1hd-fte rpm drops when AC engage (1 Viewer)

[Uwiik]

I have been struggling with idle to 1300 rpm roughness on my 1HDFTE LC100. On idle with AC clutch disengage I can go back and forth between D to N without any drop in idle rpm and engine is purring like a kitten. However, with the AC clutch engaged, idle RPM would go up to 900-925 when the gear is on N then drops to 800-825 and stays there when moved to D, engine would sound rough when this is going on, similar to what you would hear from one or two injectors going bad.

What could be the culprit? At first I was thinking about getting the all the brand new injectors verified again. However, I began to doubt it has anything to do with fueling upon realizing that with the AC clutch disengage everything are purring like it should be, engine would idle fantastically both on D or N, now perhaps the problem lies on vacuum leak from AC solenoid or something causing extra strain on the engine when AC clutch engage?

Fuel pump is new, all 6 injectors are new, all fuel pipes are new, compression has been verified, odo is 125000km. With diesel engine it’s either compression or fuel because there is no spark to consider, my truck is otherwise running fantastic with good fuel economy and plenty of power but something is not right between idle to 1300 rpm. Above that rpm everything is fantastic.

Please advise and thank you very much!!

 

[Dusten]

Idle speed is controlled by the ecu.

That said the fsm calls out 550-650 for idle speed on the 1hd-fte so you're idling quite high anyways.

 

[Jorgito]

Idle up on AC is standard, I didn't wire that up for my HD-FTE conversion as I don't see that as necessary. I would suggest connecting with 1hd-fte Facebook groups where most of the Aussies are and can suggest more. There is only a limited number of people with this engine on this forum, unfortunately.

 

[Dusten]

Idle up on AC is standard, I didn't wire that up for my HD-FTE conversion as I don't see that as necessary. I would suggest connecting with 1hd-fte Facebook groups where most of the Aussies are and can suggest more. There is only a limited number of people with this engine on this forum, unfortunately.

His is dropping idle.

 

[Uwiik]

What usually is the cause? And yes I am dropping idle

 

[OEMGUY0720]

It’s “possible” there is a leak in one or more of your vacuum hoses.

 

[Uwiik]

It’s “possible” there is a leak in one or more of your vacuum hoses.

High probability of this. Car been abandoned with dead engine and trans for 4 years before I bought it 2 years ago, restored it and just began driving and tuning it for a couple of months.

Can anyone be kind enough to share vacuum hose diagram/s of 1HD-FTE powered LC100?

Thanks a bunch beforehand!!

 

[Uwiik]

CORRECTION!!!

Apparently I am idling normally.

Dead on 600 rpm both on N and D with AC clutch disengaged/OFF. Idling silky smooth.

Slightly above 800 rpm with AC clutch engaged gear on N/P - Idling still silky smooth

Idling drops to 700 with AC clutch engaged and gear on D. This is where idle gets rougher with more felt vibration. Vibration is the worse at 1300 rpm and silky smooth at anything beyond that…

I basically cannot have two power OR vacuum hogging parts operating together (D gear and AC clutch ON in my case). I am not sure which one to chase down first but I think the two prime suspects would be fueling under 1300 rpm (dirty injectors?? Bad fuel pump?? Both brand new??) or vacuum leak.