1.8 issue

[ralphtown]

OK,heres the thing.

I bought this nice Mk3 1.8 in December from a nice 83 year old gent.
I,m only the 3rd keeper.

I enjoyed driving it daily.
Until MOT time.

Car has failed on emissions.
High Lambda readings which I know means its running lean.
I was advised to buy a new Lambda sensor,which I did even tho I knew nothing was wrong
with the one on the car.
I was advised to buy a throttle body,which I knew was wrong but I got one from a low mileage scrapper (same engine code).

I got one of the diagnostics guys round who found a slight air leak in the manifold/exhaust gasket,so I replaced it.
I,ve checked all the hoses and replaced the one that usually lets the side down,just in case I could,nt see the split.

I,m now ready to scrap this piece of sh*t coz its still failing and I have no idea where else to check.
This week,I will have the diagnostic guy back,just so I can make a list of any fault codes but aside from that,is there anywhere else I can check for an air leak on a 1.8 ADZ engined Golf?

Thanks.
RALPH

[Leon27]

Dont give up!

I had one and although my emissions were never out I did have to change the throttle body mounting plate as it was split. If its split and letting in unmeasured air this would cause a lean mixture. I assume when you replaced the throttle body you saw the rubber plate it sits on, check it for cracks.

There are a 2 Vac hoses that go in to the round intake part that sits over the throttle body, as with all VW's they perish so check them and where they originate from.

One way of checking for air leaks is to get carb cleaner/brake cleaner and with the engine running spray it on the intake air parts and vac hoses. Try do it on a cold engine. If the engine revs rise after you've sprayed a particular area then you would have found your air leak.

Hope that helps

[ralphtown]

Thanks Leon.

Yeah,I had to replace the TB flange(thats what VW call it).
It was split.
In fact,it was in 2 pieces.
But the car was still driving fine.

Do you mean the 2 very thin almost drinking straw like hoses?
I,ve had a good look at those.
One of them goes to a little solenoid type affair on the left inner wing,which has something to do with the fuel supply/return.
They seem to be OK.

I,ll have my guy come round on Tuesday and give me fault codes.
I,ve had the downpipe off whilst I was replacing the gasket and I checked the hoses back there.

A clue MIGHT be that if you clamp up the fuel return pipe from the TB the engine becomes super smoothe.
But on the gas analyser it goes from red(lean) to green to red(rich).
So I was thinking fuel pump but they tend to either work or not work.
No half way house.

With the suspension work and rubber bush replacements,the car drives really well.
Nothing on the MOT bar this bloody lambda reading.

RALPH

[Leon27]

Is the engine running rough when cold or anything? Clamping the fuel return would in theory not allow excess fuel from leaving the injector thus possibly making the mixture rich, which was proved as you say on the gas analyser. But you are right, doesn't sound like a fuel pump issue.

Seems like you have covered most known faults however still try the brake cleaner method when you get the chance. Also after reading the memories don't be disheartened if there aren't any codes, the MK3 diag system is quite primitive. Check status' especially the coolant temp sensor as this determines how much fuel is put in the engine.

By the way, does it fail on idle only or through all idle and fast idle tests?

[dom]

How much did you fail by?

If not very much then i'd drop some redex into the tank and thrash the car to within an inch of it's life for a few miles before taking it to the test centre. Should see the emissions drop a bit 

[ralphtown]

Leon,
Tell me where the coolant temp sensor is located.

I,ve tried the redex thing.
Drove it at highly illegal speed from Junc 25 M1 to 28 and back but had to put it back
in the lock up coz we could,nt get access to the gas tester.

No idea if its REALLY high,MOT man not very helpful.
I think he,s pissed off with us blagging his gas test machine.
But he,s cool.
Not many folk would put up with Robin and I popping round every couple of days

RALPH

[zdebx]

He must give you a test sheet showing by how much it failed and the possible reasons of why...

Perhaps try another garage?

[Leon27]

You'll see a coolant pipe going into the head with a square electrical plug on it, unplug that and you'll see the temp sensor.

[ralphtown]

I,ll check that once I get my new part.
I,ll pop back in a couple of days once my diagnostics guy reads the codes.

I,ll post them up so we can find out whats wrong,assuming he does,nt know of course.


RALPH

[ralphtown]

By the way,is that your ride,Leon?
The silver Mk3

Looks good.
Does,nt look too messed around with.


RALPH