[Hohocc]

Gidday all,
My H20a has a misfire on acceleration, worse when cold, not bad when warm but never quite goes away. More under higher load. Occasionally stalls when you put your foot on the clutch, but always restarts immediately.
One of the possibilities would appear to be a vacuum leak, so I DIYed a smoke tester.
The only leak I have been able to identify is from the top of the IAC valve, and I'm wondering if this is a defect or if that is how the IAC is designed?
So under the IACs round top cover (which more or less just sits on top, ie not crimped or sealed in place), there are 4 small holes at 90 degrees to each other, all probably less than 1mm diameter. When smoke testing there is smoke coming from these 4 holes.
So if the IAC is increasing the airflow, does it get some of this airflow from these holes?
If anyone can advise if this is normal, or not normal, I'd really appreciate it.
Thanks in advance.

[fordem]

The IAC valve should not be leaking, and I don't recall that cap being removable - I may or may not still have one knocking around I'll see if I can locate it - what the IAC valve does is control airflow between the two holes on the underside - in one hole, out the other.

[Hohocc]

Thanks Fordem, I was hoping you would have some input!
That's very helpful info. I'll source a replacement IAC vale, re smoke test, and assuming no leaks, see what difference it makes.
Will report back with results...

[fordem]

I did find the old IAC valve and as I recall that circular cap is firmly attached.

The stall & restart thing, if it's happening when you're coming to a stop, is most likely the EGR valve - it opens when the engine is on the overrun and if it does not close properly, the engine stalls, when you go to restart, the ECU will cycle the valve open & closed and this time it closes allowing the engine to idle. A good cleaning should solve that problem.

[Hohocc]

Thanks for the extra info.
In this vehicle there is a blanking off plate fitted in the egr valve, which was there when I got the vehicle.
I may at some point remove it, but since it has been a constant in my ownership I'll leave it unchanged until the current issue is sorted.
Car is a 95 Escudo, coming up on 318000km, which is a pretty high figure for cars in New Zealand. Has 1 last oil leak to sort out too, but that's not an issue for today!
Thanks.

[fordem]

Hohocc wrote:

Thanks for the extra info.
In this vehicle there is a blanking off plate fitted in the egr valve, which was there when I got the vehicle.
I may at some point remove it, but since it has been a constant in my ownership I'll leave it unchanged until the current issue is sorted.

I would leave it.

[Hohocc]

Well, update...
Haven't had much time to work on it but did manage to obtain an IAC valve from a used vehicle with about half the km on it and fitted it, but unfortunately the symptoms are unchanged.
I'm away tomorrow for a couple of weeks but will smoke test the new valve to at least see if it has the same leak as the old one when I return.
It's certainly possible to have 2 faulty valves, but in any case my investigations will continue...