Engine feels out of balance
11-27-2016, 06:58 PM
#1
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Engine feels out of balance
Hello, first post but not a stranger to this forum. I have read a lot of good things here, I would like some help. Also, I tried a search first and turned up nothing. I have recently rebuilt a 90 renix motor due to piston slap. Since the motor has been back in it feels as if it is unbalanced. It has a terribly rough idle to the point that it shakes the steering wheel. If I rev the motor when it comes back down I have a bottom end knock towards the back of the motor. The vibration is present from about 500-1200rpms with 1100 being the worst area for it. When I drive down the road on the gas above 1200rpm it drives just fine like it should, but it's when I let off the gas and it settles down. The engine temp has no bearing on the vibration, it does it both cold and hot. When it is cold it will die intermittently when I try to take off from a stop on a hill and sometimes just when its put it in drive.
I have pulled injector connectors while running to try and narrow it down and that isn't it. I've also ran it with the valve cover off and backed off the rocker bolts slightly and that didn't change anything. Any and all help would be appreciated on this matter.
I have pulled injector connectors while running to try and narrow it down and that isn't it. I've also ran it with the valve cover off and backed off the rocker bolts slightly and that didn't change anything. Any and all help would be appreciated on this matter.
Last edited by White90renix; 11-27-2016 at 06:59 PM. Reason: Spell check
11-28-2016, 03:41 AM
#5
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I'm subscribed. Have had this issue for some time now myself on my '87. It's also white! Almost identical RPM to what you're reporting. Tried injectors, trans mount, distributor re-index, plugs, wires,
Have you changed the harmonic balancer? What about the CPS?
Have you changed the harmonic balancer? What about the CPS?
11-28-2016, 07:19 AM
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Year: 1990
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11-28-2016, 07:20 AM
#8
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Got all the grounds back on at a clean and shiny dipstick tube stud?
11-28-2016, 07:20 AM
#9
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Tip 27 done?
11-28-2016, 11:14 AM
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Last edited by White90renix; 11-28-2016 at 11:15 AM. Reason: Addition
11-28-2016, 03:30 PM
#11
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The firing order is correct im pretty picky about marking things with a sharpie and i used an FSM during the rebuild. This was a very limited rebuild i.e. gasket kits, pistons, rod bearings. The distributor was never removed, nor was the cam, gears, or chain connecting the cam and crank. Would the distributor still be a potential problem?
11-29-2016, 04:01 PM
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11-29-2016, 04:51 PM
#13
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Year: 1990
Model: Cherokee (XJ)
Engine: 4.0