High idle - the endless saga

[Sprinter86]

Oh FFS this page refresh is doing my fuckin head in!! I give up.

I more or less agree with slydar, i had more info that might help aswell, but if i try and explain my page will refresh on me again.

[Golberg]

Using a smallport TB for the record.

I did modify it to suit the RWD manifold breather (drilling out one side and expoxied the other up). But the cut 'n' shut job is done in such a way that the original breather line is welded over and sealed. I haven't double checked it, but I am pretty sure the port in the throttle body is blocked off on the current manifold now too. Will check again.

Idle control is still the original thermostatic system, but it seems to still work as when warm the idle comes down to about 1800 rpm.

I'll check the butterfly on the throttle body too, it isn't actually meant to seal entirely is it? I know mine is at a slight angle when the throttle is released. And would allow a tiny bit of air in. Where would it normally pull air from on idle?

[Nikkojoe]

It should be at a slight angle when the throttle body is fully closed - returned completely position(ie no visible gaps at the top and bottom of butterfly). If there are, your throttle cable or throttle return screw needs adjusting.

Idle level is controlled via the idle screw on the T/B.

[ke70dave]

yer id be looking at your throttle body

i had this drama when i first got my bigport goin, just wouldnt idle low at all.

what i ended up doin was getting rid of every stinking pipe or hole in the throttle body, either plugging them or screwing a bolt into them. got rod of all of the themostat controlling devices, made a plate up for that.

and to adjust the idle i just use the little alen key bolt that cracks open the throttle itself (like on a carby)

the only problem with this is there is no idle up when its cold, it always idles at 900 rpm, so can be a pain when its real cold, i usually just let the engine warm up for a minuite or 2 and its fine. though time will tell as we start to get colder and colder temperatures.

i did start the car in toowoomba at midnight about 3 weeks ago, and it started up first time and was quite surprised how well it drove given the temperature (prolly 10 deg or something maybe). so its not that bad.

[Golberg]

Alright, new information, did some testing.

When I block the bottom most hole inside the TB (I think it feeds the air supply to the thermostatic idle adjustment), the idle comes down to 1200 rpm (from 2200). Now even if the thermostatic unit was working correctly it shouldn't change the idle by 1000 rpm now should it?.

When I put my hand over the entire throttle body the engine just wants to stall.

Note: These tests were done with the idle screw all the way in (minimum air flow), and with the engine cold.

[Roo.]

dont have air in you cooling system? can cause a high idle

[--Redwork--]

Cover the hole or block it up on the other side...
I just blocked everyhting I could on mine.. Then set idle with the buterfly adjuster..

See told you it would be that..