my 02 truck is really running rough and I'm thinking it might be an injector. It almost feels like a miss, especially when it is cold.
How can I diagnose this and then find the right injector that is bad? How hard is it to change one of these?
Thanks
Bob

 

Replace the CPS, My 02 had the same idle issue as yours and I replaced the CPS and
it idles very smooth now, no more miss at idle. These injectors rarely go bad, but the CPS do go bad, its easy to change yourself.

 

Ok my psd has a miss at a idle when warmed up, mostly after a hard pull or exiting the freeway. Do you think this could be the cps also? It really feels like only one injector isn't spraying. I'm no expert but I would think a bad cps would make for a more random miss. I should just get a new cps anyways and keep the old one for a spare.

BTW scratch, I asked this same question a while back (how to find a bad injector) and was told to make/use a breaker box to cut out the injectors one at a time.

 

My 02 did the exact same thing, especially after pulling my horse trailer, I would come to a stop and the truck would almost buck it would miss so bad. I just lived with it for 58,000 miles, until this last weekend I decided to change the CPS, and now its perfect. Mine even smoked with the old CPS, now nothing.

 

that would be the second CPS in a year if that is the problem.
Bob

 

The alternative would be to remove the valve covers, and with the engine running unplug the injectors one each. A diagnostic tool that is capable of performing an injector buzz test (electrical self test) might also be helpful.

 

I was told not to un-plug the while running because they run off 110 volt or something like that, might slow your heart a little!

 

That is correct. Personally, I wouldn't do it, nor was it my intention to recommend it. I was just saying that several have done it several times without dying....still risky playing with high voltage systems.

 

Well I just installed the $100.00 CPS and had no luck. Didn't help the miss at all. So I'm going to try a few other things before taking it to the dealer.

Check to see if the truck has a chip, if so remove it and see if it runs better.

If it doesn't have a chip I'll take it in and have the puter flashed to erase any performance tune it might have. (Don't know the history of mods the truck has.)

If that doesn't work I guess I'll price out the injector harness, and swap them out.

Last thing I will look into, finding out how to replace injectors.

This rig is starting to wear me out.

 

I may be off on this but here is an idea,I have been having some problems with my truck and have been looking at this as the problem.
Troubleshooting High Pressure Pump Problems

It is quite difficult to properly diagnose Powerstroke HP pump problems without some special purpose tools. I'd like to give you a set of simple symptoms that point to a misbehaving high pressure oil pump, but even that is difficult to do because other components of the HEUI injection system can cause similar symptoms. Furthermore, we have reviewed the Ford troubleshooting procedures and observed the actions of Ford Diesel technicians. In our opinion they do not have the tools or procedures to identify a pump problem. (My apologies to Ford technicians...) For example, Ford Powerstroke technicians do not have any means of measuring pump flow, something that we think is critical to properly troubleshooting pump problems.

Here is a list of symptoms that would make us suspect a problem with the high pressure oil pump:

a) rough idle when hot, but generally OK when cold, although it may idle rough when cold as well

b) a stumble (not cackle) when the accelerator is pressed firmly in the 1000 to 1500 RPM range

c) the engine has difficulty keeping a steady idle speed WITH THE HVAC SYSTEM TURNED OFF

d) long crank time in cold temperatures (below freezing)

e) lack of acceleration on initial application of throttle when engine is first under load. (We are verifying this symptom.)

f) lack of acceleration in the first portion of accelerator movement. (We are verifying this symptom.)

 

more info
http://www.diesel-central.com/News/oil_pump.htm

 

>b) a stumble (not cackle) when the accelerator is pressed firmly in the 1000 to >1500 RPM range

This is what my psd does. It feels like a harmonic "wobble" at 1100 rpm's

 

i have a 2000 psd, runs rough ,had injectors ckd ,ok ,my truck has the same symtoms , runs ok at idle,but runs rough when hot,might have a bad hpop,driving me crazy,trying to figure out what is wrong,thanks for info

 

A scanner capable of an injector balance test is pretty effective on the newer 7.3's. I know that doesn't help the shade tree, but it may be the simplest and least headache prone approach. You can also monitor the injection pressures and see if they are low.