Intermittent high / fast idle?

Lester Burnham wrote:

iacv is the likely fault, under larger throttle openings they open, when
throttle is released they should close, but if they are dirty then they can
stick open or close very slowly.  The long term cure is to run on good
petrol and oil (and change it regularly)  To prove it is the iacv just
disconnect it and take it for a drive, you may well have warning lights and
it may not idle, but if the 3 - 4 k revving is gone then it is very likely
the iacv , next would be remove and clean it or replace it, depending on
ease of access and cost.

On Wednesday, 20 July 2011 11:27:44 UTC+1, Mrcheerful  wrote:

Thanks for that.

I've sorted issues before with IACVs on other cars - and actually found tha=
t once either cleaned up, or replaced, I didn't have a repeat of the proble=
ms, I tend to drive 50 or 60 miles at a time, so always used to find that o=
nce cleaned or replaced they largely stayed clean (same with the throttle b=
ody).

I did find on one Volvo (S70) that when the IACV was playing up, and / or u=
nplugged, warm / hot idle was high.

I'll try and give it all a good clean today. I'll also try and unplug the I=
ACV if I can get it to idle hot again, and see if that shows a difference.

Thanks again.

In article

Likely a problem with the ICV. (Idle control valve). They are commonly a
stepper motor moving a valve, controlled by the ECU. Removing and cleaning
can often work.

--
*Money isn't everything, but it sure keeps the kids in touch *

    Dave Plowman        dave@davenoise.co.uk           London SW
                  To e-mail, change noise into sound.

Update: got chance to have a tinker under the bonnet at lunchtime.

I was wrong about the type of throttle - it isn't electronically actuated, =
it does have a cable, it just wasn't that obvious from my first looks. I re=
moved the induction trunking to the throttle body - have to say, the thrott=
le body and plate looked quite clean.

The IACV was where I thought it was, bolted to the rear / firewall side of =
the throttle body. I removed it and gave it a good clean with carb cleaner.=
 Looked a bit black inside, but not as filthy as I imagined it to be. Took =
a bit of cleaning with some cotton buds, to get the metal flap and other ar=
eas as clean as I'd like. As with other IACVs, when I'd finished cleaning i=
t, I could feel the flap move a bit inside, when I swung the IACV - so seem=
s to be moving freely as it should.

Put it all back together and ran the car up to temperature (parked up, mind=
, not driving) and the idle speed behaved perfectly, but then I'm not so su=
re it wouldn't have done the same prior to cleaning it. Even when warm, bli=
pping the throttle had no lag or hesitation about the idle returning to whe=
re it should be.

Road testing and general driving should give more of a clue as to whether t=
hat's done the trick.

If it still plays up, I'll unplug it, see what difference that makes.

Thanks for the help, chaps.

Lester Burnham wrote:

it would behave while stationary as the opening is only done in response to
throttle opening combined with road speed.

Further update: did journey of about 5 miles to nipper's nursery
again, when I got there, engine was warm, idle about 2k revs. With the
engine on, unplugged the IACV. Revs dropped a fair amount (at a guess
to about 1200-1300rpm - experience with iffy IACVs in the past tells
me that tends to be where the engine idles at, when warm, and IACV is
either broken or unplugged).

After that, switched off, took ankle biter in to nursery, then drove
another couple of miles, filled up with petrol. After that (ie turning
on after filling up) then check engine light came on - I'm guessing
that's almost certainly due to unplugging the IACV, and idle trim
being out of bounds? I'm ever hopeful, that the Kia's engine software
is one of those that doesn't need the light turning off with a
specific tool / gadget (some cars, seem to right themselves where
check engine lights are concerned, when it's been fixed, and several
ignition cycles have been done, others, though, seem to require a
software device to reset it).

Drove about 60 miles, then, car behaved as expected, warm idle
1200-1300rpm (as I'd expect with the IACV unplugged) but no issues
when blipping the throttle, idle returns to it's previous point.

During the day, I've left the plug connected - to avoid any moisture
ingress into the connections. I suspect if unplugged when started from
cold, idle will be a bit too low (from what I've experienced in the
past, 400-600rpms with a broken / disconnected IACV).

So I'm going to source a replacement, should be able to muddle through
with it until then. Conveniently, you can read the part number on the
IACV with it all connected up. What I'm wondering is, whether the
crafty Kia people did that simple out of cleverness, pure dumb luck,
or because the IACVs they use have a propensity for failure.

Thanks for the advice, chaps, will probably update the thread once
I've put on a new IACV, just to confirm / deny it's properly cured the
issue.

In article

Generally, they are not the most reliable of devices. The ones used on the
Range Rover with the old Rover V8 are a constant source of problems.

--
*The longest recorded flightof a chicken is thirteen seconds *

    Dave Plowman        dave@davenoise.co.uk           London SW
                  To e-mail, change noise into sound.

3rd update!

Not meaning to mither, but it may be of some use to somebody else...

I drove around for a couple of journeys with the IACV unplugged
(although plugged it in when stopped, to try and avoid any moisture
ingress). Truth be told, it didn't seem a world away from where it
should be - most noticably, the idle speed was consistent, but higher
than it should be (at a guess around the 1200rpm mark). That was the
same whether the engine was warm or cold (I started it up, after being
left around 8 hours, parked up) and the cold idle was at this point
(but remained at that point). No issue with blipping the throttle
leaving the revs high, though. As I mentioned in my previous post,
after about 3 cycles of the ignition, with it unplugged, the check
engine light came on.

I bought an aftermarket IACV (was just shy of =A350 - Kia dealers wanted
around =A3150, and other sites selling OEM spec ones seemed to be in
that order).

Looking at it, and inside at the workings (from what you can see down
the tubes) it looks identical to the OEM one I took off. Design looks
identical, markings look identical, I supposed the gubbins inside
might be of inferior quality, but doesn't look to be from the outside.

Anyway, I've put this new one on the car, and it behaves perfectly as
it should do - but only tested with the car stationary. After 3 cycles
of ignition, the check-engine light went out - so yay on that score.

I'll probably post one more update as to whether it's truly fixed the
problem when I've had chance to drive it properly, and get the engine
fully warm.

On Fri, 22 Jul 2011 14:22:46 +0100, Lester Burnham  =

4th update!

Not quite as positive as I'd hoped. For 3 or 4 days I thought I'd got
it sorted - with a replacement IACV (new, but pattern part). Over
mainly distance journeys (around 60 miles at a time) and some shorter
journeys, it behaved perfectly with the new IACV, when it would have
definitely showed behaviour as before replacing the IACV.

But today was a different story - quite a warm day, just short
journeys, with the kids, mile or two at a time, often with the air-con
on a lot. It happened again - revs creeping up to around 2k when
idling and stationary - and it sort of creeps up there, too. Any blip
on the throttle would make the idle rise to, say, 3k revs and stay
there.

One other thing I noticed, when it's doing this - say stopped at
traffic lights or at a junction, when it's idling high like this,
switching on the air-con brings the idle down to about 1k revs - which
seems a lot of change, accepting that an air-con compressor is a far
amount of drag on the engine.

One other factor - one of the drive / auxiliary belts must slip at
times - most noticable at low engine speeds, with the air-con on. I've
not noticed the battery / alternator light flickering when it's doing
it, though. I'll have to get that sorted, it's nagging at me that it's
in some way related.

So I'm left with the following possibilities:-

1. Original IACV was bad, new one has gone bad in a short number of
days - a possibility. I'm pretty sure that when it's revving high, if
I unplug the IACV, the creep / rise in idle revs to 2k, won't happen,
so it's clearly related.
2. Some condition of the engine, is making the IACVs go bad.
Everything seems OK, otherwise, no oil consumption, fuel consumption
seems about right. When I'd looked at the throttle plate / body, it
was cleaner that I'd expected - truth be told, the trunking to the
throttle body, and the clip and bolt looked like they'd never been
apart or unfastened - so I expect nobody had ever had it apart before
I did.
3. Some condition, fault, or problem is making the ECU tell the IACV
to behave this way. Seems odd, and unlikely, but if it's the IACV
that's making the engine race when it should be idling (and unplugging
it when it's doing this, and seeing the revs drop to where I'd expect,
were the IACV not operating implies that), and there's a certain
degree of unlikelihood that a new replacement IACV is either broken in
less than a week, or made bad by some condition of the engine - then I
have to at least accept the possibility.
4. Some other fault / problem / issue is causing this behaviour, and
unplugging the IACV when it's doing it, stops it, but masks the true
cause - dunno how plausible that is.

There's no check engine light on, or any other warning lights on - and
they all seem to work correctly - come on when the ignition is turned
on, go off when the engine is started. Nor is there any behaviour or
condition of the engine I can look at that seems overtly wrong - with
the exception that I can hear one of the belts slipping at times, at
low engine speeds, especially with the air-con on.

I think the next course of action will have to be unplugging the IACV
for the moment - it's more tolerable to have a permanently slightly
higher idle, than one that is far too high when the engine is hot.
This will no doubt, put the check engine light on, like last time,
which went away, after installing the new IACV, plugging it in, and 3
cycles of the ignition / engine start.

After that, I think I should probably buy one of those cheap code
readers / erasers, plug in the IACV, clear any codes, drive it, see
what happens, hopefully it will do it again, and read the codes.

In the meantime, any thoughts, ideas or suggestions welcome!

And I was so sure it was fixed, too.

On Wed, 27 Jul 2011 21:41:26 +0100, Lester Burnham  


Small airleak somewhere?

I wondered about an air leak, but thought if that were the case I could
expect the problem permanently, even when cold?

There are times when it takes provocation to do it. Yesterday, I ran with
the IACV unplugged - thinking it was the problem again, and found with it
unplugged the first time, the car was much less problematic. What I found,
though, made me reconsider the IACV as being the fault, and merely
contributing to it when it happens.

I had two journeys of around 60 miles to do (home -> office -> home) -
mostly motorways, and a couple of small journeys at both home ends. I
noticed, part way through the morning motorway run, that the idle was higher
than I would have expected (this is all with the IACV unplugged) - blipping
the throttle doesn't seem to affect it with the IACV unplugged - but again,
turning on the air-con, drags the idle speed down to about 1k revs.

So I'm guessing the hot idle rising is independent of the IACV, and perhaps
with the IACV connected, the only issue being that throttle blips when
idling, can push the idle up further.

Anyway, when I'd driven back to my home town, and had to collect my son on
the way back home (by this point, I'd have driven a little over 60 miles),
the car was idling around 1700-2000rpms, IACV was unplugged, I parked up,
nipped in to my parents to collect my son - would have been in their house
2-3 minutes, no more than 5, so the car would have still been warm. Got in,
started, car idled about 1k revs (IACV still unplugged - I suspect had it
been plugged in at that point, idle would have been at the normal
800-900rpms). I then drove a short distance to my house, parked, left the
engine running, and opened the bonnet - it would have been idling about
1700-2000rpms at that point. I tried unplugging the MAF (wondering whether
that's what was causing this - and I'd read that often, unplugging it when
engines are playing up, and it having no effect, is kind of suggesting it's
knackered) - that seemed to make the revs rise ever-so-slightly.

So I then plugged in the IACV, and the revs dropped to a completely normal
level (I suspect around 800-900).

Before doing that, I was inclined to think maybe cleaning the MAF (it's a
Bosch MAF, from memory, similar is used on several cars / engines - in the
trunking betwixt airbox and throttle body) - I'd read that being very
gentle, and spraying on a little carb cleaner and letting it evaporate off,
can often clean the thin wire.

Now, though, and I think I'm going to be more cautious and not throw parts
at it. I've ordered a cheapo, generic code reader, I plan on resetting /
clearing all codes, and / or leaving the battery disconnected for a bit,
connecting it up, plugging in the IACV, then driving it as normal, and
waiting for it to play up, then seeing what the code reader says.

I'm partly wondering whether there's some odd adaptation going on, here, and
being confused at times with the IACV being unplugged (definitely brings on
the check-engine light). But still, there could well be some real problem,
here, and I'm just a bit puzzled with it.

Any of what I've written sound daft, or is there any other approach anybody
would recommend (and yes, I have considered just taking it to a dealers /
garage to sort out, but experience has shown me - especially with main
dealers - that with problems that are either intermittent, or dependent on
temperature, they can be quite ineffectual, time-consuming, and
inconvenient - in terms of having to get the car there, and often not having
a courtesy car to give you - albeit at short notice)?

And sorry to mither and go on about it, but I'd love to be able to have
sorted - or at least diagnosed this.

On Fri, 29 Jul 2011 08:44:58 +0100, Lester Burnham  


It'll still be there but the IACV will br almost closed instead of open  
when the engine's cold.

Would you expect a check engine light, at some point, though, with an air
leak? 'cos surely if it's unmetered enough to disrupt warm idling, it's
enough (over time) to trigger some condition. That said, reading the codes
may be much more revealling.

The only thing that seems to bring on the check engine light at present, is
leaving the IACV unplugged for 3 cycles of the ignition / engine start.
Reconnecting it, and 3 cycles later, it goes out.

What's swaying me away from induction air leak, being that it only seems to
be certain conditions triggering this. Today I just drove a shortish
journey - and I've kept the IACV plugged in, now - the car temperature gauge
got fully into the normal bit, and the IACV responded to bring the idle down
from cold (little over 1k revs) to normal warm idle (800-900) and I drove
for a few miles, locally, and had no issues.

I would have thought an induction leak would have meant it would behave the
same any time the temperature got to the point where the IACV is bringing
the idle down to warm / hot engine speeds - but that's not necessarily
happening - and as I mentioned from my use, yesterday, after an hour, or so,
driving, stopped for a couple of minutes, when I started again it idled
perfectly 'til I'd been driving for a minute or so.

I guess if nothing else, one thing I've found is initially thinking it was
the IACV, it seems to behave like this with it disconnected. Roll on the
fault code reader arriving.

And thanks for your suggestions - anything making me think over it is help,
and I'd really love to crack this nut.

Me too!, my olde Audisaursus has an almost identical fault thats more
annoying that anything else. Its doing almost the same thing odd in that
when its in fault mode the revs will go from 850 odd to 1500 as if your
blipping the throttle. If you should rapidly switch the ignition on and
off it more often than not settles down to 820 rpm till you put your
foot on the go pedal when  its off again.

IACV changed original was duff so I reckon theres another part faulty
somewhere MAF seems clean must get around to checking some resistance
readings. It is much worse when hot, both temp sensors changed, almost
behaves itself when cold from start..
--
Tony Sayer


                

Have to say, I'm wondering about coolant temperature sensor. But then I
don't want to blindly go buying parts - but it does seem at least as if it
may be relevant. I just would have thought I'd get an engine light. I think
the fault code reader, when it arrived, may shine more light on it.

Oddly enough, in other cars I've had, I've had check engine lights come on -
or at least definite symptoms - for bad sensors - but in those cars, no
warning lights from either bad, or disconnected IACVs.

Like yours, mine is fine from cold, and often (for short periods) fine when
warm or hot. But when it starts happening, it doesn't yo-yo, if you slow
down to stop, the revs may naturally fall to somewhere, say 1300-1500 revs,
before declutching. Then when stopped, either in neutral, or in gear,
waiting to move, with the clutch down, the revs stay at that point, and
progressively rise to settle at around 2k. Air-con compressor being turned
on, drags it down to around 1k, if I turned it off, the revs would rise to
about 2k again. With the IACV connected, blipping the throttle would see the
revs stick at their highest point. Blipping the throttle with the IACV
unplugged, has the revs rise a bit, then drop down to about 2k.

And also like you, turning off the car, then restarting it can often see it
behave normally - at least until driving around a bit.

Thanks for replying, the info is all sinking in.

Just one other thing (said in a Columbo manner...) - I've read a couple of
comments, now, from web links suggesting an alternator issue for these
symptoms. One was unqualified, the other in relation to a 2005 Mini, and
said that the ECU had detected low voltage from the alternator, and decided
to up the revs.

Does that sound tenable?

I mentioned, previously, that occasionally I can hear one of the drive belts
slipping (tends to only really be noticable when the air-con is turned on),
so I suppose that could be contributory.

If it was the alternator, should I expect to see any flickering or blinking
of the battery warning light? Or failing that, would a fault code likely be
logged?

Also worth noting, once when this problem occurred, I'd just left on
motorway, and was waiting at a junction on a roundabout to join another.
This would probably be when I'd first really noticed it. So I was
stationary, the car was revving away at about 2k revs, I'd blipped the
throttle and the revs had risen to 3k. Not wanting to sit there for a while,
waiting for the lights, with the engine blazing away at 3k, I turned off -
that may not have been the best thing to do, but it didn't seem good to sit
there with it running at 3k revs, either. Then I struggled to start it
again. But it didn't turn over and fail to fire, it just didn't turn over. I
was stuck for a couple of minutes like that, with my hazards on, and people
having to drive around me, expecting I'd have to call out breakdown cover,
when I tried again, it turned slowly, then started. Slightly before that,
I'd noticed a little smoke from the side of the bonnet. After that, I drove
to my destination, everything seem fine, when I got there, I had a look
under the bonnet, and could see no rhyme or reason for the trace of smoke I
saw.

Needless to say, ever since, whenever I've had it rev like that in traffic,
I've never turned it off, I've always managed it some other way.

On Fri, 29 Jul 2011 10:54:54 +0100, Lester Burnham  


No idea on that car, looking `at the live readings would be revealing.


Has it got the irritating VAG failure mode where the engine management  
temperature sensor is completely seperate to the dashboard one?

Not sure about that until I look into it more. The temperature gauge seems
to behave normally, and settles in the region that other owners say is
normal (always stays a little below halfway - I'd normally think that was
suggestive of the thermostat needing replacing - but it appears to be normal
for the model).

Just seemed to be frequently mentioned as the fault for plenty of similar
symptoms, from googling it (CTS, that is). That said, so is the TPS. I think
when I experience it happening again (still awaiting the fault code reader),
and I've got an opportune moment to stop, I'll see what unplugging the CTS
and TPS does to the idle behaviour.