Got busted @ MOT, advices needed.

[k.alle]

So, took the car to the Swedish MOT today and it failed, a little rust and some general crap that is no biggie and there's these two posts:

1. Engine, oil leakage.
2. HC level @ idle, too high.


First off the oil leakage.
I had the car at my local VAG shop for a timing belt renewal and they changed those seals up front, camshaft and crank so they are fresh.

I did a engine wash yesterday as I knew there had been leaks before, and then took it to MOT.
On inspection it had a curtain of fresh oil on the left hand of the engine, dry on the right side.
In my service notes it seems like a previous owner has changed the valve cover seal about 1.500 miles ago.
So what can cause this on the left side, what should I look for, I need to have an idea before I just end up staring at nothing.



Secondly, the high HC level.
Here's the full list of readings that I recieved:

CO: 0.1 (0.5)
CO 2500 0.0 (0.3)
HC 140 (100)
LAMBDA 1.02 (0.97-1.03)

As soon as he revved the car slightly the HC level dropped to ~30-40 and stayed there as long as he revved it slightly, but would not hold @ idle.
I guess I could clear the car through MOT by fueling it with E85 the next time, but something is playing up and I would like to know what.
Any givens that I should look at first?



Cheers guys & gals!

[A80Avant]

i had the same problem and it seemed that oil was burning through the piston rings in my case.I couldnt pass greek MOT @idle and everything was OK @ 2000rpm.
I dont think the cyl head cracks i had were the issue,and when the head was out the valves had a quite redissh look,which seems that the oil was getting through and screwing the MOT results

[A80Avant]

however since you also have the oil leak,it could be just a head gasket problem which is causing both.
do you get any water droplets in the oil?Any bubbles on the dipstick?

[k.alle]

Hmm, I have never noticed any water in the oil on the dipstick It has only been "just oil".

Looking back at previous MOT's the HC level has varied throughout the years.

1997 (register) it had HC 18
1999 HC 87
2002 HC 40
2003 HC 23
2003 HC 83
2004 HC 97
2007 HC 01
2008 HC 140


So according to my records it has only been below HC 83 three times.
Weird.

[EDIT]
I can't count, it's 4 times of course.

[BrianSmith_S2]

Hmm, I have never noticed any water in the oil on the dipstick It has only been "just oil".

Looking back at previous MOT's the HC level has varied throughout the years.

1997 (register) it had HC 18
1999 HC 87
2002 HC 40
2003 HC 23
2003 HC 83
2004 HC 97
2007 HC 01
2008 HC 140


So according to my records it has only been below HC 83 three times.
Weird.

[EDIT]
I can't count, it's 4 times of course.

would it be worth giving the inside of the throttle body housing a good clean with a spray of carb cleaner, maybe a bit gummed up?

[k.alle]

would it be worth giving the inside of the throttle body housing a good clean with a spray of carb cleaner, maybe a bit gummed up?

I actually had a look some weeks ago when I replaced the TPS, looked fine to me.
There was no build ups or anything so I just bolted it back.

I'm thinking of doing a pressure test to see if I find any leaks on the air side.

Did notice a couple of things, driving to and from MOT.
Occasionally when in 4th gear (only gear i noticed on) and I stomp the pedal, it is only giving 1.1-1.2bar of boost, and a slight fluctuation on the needle.
And then next time around I have 1.4bar steady boost.

I'm not sure it's related to the above but if I "surprise" the car with some random WOT's it behaves quite weird.
It's like it's getting panic and don't know what to do until I reach 4.000 RPM where it completely blasts away in comparison, ketchup effect.
When I don't sneak up on it like that and open the throttle from almost closed to full in about 1-2 seconds it pulls hard throughout the rev band, from first boost to the red line.

Anyone had these symptoms, perhaps it is irrelevant to the HC issue.



[EDIT]
Oh, and I have a quite high MPG doing say 60 MPH, it lies around 9.5-11.0 if I should believe the onboard computer.
Of course I am feather light on the throttle when doing 60 MPH.

[dkw_dude]

I'm thinking of doing a pressure test to see if I find any leaks on the air side.

Do the pressure test. Pressure test the PCV system too, @ low pressure. I had similar problems, found a small leak in a PCV hose. Corrected it and all was ok. These engines will need to be "airtight" in every way to perform at their best. Even on the exhaust side.

[k.alle]

Will probably give it a try to.

One thing though, how do you guys pressure test?
I for one just add pressure behind the MAF and plug the PCV system.
The problem is that one can not get any pressure to stay, because of it going through some valves and out through the exhaust.

But it's usually easy enough to spot an air leak anyways.
Does anyone plug the throttle body?

[UrS4boy]

Will probably give it a try too.
One thing though, how do you guys pressure test?
I for one just add pressure behind the MAF and plug the PCV system. The problem is that one can not get any pressure to stay, because of it going through some valves and out through the exhaust. But it's usually easy enough to spot an air leak anyways.
Does anyone plug the throttle body?

You need to plug a lot of things if all you want to do is test the intake tract. The URL link below is to a post I made about pressure testing an AAN but it probably applies in general to the ABY and 3B, particularly with regard to the BPV and the ISV.

http://forums.audiworld.com/s4s6/msgs/217734.phtml

Hope it helps.

[newsh]

Check carefully you dont have a small leak where the vac/boost line joins the ECU.

[k.alle]

Update.

I think I found my idle problem tonight.

First off I pressure tested, it was sealed up nicely, didn't test higher than 1.5bar though but all vacuum hoses and such were holding up nicely.

Then proceeded with removing the electric connection on the ISV and the car was happy I can tell you.
It idles like a dream now at 900 RPM and no small missfires/studdering/hesitation or anything, and it doesn't mess about when slowly pulling through the revs.
All nice and smooth so it has to be the ISV, right?


Secondly I also located the oil leak, I think.
It is the sensor located above the oil pan at the far end of the front of the engine.
One sensor is really big and bulky and has two wires connected to it, oil temp?
And one sensor directly below it that is smaller in size with a rubber boot and a single wire IIRC, that's the one that's leaking.

Anyone know what sensors I mumble about?
What are they?


Cheers!

[UrS4boy]

Update.

I think I found my idle problem tonight.

Secondly I also located the oil leak, I think.
It is the sensor located above the oil pan at the far end of the front of the engine.
One sensor is really big and bulky and has two wires connected to it, oil temp?
And one sensor directly below it that is smaller in size with a rubber boot and a single wire IIRC, that's the one that's leaking.

Anyone know what sensors I mumble about?
What are they? Cheers!

Not sure if I understand where you are pointing to. Is it anything in lower figure in this post:

http://forums.audiworld.com/s4s6/msgs/116988.phtml ?

[k.alle]

I think you misunderstood me, the sensors is located at the other end of the engine, not the flywheel side.
They sit behind the alternator/generator and above the oil pan.
Not easy for a swede to explain the position in words
Perhaps it is the oil pressure sensor (1.8 bar?).

[k.alle]

I think I found it in the family album:





Will the thermostat be an easy swap when I've dug myself into the oil pressure switch?
Any experience on replacing this bad boy, how much will have to come off on a LHD car?

[UrS4boy]

I think you misunderstood me, the sensors is located at the other end of the engine, not the flywheel side.
They sit behind the alternator/generator and above the oil pan.
Not easy for a swede to explain the position in words
Perhaps it is the oil pressure sensor (1.8 bar?).

You didn't scroll down to the second "picture" in the post I linked to. It clearly shows (in grey) the oil pressure gauge sender and the F1 Oil pressure switch, which you have now found in ETKA.