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runs worse than before

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Old Aug 28, 2015 | 05:25 AM
  #1  
Gauge's Avatar
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From: Largo, FL
Year: 1995
Model: Cherokee
Engine: 4.0 HO
Default runs worse than before

So I removed a motor that made a ton of noise... Ticks, knocks, squeaks and squeals, but still had the power. The newer motor doesn't make any of those noises but it doesn't seem to have the power. It's bogging down when I get to 2k RPMs and over. There is a white vapor coming out of the exhaust (maybe dumping fuel like crazy)... I installed a bunch of upgrades (already had the header back exhaust; installed neon injectors, 99+ manifold and gasket matched the throttle body, header, intake manifold and head) can't imagine it would take to terribly long for the PCM to relearn. I've barely driven it 30 miles so far and have gone through almost a quarter tank of gas.
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Old Aug 28, 2015 | 05:28 AM
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Old Aug 28, 2015 | 07:19 AM
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From: Largo, FL
Year: 1995
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I did build an adjustable MAP sensor. I just have to install it. Maybe that will help?
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Old Aug 28, 2015 | 08:06 AM
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From: Oroville, CA
Year: 1995
Model: Grand Cherokee
Engine: 4.0 with all of the noise and clatter
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You have a possible head gasket issue.
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Old Aug 28, 2015 | 08:24 AM
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I just built this motor. We basically rebuilt the head. The lower end, I just replaced the lifters, timing chain and oil pump. All gaskets are new.
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Old Aug 28, 2015 | 08:29 AM
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From: Oroville, CA
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The steam from the exhaust indicates a problem, it's not just normal byproduct of combustion and catalytic converter doing its job steam.
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Old Aug 28, 2015 | 09:00 AM
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timing is probably off
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Old Aug 28, 2015 | 09:09 AM
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Originally Posted by ehall
timing is probably off
We made sure we got that spot on, during assembly.
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Old Aug 31, 2015 | 02:10 PM
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I dropped it offat a shop yesterday, to have them check it out. So far, all they can tell me is that my number two injector is dead; the pcm is supplying voltage to it but it's not firing... Or it could be stuck open. I told him that I just put neon injectors in the for the upgrade and he tells me that could be an incompatibility issue, since it has a different spray pattern
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Old Aug 31, 2015 | 09:02 PM
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From: Oroville, CA
Year: 1995
Model: Grand Cherokee
Engine: 4.0 with all of the noise and clatter
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Originally Posted by Gauge
I dropped it offat a shop yesterday, to have them check it out. So far, all they can tell me is that my number two injector is dead; the pcm is supplying voltage to it but it's not firing... Or it could be stuck open. I told him that I just put neon injectors in the for the upgrade and he tells me that could be an incompatibility issue, since it has a different spray pattern
The injectors will always have voltage, the ground is switched on and off to fire the injectors. The spray pattern won't cause a problem.
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Old Sep 2, 2015 | 06:28 PM
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...

Last edited by Gauge; Sep 2, 2015 at 06:33 PM.
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Old Sep 2, 2015 | 06:31 PM
  #12  
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From: Largo, FL
Year: 1995
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Threw in a stock injector for now; that took care of the idle and throttle issue. Runs way smoother now. Now, for the scary part... Finding out where all of my coolant went.
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Old Sep 2, 2015 | 07:34 PM
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Year: 1999
Model: Cherokee
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If you are running rough, have white smoke and missing coolant... As Bustedback said above, sounds like a head gasket.

Although you just did this, its possible there was an issue with the gasket
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Old Sep 2, 2015 | 08:52 PM
  #14  
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Year: 1995
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No more running rough or white smoke...
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Old Sep 2, 2015 | 09:23 PM
  #15  
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From: Ottawa Canada
Year: 1999
Model: Cherokee
Engine: 4.0
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Still losing coolant?
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