Hello !

My idle was very high +2000 rpm on my ae86 gts map.
I read many topics to find the good way.

I had a vacuum leak, so I replaced the tvis and throttle gaskets and after checking with smoke, no more air leak here.
I took the oportunity for cleaning the aav and testing it with hot water to confirm that it is working properly.
Then I adjusted the tps with an ohmeter.

Now, I have a surging idle between 2000-1000 rpm.
Idle screw almost closed, Air from coolant purged, ignotion timing ok, resistance checked for the tvis yellow sensor and the 2 brown and green sensor. All are ok regarding the 4a manual.
No change with finger on aav hole.
Throttle body is clean and it is the rwd one (I checked that too).

I am thinking of a bad tps because the fluctuation stops and idle raise when I unplug the tps or the map sensor.
Also, maybe my throttle plate is used but I did not see any topics about this possibility.

Any other idea ?

When I check with light, I can see that my throttle plate is not closing totally even without stop screw. I am thinking about replacing the plate but the screws looks very hard to remove or using a sealant like tomei throttle coat in Japan.

Who tried this rebuilt / sealant ?

Thanks

I tried to remove the throttle plate and ran into the same problem. I even applied heat to the throttle plate and could not remove the screws. One possible option is to grind down stop to allow for more travel or see if you loosen the nut on the cable side of the shaft. This might allow the plate to shift and adjust or center in the T/B bore.

There should be a set screw with a nut that stops the plate assembly at a "closed" point. you can adjust that, if needed, to have it close a bit more.

That's if adjusting the throttle cable doesn't work.

Thanks guys for your help.

My problem is resolved. I checked again the valve with hor water and I replaced the tps.
No more surging idle but my idle was too high at 1600 rpm.
As I said, I had a gap between the throttle plate and body even with the stop screw totally unscrewed. I mean you can see the light coming throught.
I have 2 other tvis from an ae92 and one TB is ok, totally closed and the second one is the same as my rwd TB, with a litle gap mainly on the sides of the plate.

In Japan, I found that we can resolve this gap by using a coat called Tomei throtle body coat. Sorry, I use my phone to post, I cannot post a picture.
Btw, this coat is just Molybden, called Mos2.
I bought it in spray from another brand : the dry coat Mos2 from loctite LB 8191, MoS2 dry lub.
You can spray it directly or spray it in a small container and apply the lub all around the plate with a paintbrush.
I resolved the gap in TB and my idle drops to 1100 rpm.

Thanks again for your help, I will control the timing now.