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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40vpurpletop
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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
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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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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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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
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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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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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SR85DET
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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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