Idle speed drops to 500rpm for a second or 2

[Ferrari7]

i have a totally unmodified 2002 Corolla 1.5 Xli(A). Occasionally, and i must stress- unpredictably, idle speed drops to 500 rpm and vibrates the car REALLY violently for 2 or 3 seconds before climbing back up to normal. It does not always happen, and when it does, its always after at least 15s or so of idling at the red lights with tranny in drive mode and aircon on. And the vibration always lasts 2-3 seconds at most, before rpm goes back to normal. 99% of the time, she can idle all day and not exhibit this problem at all. Apart from this unstable idle speed poblem, engine is still as good as brand new. Powerful, rev-happy and redlines all day with ease.

 

Throttle body has been dismantled and throttle valve cleaned thoroughly, twice infact, but to no avail. I use Shell 95 UL all the time. Belts are fine, sparks plugs are new, air filter is new, ATF is new and engine oil is changed religiously. Should i change fuel filter? (Manual says change every 8 years; girl's barely 3 years old)Could this be an idle control valve problem? Its really expensive to change. . . at least 200bucks brand new. . . . Anyone has the same problem? Is Borneo able to resolve it? Help!

[Muar_chee]

u won't know if Borneo is able to resolve it untill u go to borneo and ask them help u solve.

[Mzrmazda3]

Bro, you sure that the fuel filter changed every 8 years

[Yeobh]

In the course of cleaning the throttle body, by chance you may have cause further damage to the throttle sensor - resulting in poor sensing of air speed and temp.

Edited June 8, 2005 by Yeobh

[Johnchong]

Hellooo...

Ur car's a girl? Oh dear, that means I've molested her.

[M5m3]

I have ths same problem. driving a picnic. BM told me this is the characteristics of VVTI engine. cannot resolve, only minimise.

 

Mine is worse than yours - this happens every time I slow down and stop at junction. but the violent vibration happens only once in a while. normally it will just vibrate a little.

 

Guess this is just irritating. my FC is still ok. So I just have to live with it.

 

Another of my friend also has similar problem. picnic as well. But have not come across my friends driving corolla complaining about this.

[Ferrari7]

Did BM really claim that a rough idle is the characteristic of VVT-i? I think its really fantastic! You must be really good-natured not to have given the customer service personnel a piece of your mind.

[M5m3]

I spoke to the technician not the cusomer service.

 

that's y i gave up and decided not to go back to BM. I'm still looking for solution to this irritating problem.

 

Read about toyota specialist in WheelsAsia - one in River Valley and another Hanip (or something like that) guy. Have you heard anything about these 2 workshop ?

[Elfenstar]

in a na car, it would most likely be the idle control valve. Get some electrical contact cleaner, take it out and clean it... Could also be the oxygen sensor at the exhaust section, or AFM. Could be, but unlikely to be the throttle positioning sensor.

[Oink]

i'm not too sure if this will help, but you can try it as i know some resovle the problem after changing the battery...cos the battery is faulty...:)

[Ahdi]

agree wif u.....battery not enuff power or alternator..

cos my dad car oso haf somthing of this problem...when turning steering wheel, at stationary position, rpm drop oso....believe teh power steering uses power, thus ropm drop b4 charging back....

[York]

unlikely...prob lies wif the battery...

most probably is the throttle body or aircon compressor clutch prob...

If u 'off' the aircon...dun ve tis prob when idling rite...

Edited June 28, 2005 by York

[Ferrari7]

BM is really CMI. . . Like u, I have given up on them.

I have heard of Hanip, but never been there. . .

FYI i sent my car to Ricardo workshop at Sin Ming. They claim to be Toyota specialists. IMO they are incompetent at best. Besides, they worsened the situation. Maggots.

[Elfenstar]

If BM are reluctant to fix probs by saying that "thats the ay it is", have you guys thought of going to a really good workshop and pay them to diagnose and write a report on the problem then bring it back to BM and make them fix it???

[Yeobh]

If you can locate a shop that have an automotive oscilloscope ( an also have the expertise to interpret wave form readings) that have few channels to sense wave reading of secondary voltage ( KV ), primary voltage and low voltage signals - your chances of narroiwng down to the source is very near.

So far I have not come across such set-up in Singapore

[Elfenstar]

i don't know of one in aust either... the workshop i go to had the old tech ones analoge output ones, but they were spoilt and never had the chance to see it used, much less know how to interpret the data. Sorry.