IAC failed?

lamagra69 · 20-10-2010, 08:17 PM

Long time lurker 1st time poster :P

Just went for a drive to the shops in my au2 Xr6 and at times it felt like the car had cruise control on(sitting happy at 40 in 2nd with no throttle)

When i got home the car sat between 2-3 grand and was slow in droping revs after i gave it a stab.

Pulled the IAC lead off and there was no change, (normally the car would stall)
Does this sound like a new iac for me? any ideas on prices?

Cheers

frd906 · 20-10-2010, 08:54 PM

sounds like it, if you can get one from the wreckers and try it first, before you fork out for a new part and find it wasnt the cause

lamagra69 · 20-10-2010, 08:56 PM

Yeha you pull it it just down the road from me so i guess thats the best option.

Ty for the info.

frd906 · 20-10-2010, 08:59 PM

No worries mate.

stev3n · 20-10-2010, 09:10 PM

Check that you don't have a leaking inlet manifold gasket.
One way to check cheaply is to spray Aerostart around manifold while it's at idle, if revs pick up you have a leak in inlet manifold gasket.

Good luck.

lamagra69 · 20-10-2010, 09:26 PM

I did have a porous inlet gasket that made it idle like crap about 3 months ago, changed it and it ran all good till now.. ill Give it a go 2morz as well but wouldent you be able to hear it leaking through?

lamagra69 · 24-10-2010, 12:59 PM

Ok an update to what is going on,

Changed t he idle air control (240 from ford 40 from a wreckers) no change.
Checked all of the vacuum lines that I can think of there doesn't seam to be any leaks.
Checked all the inlet manifold gaskets doesn't seem to be any leaks.

Can anyone think of anything else before I pull the manifold off to look for cracks ect?

Car sits at idle on 2grand sometimes dropping to normal idle but misses and runs like crap. Once you are over 2 grand it runs fine.

Cheers

frd906 · 24-10-2010, 01:04 PM

sounds def like a idle issue, what about changing the throttle postion sensor on the side of the throttle body

SLO247 · 24-10-2010, 02:27 PM

Its probably the TPS on the throttle body, I had exactly the same issue and thats what it was.

New are prohibitively expensive, so try a few second hand ones and see how you go.

lamagra69 · 24-10-2010, 03:24 PM

Cool thanks guys,

Took off the TPS and had a play with the engine running, seemed to fluctuate the revs a bit.

Now just to find one :(.
S1 has a different plug and shaft from the butterfly, and the 3 AUs at the local wreckers are absolutely gutted lol.

SL0247 did you notice you car absolutely chewing fuel when your TPS went?
I used 3/4 a tank in nearly 100 km :(

frd906 · 24-10-2010, 03:31 PM

could also be the ecu playing up

lamagra69 · 24-10-2010, 03:49 PM

What's getting me though, if I pull the IAC plug off the car would normally stall right away cause it has no air?

Im going to try the TPS if that dosen't fix it then I might look at the manifold before I fork out for a new ECU.

1 Other thing has anyone had any luck hooking up a OBD2 scanner to the ECU? I have a cable but cant get anything to recognise the ECU on my PC

webby_191189 · 24-10-2010, 10:46 PM

Quote:

Originally Posted by SLO247

Its probably the TPS on the throttle body, I had exactly the same issue and thats what it was.

New are prohibitively expensive, so try a few second hand ones and see how you go.

pretty sure genuine at cost price was bout $50 for the tps and $160 for the IAC.
Also found at cost price genuine was cheaper than repco and bursons

lamagra69 · 26-10-2010, 05:47 PM

Quote:

Originally Posted by webby_191189

pretty sure genuine at cost price was bout $50 for the tps and $160 for the IAC.
Also found at cost price genuine was cheaper than repco and bursons

Ford wanted 240 for the IAC not sure about the TPS but I picked one up from the wreckers for 20$

but.... still the same problem

I think this weekend I will pull the intake manifold off and change the gasket, Its the only thing i can think of.
It must be Air getting into the system past where the ECU knows because it will still rev happily at 2K with the IAC disconected or blocked off.

Anyone have anytips on changing the inlet manifold gasket?

And thanks for all the help and suggestions so far guys.

lamagra69 · 27-10-2010, 08:34 PM

Ok 1 last thing before I pull the manifold off,
What is this???
Its just behind the windscreen water reservoir

After some spaghetti of vacuum lines it plugs into this

All i could find out about it was an EPC is a fluid control valve used on car vacuum systems and that it can be used on car Auto trans, (i have a manual 5speed)
What gets me is that it plugs into the firewall just behind where the airbag is on the passenger side and goes no where near the trans.

I don't really wana run the car to see if its vacuum leak if its conected to the airbags, they scare me lol.

So does anyone have anyidea what it is and what will happen if I unplug it?

Cheers

frd906 · 27-10-2010, 09:47 PM

looks like its part of the vacum