4G91 Idle problem > Throttle Body > RPM >

[YC. Tan]

Yosh! I believe this is the problem of all 4g91, and a lot of the owners out there wish to find a thread to get direct solution. This is a question for all, ladies and gentlemen, kindly assist. We are just looking forward to having a smooth ride.

Problem:
1. When air-cond kicks in, RPM drop from 1000 to 500-600, car vibrate ridiculously.
2. (A/T) When switching to D or R, car vibrate and might die down.

I've done several researches, and found out that the problem should come from a component in the throttle body, the ISC or Stepper Motor or Idling Valve. Some recommended Toyota's FICD, but that is a bypass but we would like to have solution.

Begging for:
1. What is stepper Motor? What is ISC? What is Idling Valve?
2. Where can we find a service center for ISC? We don't want FICD that only solve the problem temporarily.
3. Where can we buy the ISC? Stepper Motor?
4. How can we service it?

Thank you for your generosity by providing the solution. I hope the first following post will be the best solution for above stated matter. :) So it will ease everyone's effort to search for answer. :) Thank you for your co-operation VERY MUCH!

E-mail is accepted as well: [email protected]

 

[X.O]

my injected manual 4g13 has this problem too. mine engine can even die off after a light rev when the engine is cold. i heard the solution to this problem is to keep the air con on... but mine doesnt seem to work as it still vibrates.

do help us out those who have a ideas and solution to this problem thank you :)

 

[^pomen_GTR^]

errr...toyota FICD was the alternative to control idle (without costing bomb to replace TB)....it bypass the ori one and we control/adjust separately on the FICD.....many 4g91 user including my fren use this as cheaper solution...

 

[calvin9683]

agree wif pomen... the toyota FICD is not a temporary solution....
u can try searching in 91gang thread where someone shared a diagram on how to wire it up....

 

[skylee834]

last time i also face this problem,now after so many year,i never have this problem...
what i do is,open up the whole Tb,clean it up,open the stopper motor,u can saw the head of motor in good condition and normally will very dirty,if the head damage ,u need change it.if good ,just clean it...
important thing:Don't use WD40 to clean it,it will damage ..i kenal liao...
just experince to share....

---------- Post added at 02:40 AM ---------- 6 hour anti-bump limit - Previous post was at 02:29 AM ----------

to avoid this problem,u also need to use air breather for the hose from plug cover to air hose near TB...