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What is too high of an idle in park

19K views 12 replies 5 participants last post by  scott_11 
#1 ·
Im running out of options for my stalling problem so i figure ill start all over again with the idle speed lol. Ive noticed my idle rpm drops quite a bit from neutral to drive and i wasnt sure if its normal for these trucks to go from 900 to around 740 rpm. I read it should range from 750-800 with ac on in drive but that would probably have the truck at 1000 or more in park. Im just worried that i will have it too high and the truck will want to keep pulling at a stop.
 
#2 ·
Mine is at a needles width or so under 1000 rpm when it is fully warm. In gear i'd say it is around 750 when hot. Have to check. It does want to push at a stop but that is the nature of any auto.

When its real cold on first start it idles like a line above 500 rpm for the first 30 seconds or so unless you bring the rev up for like 20 seconds.

If i put it in gear on a below freezing start its under 500 rpm.

If i were to lower the idle speed from what it is at temp I'd need a fast idle for sure when cold. I just leave it alone.
 
#4 · (Edited)
750Rpm Warmed up in drive with ac on is the service spec... If your truck pulls to much in "D" it might me to high line pressure or the TV cable is to tight.. It is normal that it creeps in drive. If the idle is lower than 750 in drive, lets say 550-600rpm it will stall when cold, specially when reversing and turning... the powersteering pump drags the rpm down a bit when turning and in revers the pressure in the tranny rises bringing the rpm down aswell... but if you are at the right rpm and it still stalls there is something wrong... 700-850 in Drive is allright but much higher than that adds friction and heat while stopped at a red light so if you go say 1000rep in drive, switching to "N" on a long light is a good idea but still adds additional wear to the valve body
 
#5 ·
I had a bd valve body installed which boosted the pressure up quite a bit im sure. I got it around 950rpm in park and approximately 750 in drive with ac. I gave that a try to fix the stalling but with no luck. Had it running for a while earlier and after a while the idle just kept going down more and more until i reved the snot out of it and it coughed out a sh!tload of white smoke. After that it idled good again so i shut it down for an hour or. After supper i fired it up to bump the idle up and it sputtered and spewed white smoke. Im almost wondering if an injector is gummed up on me now. before it just did this randomly now its every time it runs. The trucks lucky i like these 12 valves so much or id be moving on to something more modern lol. Ive owned it for a year and havent been able to enjoy it yet.
 
#6 ·
well if it stalls in park then its not related to the tranny, then it sounds more like an air leak.. or low fuel pressure lift, pump or OV
 
#7 ·
Ya i stretched the spring in the ofv but that doesnt necessarily mean its any good. Just really boggles my mind how it acts up when warm. If I was back to work right now id be happy to use this as an excuse for some better injectors but if im gonna order them i may as well put the new transmission on order too lol. The lift pump definitely looks like its had better days but i thought if it was going it wouldnt just act up when truck is semi warm. It very well could be sucking air though i noticed the rubber over the primer bulb is gone. wish it wasnt so friggin hard to get at or id take it off for a better inspection.
 
#8 ·
you see the rubber on the prime button is only a dust guard. instite the button is a piston seal by a o ring and pressed back by a spring and when the button is pressed all the way out it seats in another oring also sealing it.. the housing of the prime unit is plastic so any dirt getting at it might damage it... the fuel heater assembly bight be leaking or the fuelstrainer clogged up.. and remember ther is also a strainer in the tank that can "un likely" clogg up... Im leaning towards an airleak.. seem to me your going hunting sir
 
#9 ·
I forgot to mention I removed the pre-heater and cleaned up the filter. It was pretty clean even before i took it out. Hopefully the strainer in the tank is not the problem. Could be pretty fun getting box off after all these years. The truck really sounds like it bogs reving it over 2200 rpm but if i read correctly thats when they de fuel so i assumed that was just to do with that. If i put the peddle right to the floor from idle it does a spudder and following some black smoke a puff of white smoke shoots out so you just may be right about the air leak.
 
#10 ·
If you dont have a fuel gauge, I recomend installing one.. it saves a whole lot of trouble... pressurize the tank.. to 5-10 psi.. no more, and see if it leaks... I further moe recomend just replaceing all the lines to marine dieasel rated hoses.. its not as bad as it sounds.. you need to remove the starter and the liftpump/prefilter unit to get to the return line and you could inspect the pump aswell... or replace it...

if an injector is plugged or not working you should get it to run o the remaining 5 cyl... but its a good practice to have the injectors tested and re-set to stock pop pressure...

also your timing may also have slipped... have you placed the motor on TDC and flipped the timing pin on the injection pump?
 
#11 ·
I think I will go ahead and order a fuel gauge kit from tork tek tomorrow. I have never looked in to the timing yet but am starting to wonder if maybe it is out a bit. I will look in to fuel lines more after i pressure test the fuel. Hopefully it doesnt take too long for the pressure gauge snubber and gauge to come in. I hate having to put my projects on hold
 
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