Adjusting cold idle - how to do?

[oldskull]

205t16 Wrote:i recently installed a new engine in my 86 and for some reson my idle speed when warm drops from 1100 to 1000 every couple of seconds up and down. any ideas on why this might be happening.

you may get some info here, http://www.aeu86.org/viewtopic.php?t=2500&highlight=

[Black Betty]

Hope this info helps lads!





The 2 little coolant pipes that go into the valve is to warm up the wax stat and allow the idle to drop down to the specifed 800rpm when warm!

[Knudsen]

Looks to me, that its not possible to lower the idle when the engine is cold...

[Ivan141]

It is, but not with any adjuster screws.. If you look closely in the first of the 3 little pictures above you'll see a hand with the thumb over the airport (which is also marked in the picture). You need to restrict this inlet, that way the amount of air that is bypassed when the engine is cod is less, and the idle will come down accordingly.

[Black Betty]

Ive nver let the revs bother me, all of my 4AGE engined cars ive owned (3 AE82's and 2 AE86s) have all revved at 2500rpm when 1st started(which doesnt last very long at all), but i find this no problem as it warms the engine up quicker, and once its got to normal operating temp it ticks over at 800rpm like a good little boy!

[Sanity Clause]

Step 1:

Make sure that the hot water is circulating through the AAV via the 2 rubber hoses.

If you disconnect the 2 hoses from the AAV, and then connect a piece of clear plastic tubing between them, you'll be able to see if water is circulating ok. You'll be able to feel when it's hot.

If everything appears to be OK, then go to step 2. Otherwise, read on....





The 2 pipes at the bottom of the photo above, are the ones that these hoses connect to. The top one is part of the thermostat housing and is the hot water supply.

If you find that water is not circulating properly, you could have a blockage in the pipe which runs from the heater.





That's the thinner one of the 2 pipes in the above pic. Water is pumped down the large pipe to the heater. The thinner one returns the water to the AAV.
This particular one was blocked with solid black gunge. Probably due to not using the correct coolant mix (or maybe just plain water?).

Here's what it looks like in situ...




If that is the problem, you'll need to take off the inlet manifold before you can unbolt it.
Once you've got the pipes off, see if water runs through them. If not, clean them out with a very long screwdriver or something similar!


Step 2:

If you find that hot water is circulating properly, and your tickover still doesn't drop, test the AAV. Remove the throttle body, and unbolt the AAV.





Carefully pour some hot water into the pipe.
If it's working ok, you should see the thermostat close (through the elongated hole on the left, in the above pic).





Here's the part number, if you need a new one.


Hope this helps,
Steve

[SutteR]

Great writeup Steve! Added to favorites.

[Ivan141]

Very clear write-up indeed....Banpei! put this one in the how-to section!