Hello everybody, I have a 2000 7.3 with 6 speed. It seems to idle a little rough when warmed up, and real rough at 1200 rpm with no load on it. I had that camshaft position sensor recall done about 6 months ago, so I dont think that would be causing it. I know that i am probably due for an oil fuel filter change, but could this cause it to run rough at that rpm? Is it an injector? It doesnt have any idiot lights on at all. Thanks

 

I'll give you a bump!!

 

I have the EXACT same thing. Amiller, a really good forum diagnoser and 7.3 guru, helped me diagnose it as nothing to get excited about. We chalked it up as slightly worn injector internals(160,000 miles then. 180,000 miles now). The diagnosis we performed was UVCH ohming from the IDM pigtail. Everthing Ohmed ok.

He told me that as long as it didnt do it under load or start smoking white at idle, there is nothing to worry about. that was 30,000 miles ago and my injectors still show no signs of needing replaced and has not become more pronounced.

 

It sounds like a worn injector to me as well.
It's an easy fix if you want to change it out and the easiest way to do that is with a cylinder contribution test. The bad injector will have the highest percentage of rpm drop. Replace that one injector and it will smooth out.
Retorque all the rest along with all the rocker pedastal bolts.
Make sure that the wiring harness connectors are tight and corrosion free.
Done.

 

I can't say enough good things about re-torquing the injectors and rocker arms. Made my engine sound brand new again.

If you do a contribution test, and follow up with a rotational velocity (perdel) test, you need to be aware that the new CPS you got from the recall has been known to show higher percentages on #3 & #8 cylinders without the injectors being a problem. The #8 cylinder usually shows a higher percentage due to it's location & point in the firing order.

 

How do I go about doing a contribution and a rotational velocity test? Do I need special tools for this? Thanks so much for the help. You guys are awesome at trouble shooting.

 

Yes it takes an expensive scan tool (around $350), or you can pay a local mechanic to do this for you. You'll just have to find a diesel mechanic who has the proper tools.

 

My Diablo Predator will do what you need.
I used it to diagnose a bad #4 injector.