rough running new motor
Thread Starter
Seasoned Member
Joined: Feb 2011
Posts: 262
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From: ankle deep in misery
Year: classified information
Model: Cherokee
Engine: .30 over 4.0
i agree odd timing but im not ruling it out as it runs the cam & crank sensors. both were put in with care & went together smoothly. the computer has been drowned many times but not in last year or so. computer & map are only things i havent tried
CF Veteran
Joined: Mar 2010
Posts: 47,923
Likes: 38
From: Broward County Fl.
Year: 1989 xj sport 2dr
Model: Cherokee
Engine: 12 hole bosch Injectors
possible split vacuum line to map they split all the time,also possible pinched cps wires between motor and trans?
Thread Starter
Seasoned Member
Joined: Feb 2011
Posts: 262
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From: ankle deep in misery
Year: classified information
Model: Cherokee
Engine: .30 over 4.0
all vaccum lines look like new & have been checked,rechecked & checked again,grounds checked couple times .
CF Veteran
Joined: Mar 2010
Posts: 47,923
Likes: 38
From: Broward County Fl.
Year: 1989 xj sport 2dr
Model: Cherokee
Engine: 12 hole bosch Injectors
with out being there to hear it its hard to help id say if it ran b4 parts change the answer is in what you changed some wear if it was me id put the old parts one one at a time checking after each part ,except for the flex and cam if you sure there all good ,what has me is the rotor button problem
Last edited by freegdr; Apr 7, 2011 at 09:22 PM.




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
lol it has old cap & rotor on it now as well as old cam & crank sensors, as well as the idle air control. none changed the running rough so the old part was put back on. only new parts currently on it are flex-plate,plugs,wires,header.
CF Veteran
Joined: Mar 2010
Posts: 47,923
Likes: 38
From: Broward County Fl.
Year: 1989 xj sport 2dr
Model: Cherokee
Engine: 12 hole bosch Injectors
ok my next step then would be to get atest light ground it to the battery and stab the spark plug wires at the dist cap one wire at a time the ones you stab and there is no change in the way it runs are the problem ones
Thread Starter
Seasoned Member
Joined: Feb 2011
Posts: 262
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From: ankle deep in misery
Year: classified information
Model: Cherokee
Engine: .30 over 4.0
CF Veteran
Joined: Oct 2009
Posts: 2,867
Likes: 16
From: Fauquier County, Virginia
Year: 1991
Model: Cherokee
Engine: I-6 4.0 HO
Good spark and the fact that it actually starts usually eliminates the CPS. The TPS could still be the issue. And you said ALL vacuum lines are fine, meaning the MAP line from the firewall to the intake manifold is ok. All injectors were hooked back up correctly?
Are there any strange noises coming from the engine when it is running?
Are there any strange noises coming from the engine when it is running?





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