EDIT: PROBLEM IS BACK! The MSD coil ended up not being the issue. Problem was away for a bit, but now it has unfortunately returned. Back on the hunt!
First off, big thanks to this forum for being great. Lots of information here that have helped me in various ways over a few years. Hopefully I can contribute now that I’ve took the time to join!
TLDR: Bad MSD 82738Ignition coil, somehow caused an erratic / bouncing speedometer.
To begin with, 2000 Sahara 4.0/ 5 speed, fed emission model ( Single catalytic converter)
My speedometer has had little fits of bouncing for a while. I’d gotten used to the occasional bounce and just equated it to it being a 20+ year old Jeep… until last week, after a trip down some gravel roads at Red River Gorge, it decided to be completely useless.
After this trip, my speedometer would constantly bounce around erratically, effecting idle pretty severely. Sometimes dropping my idle to as low as 100-200 RPM without giving pedal input. Made it a massive pain in the rear to drive, so decided to get to fixing.
I started with popping my VSS plug off, and blasting the bejesus out of it with CRC electronic cleaner. The red clip for the plug was broke, but otherwise not very dirty. 0% improvement.
After dealing with Speedo gear changes on a TH350, I didn’t want to pop mine out and open that can of worms and check it yet, so figured I would check some of the electrical bits and make sure it wasn’t something of that nature..
Checked/removed/cleaned/reinstalled the ground on the passenger side of the block, per another thread 0% improvement.
Changed B1S1 oxygen sensor to NTK 23179 as recommended on another thread (by the way, 23506 AND 23099 have been superseded to this , have no issues out of it yet. I work for the jolly green parts store, and we’re working on getting them stocked into DC’s) and it also proved 0% improvement. ( was hoping my original was shorted or something, and this would fix the speedo issue)
Next I decided to change my spark plugs. Maybe a fouled plug was doing something weird with the OHMs.. changed to Champion Iridium 9034.. and Jesus p. Christ what a misfire!
I next decided I had the day off, I’d do some experimenting. I chucked the MSD coil, and stuck my 23 year old factory coil back on. No improvement on the misfire but… SPEEDO PROBLEM IS GONE! After switching back to my factory coil and XP985’s, I now have a SMOOTH idle, SMOOTH throttle response, and a WORKING SPEEDO!
I’ve read a couple of threads saying the MSD 82738 is a waste of money, but no probs with using it. Well I’m here to say, mine was a turd and a half.
First off, big thanks to this forum for being great. Lots of information here that have helped me in various ways over a few years. Hopefully I can contribute now that I’ve took the time to join!
TLDR: Bad MSD 82738Ignition coil, somehow caused an erratic / bouncing speedometer.
To begin with, 2000 Sahara 4.0/ 5 speed, fed emission model ( Single catalytic converter)
My speedometer has had little fits of bouncing for a while. I’d gotten used to the occasional bounce and just equated it to it being a 20+ year old Jeep… until last week, after a trip down some gravel roads at Red River Gorge, it decided to be completely useless.
After this trip, my speedometer would constantly bounce around erratically, effecting idle pretty severely. Sometimes dropping my idle to as low as 100-200 RPM without giving pedal input. Made it a massive pain in the rear to drive, so decided to get to fixing.
I started with popping my VSS plug off, and blasting the bejesus out of it with CRC electronic cleaner. The red clip for the plug was broke, but otherwise not very dirty. 0% improvement.
After dealing with Speedo gear changes on a TH350, I didn’t want to pop mine out and open that can of worms and check it yet, so figured I would check some of the electrical bits and make sure it wasn’t something of that nature..
Checked/removed/cleaned/reinstalled the ground on the passenger side of the block, per another thread 0% improvement.
Changed B1S1 oxygen sensor to NTK 23179 as recommended on another thread (by the way, 23506 AND 23099 have been superseded to this , have no issues out of it yet. I work for the jolly green parts store, and we’re working on getting them stocked into DC’s) and it also proved 0% improvement. ( was hoping my original was shorted or something, and this would fix the speedo issue)
Next I decided to change my spark plugs. Maybe a fouled plug was doing something weird with the OHMs.. changed to Champion Iridium 9034.. and Jesus p. Christ what a misfire!
I next decided I had the day off, I’d do some experimenting. I chucked the MSD coil, and stuck my 23 year old factory coil back on. No improvement on the misfire but… SPEEDO PROBLEM IS GONE! After switching back to my factory coil and XP985’s, I now have a SMOOTH idle, SMOOTH throttle response, and a WORKING SPEEDO!
I’ve read a couple of threads saying the MSD 82738 is a waste of money, but no probs with using it. Well I’m here to say, mine was a turd and a half.
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