help rough running sometimes
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help rough running sometimes
looking for help 97 7.3 diesel that starts fine but when off the pedal fast or on [R.P.M.]chek engine light comes on [runs rough for about 5 or 10 seconds then is fine again [moving or not moving] looked under valve covers wiring looks good. chek for bad codes all seem fine.
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From: Herndon KY
Welcome to FTE somebody here will shoot you a link with all of the Acronyms, TPS is a throttle position sensor, there are several issues that could be causing the problem, more detail would be great, I would look on the back of your HPOP (high pressure oil pump) there is a cylinder there IPR injection pressure regulator there is a brass nut on the back of it, make sure it is snug, you can overtighten easily, but it also comes loose easily.
More detail would be great
More detail would be great
Post Fiend
Joined: Mar 2007
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From: Johnson City, TN.
Oh I am sorry I didn't pay any attention. Welcome to FTE and post often. Try this link it has good info.
http://pages.prodigy.net/stevebaz/_i...az/index3.html
http://pages.prodigy.net/stevebaz/_i...az/index3.html
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more detail[try] starts fine,idles fine,if you push the pedal down to fast[about 2 thirds of stepping on it] chek engine light comes on and it starts to run rough.take foot of pedal it will clear it self in about 5 to 10 seconds.then idle fine again,it also will do the same thing if you take your foot off to quick [drop r.p.m. to fast] the only way stop this is to slowly on and of the pedal then it does not happen [runs fine]
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Joined: Aug 2006
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Originally Posted by 61oldgoat
more detail[try] starts fine,idles fine,if you push the pedal down to fast[about 2 thirds of stepping on it] chek engine light comes on and it starts to run rough.take foot of pedal it will clear it self in about 5 to 10 seconds.then idle fine again,it also will do the same thing if you take your foot off to quick [drop r.p.m. to fast] the only way stop this is to slowly on and of the pedal then it does not happen [runs fine]
A failure of the TPS ,usually ends up with Idle only,,,or a miss due to a bad Or flat spot,If you have a DVO meter , you can test the TPS....
You need to put a voltmeter across the GY/W and the GY/R wires on the connector to the TPS. With the key on, watch the voltage across the range of the throttle to see if there is any flat spots. You should see no less than .37 volts at idle position and no more than 4.5 volts at full throttle. The the third wire, (BRN/W), is the ref. voltage and should be 5 volts all the time.
Last edited by Action4478; Jan 7, 2008 at 04:47 PM.
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Joined: May 2007
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From: Belair md
you said checked for bad codes and all is fine? i assume that means you tried to pull codes? what scanner are you using? if it is definatly compatable then leave it hooked to the truck and get the truck to have the light come on. do not turn the truck off, scan for dtc's with it running. sometimes 7.3's will clear the code for some reason if you shut it off. dont know why. i've had it happen on several before including mine when i had a burnt under valve cover harness that was intermitantly shorting out. the check engine light would come on and go off at times. when i would get home and shut it off then go get my scanner and try to pull codes the pcm was clean.
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i borrowed the scanner and tried to pull the codes,the scanner book said that the scanner could be brunt out if left on with it running,so only tried with key on,tried it about 5 times after running engine and getting it to run rough,green ligh comes on[scanner] book says green light means all fine,can not remember scanner make.went for drive on rough road [pot holes] fast it ran fine as long as you were not fast on or off the r.p.m. hoped if it had a wire that was shorting out it would happen,it will happen 20 out of 20 times,so it not even like its a intermittent problem
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