Idle hanging at 2000rpm

[RadoTD]

Hey, so I've just started playing with my injection pump... leaving stock boost for now but trying to pull some more power out of it. Engine is bone stock until now, 1.9L AAZ with it's stock (joke) boost pin.

I've turned the max fuel screw in to where I'm just getting a small puff of black smoke if I floor it from 1500rpm, no smoke anywhere above that though. Throttle response and power are great

My only problem is that the idle will sometimes hang at about 2000rpm.

I've adjusted the idle down so when I start the car, it sits at 900rpm, but once I'm driving, if I rev the engine or push the clutch in at 2000rpm+, the idle doesn't return back to normal. At 1500, it usually very slowly returns back down.

I'm wondering if I'm boosting enough at 2000rpm with no load to hold my boost pin further in? Could shimming or replacing the spring on my boost pin solve this? The fact that I puff a cloud of black smoke at low rpm's might mean my spring is too soft as well. I know I can move the throttle on the splines 1 notch towards idle, but I don't think that's my problem here. Any ideas?

[Rabbit on Roids]

you probably screwed the fuel pin in too far, or you shimmed the governor wrong...

the puff of black smoke is un burnt diesel, the turbo isnt spooled at idle. it has to spool up before it starts boosting and cleaning up the smoke.

[rabbitman]

The boost pin being pushed in won't affect anything unless your holding the go pedal down/mostly down.

Turning the max fuel screw in messes with the idle pretty bad, like really low idle speed with a cold engine and a high idle when the engine is hot.

[RadoTD]

I haven't touched the governor yet.

Figured out what it is though... for some reason, my throttle isn't always going back to the min throttle screw. I turned the max fuel screw out about 1/4 of a turn which made the problem slightly better for now, but it still sometimes likes to hang higher. The thing that doesn't make sense though is that if it's sitting around 1500rpm, I can drag the clutch to drop it under 1000 and it stays there. Maybe some internal pressure on the throttle shaft holding it out a bit..

So, looks like all I have to do is move the throttle on the shaft and set up my max fuel and idle again!

[rabbitman]

Will it hit the idle stop screw if you push it towards it?

I had a problem just like that (except it would slowly go down to idle) and fixed it by filling the "dish" in the IP lever with a spray lube, it was just gummed up.

[RadoTD]

Will it hit the idle stop screw if you push it towards it?

I had a problem just like that (except it would slowly go down to idle) and fixed it by filling the "dish" in the IP lever with a spray lube, it was just gummed up.

Yeah, I can push it back. Sometimes it goes right back on it's own, sometimes it sits .5-1mm away. I got a little trigger happy with some jig-a-loo, didn't do much though.

[Rabbit on Roids]

I haven't touched the governor yet.

Figured out what it is though... for some reason, my throttle isn't always going back to the min throttle screw. I turned the max fuel screw out about 1/4 of a turn which made the problem slightly better for now, but it still sometimes likes to hang higher. The thing that doesn't make sense though is that if it's sitting around 1500rpm, I can drag the clutch to drop it under 1000 and it stays there. Maybe some internal pressure on the throttle shaft holding it out a bit..

So, looks like all I have to do is move the throttle on the shaft and set up my max fuel and idle again!

no, your thinking is wrong. you need to back your fuel screw out more. the fuel screw or governor mods are what causes that to happen. i know what makes it do this because my engine used to do this REALLY BAD. like it would hang, then it would GAIN rpms. and like you say, drag the clutch and it would be fine. if you back it out another 1/8 turn probably, it will probably make your problem non existent.

if you move the throttle on the throttle shaft, you probably will have no throttle. or if you move it the wrong way, it could just run away. try spraying some lube of some sort on the spring assy and throttle shaft. it makes it alot easier to move, least it did with mine.

[hippiekiller]

I agree that the fuel screw is just that, a 'full load' adjustment, without proper adjustment of the governor mechanism or the LDA all turning that screw does is mess with your idle and make your engine run too hot...also, I've found that disconnecting the throttle cable should let your engine idle at the correct speed if everything is well lubed...then bumping it by hand will let you know if its hanging up on anything....