1994.5 - 1997 7.3L Power Stroke Diesel  

Rough Idle - New Guy Here!

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  #31  
Old 04-02-2015, 06:53 PM
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I'm willing to try it tomorrow. I have a video but not sure how to load. It...

Link??

http://s1341.photobucket.com/user/bl...tml?sort=3&o=0
 
  #32  
Old 04-02-2015, 06:57 PM
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if nothing else, toss it on youtube, and copy/paste a link.


Edit- The link works. I'm not sure what to say here, as this part is sorta above my experience level. One of the guys that been here longer can probably help you more than me. I think if it was a bad injector, you'd hear a dead skip in the idle, if that helps at all. I think this may be beyond the help of an additive. Did the engine do this when you bought it, or did it start doing it after you bought?
 
  #33  
Old 04-02-2015, 07:12 PM
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Drain the fuel bowl, fill it up with diesel 'power service' and see if that helps.
 
  #34  
Old 04-02-2015, 07:13 PM
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When I bought it. The boy said he did it when he got it too. So it has been doing it for a while... this is my first diesel, so IF it would be an injector, how hard is that to change? They'really expensive enough as it is so if I can save some cash I'd like to try to...

Thinking outloud, I only have throttle like after 1200 rpm or so, while both tanks and nothing is leaking externally.
 
  #35  
Old 04-02-2015, 07:23 PM
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You could probably find a decent "How to" on youtube to test injectors, and/or replace them. Could you explain what you mean by "only have throttle after 1200 rpms"?
 
  #36  
Old 04-02-2015, 07:27 PM
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Like idling at 750 give or take a few... I can push in the peddle and it jumps to 1200 or 1000 or so after 1/4 way in. Like its either on or off its almost impossible to push it barely in to go down the road ya know?
 
  #37  
Old 04-02-2015, 07:30 PM
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Originally Posted by 96F250SD
I can push in the peddle and it jumps to 1200 or 1000 or so after 1/4 way in. Like its either on or off its almost impossible to push it barely in to go down the road ya know?

I think that problem would be unrelated to the other issue. Could be a problem with the TPS (Throttle Position Sensor) A little bit of lag is normal, I have an inch of pedal play before my rpm increases, but the part about it not allowing slight increases is definitely not supposed to be that way.
 
  #38  
Old 04-02-2015, 07:32 PM
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I was thinking the sensor as well...once I get the idle figured out I will start driving it daily... hope some one else comes along n throws out ideas...
 
  #39  
Old 04-02-2015, 07:36 PM
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Why do you have your air filter disconnected? That's a good way to trash your turbocharger compressor wheel.

I would start with a fuel pressure check, at the schrader valve. Next, get the truck on a diagnostic device, and at least do a buzz test. Is it good enough at higher RPM that you can drive it around enough to get the engine hot? If so, you'll also want to do a cylinder contribution test.
 
  #40  
Old 04-02-2015, 07:42 PM
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I ripped the boot accidently getting it off. It has since been replaced, but thanks for pointing that out. what is a Schrader valve, where is it, and how? Buzz test? And it will drive fine over 1000 rpm or so, and will get warm no problem. I drove it 75 miles home on the interstate no problems Other than a blown taillight. I'll check into all the above and what they mean and report back probably tomorrow evening.
 
  #41  
Old 04-02-2015, 07:49 PM
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The Shraeder valve will be on the Fuel Pressure Regulator. It'll look like a tire stem.
 
  #42  
Old 04-02-2015, 07:53 PM
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Assuming I can rent the tool from o'reilly's and check it? I'll have my gf help me crank while I read the guage.
 
  #43  
Old 04-02-2015, 08:26 PM
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I think it may need to be running for this. The fuel pressure varies heavily between RPM levels. You can actually check it with a tire pressure gauge, but as for the exact procedure, I don't remember. One of the others could probably walk you through it. Or, like you mentioned, you could probably rent an actual gauge.
 
  #44  
Old 04-02-2015, 08:31 PM
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Never thought of a tire pressure guage. I will do that then... going to look up what it needs to be pressure wise at rpm level
 
  #45  
Old 04-02-2015, 08:36 PM
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Schrader valve - as usual the wikipedia definition is incomplete at best, but you get the idea. On the fuel pressure regulator (forward driver's side of the fuel bowl), you'll see a black cap. Under that cap is a valve that looks like a tire valve. That's a schrader valve (so are "conventional" tire valves). Harbor Freight makes a cheap fuel pressure gauge that will work on it. In a pinch, you could use a cheap dial or stick tire gauge from the parts store; just don't use it again on a tire.

Buzz test, contribution test, etc. are the diagnostic tests that you do with a communication device connected to the data link connector on the bottom of the dash. That's also how you obtain diagnostic trouble codes, and can monitor certain sensor/control data.
 


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