Rump, Rump, Rump...

[jdurham]

... is the sound my truck makes at idle (sometimes). It never has done it before, so I assume it is a byproduct of turning in the fuel screw 2 turns. Is this a common thing, or did I mess something up?



By the way, I LOVE the way it runs now!

 

[JLEONARD]

Jim,

Reads ( I can't hear it) like a low idle... . what rpm is she idling at?

Jay

 

[jdurham]

I don't have a tach, but it seems to be idling high enough that it shouldn't do it, and it only does it sometimes...

 

[jdurham]

Just drove the truck again, trying to pay attention to when it does it. It will even run like that off idle as in moving down a residential street, but when you step down on it, it smoothes right out. Any ideas?

 

[Greenleaf]

Sometimes the farm tractors will do this after we finish turnen the screws to 'er. I've found it to be in the governor controls [settings]. I have had some luck in readjusting the gov spring to help somewhat, but still have some "hunting".

 

[RDusch]

Jim,

thats exactly how my truck runs now, the idle i can stand it's when i let my foot of the brake to roll forward in traffic, the truck moves just like the exhaust sounds, it just jerks forward kinda feels like your trying to stop and old truck and forgot to push in the clutch, but as soon as i accelerate it smooths out ... ..... Rick

 

[jdurham]

Greenleaf, I don't have a clue as to how to make the governor smooth the idle. When I did this, I put the pods in and put two turns in on the fuel screw. I did nothing to the timing, so I don't know where it is, and don't know if that would help.



rick and Jay, I have noticed that my idle seems to fall off a little after a long wide open highway pull. I get off on an exit ramp and stop, and the motor seems to idle lower, rougher, and the oil pressure gauge drops (sometimes to zero), and the oil light comes on. I might drive another block and stop, and the problem goes away. I find that to be puzzling, since it is inconsistant, and I can't think of anything that would change the idle like that.



I pulled a full load this weekend. I don't know how much weight, but it had my mud flaps almost dragging the ground. The truck ran great, I could pull 1200* easy pulling a mountain, but could easily back off just a little and the temps would fall and the truck still pull well. At full throttle on level ground it stayed around 800*. The water temp did seem to rise higher pulling the hilld though, I once got to the last mark at the edge of the normal range.



I might be dreaming this, but it *sounds* like the turbo spools faster and louder than it used to , but it is a little more smoke than I first realized.

 

[mopar2ya]

rump rump rump?

hello,seems to me you need to adjust the power screw,2 turns or not,with the truck at idle,turn the screw in or out to get the best idle,it seems like your not giving it enough fuel to run at idle,don't be afraid of it,you can't mess it up, at 800 egt theres not enough heat there so theres not enough fuel,you should be at least 1000 egt,i would think your boost is low also,like around 20 maybe,by turning the screw you should find a sweet spot,from there you can tweak for best power, hope this helps,enjoy joe

 

[BushWakr - RIP]

As the fuel screw goes in, it "tricks" the pump into a higher idle... at least that's how it was described in a TDR article some time back.

You should not be seeing your oil light come on though... . I'd raise the idle a bit more. I find my idle fluctuates a tad now and then too. . like you, after a good hard highway run it will twitch a bit + or - 30-40 RPM

Once the fuel screw changes the idle speed you are now entering the area of decreased pump life. Again, that is from a TDR article... I think it may have been Joe D's article.



Anyway, the POD's send in a lot of fuel at idle without any low end pump tweaks.

Raise your starwheel right up near the top of the threaded center. Do not go more than "almost flush" in terms of top edge of starwheel/threaded shaft.

This way you'll minimize low end fueling which the nozzles can usually provide on their own.



Bob.

 

[hdm48]

When I ran the PODs mine would do the same thing. Never could figure out when it would do it or when it wouldn't. Except for when I first get off the freeway. The DDs I'm running don't do it at all.

Must be a POD thing.

A little more timing helped, but didn't cure all of it. One thing I did notice though, when I started running Amsoil in my fuel, that really helped. Maybe because it was burning more of the fuel?

But here is a good idea. Don't stop. Lock in the hubs (we got em) and run over all those rice grinders.

I get so sick of those things that sound like a beer fart. And they complain about our trucks being loud?









Dave

 

[Scot]

I notice the POD's giving a rough idle after the truck has run a long distance. I ran down to Houston pulling a 16' trailer and noticed it while I was there. Came home and it did it the next day. Has not done it since. My pump is slightly turned up. Prior to the POD's it was at +1. 5 turns. I brought it back to 0 when I installed the injectors. SW Metrofuel turned it up a bit after I "shortened the life" of the old one.

 

[jdurham]

Many thanks to all who have responded. Just to clear some things up:



Bob,



I did have to back my idle down after putting the pods and the two turns in on the fuel. Does that mean I need to back off the pump to keep it alive?



Mopar2ya,



It smokes at idle slightly, and gets worse (or better ) when you lay into it, so I don't think it's starving for fuel ever...



hdm48 and scot,



One thing I forgot to mention is that it DOES idle low after a long pull, but it did the same before the injectors and pump adjustment.



Thanks,



Jim

 

[mopar2ya]

rump rump

hello, my power screw was turned in 7/8 of a turn with stock injectors, a local built me a set of 370 injectors to my specs and installed them, the truck run good but had a rough idle,egt around 800 and light smoke,i removed the lock collar and turned the power screw in and the idle was smooth but high, so i adjusted the the idle screw down, the result was smooth idle like before the new injectors and now my boost is up to 26 lbs and 1000 egt and a bunch quicker, i only replyed because i had and solved the same problem,i'm not one to be a know it all ,nor do i reply to anyone then i know nothing,i'm sorry if i offended anyone,i was trying to help, enjoy joe

 

[jdurham]

mopar2ya,



Thanks. No offense taken, I'm just trying to figure out the problem... Bush said that increased idle speed shortened pump life , so I want to figure out what to do next...



Thanks.

 

[BushWakr - RIP]

It isn't the increased idle that shortens pump life... I think that message got kinda twisted. . I'll have another wack at it . .



When turning in the "full fuel screw" the pump reaches a point were this adjustment results in a higher idle. . (Due to the screw setting/effect)

When this point is reached we are beginning to "infringe" on the pump's life span. The higher idle is a symptom, not the cause.

You are basically increasing the pump's internal pressure/load so that impacts pump lifespan/durability.

Some will not see/have any major impact and others will end up with noticable impact.



Hope that clarify's this a bit more... .



Many of us are in the high risk area with our tuning/tweaks...

We can expect a shorter pump life than those who do none of these things.

I have never had an idle of less than 800-850 RPM. If idle was less, I'd reset pretty quick.

This assures a decent RPM to maintain oil pressure and enough RPM to keep the idle (on auto's) at a decent level, not to mention the impact of AC on idle speed.

As I approached the max setting on my pump, I was unable to bring my idle RPM below 850. This was because the threaded rod on the throttle linkage was not long enough to compensate.



Bob.

 

[Power Wagon]

Originally posted by jdurham

Greenleaf, I don't have a clue as to how to make the governor smooth the idle. When I did this, I put the pods in and put two turns in on the fuel screw. I did nothing to the timing, so I don't know where it is, and don't know if that would help.



rick and Jay, I have noticed that my idle seems to fall off a little after a long wide open highway pull. I get off on an exit ramp and stop, and the motor seems to idle lower, rougher, and the oil pressure gauge drops (sometimes to zero), and the oil light comes on. I might drive another block and stop, and the problem goes away. I find that to be puzzling, since it is inconsistant, and I can't think of anything that would change the idle like that.

The injection pump is getting quite hot, and the thinner fuel is harder to pump... so, it pumps less fuel (and more bypasses the injectors, too) causing a slightly slower idle.



My truck will do the same.

 

[Greenleaf]

If you haven't yet I'd be looking into a timing adjustment. This will be my first mod I'll be doing to my truck. Just had the SP144 delivered today. The wife doesn't think I need to do any engine mods, so I reminded her who's boss and settled it. Will begin the adjustment just as soon as I finish the dishes and take out the trash.



When performing pump mods to the farm tractors, I always look at timing and adjust. The best method is to use "port closure". This method will eliminate error due to worn timing gears and ever present inaccurate factory timing marks. These can and do vary. By removing delivery valve from #1 fuel port and rotating pump up to the point when fuel flow stops this is the point of port closure [true start of injection]. Doing so you have eliminated inaccurate marks and worn parts. I suppose this method could be adopted for use on our truck engines. Not so sure it would be necessary as the 1/8" advance seems to be the popular method.



Upon turning up the pump on the tractors they seem to run faster at slow idle. Also notice erratic governor operation. By adjusting gov settings, it has helped some but the most effective solution I've come across is in the replacement of worn gov components.



Would be nice if we could hear from someone who has recently installed a fresh pump. Perhaps this condition is related to worn gov components or simply isolated to my particular application.







Continue to fund : The COALITION TO DENY RICE THE RIGHT OF PASSAGE... ... ... . buy more DIESEL!!!!!!!!



Scott