Low idle, miss at idle, no codes, no problems under load

Idle issues have always been my issue, take a look at the following

-Clean/inspect IAC/housing (idle air controller)

-Check intake filter

-Fuel pressure at fuel rail(should be 80+ at key on but not running iirc)

-Inspect spark plug gap

-Inspect Fuel injector O ring(normally throws a code for misfire but ive had it happen without)

-Throttle position sensor may be bad, cant remember how to check/clean, I think it may be whole unit.

-Upstream O2 sensors(cant check, have to replace them. If you have a decent milage on your jeep 80,000+ and theyve never been changed its a good idea anyway, my MPG went up by 2 cause mine were roasted)

-Check vaccum lines for tears etc. (normally causes high idle but still annoying)
 
DylanM345 said:
Idle issues have always been my issue, take a look at the following

-Clean/inspect IAC/housing (idle air controller)

-Check intake filter

-Fuel pressure at fuel rail(should be 80+ at key on but not running iirc)

-Inspect spark plug gap

-Inspect Fuel injector O ring(normally throws a code for misfire but ive had it happen without)

-Throttle position sensor may be bad, cant remember how to check/clean, I think it may be whole unit.

-Upstream O2 sensors(cant check, have to replace them. If you have a decent milage on your jeep 80,000+ and theyve never been changed its a good idea anyway, my MPG went up by 2 cause mine were roasted)

-Check vaccum lines for tears etc. (normally causes high idle but still annoying)
Click to expand...

Forgot to mention when replacing sensors etc always go with the recommended brands here. El cheapos from orileys and autozone cause nothing but problems(bad quality, crap out too soon etc)

Hope this helps!
 
WestCoastDan said:
Which brand of new O2 sensor did you use?

Aside from all of the other troubleshooting and replacement parts you've added, your description of the problem (low, rough idle that clears up when RPMs increase) is exactly what our '03 was doing before I replaced the front (upper) O2 sensor.
That resolved my issue instantly.
Click to expand...

I used NTK sensors. Zero change in anything once I changed them all.

I have changed everything possible accept T-body, injector O-rings and CPS. If these don't fix it, not sure man!!!
 
Sooooo, this weekend I did the following:

Compression check- 158-165 all cylinders (engine was a tad warm at the time)
Checked cam timing- was a little off realigned
Checked fuel pressure- was 43 when engine off and 55 while running (was erratic when running, bounced around, more like a flutter)
Pulled injectors- had 3 cracked and replaced all of them
New injector heat shield

All of this to yield the exact same running and issue!

All I have left to replace is cam sensor and crank sensor????
 
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