idle Air Control Valve, and it seemed to handle much of the problem, but it started happening again, eventually dying by the side of the road, and not starting. Cranking fine, no gas smell, but won't start.
To make a long story short (too late), I plugged in my little bluetooth OBD reader, and fired up my laptop. Using ScanMaster ELM but saw no errors. I turned it over and it fired up awesome. Voltage was at 14V and rock solid. No bouncing tach, no sputtering under load. It ran better than it had in a months.
I figured the software did something so I unplugged the scan tool. Immediately the voltage went wild.
Plugged the scan tool back in and it runs great, not a blip.
WTF? Could this be a bad PCM?
04-22-2015, 08:21 AM
#2
::CF Moderator::
Join Date: Aug 2011
Location: Prescott, Az
Posts: 43,874
Received 1,526 Likes
on
1,238 Posts
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
1996 Jeep Cherokee Sport 4dr with a 1997 4.0l (not HO) engine. Original motor threw a rod.
I've had this problem for a little while now.
Very high voltage, tach bouncing wildly, GEN light coming on, stalling when coming to a stop, no start, etc. After reading a bunch on here (best Jeep advice ever!), I sprayed half a can of throttle body cleaner into it and pulled off and cleaned up the Idle Air Control Valve, and it seemed to handle much of the problem, but it started happening again, eventually dying by the side of the road, and not starting. Cranking fine, no gas smell, but won't start.
To make a long story short (too late), I plugged in my little bluetooth OBD reader, and fired up my laptop. Using ScanMaster ELM but saw no errors. I turned it over and it fired up awesome. Voltage was at 14V and rock solid. No bouncing tach, no sputtering under load. It ran better than it had in a months.
I figured the software did something so I unplugged the scan tool. Immediately the voltage went wild.
Plugged the scan tool back in and it runs great, not a blip.
WTF? Could this be a bad PCM?
I've had this problem for a little while now.
Very high voltage, tach bouncing wildly, GEN light coming on, stalling when coming to a stop, no start, etc. After reading a bunch on here (best Jeep advice ever!), I sprayed half a can of throttle body cleaner into it and pulled off and cleaned up the Idle Air Control Valve, and it seemed to handle much of the problem, but it started happening again, eventually dying by the side of the road, and not starting. Cranking fine, no gas smell, but won't start.
To make a long story short (too late), I plugged in my little bluetooth OBD reader, and fired up my laptop. Using ScanMaster ELM but saw no errors. I turned it over and it fired up awesome. Voltage was at 14V and rock solid. No bouncing tach, no sputtering under load. It ran better than it had in a months.
I figured the software did something so I unplugged the scan tool. Immediately the voltage went wild.
Plugged the scan tool back in and it runs great, not a blip.
WTF? Could this be a bad PCM?
05-13-2015, 03:29 PM
#3
Newbie
Thread Starter
Join Date: Mar 2012
Location: Port Alberni
Posts: 10
Likes: 0
Received 0 Likes
on
0 Posts
Year: 1996
Model: Cherokee
Engine: 1997 4.0l
05-13-2015, 06:45 PM
#4
CF Veteran
Join Date: Aug 2010
Location: Canton, MI
Posts: 8,357
Likes: 0
Received 82 Likes
on
67 Posts
Year: 1999
Model: Cherokee
Engine: 4.0
This is an odd one. I've only seen one other post where the Code reader/scanner actually make the Heep run. There was no follow-up on these posts to ID the fix.
Me thinks it's a ground issue, fixed by the DLC ground, where the scanner (hooked up) completes the ground path from the battery to the chassis. Meaning, the ground cable from the battery negative post to the right inner fender is compromised (corroded) and/or the bonding strap from the firewall to the #14 cylinder head bolt is compromised (corroded).
Disassemble these grounds and scrub the ring terminals clean using 400 grit sandpaper, and wire wheel the fender and firewall sheet metal nice and clean. Reassemble and give another try (without scanner hooked up).
Me thinks it's a ground issue, fixed by the DLC ground, where the scanner (hooked up) completes the ground path from the battery to the chassis. Meaning, the ground cable from the battery negative post to the right inner fender is compromised (corroded) and/or the bonding strap from the firewall to the #14 cylinder head bolt is compromised (corroded).
Disassemble these grounds and scrub the ring terminals clean using 400 grit sandpaper, and wire wheel the fender and firewall sheet metal nice and clean. Reassemble and give another try (without scanner hooked up).
Thread
Thread Starter
Forum
Replies
Last Post
zumer715
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here
18
07-08-2022 05:17 PM
95cherokee89
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here
59
10-16-2015 03:17 AM
Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)