Idle problem

Hi all, my 96 starlet ep91 has a high idle which I can't get down, checked for vacuum leaks. Doesn't have any. so when the car is warm the idle is high a d cold is lower. I disconnected the IAC and the idle dropped to where it should be so got another IAC and put it on, which didn't do anything but when the connector is disconnected the idle drops. Don't have a tacho so can tell any rpms. Any help would be much appreciated to help clear up my issue
 

dac69er

Super Moderator
Is this on a turbo or a 4efe UK car?
Has it always done this or just started?
Do you have any engine warning lights and have you done an ecu error check?
 

Jay

Admin
Wouldn't be the first time I've fitted a faulty part with another faulty part but we'll assume the ICV is doing what it should be doing. I've seen a few faulty waxstats in my time which might be worth testing.

The waxstat is the heated component under your throttle body which has air and water piped to it. It's designed to raise the idle when the engine is cold but if the wax breaks down it'll cause idle issues. Let the engine get up to working temperature and pop your air intake pipe off the throttle valve for access. You should see a small hole on the bottom of the valve in front of the throttle flap. If you stick your finger over this hole and the idle falls to normal it's an indication the stat is malfunctioning.

Hope that makes sense!

Jay
 
I'll give that a try. Could it be possible that the coolant temp switch is faulty and faulty readings are being picked up which raising the idle
 

Jay

Admin
A coolant temp sender would generally cause starting issues and a low idle if anything, an incorrect reading will lead to a richer mixture being used - that high idle signals that air is a factor (which the CTS cannot add).

I hope that also makes sense!

Jay
 
I think it must be the IAC I bought. They are quite expensive new, I have seen new ones on eBay for 30 quid, think the manufacturer is trofom, don't know weather they are reliable or not.
 

dac69er

Super Moderator
Wouldn't be the first time I've fitted a faulty part with another faulty part but we'll assume the ICV is doing what it should be doing. I've seen a few faulty waxstats in my time which might be worth testing.

The waxstat is the heated component under your throttle body which has air and water piped to it. It's designed to raise the idle when the engine is cold but if the wax breaks down it'll cause idle issues. Let the engine get up to working temperature and pop your air intake pipe off the throttle valve for access. You should see a small hole on the bottom of the valve in front of the throttle flap. If you stick your finger over this hole and the idle falls to normal it's an indication the stat is malfunctioning.

Hope that makes sense!

Jay
my UK ep91 didnt have a wax stat it had an electrically controlled valve. it could be that playing up causing an issue. check the connector is still plugged in, if it is, unplug it and check it doesnt have water in or something silly.
probably worth changing the throttle body if you still have issues and if the IAC has been changed and has made no difference.

you can see it on this ebay add: http://www.ebay.co.uk/itm/Toyota-Starlet-P9-1-3-65KW-Butterfly-valve-22270-11010-/351669898726?hash=item51e128cde6:g:wH4AAOSwR0JUOUPJ


always worth doing an ecu error code check as it is free. it may show something up.
 
My IAC is the same as the one in the add, it has a green connecter screwed on to an aluminium piece, it could be possible that this is faulty which mkajes the IAC to not opening, I done the test, where you take off the intake pipe and put my finger over the vacuum hole. when I done this, the was a significant drop in the idle, which indicates that the IAC is faulty.
 

Jay

Admin
I still inclined to think the waxstat below the throttle body is goosed. The workshop manual calls it an auxiliary air valve. This is the test you did and it states to replace it:

 

dac69er

Super Moderator
im not sure 100% how it works on the 4efe with the electronic control, but on the 4efte, it works as per the following:

- cold start: coolant flowing to wax stat is cold, wax stat is fully open allowing maximum air to idle control valve. idle control valve either pulse or opens (i am not 100% sure) to add extra air for cold start.

- warm engine: coolant flowing to wax stat is hot (as well as ambient temp in engine bay). wax stat closes off to reduce the amount of air to IAC valve. the IACvalve continues to pulse/open.

idle control valve only pulses/opens on idle, it stops completely once off idle.


i would imagine the electronic valve used instead of the wax stat just opens or closes, based on the temp of the coolant measured by the ecu. if you disconnect the IAC valve, does the vacuum from the port in the throttle body reduce? if there is a change i would say the IAC valve is fine and i would look at the valve wiring underneath the throtle body.
 

dac69er

Super Moderator
I still inclined to think the waxstat below the throttle body is goosed. The workshop manual calls it an auxiliary air valve. This is the test you did and it states to replace it:

the later 4efe does not have a wax stat. it is electronic!!!
 
I disassembled the IAC which I took of the car, I screwed off the green electrical component and there is some sort of magnet cylinder which rotates and opens and close a valve. I guessing that the electrical component opens and close this. correct me if im wrong.
 

Jay

Admin
My apologies, I'm too used to working at turbo models for all this. I do however have a spare NA throttle body if you want to borrow it for fault finding purposes?

Jay
 
Yea, that would be a good job, would really love to get this problem fixed as my fuel consumption is awful and costing me a fortune
 

fiddlersport

Fresh Recruit
I had same problem on the glanza

removed the wax stat under throttle body and gave it a good clean and idle is perfect now
the green sensor on thermostat housing also had been replaced just incase that was the issue

cheap fixes
 

uksolo

Fresh Recruit
I still inclined to think the waxstat below the throttle body is goosed. The workshop manual calls it an auxiliary air valve. This is the test you did and it states to replace it:

Hey Jay,
Dude, I need that workshop manual. Can you share it with me?
My email ID is
soloukg@gmail.com

Your help is much appreciated in advance.
 

Jay

Admin
Hi bud, I only have a paper copy of that book.

Is it specifically the 4EFE you are looking for or is it a 4EFTE?
 

uksolo

Fresh Recruit
Hi bud, I only have a paper copy of that book.

Is it specifically the 4EFE you are looking for or is it a 4EFTE?
To be very honest, I am not 100% sure. I searched for the differences in 4EFE vs 4EFTE but the more your search, the more you get confused.

So far I have learnt that Connecting rods of 4EFTE are thicker and Piston heads are dish shaped as compared to 4EFE, which are dome shape. But I can't verify these for sure because I have to disassemble the engine. (At least disassemble the Head).IMG_20210110_153600.jpg
 
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