4AGE idle and wiring questions!

[shortround]

Hi guys, A couple of questions. Any help is much appreciated.

First the background info: my car has a smallport motor with a JDM AA63 4AGE bigport computer and AE86 wiring loom. Last weekend I spent some time trying to get the engine to idle properly. At the time the lowest I could go after setting the timing was around 1400RPM, with a huge hesitation on throttle.

After a bit of mucking around and replacing a busted TPS, I think I have put it down to the ISCV. Even when the car is at running temp, the ISCV remains open. If I block off the hole just before the butterfly in the throttle body, the idle drops down to around 500RPM. I am now in the middle of replacing it. Does this sound reasonable? Has anyone just removed the ISCV completely? Does it have much of an effect driving the car when cold?


(not my photo!)

Next up; I seem to be completely missing a variable resistor (as per the image of the manual below). It has some bearing on the idle yeah? Do I need it?




Last one; See the image below. Can anyone name what these plugs are for? I guess one of them would be the variable resistor? and one of them for the CO2 sensor in the headers (possibly the one with the plug stripped off)?



Thanks!

[ae86]

i have same idle problem, happened last winter too, never happens in summer i just have a hunch about melbourne weathe playing with it, if i play with throttlle a little settles down though.

[Golberg]

Those 2 pipes which point down, do you usually have them connected to the water system? Because they need to be for the ISCV to actually work.

Plugs:
1. Looks like the engine loom's original starter wire (if the wire on it is black with a white stripe this is definitely the case).
2. Probably your original O2 sensor plug as said.
3. Usually plugs into a sensor in the air-conditioning compressor.
4. Connects to an earth strap.
5. NFI

EDIT - Thankyou for asking clear concise questions and supplying all the necessary information from the beginning. There is a lot people could learn from you about how to ask a question.

[jdm86gtz]

If the ECU use an O2 sensor you won't have the variable resistor. European AE86s have the variable resistor, Japanese AE86s have an O2 sensor, so if you have a Jap AA63 engine you should have O2 sensor.

[44GTE]

I have had the same issue with high idle.

The iscv is not cheap at around $300 Trade from toyota and there was none in the country a week ago.

Two quick short term fixes are

1/ Removeand make up a plate and blank off the entire lower section. this will have issues when first starting in the cold though and you will have to use the throttle to keep the car idling for approx first 30 sec then it shold idle by itself after that as long as it is adjusted to do so with the idle screw located at the top postion.

2/ I didn't have time or material to make a plate so i have put a full gasket in plate made out of Aluminium tape which totally blocks of the ISCV port so as no air bypass etc. This then works as mentioned above.

Proper fix is


Get another ISCV from another throttle body , they are all the same i believe on Bigport / smallport and fiz the problem for good, or order brand new from toyota and lighten the pocket a fair bit .

Cheers

[shortround]

thanks guys, that helps alot!!

44GTE >> I have a spare throttle body/iscv which I will hopefully get a chance to try over the weekend. I tested the spare iscv in boiling water, and the valve seemed to close ok. If that one doesn't work then I will just block it off like you suggested!

[yoshimitsu9]

3sge throttle body should very possibly be very close if not the same as an 4age throttle body. so next time you go down to pinch a part, pull a ISCV off the 3sge to have a look at the similarities.

or alternative method is just use a 3sge throttle body, it bolts straight on, tps is bolt on (exact same part number as 4age) and shouldnt have any problems what so ever plumbing it up to the coolant system

[ae86]

im getting idle problems too, sometimes goes down then jumps back up to 2000

[mick]

I also have idles problems car constantly idles between 1000rpm and 2000rpm its a 4age any ideas?

[1sik20valve]

same prob guys
need more ideas