My car runs Win98

March 2, 2008 8:55 PM

Ok, on top of the starter issues, my car has begun to idle very strangely...

I last asked here about my car not starting---not that this has been fully resolved, but it works most of the time. Unfortunately, this makes it very difficult for the mechanic to find anything wrong with it.

Be that as it may, I have another issue. At about the same time, it started idling very strangely. It usually should idle at around 1000rpm, but sometimes when you start it, it idles at 2000rpm---moreover, when you put the clutch in after coming to a stop, it idles up and down from around 1200rpm to 2000rpm between two to seven times. Needless to say, this is not likely normal behaviour.

What makes it more confusing is that, much like the joke says, if you shut it off and turn it back on, it runs usually runs normally.

Now, this has been happening more and more often, but only since the starter issues began---which suggests that there is likely some relation there.

I've looked online, and about all I can find is information relating to similar problems in other makes of car, which seem very manufacturer specific, and totally not helpful---other than, perhaps, I need to replace my sparkplugs. Or maybe fiddle with the timing belt. Which, it should be noted finally, has never been replaced in all 226666 odd kilometers of driving.

posted by vernondalhart to travel & transportation (9 comments total)

This sounds like one possibility for this may be a vacuum leak somewhere. There are various systems and sensors that are controlled by the ECU that rely on a sealed or known leakage of vacuum. Look for any rubber hoses or the like coming from the inlet manifold and check them for condition - there may be a lot of them. Any damaged or cracked ones (pull them around a bit and check for fraying or chafing too) need to be replaced. Wiggle them when the car is idling and see if it makes a difference.

Other alternative is that a sensor somewhere is failing and the vibration of turning it on and off jiggles a loose connection back into place.

Is there any reason you haven't booked this in to a dealership/garage with the widget to get the problem diagnosed? If it is a sensor (as suggested in the other thread) without knowing which one, you are shooting in the dark. The best way of finding out is to check for error codes.

If this is a problem that you can make happen - ie find something that produces a reliable fault - this may be time well spent before booking it in. Nothing temporarily cures an intermittent fault like being within 2 miles of a diagnostic machine...
posted by Brockles at 9:07 PM on March 2

My car has an automatic choke*. Shortly after starting, more often than not, the car will idle very fast. I can sometimes get it to reset with a sharp jab on the accelerator (the advice given by the previous owner), or I can just wait a couple of corners and it'll settle.

Heh... just checked your first post. Yours is a 95 Geo Metro, which, it seems, is really a Suzuki Swift. Mine's a 93 Holden Barina, which is also really a Suzuki Swift. Maybe ask your mechanic to take a look at the choke.

*which is a crap idea to start with. harumph.
posted by pompomtom at 9:27 PM on March 2

(oh, I should add: this behaviour doesn't happen on a second start, like yours)
posted by pompomtom at 9:28 PM on March 2

Unfortunately, I can't make any of the cars problems occur on command, which is why I haven't really brought it in to a mechanic. I can't afford to leave it with them for hours as they fiddle with it not having problems.
posted by vernondalhart at 9:29 PM on March 2

Oh, and the idling issue does seem to go away while driving, only if I shut it off and start it again.
posted by vernondalhart at 9:31 PM on March 2

My car ('95 subaru) did all the things yours is doing. A new temperature sensor solved the problem- not only did the mechanic suspect it, the computer diagnostic showed it as well. Take your car to a mechanic that has the proper diagnostic equipment for your vehicle (as well as being a good mechanic).
posted by oneirodynia at 9:53 PM on March 2

One other thing that may be wrong is that you have a faulty throttle position sensor. This is a small gadget that tells the computer how hard your foot is down on the gas. When it acts up, your idle will often be all over the place. It tends to be about a $40 part, and if there's nothing in the way it takes 5 minutes to replace.

By the way, love the thread title.
posted by azpenguin at 7:23 AM on March 3

A bad oxygen sensor can cause both starting and idling problems.
posted by jamjam at 12:04 PM on March 3

Many things can cause both issues. This is why you need to get it diagnosed properly. There is (apart from checking vacuum hoses and all wiring for chafing etc) very little you can do to save time or money before this stage.
posted by Brockles at 12:22 PM on March 3