running rough
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Senior User
Joined: Nov 2006
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running rough
I have a 2000 excrsion 7.3. Today on my way home it started running rough. The CEL did not come on and my brother has my code reader. Rough at idle and high RPMs. Espcially rough just under 1k RPMs. Seems to have normal power.I did the UVC plug fix about a year ago. Any other thoughts? 
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Senior User
Joined: Nov 2006
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Okay, I got my code reader and no codes. Could a bad/cloged injector cause this? If so would that cause a code? what about a bad motor mount? Do these motors have harmonic balancers? My brother knows of some one who had theirs replaced after it "went bad" He was unsure if it was a diesel.
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Post Fiend
Joined: Mar 2007
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From: Texas
What kind of code reader do you have? Can you monitor any live data or run any tests? Did you run really low on fuel before this started? Have you looked to see if the fuel pressure looks good?
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low performing fuel pump, sticking IPR, CPS starting to fail? just some ideas. I know my truck was idling slightly rough. Not to bad, only really noticeable in the sound (slightly fluctuating idle, 560 and 600 rpm and a slightly wobbly stick. Changed my CPS from grey to black and ahhhhhhhhh! Nice and smooth!
Now to just change my oil and get rid of my romps when letting off the fuel and putting in the clutch from a higher then idle rpm.
But get that code reader on there and get some live statistics and post them. Might give you and us some in site.
Now to just change my oil and get rid of my romps when letting off the fuel and putting in the clutch from a higher then idle rpm.
But get that code reader on there and get some live statistics and post them. Might give you and us some in site.
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Joined: Dec 2006
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Let me chime in a little on my problem. I have an early'99 7.3 a/t with 130,000 and my truck runs fine going down the road. When you start it up cold in the morning it runs fine and idles smooth. After it has been completely warmed up, aprrox 20 miles to work, it has a little bit of a rough idle. It seems like most peoples trucks are the exact opposite, rough idle when cold, mine is smooth when its cold. I have a gray cps installed but a black one is on its way via ebay this week. I took it in to the dealer and was convinced #8 inj was bad. It was failing the cct and also failed the bench test. After the inj replacement it was still failing the cct about 1 out of 3 times. Popped in a new gray sensor, no change, put in new icp sensor, no change. Oil change, and fuel filter just changed as well. Here is another thing it does. My regular idle is about 750 rpm, if you rev it to aprrox 1000-1200 and let off, the idle will drop to about 500, stumble just for a split second and then back to 750. Does this sound right????
Post Fiend
Joined: Mar 2007
Posts: 26,966
Likes: 50
From: Texas
Let me chime in a little on my problem. I have an early'99 7.3 a/t with 130,000 and my truck runs fine going down the road. When you start it up cold in the morning it runs fine and idles smooth. After it has been completely warmed up, aprrox 20 miles to work, it has a little bit of a rough idle. It seems like most peoples trucks are the exact opposite, rough idle when cold, mine is smooth when its cold. I have a gray cps installed but a black one is on its way via ebay this week. I took it in to the dealer and was convinced #8 inj was bad. It was failing the cct and also failed the bench test. After the inj replacement it was still failing the cct about 1 out of 3 times. Popped in a new gray sensor, no change, put in new icp sensor, no change. Oil change, and fuel filter just changed as well. Here is another thing it does. My regular idle is about 750 rpm, if you rev it to aprrox 1000-1200 and let off, the idle will drop to about 500, stumble just for a split second and then back to 750. Does this sound right????
Post Fiend
Joined: Mar 2007
Posts: 26,966
Likes: 50
From: Texas
A buzz test on a cold engine will tell you if the poppets inside the injectors are sticking, but you need a fancy scanner or gauge to do that.