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 When AC on, car shakes badly when idling, When AC off, car is quiet when idling

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mot88
post Jan 30 2017, 11:42 AM

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QUOTE(ricko99 @ Jan 30 2017, 02:48 AM)
Sorry for bumping old thread. My saga lmst has the same issue, idle with air cond on it shakes and rpm back to normal when accelerating. Would you mind showing which screw are you talking about to tune the idle rpm?
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To remove suspense, you may refer to the picture of post #2399 in the link below.
https://forum.lowyat.net/topic/2900268/+2380

If the air con idling adjustment does not change even after adjust, then it could be the gold coloured round thing tht screw attached to it (called air con idling vacuum pump or 'vacuum actuator' in the pic) is spoilt. Pls make sure it is Denso brand when replacing. Cost about RM 90 few years ago. Local brand costs half the price but only last few months. Denso last for years. I purchased the Denso part from a spare part shop in OUG years ago.

Pls also check for vacuum hose for leak (those small hoses) as they tend to crack at either end of joint. It will cause the adjustment take no effect.

Note:
1)You need to rev a bit after each adjustment for new setting to take effect.

2) Proper way is to adjust the base timing without the air con screw then only adjust air con idling screw.

This post has been edited by mot88: Jan 30 2017, 01:42 PM
mot88
post Jan 30 2017, 04:52 PM

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QUOTE(ricko99 @ Jan 30 2017, 04:09 PM)
Did what you suggested, adjusted both screws and currently the car idle without ac is at 1.1k - 1.2k rpm and with ac on at full blast it's at about 800 -  900 rpm.  Is it okay? Because anything below 800 is quite shaky already even the front bonnet shakes really hard. I'm afraid the fuel consumption might increase as before this my idle rpm without ac was 1k

Also, in the long run, is it better to install Toyota FICD to regulate the rpm?
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without air con should be ard 800 to 850rpm and with air con ard 950 to 1k rpm.I dont have the factory spec for exact figure.

Looks like your fast idling is not working. To get the it to work 3 items must be working
1) air con vacuum pump /vacuum actuator.
2) FICD (carb version)
3) vacuum hose not leaking and correctly attached.
For hose it should be run from engine block to ficd (denso carb version) and another hose from ficd to a/c vacuum pump.

Yes, the proton wira carb has ficd as well. LMST shld hv as well as using the same drivetrain. It looks like toyota ficd, attached to firewall with 2 small vacuum hose attached to it.

Last time,not working, I changed 3 items after fed up workshop doing it using generic local parts. Item 2 seldom spoilt but I changed it as not tht expensive.

1) approx m90 (oem denso for carb)
2) approx rm 80 (oem denso)
3) vacuum hose rm 2 for 1 feet ( abt 4 to 5 feet )
(price quoted is few years ago)

Correct vacuum connection is priceless..as even changed all 3 items but connection is wrong, fast idling (i.e with air con on) will not work.

This post has been edited by mot88: Jan 30 2017, 05:10 PM
mot88
post Jan 30 2017, 07:39 PM

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QUOTE(ricko99 @ Jan 30 2017, 05:25 PM)
So if I get you correctly, it means idle rpm with ac OFF should be lower than idle with ac ON?
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Yes..If set properly and fast idling working, the rpm will drop a bit when air con on and then climb bk to slightly higher.

The fast idling is mechanically activated, tht explain the delay is more than electronically controlled.

If u need to set the rpm of air con off higher to compensate the load imposed when air con is switched on, tht explain tht fast idling mechanism is not working.

This post has been edited by mot88: Jan 30 2017, 07:39 PM
mot88
post Jan 31 2017, 11:05 AM

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QUOTE(ricko99 @ Jan 31 2017, 03:13 AM)
I played around with both screws again and I set my idle ac off rpm to 850. When I switch on my ac it drops to 700ish and once I rev the engine a bit, it hovers around 950ish. If I don't rev, it takes quite a while before the rpm goes up. I've checked the vacuum hose and seems like there's no leakage or anything like that. I checked my FICD is probably cap ayam brand (pacific or sth like that) but looks like it's adjustable as it has this one part that I can turn left and right. I think my hose connection are correct as well
From my experince, the correction of fast idling load should be 2 to 3 sec. The 1st thing is to ensure related hoses fit tight. Over time the hoses expand at the join end (bulging effect) causing it not air tight. Can cut at bulging area if the hose still have enough lenght. Not suggesting you to do that but thats maybe the root cause.Best to take out the hose to inspect. It could have micro crack.

Since it did climb back, but take longer, it shows the fast idling mechanism work but may not be optimum. I didnt adjust and dont think there is any adjument screw on the denso ficd for carb version. Maybe Proton changed the FICD supplier for newer batches.

Your hose connection looks correct based on your photos. Raw suction from engine block to FICD. Ficd block suction to a/c vacuum pump when air con off. When air con on, the ficd open the valve for suction to a/c vacuum pump, in turn pull the carb cable to add more air/fuel mixture.

For your reference on the adjustment screw at Toyota FICD for fuel injected car. Looks to me redundant for carb as there is adjustment screw at a/c vacuum pump (efi dont have a/c vacuum pump and rely on ficd screw for adjustment).
http://www.diytacra.com/2010/11/ficd-fast-...device.html?m=1



This post has been edited by mot88: Jan 31 2017, 11:28 AM

 

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