20v Blacktop High Idle

40vpurpletop
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20v Blacktop High Idle

Postby 40vpurpletop » Tue Mar 21, 2017 9:22 am

I'll try to keep it short. I searched the forum but got lots of unrelated posts.

Engine: 20v blacktop stock with power steering and A/C. No intake with ITG filter. Vacuum routing looks correct. ISCV was cleaned and is hanging behind engine with breather filter on the open end. Possible failing or failed VVT pulley.

Problem: Engine idles at 1500rpm

Symptoms: 1500rpm when warm. Was like this when I first got the car then a few months back it started to idle great at 900-1100 when warm and felt smoother but could be my OCD. Then started to creep back up so I changed the vacuum tubes. Old tubes slipped off easily and new silicone tubes fit snugly. After that, the engine started to idle at 1500rpm. I will check for leaks and the timing this weekend and update. I cleaned the butterfly valve and inside the itb so I don't think it's slightly open. I made sure to manually close it to see if it drops the idle but didn't.

Also, once warm and I accelerate and come to a stop, idle will be at 1400 - 1500rpm. After about 20 seconds or so of idling, the idle will drop 300rpm. Don't know if this is normal as I am unfamiliar with this engine.

With A/C on idle drops 300rpm to around 900-1100. Read there is idle up for the A/C but unfamiliar with how it works. Should it keep the idle the same before the A/C turns on?

Sorry I guess this wasn't short. Thank you in advance for any help.

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jondee86
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Re: 20v Blacktop High Idle

Postby jondee86 » Tue Mar 21, 2017 3:32 pm

Unless someone has been farking with the ITB's all the idle air for the BT will
go thru the ISCV. Therefore, if you have an idle speed problem, especially one
as you have described with the idle sometimes good and sometimes bad, the
ISCV is your first port of call.

Yes... I know that you have cleaned the ISCV, but did you check that you cleaned
it good ??? Did you take it off the engine, remove the solenoid (and thats all you
need to remove) and run carb cleaner thru the tubes until no more black crud
comes out ? Could you turn the spindle by hand and feel no binding and make the
valve "click" when it went full travel in either direction ?

Did you let the carb cleaner evaporate and then run some WD40 thru the valve
before putting the solenoid back on ? If you did all that it should work fine. If you
didn't, then make that your next tuneup job :)

AFAIK the AE111 does not use a separate A/C idle-up valve. The BT ECU adjusts
the idle speed using the ISCV. But there probably is an A/C amplifier and some
other stuff that you would need to take from the AE111 to provide the BT ECU
with the correct input signal for idle-up. If you don't have that extra stuff, you
will most likely need to grab an old style A/C idle-up solenoid from another Toyota,
and wire it to open when the A/C compressor clutch is energised. Maybe there is
still an A/C solenoid valve on the car or in that box of bits that came with the car ?

Cheers... jondee86
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persists in trying to adapt the world to himself. Therefore, all progress
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Re: 20v Blacktop High Idle

Postby 40vpurpletop » Tue Mar 21, 2017 5:03 pm

Thank you jondee86. I did remove the the ISCV and shot carb cleaner through it. I did not see any black crud come out of it nor any other stuff. I didn't shoot WD40 however. I didn't take apart the solenoid because I wasn't confident I could put it back together right as all the instructions I found online were too old and the pictures were missing.

I wouldn't be able to recognize A/C idle up stuff so I'll research that.

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Re: 20v Blacktop High Idle

Postby jondee86 » Tue Mar 21, 2017 5:39 pm

Just two little screws and the solenoid lifts off like so...

Image

You don't need to take anything else off. You can see the spindle poking out and
the idea is to make sure that the rotating part is completely free to move in both
directions. There is a clockspring in the base that will try and return the rotating
part to a central position, so you will feel it resisting a little bit. What you don't
want is the valve sticking and not wanting to spring back by itself.

Cheers... jondee86
The reasonable man adapts himself to the world; the unreasonable one
persists in trying to adapt the world to himself. Therefore, all progress
depends on the unreasonable man.

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Re: 20v Blacktop High Idle

Postby 40vpurpletop » Tue Mar 21, 2017 5:54 pm

I read the two screws are preset at the factory. Should I be marking them with a little paint to make sure they are screwed in the same position?

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Re: 20v Blacktop High Idle

Postby jondee86 » Tue Mar 21, 2017 6:43 pm

The cover for the bi-metallic clockspring has some adjustment that is set by the
factory, sealed with a smear of silicone and the screws marked with red paint.
And the screws that hold the solenoid on are marked with paint, but I think that
is just a factory thing to confirm that they have been tightened. I've had a couple
of valves apart and I don't recall that there was any problem in getting the solenoid
back in the right place :)

Cheers... jondee86
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persists in trying to adapt the world to himself. Therefore, all progress
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Re: 20v Blacktop High Idle

Postby 40vpurpletop » Sat Mar 25, 2017 12:21 pm

I think I'm going crazy because I just tried to check my timing and I couldn't see the mark. So I painted it white and I still couldn't see the mark. So I thought maybe I should check the bottom of the pulley and sure enough, that is where the mark is at around 6 o clock. Pulley off?

No, I just checked TDC and when it's TDC the timing mark is where the timing numbers are? Am I going crazy? Is my timing that off or is it something? Would my car even run? My distributor is relocated to the front of the engine if that does anything and I don't have a diagnostic plug to short but I think I found what I was supposed to short on an early model AE86 except mine was blue instead of yellow. Is it the vvt pulley? I'm pretty sure mine is shot but I read it only advances 15 degrees or so.

At this moment, I'm going to not play with the timing as my car is running and will wait for someone more knowledgeable to respond. Thanks.

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Re: 20v Blacktop High Idle

Postby jondee86 » Sat Mar 25, 2017 1:22 pm

Try clipping the timing light onto different plug wires. One of them will spark at
around the correct position. Use that one to set/check your timing.

Cheers... jondee86
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persists in trying to adapt the world to himself. Therefore, all progress
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Re: 20v Blacktop High Idle

Postby 40vpurpletop » Sat Mar 25, 2017 1:25 pm

jondee86 wrote:The cover for the bi-metallic clockspring has some adjustment that is set by the
factory, sealed with a smear of silicone and the screws marked with red paint.
And the screws that hold the solenoid on are marked with paint, but I think that
is just a factory thing to confirm that they have been tightened. I've had a couple
of valves apart and I don't recall that there was any problem in getting the solenoid
back in the right place :)

Cheers... jondee86


Should there be play with the spindle? I can freely move it around open and close but it doesn't spring back to a neutral position. I turn clockwise till it stops and I hear a metal contact sound but it doesn't spring back or anything. It's the same the oter direction.

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Re: 20v Blacktop High Idle

Postby jondee86 » Sat Mar 25, 2017 3:15 pm

Sounds a bit like your spring gave up ? This is what you should find inside
when you remove the bottom cover...

Image

I just went and checked a spare valve I have here, and you can definitely
feel the spring starting to windup/resist as you turn the spindle. There is a
bit of free movement at center, but the spindle does move back towards
center when released.

There is no problem in taking the bottom cover off. You will find that it is
sealed with a thin smear of silicone, and providing you don't rub all the silicone
off you can just screw the cover back on and it will still seal well enough :P

Even if the spring is broken (in which case just leave it out) the valve should
work (I think :? ). The operating coils operate in tandem... to move the spindle
one coil gets more volts and the other gets less. Give it a try and see what
happens !!

Cheers... jondee86
The reasonable man adapts himself to the world; the unreasonable one
persists in trying to adapt the world to himself. Therefore, all progress
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Re: 20v Blacktop High Idle

Postby 40vpurpletop » Mon May 08, 2017 10:43 am

Update on this issue.

So I bought another ISCV on ebay and the idle is still high. With the newer one, it surges a bit. Either both are kaput or it's not but I will need another one that works to know.

Other related or non related issues I noticed. The idle hangs when I rev up. So when I rev, it will go up and then hang for a second then drop down. Also, when starting the car cold, the idle will raise up to 2k somewhat fast, then drop really fast then goes back up to 2k. The times when my idle is good, the idle would go up more controlled then move down and settle at 1.5k to warm up. Not sure what it is, maybe I need to adjust that thing in the middle of the throttle bodies but I don't know how.

Thank you again.

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Re: 20v Blacktop High Idle

Postby jondee86 » Mon May 08, 2017 4:12 pm

That thing in the middle is a vacuum servo that extends and holds the throttles
slightly open when the engine is off. Once the engine starts, vacuum retracts the
rod away from the throttles to allow them to close completely at idle. Sometimes
the servo can come loose and still be holding the throttles open a little even after
the engine starts. Worth checking, but this does not sound like your problem.

There are two other things (apart from the ISCV) that can mess with your idle.
One is ignition timing. Advanced ignition timing will raise the idle speed. The
other is the setting of the TPS. If you haven't checked the setting of the TPS, now
would be a good time to get some feeler gauges and a small packet of patience,
and make sure the TPS is set correctly. Here is the page from the FSM that
describes the procedure...

Image

Once the obvious things have been checked and confirmed to be correctly set,
then, if you still have the problem, we can start looking for oddball causes :)

Cheers... jondee86
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persists in trying to adapt the world to himself. Therefore, all progress
depends on the unreasonable man.

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Re: 20v Blacktop High Idle

Postby 40vpurpletop » Sat May 13, 2017 1:26 pm

I tested the TPS and it appears to be within range. The only thing I'm not sure about is the 1mm resistance. I didn't get infinity reading but I'm not sure what that looks like on my multimeter.

I mention previously my timing was way off when reading like this can't be right off. I did try different sparkwires but they were all the same. I haven't tested another timing light but I have no reason to believe the one I have now is broken.

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Re: 20v Blacktop High Idle

Postby jondee86 » Sat May 13, 2017 7:11 pm

I wouldn't get too stressed about the timing mark being at the bottom if the engine
can run or has run OK the way it is now. There is probably a way to correct that by
rearranging the plug wires... I think moving all four wires one step forward or back
in order on the cap should work... try it :P If you get the mark to the top, then set
the timing according to the FSM. If you can't put the engine into diagnostic mode,
shoot for around 16-17 DBTDC at idle.

The ISCV should be bolted to the head/block whatever it is normally bolted to. The
spring in the base is actually a bi-metal spring and does respond to temperature. So
find at least one 8mm bolt and see if you can get it bolted down in a position where
it will get up to engine temp. Don't know if it will help, but can't do any harm.

Looking back over what I wrote earlier, I may have put you wrong about needing an
A/C idle-up valve. The ST had one but IIRC the BT moved up a step and the ECU uses
the ISCV to hold the rpm steady when A/C clicks ON. The ECU monitors engine rpm
and is programmed to target 950rpm warm idle speed. If the idle speed goes up or
down the ISCV is adjusted to pull it back to 950rpm.

Here is a bit of reading... http://www.my-acoustic.com/Car/engine_o ... IDLING.htm

Cheers... jondee86

PS: Did you check the replacement ISCV to see if the spring return on the spindle
felt any better than the one you took off ?
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persists in trying to adapt the world to himself. Therefore, all progress
depends on the unreasonable man.

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Re: 20v Blacktop High Idle

Postby SR85DET » Mon May 15, 2017 9:00 am

Not sure if this was mentioned as I didn't see it skimming through but, check your throttle cable and make sure it's not too tight. It happened to me while doing my swap. It made my throttle adjustment more than likely pointless. But I also went through the TPS and adjusted it for same measure l. Car idles well now and stable, not too high.

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Re: 20v Blacktop High Idle

Postby 40vpurpletop » Fri Feb 16, 2018 2:34 pm

Hello all. Just wanted to circle back to this.

This is what happened so far since my last thread. I've replaced the VVT pulley with a new one and purchased another ISCV. The car was a zenki so it doesn't have a diagnosis plug. I think I found the round plug that is one the older models but when I ground them, it doesn't seem to do anything.

So with my old one, currently when I cold start the car, the idle revs high up to 2-2.5k then drops suddenly, then picks up and warms up at 2k idle. With the one I purchased, the idle goes up and drop down slowly like it should but cold idles at 1.2-1.3k rpm.

Once the old one warms up, I idle at around 1.1k. With the newer one, my car idles at 2k-2.5k. So I'm unsure if both are defective or something else.

My cars still hangs when I rev up. So if I rev it, it will hang at the top then drop down. The mechanic that installed my VVT pulley said there may be a vacuum leak but I can't seem to find where it is. I replaced all the vacuum hoses I can reach but no help. Are there any vacuum hoses in hard to reach areas?

Also, my engine seems to be pinging at higher rpm under higher loads. Didn't do this before. I tried checking the timing but like before, the pulley mark is at the bottom of the pulley and changing wires with the tool doesn't work.

So that's about it with it now. I think I'm just going to replace the engine at this point or would a standalone help? Thanks ya'll!

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Re: 20v Blacktop High Idle

Postby jondee86 » Fri Feb 16, 2018 3:49 pm

Can't figure why your timing mark is so far out from a distance, so easier to revert
to first principles to try and get the timing set correctly.
1. Remove plugs and set cylinder #1 to top dead centre on the compression stroke.
Do this by putting a thin rod down the plug hole and rocking the engine back and
forward so that you mark TDC when the engine is halfway between the point where
the piston stops rising and the point where it starts falling. When you have a socket
on the crank pulley bolt you will see what I mean.
2. Clean the timing scale on the lower timing belt cover.
3. Clean the rim of the crank pulley opposite the zero mark.
4. Using a white paint pen, mark the zero indicator on the scale and put a mark on
the rim of the crank pulley as near as possible to the zero mark. Now you have new
timing marks where you can see them :)
5. Start the engine and let it warm up to operating temperature.
6. Make sure the throttle opener is not holding the throttles open.
7. Do whatever you have to do to get the idle speed down to around 900rpm. This
may mean taking the filter off the ISCV intake and partially blocking the end of the
tube to bring the idle down.
8. Attach your timing light to the #1 lead and see where the mark you made on the
crank pulley sits against the timing scale. You are looking for around 17 deg +/-.
9. Adjust the distributor base until you get 17 deg before TDC and lock. When you
adjust the distributor base, the engine rpm will also change.You will need to adjust
idle back to 900rpm and recheck the timing.
10. Rev the engine to around 2500rpm a couple of times and see if the engine
returns to idle as it should.

Report back. You may have other problems, but you gotta tackle them one at a time
and getting the timing right is step one :)

Cheers... jondee86
The reasonable man adapts himself to the world; the unreasonable one
persists in trying to adapt the world to himself. Therefore, all progress
depends on the unreasonable man.

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Re: 20v Blacktop High Idle

Postby abdu91 » Thu Aug 30, 2018 12:25 pm

buddy remove the round shape thing attached under the throttle. check the vacuum pipes. that round thing isn't need that's the whole **** man I've been there and diagnosed it after a month.
20v

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Re: 20v Blacktop High Idle

Postby abdu91 » Thu Aug 30, 2018 12:27 pm

and close the unneeded pipes so the car idles properly.
20v

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Re: 20v Blacktop High Idle

Postby Jester_Borris » Mon May 27, 2019 11:46 pm

Hello,

I’m sorry to hear of the troubles you are having. My ISCV was a mess when I started my 20V swap. This is an issues that can affect any vehicle with a separate Valve for idle air. Furthermore, you can get get TDC on an engine for the compression stroke or the exhaust stroke so when checking base timing, be sure to check the cams as well.

Jondee’s recommendations are good ones. My first start on my 20V setup was on reversed timing and an idle of 1700 RPM. The engine held idle and even tried to rev. I use a distributor cap relocation kit and didn’t account for the flip of position changing the firing order on the cap. Obviously, correcting the distributor cap situation made a huge difference.

When it comes to vacuum leaks, they can be a cause for high or erratic idle. The suggestion to check the vacuum hardliners located under the ITBs is a good suggestion. For finding a vacuum issue I can not recommend a smoke test highly enough. In my area the testing can be had for about $65. You can also make your own smoke tester. I have linked to a video that shows this.

https://youtu.be/L9CDZ9lu6Rs

Idle control for the 20V is managed through the ECU and issues like yours, with these engines, tend to come down to a physical part such as the mechanical timing, ignition timing, ISCV, or a vacuum issue. Breather filters in the wrong spot on PCV systems can be a source of vacuum issues so keep that in mind as well.

If the advice isn’t clear or the situation doesn’t improve you I may want to consider posting a video or some pictures of your setup. Seeing what you are will help.
1986 AE86 - 20V Silvertop 4A-GE w/ Blacktop ECU