**please help** trouble with idle and voltage
CF Veteran




Joined: Nov 2010
Posts: 5,840
Likes: 117
From: In the middle of Minnesota!
Year: 1999
Model: Cherokee
Engine: 4.0
Thread Starter
Seasoned Member
Joined: Oct 2011
Posts: 348
Likes: 0
From: Chicago
Year: 1989
Model: Cherokee
Engine: 4.0
Well my ignition coil has got warped fins and rusted. So I'm going to buy a new coil this weekend and see if it that. If it is then I will attempt to repair the old one and do I DIY for it.
CF Veteran




Joined: Nov 2010
Posts: 5,840
Likes: 117
From: In the middle of Minnesota!
Year: 1999
Model: Cherokee
Engine: 4.0
You can't tell if a coil is good by a visual inspection. You should test it for both primary and secondary resistances with a manual and a meter.
You can have a good coil that looks rough and you can have a bad coil that looks good.
It's what's inside and how it performs electrically that counts....
You can have a good coil that looks rough and you can have a bad coil that looks good.
It's what's inside and how it performs electrically that counts....
CF Veteran
Joined: Jun 2011
Posts: 2,858
Likes: 1
From: Nor-Cal
Year: 1990
Model: Cherokee
Engine: The venerable 4.0
You have to test for resistance at different parts of the coil. Usually when I do it diagnosing other cars I just Google the resistance and it comes up...
Thread Starter
Seasoned Member
Joined: Oct 2011
Posts: 348
Likes: 0
From: Chicago
Year: 1989
Model: Cherokee
Engine: 4.0
OK nvm. I rated a new coil and it is within the range tho old one is. So the coil isn't the problem. I don't know where to start looking now. I dread buying a new ecu. Its not even worth it to me.
Seasoned Member
Joined: Jul 2011
Posts: 385
Likes: 0
From: Montreal, Canada
Year: 1998
Model: Cherokee
Engine: 4.0 I6 HO
in my personal experience when ever the dash lights start getting dim and not too long after the the jeep wont turn over and just does the clicking sound like a machine gun 90% of the time its the alternator....
have you checked your alternator? what about the 2 pins on it? these are prone to breaking from simple vibrations, happened to mine this summer....
have you checked your alternator? what about the 2 pins on it? these are prone to breaking from simple vibrations, happened to mine this summer....
CF Veteran
Joined: Jun 2011
Posts: 2,858
Likes: 1
From: Nor-Cal
Year: 1990
Model: Cherokee
Engine: The venerable 4.0
Also you have a renix right? When you took the valve cover off ya sure you didnt pull or strain some of the wiring.... Actually REALLY sounds like the ground strap from the engine to the body! Big time!! Check it!! A good idea to run another strap from the firewall to the back of the intake. Heatshield bolt works nice. Also really clean and polish the connections at the dipstick bolt. I don't know if it was said but do you think your battery might be bad?
Last edited by Slick761; Dec 2, 2011 at 12:36 PM.
Thread Starter
Seasoned Member
Joined: Oct 2011
Posts: 348
Likes: 0
From: Chicago
Year: 1989
Model: Cherokee
Engine: 4.0
idk what I have to be honest. And where is this strap at? And also the engine is turning but not turning over all the way. I replaced the CPS and I tested my ignition coil and it was good. So I will be removing the ECM and seeing how it looks and hope and pray its good.


