ON Aircond, RPM Drop!!!

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Core2

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Oct 20, 2008
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Dear Friend,

I have some problem about my car. My engine is 4AGE 20V(Blacktop)

Normal idling is 1000rpm, when i switch ON aircond, RPM drop at 600rpm and 500rpm.

* any sifu please tell me where to adjust to become RPM up when switch ON aircond.
 
Last edited:

scottwrx

500 RPM
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Nov 18, 2007
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bro... which part of a.star r u in? u r facing the same problem as my fren, in kangar..... if u wan, drop me a sms, i will bring u n my fren to a toyota sifu, really sifu one... represent malaysia for technical competition n won.. but standard toyota only lah.. damn good in trouble shooting,
going there next week.. 012 4900525 scott.
 

EvolutionZ

5,000 RPM
Helmet Clan
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Aug 3, 2007
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my 4age 16v faced the same prob too....mine coz timing too low, when tuned up then ok already....but yours is rpm1000, consider high already.....throttle body maybe?
 

nnik

3,000 RPM
Senior Member
Sep 20, 2005
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Maybe FICD can help on this problem....
Just my tut cents.....plus this thing so popular on mitsubishi/proton geng
Have a nice try
 

scottwrx

500 RPM
Senior Member
Nov 18, 2007
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one of my fren also facing same problem, even after cleaning throttle body, tuning also face this kinda problem.. what i know from him is normal driving is ok, then after some spirited driving, the rpm drop below 600 and stay unstable there... i will ask the mechanic what is wrong and get back to u all next week..
 

pcmoddingmy

1,000 RPM
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Mar 23, 2006
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Did you try cleaning the ISCV (Idle Speed Control Valve)?
 

chinozie

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Jul 5, 2004
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Did you try cleaning the ISCV (Idle Speed Control Valve)?
some mechanic said ISCV can't be cleaned...
due that there are some lubricant in it...only can be cleaned by removing the carbon residue in it...

carb cleaner not recommended...!

he's cleaned 3 ISCV...results idling not soo good...
may need to open a seperate discussion about this...:hmmmm: :hmmmm:
 

pcmoddingmy

1,000 RPM
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Mar 23, 2006
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some mechanic said ISCV can't be cleaned...
due that there are some lubricant in it...only can be cleaned by removing the carbon residue in it...

carb cleaner not recommended...!

he's cleaned 3 ISCV...results idling not soo good...
may need to open a seperate discussion about this...:hmmmm: :hmmmm:
So this means we need to re-lubricate the ISCV upon cleaning? This means the normal ISCV cleaning method has to be rechecked.

Anyways on the same topic, my car seems to vibrate quite a lot when A/C turned on. Any idea why is this happening? Maybe the A/C compressor is dying? But the A/C is still quite cold when operation. Btw, I'm using R134a gas.
 

chinozie

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pcmoddingmy - Need to recheck back...will try to lubricate back...i've did mine...idling so far, is ok...but i'm still using the small K&N filter...will swap to stock setup and see how...will update later...
 

Shield

Junior Member
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Aug 11, 2007
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ECU problem, effect idling or not?

Bump: My car facing the same problem above, i'm suspect ECU or tps sensor..... i already change iscv and throttle body but the problem is come out......

** Any idea how to check the tps or setting?
 

levin818

1,000 RPM
Senior Member
Nov 29, 2003
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After resolving ECU problem, clean up the ISCV/4-throttle and set back the TPs, the annoying idling never come back to me any longer. That time i was running with SVT auto.
Perhaps you may look into these stuffs.
 

lapsap25

Known Member
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Aug 7, 2006
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Aircond valve? Did you check? Not sure if 20V have them but my St-171 doesn't, however installed that piece,rpm drop problem settled.:nurse:
 

bintai

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Jan 21, 2009
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i'm driving ST171 with 3S-FE...facing the same problemo..so did checked and the thing is the aircond modulator was gone..only left is the socket...and it was modded with some manual regulator (old type of aircond system in carbie type car) ...switching the aircond..rpm will drop..suppose the will be an idle up...

to make thing worst...the modulator was thrown away...so i don't know hw it looks like...damn stupid previous owners..

so currently i'm rebuilding the engine...and for the electronic part..i'm looking for the stuff..i suppose we call it aircond modulator..any of u guys have that aircond modulator..please lemme know...being looking for it..017 936 00 13

Cheers