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Jeep Cherokee running rough low idle at 200-300 rpms

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Old Oct 5, 2015 | 09:40 PM
  #16  
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Oh so the first tac is 500? Alrighty then that's where it's currently idling. Gunna pull the IAC again and inspect it. Might be smart to just replace it
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Old Oct 5, 2015 | 09:55 PM
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Originally Posted by Riley Thomas Greiner
Fuel pressure was at 21 PSI when I hooked it up to a fuel pressure gauge, just did a homemade fix on the MAP with no real improvment on idle. Could the MAP affect the fuel pressure?
Fuel pressure is mechanical. Either the fuel pump is bad or the pressure regulator is bad. You can isolate by pinching off the return line from the regulator--if pressure goes up to 40 or higher then the regulator is defective, but if pressure stays low then its a problem with the pump. Not sure if the RENIX era had the ballast resistor, could be defective too.
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Old Oct 5, 2015 | 10:15 PM
  #18  
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Originally Posted by Riley Thomas Greiner
Fuel pressure was at 21 PSI when I hooked it up to a fuel pressure gauge, just did a homemade fix on the MAP with no real improvment on idle. Could the MAP affect the fuel pressure?
Nooooooooooooooooooooooooooooooooooooooooooooooooo oooooooooooooooooooooooooooooooooooooooooooooooooo oooooooooooooooooooooooooooooooooooooooooooooooooo oooooooooooooooooooooooooooooooooooooooooooooooooo oooooooooooooooooo!!!

Fuel pressure is a real issue here. Did you not read my post above?
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Old Oct 5, 2015 | 10:16 PM
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Originally Posted by ehall
Fuel pressure is mechanical. Either the fuel pump is bad or the pressure regulator is bad. You can isolate by pinching off the return line from the regulator--if pressure goes up to 40 or higher then the regulator is defective, but if pressure stays low then its a problem with the pump. Not sure if the RENIX era had the ballast resistor, could be defective too.
88 and later did. 87 was a retrofit.
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Old Oct 5, 2015 | 10:28 PM
  #20  
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Just now getting it cruiser, phone refreshing slowly. Done with MAP as that isn't the culprit after fixing that line. Pulled the IAC to double check it. Should I be able to gentle push and pull the plunger in and out on it? Also where is the return line on the regulator so I can check that as well while I have the fuel pressure gauge rented
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Old Oct 5, 2015 | 10:32 PM
  #21  
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Front of the fuel rail off the fuel pressure regulator.
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Old Oct 5, 2015 | 10:51 PM
  #22  
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Just follow that metal line till it connects to a rubber line and clamp that off?
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Old Oct 5, 2015 | 11:07 PM
  #23  
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Yes. But only for a few seconds.
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Old Oct 6, 2015 | 09:30 AM
  #24  
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Originally Posted by cruiser54
Nooooooooooooooooooooooooooooooooooooooooooooooooo oooooooooooooooooooooooooooooooooooooooooooooooooo oooooooooooooooooooooooooooooooooooooooooooooooooo oooooooooooooooooooooooooooooooooooooooooooooooooo oooooooooooooooooo!!!

Fuel pressure is a real issue here. Did you not read my post above?
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Old Oct 6, 2015 | 09:34 AM
  #25  
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Originally Posted by Riley Thomas Greiner
Just now getting it cruiser, phone refreshing slowly. Done with MAP as that isn't the culprit after fixing that line. Pulled the IAC to double check it. Should I be able to gentle push and pull the plunger in and out on it? Also where is the return line on the regulator so I can check that as well while I have the fuel pressure gauge rented
Not familiar with using the app.

I use a PC.

So this app has a mind of it's own and works on it's own timeframe?
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Old Oct 6, 2015 | 09:48 AM
  #26  
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Originally Posted by Riley Thomas Greiner
Just now getting it cruiser, phone refreshing slowly. Done with MAP as that isn't the culprit after fixing that line. Pulled the IAC to double check it. Should I be able to gentle push and pull the plunger in and out on it? Also where is the return line on the regulator so I can check that as well while I have the fuel pressure gauge rented

No.


The IAC pintle is pretty much solid if it is properly connected to the motor gearing inside of the IAC.
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Old Oct 7, 2015 | 10:48 PM
  #27  
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Replaced IAC and still surging low rpms around 500, any ideas?
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Old Oct 7, 2015 | 11:01 PM
  #28  
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Originally Posted by Riley Thomas Greiner
Replaced IAC and still surging low rpms around 500, any ideas?
Fuel pressure test?
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Old Oct 7, 2015 | 11:44 PM
  #29  
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Replaced entire fuel assembly and IAC. Was running slightly better but still low rpms. Now it starts up and immediately dies.. One step forward and two steps back
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Old Oct 7, 2015 | 11:53 PM
  #30  
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Egr resistor somehow got the ground unplugged. Still idling poorly though, could it be a plugged cat? Exhaust work by PO left exaust system rattling pretty bad
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