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[bigup316]

first changed plugs due to bad miss fire car runs great but engine management light comes on now and again and when you come up to junction put your foot on clutch revs drop to about 1000 then go up to about 1500 before dropping to normal or sometimes it ticks over on about 1000 changed throttle position sencor still does someone help only had car 2 weeks beginning to wish i had bough somthing else

[amba]

Had similar problems with my 2.5 elite that you are describing..suggest you remove the idle control valve..give it a really good clean with carb fluid and then a couple of drops of 3:1 oil on the slider to ensure it moves freely..also worth checking the wiring from the cable tray to the tps as mine had started to chaff and was causing a slight electrical short..like yours only intermittent..if you read through past questions over last couple of weeks you will find all my issues..good luck with it and hope it is a minor setback for you and your mega ownership

[bigup316]

thanks for info have just cleaned idle control valve still doing the same did notice gasket was a bit cracked and in a bit of a state would this cause the problem mine is a 1998 2.0 16v if this makes any difference

[TheBoy]

irratic idle, things to check:

clean icv
clean throttle body
check egr
check for other air leaks

[Grumpy]

Agree with everything 'TheBoy' said but would like to add a little more.

There's no point in cleaning the IACV until you've fixed the most likely cause
of it oiling up...........it will just oil up again.

You have 2 breather pipes coming from the cambox cover.
The large one goes into the large Black intake trunking that connects
to the top of the Throttle Body and is therefore upstream of the Butterfly
and the Idle Air Control Valve.

The smaller one, which is the problem, connects just underneath the Throttle
Body and is therefore Downstream of the Butterfly and the IACV.
If you follow this smaller breather you'll find it joins onto a horizontal connector just
south of the Throttle Body. It will go onto a Banjo connection with 2 more pipes
coming up to the banjo, from underneath, like an upside down 'V' shape.
These 2 pipes connect to the Engine Cooling system and are used to heat the
jet that the Small breather pipe connects to.

This jet really narrows down in the middle. Imagine an hourglass egg timer laid
horizontal. The heating from the water pipes cooks the crud coming down the
breather pipe and blocks it solid. An easy check is to pull end of the cam cover
and try blowing down it. If you can't............it's blocked.

During normal operation, the small breather pipe, being south of the butterfly, is
obviously subject to a higher vacuum than the larger breather pipe that is North
of the Butterfly. So all the crud and oil mist gets sucked in there and does not pass
through the larger breather pipe and the IACV which everyone cleans.

If it blocks, then all the crud and oil mist passes down the large breather and into
the IACV.

So check and clear that small breather connection before doing anything else.

Now we come to the IACV cleaning itself. It's not the bit you can see that's the problem,
(when you've taken it off and are looking at the 2 round holes and the valve), but the bit you
can't see.

If you are looking at the 2 round holes, the one nearest the electrical connector is where
the air comes in and the one nearest the flat end is where the air comes out.
If you look carefully at the one nearest the electrical end you'll see it is actually
deeper than the other one. This is because there are drillings at the bottom of the hole
that run right around the valve area that you can see and carry air to the other end
and exit back into the hole near the flat end of the valve. It's these drillings that block
up with crud and oil and cause your problems.

So to clean it properly you need to soak it overnight and keep repeating until clear.

If you don't clear the small breather connection just South of the Throttle Body, all you'll
do is drag oil back down into those hidden drillings in the IACV and disrupt the correct
working of your nice clean IACV in pretty short order.

This is also another reason why I don't advocate oiling the IACV after cleaning. It doesn't
need it, and it may actually get to where it shouldn't do in the IACV and cause problems.
The only place that may need a little lube is if you take off the solenoid from the IACV, and
maybe put a touch of vaseline on the shiny spindle that projects into the Solenoid mounted
onto the IACV.

Hope that helps.  

[bigup316]

thanks for info will try it tomorro and let you know what happens

[bigup316]

not to sure if i have the right pipe dont suppose any one has a picture thanks

[Grumpy]

Sorry about the picture quality, my camera has gone all Pete Tong
and I'm using my phone camera.

Small breather pipe arrowed.
Disconnect it where arrowed and try blowing down it.

Obviously it's the other end that blocks. Just follow the pipe to where
it connects just South of the Throttle body.

[Grumpy]

[Grumpy]

Sorry about the hour's gap in posting. Been waiting all day for the leccy man
to come and do to 10 yearly mains electric meter change.
Sod's law......... he came and turned the power off right when I was posting
the pics.  

Anyway, here's a pic of the IACV removed, so you know what you're looking
for.

 

[Abiton]

I've got one of them there idle valves with the endcap removed showing the hidden drillings Grumpy's described, and the second valve that hides up the far end, letting air go the other way presumably to balance any tendency for the valves to be held open by the airflow.  I'll take some photos now (hard to describe in words!).  Would someone with the necessary savvy please PM me their e-mail address and volunteer to post the pics? (If this would be useful).

P.S. If the cleanout of breathers, idle valve etc seems to make matters worse, or no better, suspect a problem with the CTS, that high revving approaching junctions sounds awfully familiar.

[Grumpy]

PM sent, Abiton.

[Grumpy]

Here are 2 of the pics kindly e-mailed by Abiton.

The first one shows the IACV broken down into it's composite parts.
Note the valve that you normally can't see towards the Flat end of
the IACV.

The second pic shows the drillings I was talking about supplying Intake air
to this valve.

When the engine is idling with the Butterfly closed, the inlet side of the IACV
is above the Butterfly and the Outlet side of the IACV is below the Butterfly.

Therefore, because of the drillings, each end of the dual valve that you see
in the first pic is connected to ambiant inlet air pressure.
The centre (outlet area) between the valves is subject to the lower vacuum
pressure generated by the 'Suction' of the engine.

The arrangement of the valves, valve differential areas and bleed area, will control
the airflow to the engine and thus the idle speed.

If you get oil down the drillings it will disrupt the correct operation of the valve and
therefore the engine idle speed.

You can see now why I said to soak it overnight and not to oil the valve area after
cleaning.

Thanks again for the pics, Abiton.

[Abiton]

Cheers grumpy  , sorry (everyone) about my poor photographic skills.

I found that my cleaning job had been very successful, but there was some asymmetric wear on the 'hidden' valve seat, so it wasn't a complete waste getting a new one, even though I had other troubles which dominated anything that this fella was up to.

Oh, and it sure looks like the o-ring/end-cap were doing some leaking!

All good now. Top car, top site.