wont idle when cold...

[*Steph*]

I don't think there's any paper in mine though

[jondee86]

The two little tubes on top are not usually looped together. One is used
for an electrically operated idle-up valve that takes air from the air
cleaner. The other is used for the fuel tank purge system, and sucks
fumes from the charcoal canister into the manifold. Some cars didn't
have a purge system fitted, and the tube was just capped off.

Tubes 1 and 2 are for the power steering idle-up. When you hit full lock
air passes from one to the other and raises the idle to stop the engine
stalling. When power steering is not fitted they are capped off.

Number 8 is a vacuum operated gadget for increasing the idle speed when
starting. It cracks the throttle open. Once the engine is running and there
is manifold vacuum, the idle speed drops to normal.

I'll have to get back to you on number 4

Cheers.... jondee86

[l1ttle_d3vil]

I know what waterline you're talking about, just had a look at mine but theres nowhere at all for it to join up to. this could be because my waterlines have been modified to suit a RWD [engine was originally a FWD].

its easy enough for me to run an extra line out of and back into my thermostat housing - would that work? I can just run a line from the engine side of the thermostat (where the warm water is) to #5 and then run another line from #6 back to the housing. that should be sweet won't it?

then the rest are just vacuum hoses etc so its easy enough to connect them up once I know where they go to...

thanks jondee, that helps. seeing as the engine is in a '75 corolla theres definitely no P/S. can I just connect a hose between those two like the lines on the top? or do they need to be blocked off separately?

[jondee86]

Nope.... don't loop them. If you do that the idle-up circuit will be
permanently "ON". Cap both of them off. I believe you can buy little
rubber caps at Super-Cheap made for the job. I measured mine at
6 mm dia. Or use a short length of tube with a bolt up the end

The little tubes at the top both suck, so there should be no problem in
looping them together.

Cheers.... jondee86

[jondee86]

OK... I checked. On a NZ new AE86 number 4 tube is capped off. So
you can cap that one off too. It's a larger tube, maybe 8 mm. My guess
is that it is used in some markets as part of a pollution control system.

Number 7 connects to number 8 to operate the vacuum idle speed
increasing gadget.

So there you go.... I'm pleased you started this thread as I have been
researching the same questions

As a matter of interest, I'm pretty certain I have read about people not
bothering to run water to the Auxiliary Air Valve. It is primarily a cold
starting aid, and apparently unless you live in an area where it gets down
to below zero, you don't really need it. I've never tried taking the water
off the valve, but maybe someone else has ??

Cheers.... jondee86

[l1ttle_d3vil]

awesome, thanks for that. it answers all my questions.

I will see about setting this up tommorow and I'll try it without water first to see what its like and let you know.
i'm also glad i started the thread, i've lost count of how many mechanics have seen my car, whether out of passing interest or to try fix problems yet no one has said anything about me missing this stuff. maybe they just presumed I'd blocked it off myself?

one of the biggest problems i've been having with my car is the engine won't start consistently each time, its something to do with the starting process and its getting a different/false reading each time. sometimes it will barely idle and is definitely not drivable (revs won't lift, stalls etc) yet other times it will start up perfect. is it likely to do with the fact I don't have the #8 idle speed valve on there??

thanks for your help guys. much appreciated

[2LTR Rona]

answered a few questions for me too

let us know how ya get on

[l1ttle_d3vil]

just one more question...
the back of the idle speed valve doesn't actually reach the accelerator bracket when it's fully extended, i'm guessing it should?

should there be a screw or something where the arrow is that you can adjust to press against the back of the valve? if so, how hard should it be against the valve? just touching? or should i push the valve-rod in so its about midway in its travel, and screw the screw in to there or what? (hope that makes sense)

and where should the valve-rod be when the engine is running etc? right in as far as it can go? and it should be right out as the engine is cranking? just want some sort of idea of what it should be doing so I can be sure it's doing the right thing.

edit - oops, here's the pic

[JamesM]

are you sure about the operation of number 8?
yes there is supposed to be a screw on the accelerator thingy.
but i know it plays a part in what the revs do in between changing gears.
and it doesnt seem to really play a part in what hapens when starting, but if u got that from the book i guess its right.
main thing for idle is the auxilary valve tho. those vavles often poo out.
if its idling so low that its stalling at least u know u got a good vacuum
so just sort the aux valve out and then adjust the idle speed with the idle speed screw.

[jondee86]

I haven't had a chance to study one working just yet. But looking at
the valve on a non-running engine, there is a small bolt that goes in
backwards so that the head rests against the knob on the valve. A jam
nut goes on the other end to hold the setting. Since it is a vacuum
actuated valve, the knob will retract when the engine is running.... and
the only time it will be all the way out is when there is no vacuum =
engine not running.

According to the instructions for a similar valve on a carbed 4A-F you
set the valve by adjusting your idle to 1400 rpm on a WARM engine with
the vacuum hose to the valve DISCONNECTED from the valve, and
blanked off (poke a small bolt or similar in the end of the hose). This
stops air leaking into the manifold and raising the idle.

Then reconnect the vacuum hose, and the knob on the valve should
retract and the idle should drop to 800 rpm.... assuming all other idle-up
systems are OFF.

Two things.... since it will be difficult to set your idle properly with the
Auxiliary Air Valve stuck somewhere between open and closed, do as
someone else suggested... block off the hole in front of the throttle
butterfly with a rubber plug. Then use the idle adjustment screw.

Second thing.... when the engine is off, the vacuum operated valve
should be capable of holding the throttle butterfly slightly open (after
you have adjusted the small bolt). If it can't do that, then none of the
above is worth a pinch of s**t !!!! I'll check a runner in the weekend
and let you know

Cheers.... jondee86

[jondee86]

Hear what you are saying ae-86_lad.

Until I check a functioning valve, I can't be sure exactly what it does.
What hangs off the 4AGE throttle body varies a great deal between
model, year and market spec. Some have a similar looking gadget
that is actually a Dash Pot (or damper). This is designed to stop the
throttle "snapping shut" when you back off. It slows the throttle return
in the last part of it's travel. To do with reducing emissions I think.

Cheers.... jondee86

[jondee86]

While we are on the subject, I'll mention something that was posted
here by someone else. Anything that leaks air into the intake plenum
on a MAP sensored engine is an "idle-up" valve.

So before you can expect to get a decent idle and easy starting you
should check :=

>> that there are no disconnected or leaking vacuum hoses.
>> no leaking gaskets on the intake manifold.
>> no looped hoses that leak air around the throttle butterfly.
>> that the butterfly is seating properly.
>> that the butterfly shaft bushings are not mega sloppy.
>> no leaks in the brake booster vacuum line.

When you are certain that you have no uncontrolled leaks, you can
start to make adjustments to your controlled "leaks" which are the
Idle Adjustment Screw, idle-up VSV and throttle butterfly.

If you have a functioning Auxiliary Air Valve, that is a temperature
controlled idle-up that operates independently of any other system.

There are a whole bunch of other factors that will also affect how
your car idles... feel free to post them

[jondee86]

Well I had a look on a NZ new 1985 AE86, and that little vacuum
servo does try and crack the throttle open when the engine is off.
Retracts about 5 mm when the engine is running. But, problem is
that the throttle return springs are stronger than the servo spring,
so it does diddly squat !!! I wouldn't bother trying to fix it.

Other thing I noticed was another electrically operated idle up valve
connected to tube #4 and taking air from the air cleaner. So I had a
bit of a play with the controls inside the car to see what it did.

Cold idle on startup 2200 rpm (way too high !!!)
Hot idle 1200 rpm (OK... a bit high, but liveable)
Hot idle with lights/demister on 1400 rpm (small VSV on)
Hot idle with aircon on 1800 rpm (large VSV on)

Which helps to explain why I could always feel the aircon click on
and off while driving. There is an air screw on the VSV which should
be able to drop the revs a bit.

So there you have it.... yours will probably be different

Cheers...... jondee86

[l1ttle_d3vil]

ok I set it all up tonight, minus the water lines. so I blocked off 1, 2, 4, 5 and 6 all separately.
it started up and idled by itself sweet, but I'm not sure if it was totally cold. im pretty sure it was, i'd only driven it up the road a few hours earlier but I will try it tomorrow to make sure.

it also idles alot higher now too, about 2000 when warm I think, then once it warms up the revs start lifting and dropping randomly. its pretty much back to exactly how it was before a mechanic tuned it up a bit, done the timing and reset the TPS etc etc - that type of stuff.

what would the next step be from here? presuming it idles properly when cold (which I will know tomorrow) im guessing it should be sweet to leave the waterlines off. should I adjust the idle screw so it idles lower? or do I need to connect the waterlines so it idles lower once it warms up?


cheers

[jondee86]

Have you connected #7 to #8, or blocked #7 off ??

Have you blocked off the air port in front of the throttle butterfly ??

I was getting about 1000 rpm difference between cold idle and hot
idle due to the action of the Auxiliary Air Valve. So you should see
about the same if you block the air port off with your finger while the
engine is running. Once you have a stable idle (hot or cold should make
no difference if the air port is plugged up), THEN you can use the Idle
Speed Adjusting Screw.

Set the idle to say 1000 rpm. Let it sit and see if it starts and idles OK
in the morning. If it does, you don't need the water lines hooked up.

Cheers..... jondee86

[l1ttle_d3vil]

yes, I've connected #7 to #8.
sorry, i'm a bit confused as to what air port infront of the TB you're talking about...which one is it?

[jondee86]

It's the lower of the two holes on the inside of the throttle body, on
the aircleaner side of the butterfly. In the page from the manual that
you posted earlier, you can see the mechanic putting his thumb over
it....

Cheers..... jondee86

[l1ttle_d3vil]

sweet, will check it tonight.

[l1ttle_d3vil]

i've checked all the revs etc, started a new thread here with the results.

viewtopic.php?p=393298#393298