Intermittent high / fast idle? - Page 2

Further update!


I'm wary this could turn into a blog-like-epic, but all the same, thought
I'd post my latest findings - to see if anybody with a sharper brain can
illuminate me.


So I'd replaced the IACV, with a pattern part, that didn't seem to cure the
problem.


Further cleaning of the throttle body seemed to have a positive effect - in
fact, I don't think I've had any instances when it's happened and blipping
the throttle has pushed the idle any higher.


Before my code reader arrived, but after I'd had an abortive attempt at
changing the CTS (speculatively bought a new one, as there's a Kia
dealership literally 5 minutes from where I live) I'd done some more
cleaning of the throttle body, as I'd had it all apart to try and get better
access to change the CTS. I also adjusted / checked the throttle cable, and
made sure the linkage and spring were all clean and moving freely. So rather
than disconnect the battery (to reset the ECU - I wanted to have a clean-ish
slate for when I code properly read the codes) - didn't particularly want
the rigmarole of having to set the clock and the radio... - I noticed the
fusebox has a dedicated fuse for the ECU, so I took the fuse out for a few
hours.


After that, things seem to improve quite a bit, really, no real instances of
it happening for a couple of days, and when it did occur, it wasn't that
bad - about 1500rpms, blipping the throttle didn't push it any higher,
turning on the air-con would make it drop right down, and in many instances,
it just didn't do it.


At this point, my code reader arrived - worked perfectly, no codes stored,
no reported issues displayed.


Any way, having that problem where you just can stop tinkering, realising I
hadn't done as thorough job cleaning the throttle body as I'd liked - and
after all the problem hadn't totally gone away - I thought I'd give it one
more go, with an old toothbrush - working on the premise that things seemed
to have improved since doing so in the previous instance.


That didn't seem to make any difference in the short term. However,
yesterday, during my second 60-ish mile journey in it, the rev problem came
back with a vengeance. When hot, and, say, leaving one motorway, stopping at
lights / junctions, revs would stay at 1500rpms (minimum) and steadily
climb - I think if I'd have left it to, probably to the rev limiter, because
in a couple of instances it had got to 3k revs and was still going. Turning
on the air-con - especially when just stopped / just as the revs started
climbing could see it halt progress, and if timed well, drop down to 1k
revs, but when the revs had already climbed to about 3k, it had limited
effect. Also, when the revs were high, and I hadn't been that quick getting
the air-con turned on, or it took a second or two for the ECU to turn on the
compressor, selecting first, and gently taking up the bite to move the car
(not leaving the clutch wearing away, though) was enough loading to drag the
revs down.


When I got a chance to stop, I plugged in the code reader - but still
nothing - no codes, and nothing else within the diagnostics on it, to point
to anything.


When I'd finally stopped, I looked to see the throttle linkage and spring
position, the throttle didn't look to be stuck open.


So now I'm puzzled, I guess the only thing that could have the revs climbing
like that - assuming the throttle is closed, linkage and cable not sticking,
is the IACV. I can't believe the IACV has gone bad, so can only think it's
doing this under instruction from the ECU. The IACV doesn't seem to be
sticking - because when stopped, revs can be around 1500, then start
climbing. Plus I haven't seen the return of blipping the throttle pushing
the revs higher, when it's happening. Although, truth be told, the revs are
creeping higher all by itself.


Vacuum leak has been mentioned, but would it keep climbing like this (3k, 4k
probably higher revs, if left to it's own devices) - but not
comprehensively - if I was just parked up, turned on, let it warm slowly at
idle, it would probably not do this. And wouldn't I likely see some error
codes from such a significant induction leak?


Next plan of action is to await delivery of one of those USB ECU live data
thingmies (ELM?) and run the software on a laptop and plug it in when it's
behaving like this, and see what all the live data monitor-ables show -
maybe that might give some clue as to what's getting the engine to behave
like this.


Do the current symptoms make any sense to anybody - any other advice? And
yes, I'm rapidly approaching the whole take it to a dealers and let them
sort it out - but, dammit, for my own sanity I'd just like to understand,
and even fix it myself.

I wouldn't place my faith on some software solution. It sounds to me like
a good old physical problem. Like as you said an air etc leak. Assuming
the ICV is operating correctly.

--
*Of course I'm against sin; I'm against anything that I'm too old to enjoy.

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

I suspect you're right about where the problem is. The only thing I was
thinking about, software wise, was that it may give me some clues as to
what's going on when it does this.

The past couple of instances, there's not been the time to unplug the IACV,
either I've been driving in places difficult to stop, and / or the revs have
gone up to high, I was more worried about driving them down somehow.

As I mentioned in my reply to Tony, I think there might have been a minor
problem with the IACV at one point - the blipping of the throttle when the
idle was high, driving it even higher - which now doesn't happen.

In terms of an air leak, is spraying carb cleaner around vacuum lines a
reasonably safe approach?

On 5/08/2011 11:19 PM, Lester Burnham wrote:

  I personally avoid using carby cleaner around the lines so its not
ingested causing other problems - its a savage solvent.

Oil is a good substitute or WD40.

Diagnostic software can only help where it has the data to diagnose. The
ICV, for example, doesn't supply any such data.

--
*When companies ship Styrofoam, what do they pack it in? *

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

This car's ECU can at least detect when it's disconnected, though - whether
that's purely electrical (don't think so based on the symptoms) or perhaps
affect on long term idle trim - with the IACV disconnected, the check engine
light came on after 2 cycles of the engine running - reverse for plugging it
back in.

Previously cars, where I've had to tinker, and at times unplug, the IACV,
and there's been no warning lights.

I think where I'm coming from with the diagnostic software, is it seems to
have a dashboard showing a fair few parameters - I was just hoping when it
exhibits the behaviour, something looks different (not necessarily fault
code producing, mind) to normal - and I think it allows some logging as well
as real-time display.

From where I'm sat, the idle going up can only be a few things, really:
sticking throttle / cable - should be physically visible, under the bonnet,
and wouldn't account for the idle now slowly, but steadily increasing; IACV
doing it - either because it's faulty, or because the ECU is telling it to;
fuelling being increased for some reason (iffy TPS, or CTS) - but would have
thought there should be error codes for that; induction leak - again would
have thought there should be error codes for that.

Given the lack of error codes, one thing that's been haunting me about this,
is somebody posting to a forum about the idle speed on a Mini (I assume the
current one, not the original one), and it being raised because the ECU was
seeing some issue with the alternator's output, and increasing idle to
compensate. In that scenario, would you either expect there to be fault
codes stored, or some other warning lights (battery?). I keep coming back to
think about this, because I'm wondering whether there would be any other
obvious symptoms, or software / codes evidence.

Yeabut how would the ECU know what -load- was on the alternator?..



Err umm .. Firmware upgrade;-!...
--
Tony Sayer

On Fri, 05 Aug 2011 19:50:55 +0100, tony sayer wrote:

[...]


It wouldn't need to:

Engine running?
System voltage low?
Up the idle rpm a bit until voltage is OK.

Chris

--
Remove prejudice to reply.

Exactly - that's what I'm wondering about. And I do wonder whether anything
would get flagged as an error.

Would account for the symptoms - increasing idle, as the increased idle
seems to have got worse.

What I'm not sure about - because, largely, car electrics are still a bit of
a mystery to me - is whether heat - perhaps especially high under-bonnet
heat - could be a factor influencing how much the alternator was playing up.

I'm also wondering whether the OBD dongle and software, might at least give
me some indications, reporting stuff in real-time, both when the engine is
behaving normally, and when playing up.

entlworld.com> scribeth thus

Well measuring the volts might not be the most accurate method to
determine the load on the alternator the amps would be the way to go but
either way I somehow have doubts this is causing the problem
concerned;!.,..
--
Tony Sayer


                

On Mon, 08 Aug 2011 11:19:23 +0100, tony sayer wrote:


As I said, the system wouldn't *need* to know the "load" on the
alternator; it just wants to know that the battery is not discharging.  
Pretty much all ECU's get voltage feedback anyway, so it's a trivial bit
of software to give added security.

Providing a feedback to the ECU giving the current in the charging system
would be expensive and pointless.

I also doubt that it's anything to do with the OP's problems, especially
as it's unclear as to whether has car has such a system.

Chris

--
Remove prejudice to reply.

Given every ECU is connected to the car electrical system, it's fair to
say it will know the voltage. ;-)

Most ECUs will alter the injector opening time to compensate for a varying
12 volt supply.  



As IMHO is having the ECU control the alternator. It's quite capable of
doing so itself. As they have been doing since first introduced.


--
*Before they invented drawing boards, what did they go back to?

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

On Mon, 08 Aug 2011 13:05:58 +0100, Dave Plowman (News) wrote:

[...]


The fact that it is supplied by the car's system doesn't automatically
mean that it will "know" the voltage in the sense of being able to detect
what the actual voltage is.


Indeed. By virtue of the trivial piece of s/w I mentioned.


Are you saying that systems that have better control of battery charge by
using the ECU are not a good thing? If so, I'm afraid I disagree strongly.

Systems like Ford's Smart Charge have significantly improved battery
life, and likewise reduced the chances of being stranded with a flat
battery. Again, there is very little cost. Existing sensors are used for
things like temperature monitoring. There is one extra wire to the
alternator. The rest is done in software.

The actual regulation is still done in the alternator; you can remove the
single extra wire to the alternator and it will still charge.

What's not to like ;-)

Chris

--
Remove prejudice to reply.

Pointless. Except to tie you into Ford spare parts.

The batteries on both my cars are over 7 years old. The one on the SD1 -=
which sometimes isn't used - has gone flat a few times too. It's a no name
far east one from the local accessory shop. The BMW one Bosch.


And as we all know software means perfect? ;-)


All rather OTT for a simple lead acid battery.

--
*Strip mining prevents forest fires.  

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

On Mon, 08 Aug 2011 16:54:13 +0100, Dave Plowman (News) wrote:


How does it do that? Many non-OEM alternators are available for my
Focus...


The battery on my last Focus was 10 years old, and still starting the car
in all conditions.


?


Absolutely not. Smart Charge is one of Ford's better ideas.

Chris

--
Remove prejudice to reply.

Well to do that it needs to know what is flowing where a simple single
point voltage measurement isn't really going to do that..


No, agreed on that;!...

--
Tony Sayer

                

On Tue, 09 Aug 2011 08:03:55 +0100, tony sayer wrote:

[...]


How do you think that the state of charge of a battery can be determined
by the current flowing?

To use the infamous "tank of water" analogy, you couldn't determine how
much water was in the tank by measuring the flow rate out of it. (Unless
you knew the original volume, and calculated it, which is something else
altogether of course.)

Chris

--
Remove prejudice to reply.

Assuming you know the external load, you can determine the battery state
by the current it draws while charging. Because the correct charger for
lead acid is constant voltage which varies the current as the battery
voltage changes while it charges.

--
*I couldn't repair your brakes, so I made your horn louder *

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

On Tue, 09 Aug 2011 10:07:42 +0100, Dave Plowman (News) wrote:


You can. For the purposes under discussion (raising idle speed to
maintain alternator output when the battery state is low), why would you?

Chris

--
Remove prejudice to reply.

Why would you want to raise the idle speed if the battery was low? Better
to fit a correctly specced alternator. It's not like as though modern cars
have a slow idle - quite the reverse.

--
*Strip mining prevents forest fires.  

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