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Lope at Start up? VP44?

Huskiemuskie
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mulcher812

mulcher812

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So I'm running 100hp injectors now. This issue started with my RV275 injectors changed them out to 75hp still an issue then went to DAP 100hp sticks with no change. The one unique thing I have noticed is that if I let the truck run for a few seconds then put it into gear everything is fine. If I jump in fire it up and throw it into reverse real quick it will lurch or lope. Fuel pressure always monitored from mechanical gauge readings haven't changed much from 17 psi at idle to 15.5 wot.

So this doesn't matter of the engine temp or runtime, hot or cold outside. I can make this happen on command anytime I start my truck.

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Huskiemuskie

Huskiemuskie

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So I'm running 100hp injectors now. This issue started with my RV275 injectors changed them out to 75hp still an issue then went to DAP 100hp sticks with no change. The one unique thing I have noticed is that if I let the truck run for a few seconds then put it into gear everything is fine. If I jump in fire it up and throw it into reverse real quick it will lurch or lope. Fuel pressure always monitored from mechanical gauge readings haven't changed much from 17 psi at idle to 15.5 wot.

So this doesn't matter of the engine temp or runtime, hot or cold outside. I can make this happen on command anytime I start my truck.

Sounds like mine... I can do the same thing clears up on it own or if I throttle past idel a little bit it will be fine.  I think my truck had a remanufactured VP... Is your original or remanufactured? did you watch my video is you like that?

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rancherman

rancherman

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Sluggish   governor  when cold?  *meaning  engine  still ambient*    I had  more than one  mechanical injected tractors that would  burp burp burp  at idle,  worse  when   rolling.  (loose cab mounts and solid rod  throttle control)  but  got  better when warmed..        All the posters  in this thread  with  killed, or near  stalled engines   when shifting to R  makes me wonder if the  2 maybe  connected..

VP's are  electronic governed right?

 

I wonder if  next time you EXPECT it to lope at start up,    open the hood,  and  have someone  grab the throttle linkage and  keep it  tight against the  idle stop... as you  fire it up.    You may have   a little  wiggling  in the engine mounts  and  throwing it in reverse REALLY torques it over and   kills it??? hmmmm,  a  sheathed pull cable  usually doesn't  cause these kind of  problems..  solid one sure would!

 

Why  would  reverse  'hit' the engine  so much harder than  D?  not modulated as much??

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rancherman

rancherman

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Rancherman...The throttle is all electronic controlled, stop and all.

Chris

I would've sworn there was a  pull cable to the  VP...  what the heck  did I  remove and replace  when I changed out my vp??

All I was  trying to say was..  sometimes  when a  engine surges,  it'll  'pull'  against the throttle.  which either  slows it down or speed it up..  just a tad.  once it  gets to 'bouncing'    it's  hard to stop...    but as  I said,  a   sheathed  cable  doesn't  respond  like a  solid rod.. because it  moves  with the engine..  

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rancherman

rancherman

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Thought so!  ha~ 

   I agree too,  since the  cable  moves  'with' the engine.

  I was just throwing out  'stupid dumb' type  things  I've  discovered over the years..  Stuff that  at first glance  would never be  an issue..    I've learned  to never assume the worst..  until  all else has been  eliminated!

 

Ya know,   immediately after startup...   the  voltage  in the  system  has to be  haywire..   the  battery just got done  spinning the engine over,  the alternator  is  just  coming on-line..  and   maybe   the grid heaters  are  still  going  nuts  (hopefully not this time of year)...  It's amazing  the  electronically controlled    IP  works  at all!

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Huskiemuskie

Huskiemuskie

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I know you did the APPS sensor voltage. Just remember one thing idle as long as the OE APPS sensor is BELOW the tag voltage then the ECM will IGNORE the APPS voltage and use internal ECM software for Idling.

It's an OE and I am below the tag voltage... So the ECM should be commanding the correct idle info to the VP... so I am wondering that the 750rpm and not 800rpm that I should have along with the lope are somehow related.... is it possible that the VP is not processing the the idle commands / rpm properly because some component in the VP is breaking down? 

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rancherman

rancherman

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I know you did the APPS sensor voltage. Just remember one thing idle as long as the OE APPS sensor is BELOW the tag voltage then the ECM will IGNORE the APPS voltage and use internal ECM software for Idling.

Yep,  I  always  believed that too..  " Ecm  manages  idle "         I wonder if  there is  some  'fighting'  between the  psg and  ecm  during  initial  spin-up..   until the voltages  stabilize? 

Would  a   stiff  turbo  (as in  cold  and  slow to spin up)   have any influence here?    

I realize   even a  'stuck'  turbo  will still allow  gasses to pass,  not as   well of course...    

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Mopar1973Man

Mopar1973Man

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It's an OE and I am below the tag voltage... So the ECM should be commanding the correct idle info to the VP... so I am wondering that the 750rpm and not 800rpm that I should have along with the lope are somehow related.... is it possible that the VP is not processing the the idle commands / rpm properly because some component in the VP is breaking down? 

 

How far below the tag voltage?

 

Idle speed is based on Engine Coolant Temperature so the colder the engine the higher the idle will be. So if the sensor is off and showing higher temperature than normal then the idle speed is reduced. Also if the pop pressure is excessive high then the timing will be retarded on the injectors so then the idle speed is lower.

 

Very rare a VP44 can't make idle. But it more common to see injector issues creating weird issues.

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