Hot IdleProblems

[d6]

Here's my recentley purchased '86 ae86 4age levin



My problem is hot idle . when the engine is cold it revs fine at idle ( occasionly 2300 rpm , but pick the throttle and that settles out. ) when the engine reaches 45% on the scale and the engine is under no load ( neutral , no rear heated window ) the engine revs up and down between 700 and 1800 rpm this makes crawling in traffic difficult and sounds terrible too. ( grief from the missus ) if a load is put on the engine , half clutch or sometimes lights , heater & fans on, the idleing settles for a few mins.

i've checked coolant level , this was low but filled and no change. btw a sports air filter is fitted. i was told this could affect it. the valve cap in the throttle body was repalced with a tyre cap that didn't make any diff either. a friend mentioned it could be a leaky vaccuum pipe somewhere.

where and what should i check next ?

i'm still kinda green ya see.

[d6]

any takers ?

[banpei]

It sounds like the problem Oldskull also suffers from:
http://www.aeu86.org/viewtopic.php?t=2500

[JonAE86]

TPS sensor is faulty.

[byd1380]

I had this problem on my MG Midget (4AGE installed). It was fine when engine cold, but when it warmed up it would hunt all over the place. I narrowed it down to the IAC valve under the throttle intake. I took it off and replaced it with a flat sheet of Aluminium, and just linked the two water pipes together, car now needs a few pumps of the throttle to get started and then takes a 30 secs before it will idle, but after that, not a problem.

Ivan

[robokill]

you can screw up your idle to 1k rpm which is fine. The screw is next to your intake!

[NZ Trueno]

When my ae85 idles it is at about 500 - 550 rpm, this is far too low. sometimes when i am just sitting at the lights the car stalls itself which is very embarrasing (either people think i am a crappy driver or they know i have a bad car http://www.aeu86.org/viewtopic.php?p=41074#41074)

I figure that screwing up the idle should fix this but i dont know how, i dont have a 4 series engine either, it is a 3au. Can someone help me? i need to know what i am looking for and where it is to increase idle speed.

[Ivan141]

I think carbs have some sort of idle air screw too. There are a few guys that know their way around those carbs here. You could try sending Ben a PM, his username is 1974KE25 around here, he usually knows his way around about every toyota there is.