rough running new motor
CF Veteran
Joined: Apr 2009
Posts: 4,734
Likes: 12
Year: 2015, 2012
Model: Grand Cherokee (WK2)
Engine: 3.6L
Internal problem.
Cam not degree'd properly. Valves not opening or closing properly. Internal friction/interference. Wrong cam. Pistons have too much variance in weight compared to one another.
I may have missed this earlier, but have you verified true TDC on #1 on compression stroke, rotor pointing to #1 terminal on distributor cap?
Cam not degree'd properly. Valves not opening or closing properly. Internal friction/interference. Wrong cam. Pistons have too much variance in weight compared to one another.
I may have missed this earlier, but have you verified true TDC on #1 on compression stroke, rotor pointing to #1 terminal on distributor cap?
Last edited by Firestorm500; Apr 8, 2011 at 01:55 AM.
Thread Starter
Seasoned Member
Joined: Feb 2011
Posts: 262
Likes: 0
From: ankle deep in misery
Year: classified information
Model: Cherokee
Engine: .30 over 4.0
ok i turned key on & off 3 times in 3 seconds and left it on the 3rd time to get codes manually. i got 2 codes 11=no engine speed sensor signal & 12=no output shaft sensor signal. i tried both these parts new yesterday. if my computer is on its way out would it throw bad signal to these?
Junior Member
Joined: Mar 2011
Posts: 36
Likes: 0
From: Northern Indiana
Year: 2001
Model: Cherokee
Engine: 4.0L
Maybe, but is the crank sensor seated all the way? Or is the tranny not fully seated against the engine? Too much of an air gap will cause some funky signals. Just trying to help!
Thread Starter
Seasoned Member
Joined: Feb 2011
Posts: 262
Likes: 0
From: ankle deep in misery
Year: classified information
Model: Cherokee
Engine: .30 over 4.0
CF Veteran
Joined: Aug 2010
Posts: 2,112
Likes: 4
From: Wantage, NJ
Year: 1995
Model: Cherokee
Engine: 4.0 I6
DRBII is the god send of scan tools. Its about $6000, but most reputable shops will have it. Hook it up and it tells you everything. Just have to make sure they have Eagle adaptor or else they cant hook it to your xj.
Junior Member
Joined: Jun 2009
Posts: 47
Likes: 0
From: Dexter, Oregon
Year: 1988
Model: Wagoneer
Engine: 4.0
DId you pull the CPS out before you put the engine back in? I damaged mine that way and it took me a week to figure out the problem, it would start but not run right.
Thread Starter
Seasoned Member
Joined: Feb 2011
Posts: 262
Likes: 0
From: ankle deep in misery
Year: classified information
Model: Cherokee
Engine: .30 over 4.0
no it starts right up, has good compression, spark ect. i thought i might of bumped the crank sensor. i removed it,looks sweet,replaced with new one & still running rough. also i got 2 codes 11 & 12 i switch both cam pickup & crank,cleared computer & rechecked the codes now im only getting a 12code which is battery disconected in last 50 starts. plugs show running rich but not wet. bout to part it out



Thread Starter
Seasoned Member
Joined: Feb 2011
Posts: 262
Likes: 0
From: ankle deep in misery
Year: classified information
Model: Cherokee
Engine: .30 over 4.0



