[dissociative]

Good day boyz!

Well recently I've been experiencing bad idling, as I observed its either:

1. After starting the car, the idling doesn't go up just below 1000RPM, but it goes and stays just around 500RPM, just like it's about to stall. I rev it a few times, but it still goes back down to around 500RPM, getting erratic, moving slightly up and down.

2. OR more commonly, after starting the car, the idling seems to go fine just below 1000RPM. But, after driving around a bit, shifting a few gears, and going back to neutral while in motion, the idling goes down at around 250-500RPM, the engine shakes a bit like its gonna stall, so I'd always have to shift to a gear to get it up or step on the clutch, hit the brakes and make a full stop, which makes it go up and seem like normal again. However, when I try to drive again, the same thing happens over and over.

Well sometimes on lucky days it doesn't have that symptom, but now I've observed that it happens quite often, like almost everyday. I've learned from reading some threads that what usually causes idling problems is our beloved ICVs, so basically as a result, the ICV is my first suspect. But of course, I need input from you guys if it is really the suspect, and if there are other possible causes too. I also learned before that having sparkplug/high tension wires in bad state may also affect idling. I've read on some places as well that the ignition coil or coilpack may also cause bad idling.

I've got a mechanic coming over in a few days so it would be much better if we don't waste time doing things which may be irrelevant, since I can't do these things by myself

So to finish of my post, here's my questions...
Is it highly probable that the ICV is the one causing this?
Are there any other possible causes of this symptom?
Can the high tension wires or ignition coil really cause bad idling symptoms too?
How would I know the state of the ICV, if I should clean it or replace it instead?
What other things should I ask to be checked and cleaned?

Sorry for quite a long post, but this is really bugging me for quite sometime now. Its terribly hard to drive well when the idling isn't stable.

Thank you guys, hope to hear from you!

 

[Demon]

replace fuel and air filters tbh

mostly the fuel filter would cause this probablem.

 

[Lyds_corsa_b]

Good day boyz!

...and girls!

Yes check the ICV and give that a good clean. Change fuel filter, air filter & use fuel injector cleaner - such as Redex. You might've filled up with some dirty fuel or something.

 

[Sneydster]

or could just need the (not sure of technical term for it) tickover rate needs adjusting. i know my clio had to have it done as it was over-revving then was adjusted too far the other way lol so was on the verge of stalling when it went to tickover

 

[Lyds_corsa_b]

Try spraying WD40 on the accelerator cable. That might be sticking.

 

[dissociative]

Hey! had my ICV and carb cleaned earlier, it was quite dirty! Idling has improved a bit but I was advised to buy a new ICV. But before that, I have a few clarifications in mind that I'd like to ask you guys.

Is the ICV also in charge of regulating the idling when the airconditioning is switched on? What we've noticed is that when switching on the A/C, the idling makes a bit of a sudden drop but goes back high around 1,250RPM and returns to slightly below 1000RPM. The mechanic says that it is most probably the busted ICV which is causing the sudden drop of idling when switching the A/C on.

And, with regards to the Part number of my Corsa B (C14NZ)'s ICV, I'm getting a bit confused. Is the ICV from the Corsa B the same as the ICV of the Astra G? I've searched on my Opel parts catalog for the part number of the ICV for Corsa B, and it displays Part No. 17112027 and Catalog No. 8 17 254, and the Astra G's ICV being different; 17112023 and 8 17 253.

Then, after searching the net, I also found a different Part no which is 17113196. All ICVs generally look the same by the photo, so is it safe to say that they'd work for my Corsa? There's quite a lot more Astra Gs here in my location, so I was wondering if the ICV for it is also appropriate for my Corsa B.

Thanks people! hoping for your replies!

 

[AdHeath1989]

EGR Valve is another common possibility

 

[richardhhha]

the idle will drop on your car when you turn the AC on because it engajes the AC pump which draws quite a bit on the engine, so dont worry about that,

so what your saying is the car was running fine then just started doing this?

need a little more info mate on this one, like, did you fill up the night before it started playing up, did you go through a big puddle things like this, got to know what you were doing and how the car was behaving before we can give you a better idea of whats up.

 

[simonutd]

what engine do you have and fuel system, you might have said but i not seen it, sorry

 

[dissociative]

My Corsa B is a 1997 5door hatch with a "Swing" badge, C14NZ, 8valve with Multec Injection(?).

The idling goes all the way down at around 500-750RPM (which I don't think is normal) when A/C is switched on; on good days it rises back up to 1,250RPM (just after the drop) then normalizes back to just below 1000RPM, with the A/C compressor successfully working. On bad days, it stays down to around 500-750RPM, and you could hear the compressor trying to switch itself on (magnetic clutch I think?), but it would usually keep failing so the idling would also fluctuate up and down.

So basically if the idling is good beforehand, the A/C compressor doesn't have a hard time turning on, hence also eliminating the idling fluctuation as well caused by the compressor trying to turn it self on. So I understand that if the ICV is functioning well, it would immediately be able to compensate the changes in idling when switching the A/C on; with not much of a sudden drop in idling and also giving a successful switching of the compressor.

Sorry for yet another quite long post, I hope I described it well. The problem began for quite sometime now, but usually there would be lucky and unlucky days. There wasn't any real changes that I made that could have caused this, and I don't think there's a problem with the gas I'm filling. Right now I'm quite convinced that these problems are caused by the faulty ICV, but I really need to make sure before I get one.