12HT Revs bouncing below idle

[logitecdogdog]

I have a 12HT and when cold because it idles abit lower its idle will go rump rump rump.... and the lights will come on the dash as it nearly stalls if i raise the revs its fine and when its warm its fine as it idles abit higher this issue still happens when warm if the revs drop below idle say if im in traffic idling in 1st gear it will romp romp romp allong and stalls very easy it has no desire to go at idle it is pretty much a petrol it wont idle up things off road and stuff it needs revs like a petrol it goes well apart from below idle people say raise the idle but if the revs reach that zone which they will in some situations it will still do it. Another example is if i just slowly let the clutch out with my foot on the brake it doesn't just labour like anny other engine it goes romp romp romp. Anny help will be greatly apreciated as this problem is very annoying

 

[logitecdogdog]

This is a video of it idling cold
http://youtu.be/hfA2Yfy_M8s

 

[roscoFJ73]

I get headaches trying to read sentences 7 lines long

So ,what are you trying to idle the engine at?

Do you use the hand throttle when its cold? That is one of its purposes.

Does it have high klms?

 

[roscoFJ73]

This is a video of it idling cold
http://youtu.be/hfA2Yfy_M8s

Ok ,I can see it has 540000 klms on the speedo. I suspect one or more cyl have lower compression than the others and they are not firing completely
DO you get puffs of smoke from the exhaust in time with "romp romp romp" noise?

For me,that would confirm a compression problem when cold

 

[logitecdogdog]

im not sure if it blows smoke in that way il have to check. The thing that confuses me is it literally goes like new it runs very well and has plenty of power and doesn't blow much smoke. Its just below idle and the idle is at about 500-550

 

[hj 60]

advanced pump timing:

How is the maintenance? fuel/air filter, water separator?, valves, injectors, compression test as it seems that one cilinder is not working along, bad/old fuel?
Adjust idle tpo factory (650 for non turbo) and start with a little throttle to build oil pressure and injector pressure, are you sure you dont have an air/vacuum leak (check hoses)
Maybe clean/test the injectors?

 

[HJ61 12HT]

For starters I think your cold idle up is not working, there is a valve that is open when cold that lets vacuum through to the idle up actuator.
That would be the first thing to check and adjust.
When you start from cold the idle should be up around 850rpm and should drop down to about 650 once warm typically...

 

[Dieseler]

What he said cold idle

 

[logitecdogdog]

Im not doubting you guys but It confuses me how it can be like a normal healthy motor exept for below idle and have low compresseion in cylinders and things like that. Also a Bit annoying today driving a petrol 4cylinder hilux that has 10x the power around idle compared to my 12ht. And What do you guys rev to when you let the clutch out I have to rev to 1100-1200 to really go annywhere and not ride my clutch

 

[hj 60]

I can not say what is wrong but only to check things so the list of possible wrong things gets smaller. I can drive away from idle, but must be carefull not to let it stall.

Yours sounds like advanced timing, but advanced timing can sound like fuel starvation, fuel starvation can sound like air in the line, air in the line can sound like faulty injector, faulty injector can sound like suger in tea, sugar in tea is to be avoided as stevia is a nice litte plant from south america that even diabetics can use, stevia is prohibited is europe because we have a lot of suger beet farms and so we continue to put toxic sugar waste in kids.

- how did I get to stevia?
Just do a little wrenching or go to a local head.

 

[blis]

You're idle rpm is too low, 12ht should idle around 700-750 when warm and 1000'ish if the cold idle-up kicks in...

 

[Greg_B]

All at normal operating temperature:

From the FSM for 2H/12HT

2H-12HT M/T idle is 650RPM
2H AT idle is 750RPM
12HT AT is 770RPM

PS idle up is 820RPM (if so equipped)

AC idle up in MT 12HT is 950RPM

AC idle up in AT 2H/12HT is 950RPM in neutral, and 800RPM in D range.

hth's

gb

 

[logitecdogdog]

An iteresting thing I found is that the cold start idle raise thing has never done annything and it doesnt rev up when using the power steering

 

[cruiserpilot]

HJ 60 , IMHO you should route your exhaust out from under your truck. Exhaust can lead to rust.
I like your truck, looks really good.

 

[Hj assault]

Here is the instructions how you can adjust 12h-t idle properly. This is fairly common problem on 12h-t. Sorry my bad english, but lets try.

Behind that big covernut (big arrow) is idle speed regulator screw. Turn it open. Then idle speed adjusted its own screw (little arrow) 700 rpm. Next tighten the idle speed regulator screw so the idle sets approx. 750-800rpm. Then rev engine and look that the engine is not stall. If it stalls, then tighten the idle speed regulator screw little bit more (big arrow) and lower the idle (Small arrow), and thats it.

 

[Dieseler]

I was driving mine the last couple of days and noticed when warm it idles around 700 at this range the motor has a little rough vibration when I was sitting at a red light I lightly pushed the gas pedal and played with the revs and noticed if I raised it to 800 or just above that it smoothed right out , also I noticed that the clutch when I take off from the 700 point was touchy to a point of almost stalling with no increase in the pedal revs .
My normal habit when driving my 61 I usually give the pedal a light tap which kicks up the revs before I released the clutch just a strange habit I have compared to driving the rest of my LCs I thinks it is because I like the growl it gives off just as I start off at the green light.

 

[pistonslaps]

sounds like a boost leak to me

 

[Jentuh]

Here is the instructions how you can adjust 12h-t idle properly. This is fairly common problem on 12h-t. Sorry my bad english, but lets try.

Behind that big covernut (big arrow) is idle speed regulator screw. Turn it open. Then idle speed adjusted its own screw (little arrow) 700 rpm. Next tighten the idle speed regulator screw so the idle sets approx. 750-800rpm. Then rev engine and look that the engine is not stall. If it stalls, then tighten the idle speed regulator screw little bit more (big arrow) and lower the idle (Small arrow), and thats it.

I'm also having the issue that the rev's drop below idle when coming form higher rev's. It is to my opinion caused by the fact that internal wear in all the linkage arms makes the reaction of the pump too slow on it's idle setting. The adjustment you suggest will increase spring pressure on the idle controller, effectively increasing the gain of the controller. This might work, but when I tried it made the regulator unstable. The engine was getting nervous on it's idle controller since the increase in gain (P action if translated to a PID controller) makes it unstable.

I learned to live with it. Idle rev a bit higher to compensate this effect a little. Only proper solution is and injector pump overhaul I believe.