[NCC74656]

my truck is idling slightly rough, nothing major but a smig. i can disable any injector and it gets worse (as you would expect) however after reenabling any of the injectors the idle gets buttery smooth for about 5 seconds and then goes back to being rough. this happens exactly the same when disabling/enabling all 6 cylinders. does this sound like a timing issue?

 

[Clunk]

Yup, mine too when the AC is on, kinda cool to me

 

[PTSCummins]

Timing is likely a tad different than the old pump. Who rebuilt the pump you installed?

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[NCC74656]

no one, its factory as far as i know. i will throw my quadzilla on there once i test drive this a few hundred miles and fix the timing

 

[PTSCummins]

One of your last posts was about installing the VP. Did you replace yours with another used one?

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[NCC74656]

yea, from teh salvage yard. i thought i broke it but i had to replace the timing key as everythign blew up

 

[CAMG3X]

I've noticed my rough idle smooths out quite a bit with the AC on. I always thought it was due to having a hot rod pump + quadzilla tuning. I tried adjusting the valve lash and it seemed to help a bit, though still quite lopie and sporadic.
Think the next thing I will try is fresh injectors...

 

[NCC74656]

yea i had hte idle buttery smoth after i rebuilt the engine, then the new VP i put in (new used) has been a bit rougher. i think ima install the quadzilla earlier than i was planing to play with tuning

 

[CAMG3X]

I'm not sure much can be done to tuning the idle with the quad besides the high idle feature.
I also get a high idle around 975 RPM's whenever cruising above 10mph. The second I go below 10mph the idle drops to around 850-860 RPM's. Never use to do that with the quad until i had the VP rebuilt/replaced.
It doesn't bother me, figure it aids with cooling/lubing the turbo.

 

[NCC74656]

i just readjusted my idle screw and apps sensor yesterday which fixed a couple of my engine codes and gave me a lower/more stable idle but i still have a slight lope. if i KNEW how far off of idle i was i would consider pulling the VP and adjusting the timing key, either shaving off a thou or adding on

 

[bigfish95971]

Idle should not be adjusted with throttle screw. It is a cabled stop only. Idle is set with the electronically set and not adjustable. APPS voltage, if adjustable. should be set at .48 to .329v. Idle should be 750 in gear)-800(in park or N) and steady except for in drive or not.
If adjustable Set the apps at .5v on Pin #3. and set the screw at where it does not move the shaft or cable a tall. It is just a stop to take slack out of the apps rotation.

After that we can deal with any other issues you have, and can not until then.

If you set the apps too high it may confuse the ECM and cause idle or surging issues.

 

[NCC74656]

ill look it over next week when im back at the shop