rpm up & down while idling, fluctuate between 1.3k to 1.6k

jedi

Known Member
Senior Member
Dec 22, 2003
108
4
3,018
car : Proton wira 1.3 Manual, year 2000

Without aircond, my rpm stays at 1500
With aircond on, when compressor kicks in, it will drop to 1100. when compressor off, rpm fluctuate between 1300-1600rpm

Especially at the traffic light, sounds like i am asking for a race with the car next to me...

I installed FICD, at least my engine won't die when it's cold, but rpm problem remains.

any clue ? thanks mates !
 

vr2turbo

Beyond 20,000 RPM!
Helmet Clan
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May 11, 2010
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I think idling tuned too high. With FICD you should be able to tune it lower when without aircon, so when air con is on, FICD suppose to compensate back, unless FICD got problem.
Normally if FICD not working, mechanic will tune idling higher without aircon on, so that when aircon is on and with the load, the idling will just be correct....
 

RENESIS VIII

7,000 RPM
Senior Member
Jun 13, 2012
7,063
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Ipoh
can try adjust the base idle set screw, to compensate rpm up/down
This one I think only applicable to MMC throttle body. VDO throttle body don't have this screw unlike our engines. Actually mine also got idling problem. Rpm is always higher than 1000 and when air cond compressor kick in, will drop to 800 and cause slight vibrations. If on a hot day, even worse because rpm will drop further to 500 and the rpm just jump up and down from 500 to 800 back and forth.
 

vr2turbo

Beyond 20,000 RPM!
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May 11, 2010
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This one I think only applicable to MMC throttle body. VDO throttle body don't have this screw unlike our engines. Actually mine also got idling problem. Rpm is always higher than 1000 and when air cond compressor kick in, will drop to 800 and cause slight vibrations. If on a hot day, even worse because rpm will drop further to 500 and the rpm just jump up and down from 500 to 800 back and forth.
Tune a bit higher to 1200 or 1300 then when air con cut in will be 900 to 1000
 

RENESIS VIII

7,000 RPM
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Jun 13, 2012
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Tune a bit higher to 1200 or 1300 then when air con cut in will be 900 to 1000
Tried already. If adjust the screw too high, then the RPM will stop at 1500 rpm and drop down again to 1000 then rise back up to 1500. Can't really adjust much. Asked a few mechanic before, all of them said throttle body problem.

During hot afternoon when RPM drop to too low when air cond on, it really troublesome because power steering is also affected. Steering becomes very heavy and I had to step on the throttle to make it easier to turn the steering.
 

vr2turbo

Beyond 20,000 RPM!
Helmet Clan
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May 11, 2010
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Tried already. If adjust the screw too high, then the RPM will stop at 1500 rpm and drop down again to 1000 then rise back up to 1500. Can't really adjust much. Asked a few mechanic before, all of them said throttle body problem.

During hot afternoon when RPM drop to too low when air cond on, it really troublesome because power steering is also affected. Steering becomes very heavy and I had to step on the throttle to make it easier to turn the steering.
Don't tune to 1500. There is a maximum, once you reach that the engine will idling like race car, going up and down......lol
Tune slightly higher from your say 1100, maybe to 1300 and try out....
 

RENESIS VIII

7,000 RPM
Senior Member
Jun 13, 2012
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Don't tune to 1500. There is a maximum, once you reach that the engine will idling like race car, going up and down......lol
Tune slightly higher from your say 1100, maybe to 1300 and try out....
Now my idle is already at 1100 to 1400. Fluctuating between these range when air cond compressor haven't kick in. I tried set the idling to be higher and rpm will be at 1000-1100 when compressor kick in but after that, rpm will go up and down.
 

Izso

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Mar 28, 2004
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car : Proton wira 1.3 Manual, year 2000

Without aircond, my rpm stays at 1500
With aircond on, when compressor kicks in, it will drop to 1100. when compressor off, rpm fluctuate between 1300-1600rpm

Especially at the traffic light, sounds like i am asking for a race with the car next to me...

I installed FICD, at least my engine won't die when it's cold, but rpm problem remains.

any clue ? thanks mates !
What model? MMC or VDO? What did you do to your car recently? Completely stock?
 

sweelt

2,000 RPM
Nov 6, 2016
2,306
248
663
Penang
Don't tune to 1500. There is a maximum, once you reach that the engine will idling like race car, going up and down......lol
Tune slightly higher from your say 1100, maybe to 1300 and try out....
hehehe....."race car"
idling is very tricky, can go crazy. Once out of accepted range, will make it even worst if keep on adjust blindly.
Get the stock setting right 1st, than find whats the culprit.
 

vr2turbo

Beyond 20,000 RPM!
Helmet Clan
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May 11, 2010
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hehehe....."race car"
idling is very tricky, can go crazy. Once out of accepted range, will make it even worst if keep on adjust blindly.
Get the stock setting right 1st, than find whats the culprit.
IACV problem dy...:smokin:
 

sanekit

1,500 RPM
Dec 9, 2015
1,616
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663
Petaling Jaya
hmmm.. mine seems to go back to 800-900 rpm idling even after i adjust the BISS screw to a few times to set it to 950-1100rpm idling no ac. LOL. my ISCV is ok tho coz when AC on the RPM will rise +200-ish
 

vr2turbo

Beyond 20,000 RPM!
Helmet Clan
Moderator
May 11, 2010
29,998
8,385
1,713
Petaling Jaya
hmmm.. mine seems to go back to 800-900 rpm idling even after i adjust the BISS screw to a few times to set it to 950-1100rpm idling no ac. LOL. my ISCV is ok tho coz when AC on the RPM will rise +200-ish
If your ISCV is running no need tune higher dy
 

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