1HDT Rough Idle

[crankycruiser]

1HDT Rough Idle - PROBLEM SOLVED.

now i found another thread on this topic, but everyone pointed to the ACSD.

Now my ACSD has been removed by the previous owner.

Has anyone got any other ideas what it may be?!?

Idle is currently set at around 800 rpm. its basically always rough unless the motor is under load (in gear and moving).

Im thinking maybe an air leak?

Motor was rebuilt 25k ago and balanced. Running a Gturbo pushing 25psi. goes great but the idle is driving me nuts!

Ray

 

[roscoFJ73]

If it was an airleak it would be very difficult to start. The leaking would have to be really bad to affect the idle.

When was the pump last serviced?

 

[finderscuba]

now i found another thread on this topic, but everyone pointed to the ACSD.

Now my ACSD has been removed by the previous owner.

Has anyone got any other ideas what it may be?!?

Idle is currently set at around 800 rpm. its basically always rough unless the motor is under load (in gear and moving).

Im thinking maybe an air leak?

Motor was rebuilt 25k ago and balanced. Running a Gturbo pushing 25psi. goes great but the idle is driving me nuts!

Ray

Check the fuel tank pickup filter? These can get pretty crudded up. Pull the back seats and under the carpet is the access door.

Otherwise, check compression and injectors.

 

[Tapage]

When was the pump last serviced?

and injectors ..

 

[Cancruiser]

Check the fuel tank pickup filter? These can get pretty crudded up. Pull the back seats and under the carpet is the access door.

Otherwise, check compression and injectors.

Don't mean to hijack the thread, but I never knew there was a primary filter by the tank. Do you happen to have a picture for the access door. Or is it in plain view once the back carpet is up?

 

[roscoFJ73]

Don't mean to hijack the thread, but I never knew there was a primary filter by the tank. Do you happen to have a picture for the access door. Or is it in plain view once the back carpet is up?

The fuel pick up has a piece of gauze wrapped around it.

 

[BCR4619]

Don't mean to hijack the thread, but I never knew there was a primary filter by the tank. Do you happen to have a picture for the access door. Or is it in plain view once the back carpet is up?

*Sigh* lol

https://forum.ih8mud.com/diesel-tech-24-volts-systems/437257-hdj81-fuel-suction-hose-filter-wow.html

 

[crankycruiser]

thanks for the replys fellas.

Pump and injectors were supposedly rebuilt 40,000 km ago.

I wouldnt suspect that the intank filter is blocked as im not having any issues higher in the revs.


so had a bit of a fiddle, found some cracked hoses, but it still didnt fix the problem. then i came across this little bad boy again.

main fuel is on the right, the little one on the left what does it do?!?

Me and this little screw had a run in when i first got the car, I wound it in thinking it was the main fuel screw.... duh.... and ive no idea if its back in the right position.........

so with it idling it adjusted it to see what it did, and wouldnt ya know it the idle went up and down according to the adjustment of the screw... so whats it bloody do?!?! seems like some sort of "mixture" screw for low revs??

*edit* have been told it was the idle adjust screw. but i thought that was external and pushed on the actual throttle control arm?!

 

[Tapage]

*edit* have been told it was the idle adjust screw. but i thought that was external and pushed on the actual throttle control arm?!

yap .. that's the way that it works .. same way that AC idle up ( vacuum device ) works ..

 

[finderscuba]

The one on the left is the Dash Pot. It adjusts idle speed. Seems redundant to me as there is an idle speed adjuster that pushes on the speed control lever. Maybe someone else can offer a better description of how the dash pot works. The FSM mentions it but it's not obvious how it functions.

 

[BCR4619]

The one on the left is the Dash Pot. It adjusts idle speed. Seems redundant to me as there is an idle speed adjuster that pushes on the speed control lever. Maybe someone else can offer a better description of how the dash pot works. The FSM mentions it but it's not obvious how it functions.

Isn't that the Total Fuel Screw? Or something to that nature

 

[finderscuba]

Isn't that the Total Fuel Screw? Or something to that nature

Dash pot.

 

[crankycruiser]

So it's a dash pot.... What's its function? Is it just another idle screw ?

 

[roscoFJ73]

So it's a dash pot.... What's its function? Is it just another idle screw ?

Its a kind of damper I think,it regulates the idle,stops it from fluctuation,.
It also stops the engine from stalling when you back off on the accelerator quickly.

Its suppose to be set when the pump is on the bench,then you use the idle screw or hand throtle to increase/decrease the engine speed.

 

[crankycruiser]

Thanks rosco

 

[crankycruiser]

So I put a new set of Injectors in this week, reco ones from a reputable place.

Still got the same rough idle tho!

 

[Squash]

Try pulling the fuel solenoid out and check the filter below, this may be clogged!
Other than that good to know if it smokes, black(unburnt fuel) blue(oil) white(coolant) may change when warmed up.

There is a fuel screw which can adjust fuel, uses a deep 12/14mm socket and flat screwdriver, you need to disconnect the throttle linkage in order to make this easy. Mark where you start and end the settings, be sure to hold the set screw when locking the nut because the setting may move. Adjust by 1/8 turns till she smokes and then fine tune. If all else is good my guess would be more fuel!!!

Lastly: Because the fuel set screw increases or decreases the amount of fuel going to the injectors you need to adjust the idle accordingly, therefore at the front of the IP you have a double nutted 10mm idle screw, loosen the outer nut and adjust rpm via your tach to specs.

Would add pics but away for now PM if required.

 

[hybric4x4diesel]

hi ,i suspect the injectors are out of tune,the 1HDT normally has two stages injector.so make sure whoever is doing the job must follow fsm standard .every steps are explain in detail nothing special about it.but since it is a two stage system then if one or multiple injectors or not set properly then imbalance rotations will be. i have done quite a bit over here.and secondly be sure used factory nozzles & installed the copper washer with the same thickness. they are a few difference washers thickness was used on these model .hope this will help.

 

[gbentink]

So I put a new set of Injectors in this week, reco ones from a reputable place.

Still got the same rough idle tho!

Souinds to me inj pump or small air leak. A small air leak wont stop it starting - but will cause it to be less than smooth. I ha that experience a few weeks ago and found a air leak around the fuel filter hoses where someone had done a dodgey job. After fixing that it was all smooth; add to that 26psi with a Bad Boy 1 it was a new car

 

[roscoFJ73]

hi ,i suspect the injectors are out of tune,the 1HDT normally has two stages injector.so make sure whoever is doing the job must follow fsm standard .every steps are explain in detail nothing special about it.but since it is a two stage system then if one or multiple injectors or not set properly then imbalance rotations will be. i have done quite a bit over here.and secondly be sure used factory nozzles & installed the copper washer with the same thickness. they are a few difference washers thickness was used on these model .hope this will help.

Australian injector shops are well versed in 1HD T as they have been dealing with them for over 20 years,not that they cant make a mistake,but Im guessing its in the pump settings or there is wear in the pump around injector head.

The engine was rebuilt 25k ago,maybe its the pumps turn.