Offroad-Express

Sometimes has rough idle, every now and then, seems alright off idle and at cruising speed, no smoke or anything, fuel filter is not very old, and has clean diesel, any ideas ?
Non turbo motor..

engine warm or cold?

When its warm, does not do it all the time

tga_4x4 wrote:When its warm, does not do it all the time

Manual or auto?
If auto does it improve when you shift to N?

The Stranger wrote:

tga_4x4 wrote:When its warm, does not do it all the time

Manual or auto?
If auto does it improve when you shift to N?

No its a manual...

Is it the model with EGR? if so maybe try disconnect the EGR

slide wrote:Is it the model with EGR? if so maybe try disconnect the EGR

No egr, she is the basic model, its weird it does not do it all the time, its almost a out of balance feel as she vibrates the truck, if i lift the revs 200 rpm its goes back to its normal self, idle is around 650 i think..

I wonder if its just the idle speed getting a bit low and engine loosing the rpm it needs to run smoothly. Maybe try wind the idle screw up a touch to 700-750rpm? Thats what most engines seem to idle at.
Double check theres no idle up thats holding it on either (ie that it is returning to idle stop).
Good luck and let us all know when you find the solution

Couple things to try.

Clean throttle body inside around butterfly with rag and carb cleaner untill spotliss, spray onto rag not into moter. may be causing your low idle problem. recomend doing this before winding up throttle stop screw.
Rough idle possible have something to do with one of the injectors, Im thinking possibly playing up at idle. when changing fuel filters we used to put bottle of wyns diesel intector cleaner direct into fuel filter then prime up and start holding revs up for a while.
otherwise sound like itll need a bit of diagnosis, possible things like timing issues valve spring pump issues, hell could be anything
hope this helps.

ladeda wrote:Couple things to try.

Clean throttle body inside around butterfly with rag and carb cleaner untill spotliss, spray onto rag not into moter. may be causing your low idle problem. recomend doing this before winding up throttle stop screw.
Rough idle possible have something to do with one of the injectors, Im thinking possibly playing up at idle. when changing fuel filters we used to put bottle of wyns diesel intector cleaner direct into fuel filter then prime up and start holding revs up for a while.
otherwise sound like itll need a bit of diagnosis, possible things like timing issues valve spring pump issues, hell could be anything
hope this helps.

Throttle body butterfly

Sounds like air in the fuel, can be caused by crap fuel filters (cheap ones), or the injector pump is a bit dodgy on the governor. Could also be a injector semi-seizing.

Cheers,

sibainmud wrote:

ladeda wrote:Couple things to try.

Clean throttle body inside around butterfly with rag and carb cleaner untill spotliss, spray onto rag not into moter. may be causing your low idle problem. recomend doing this before winding up throttle stop screw.
Rough idle possible have something to do with one of the injectors, Im thinking possibly playing up at idle. when changing fuel filters we used to put bottle of wyns diesel intector cleaner direct into fuel filter then prime up and start holding revs up for a while.
otherwise sound like itll need a bit of diagnosis, possible things like timing issues valve spring pump issues, hell could be anything
hope this helps.

Throttle body butterfly

Sounds like air in the fuel, can be caused by crap fuel filters (cheap ones), or the injector pump is a bit dodgy on the governor. Could also be a injector semi-seizing.

Cheers,

ive seen alot of low idel problem caused by crap building up around throttle buterfly (insuficent airfilter changes). peoples first action is to wind up the stop screw instead of cleaning it.
agree with possible injector semi-seizing, probelm with injector pump, but as said needs diagnosis.

Without getting off subject, I didn't know a TD42 has a throttle butterfly.
Haven't worked on many TD 42's, but quite a few TD27's N/A's

Cheers,

They don't.

ha ha ha true my bad
was thinking generaly not vehicle specific hahaha

kinda like checking the vavle clearences on a rotary ay

Yep no throttle butterfly... has donaldson fuel filter changed reg., good clean air filer K&N, was thinking injector, may do the new filter and injector cleaner thing first, runs sweet the rest of the time, plenty of grunt ( well not plenty..needs a hairdryer strapped to the side of it..)

Donaldson good brand. Use injector cleaner as directed, not as posted above as it is quite acidic and in greater concentrations can be harmful to the pump and injector nozzles.
You would be right about the hair drier

Best of luck and report back any findings.

Cheers,

All my previous TD42's have had butterfly's in the intake, not sure what purpose it serves, perhaps they had an EGR setup. Don't know if it would cause these symptoms, but is the banjo filter clean? (if it has one fitted)

DaveM wrote:All my previous TD42's have had butterfly's in the intake, not sure what purpose it serves, perhaps they had an EGR setup. Don't know if it would cause these symptoms, but is the banjo filter clean? (if it has one fitted)

Where is the banjo filter situated ?

Will try to get a pic, it's under the banjo bolt on the injector pump. It's a fine gauze filter that you need to pull out with a dental hook/bent wire as you don't notice it in there. Not all pumps have them.

http://www.4wdaus.com/index.php?option= ... atest-news

Did not get a chance to do much, but with a tank of diesel from "z" seems to have change the truck , normally use mobil, but truck idles better, seems to be quieter and no more rough idle.. coincidence ??

I was recently told that 20 litres of aviation jet fuel (kerosene) in a tank acts as a good injector cleaner. Could try that too... It certainly burns OK as I've used it for extreme cold weather to lower the waxing temp.

Could be why some of those injector clean additives smell like kero....