GolfGTIforum.co.uk
Model specific boards => Golf mk3 => Topic started by: ralphtown on 15 August 2010, 20:12
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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
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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
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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
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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?
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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 :wink:
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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
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He must give you a test sheet showing by how much it failed and the possible reasons of why...
Perhaps try another garage?
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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.
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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
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By the way,is that your ride,Leon?
The silver Mk3
Looks good.
Does,nt look too messed around with.
RALPH :smiley:
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Quick update.
I,ve had a quick word with my mate and he has removed the down pipe and checked it for leaks.
No leaks.
He has replaced the exhaust/manifold gasket and is replacing the head/manifold gasket with a genuine VW part.
I,m getting a new coolant temp sensor in the hope that IT is failing.
So,basically,is there anything else I can check or replace.
Coz we,re out of ideas.
By the way,if anyone in Nottingham is reading this and has a code reader,please get in touch.
No sign of the diagnostic guy yet.
RALPH
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It is my car, thanks dude, I'm going to keep it standard, at least on the outside.
Did you check for air leaks using the brake cleaner method?
I'd get VAG-COM free yourself, a lead for about £20 etc and see what the temp sensor is doing before you replace it. You will also be able to see what the oxygen sensor is doing, if its values are switching or its dead.
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UPDATE!!
I,ve replaced the temp sensor.
I,ve had repaired small leaks on the exhaust manifold (new gasket).
I,ve also replaced the down pipe gasket.
The hoses have all been checked and/or replaced.
The ignition timing was found to be a couple of degrees out and adjusted.
The cam timing was checked again,just to make sure something had,nt moved with the cam belt replacement.
Everything we,ve done has made no difference to the Lambda readings.
Still reading high(weak mixture).
SO!!
Can anyone supply me with the fuel pressure figures for a 1.8Golf with ADZ engine code?
This is the last chance saloon for this car.
If I can,t get it sorted by the end of September,I,m turning Japanese!!
And this one will go on ebay,spares or repairs.
My mechanic mate and I are reminded of when the diagnostics guy came,how he changed the Lambda reading by clamping the fuel return line
on the TB.
So,we,re looking at low fuel pressure as a final resort.
RALPH.
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fuel pressure regulator faulty? Have you checked the voltages, etc, available at the injectors? One side should be +12v (aka battery volts) and if you have a scope the other should be pulled to 0v (gnd) by the ECU. You'll need a scope or adapter for it that will take ~50v as there is a spike when the ECU releases the injector.
Simple one, but fuel filter?
J
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Where is fuel pressure regulator situated on the car?
Does this have any adjustment to play around with?
Fuel filter has been replaced along with a ton of other spares.
I,ll get my friend to check out what you,ve just typed.
I can,t explain that over the phone :)
Would still like to know how much in psi or bar,fuel pressure should be tho.
Thanks for the tips,I,ll pass them on.
RALPH
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My internet researches suggest fuel pressure for Golf Mk3 should be 3 bar max with 2.5 bar at idle.
There seems to be lots of expensive adjustable regulators online but I have found a replacement regulator with adjustability for less than £30.
Anyone ever used one of these or are OEM replacements cheaper than this?
RALPH
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get a VW one, more money but you know its correct then. VW ones not adjustable per-se, but they do have a vacume hose to the throttle body. If there is a fuel reg on yours, it will be either on the end of a fuel rail, or part of the throttle body (if single-point-injection).
J
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Euro car spares have given me a price of £39.99 plus vat,so around £45 new.
Can anyone better that price?
I,ll check my manual for the FPR location and get my man to check all hoses going to it.
Perhaps its pulling in some air around it,thus weakening the mixture.
I,m grabbing at straws with this motor :(
RALPH
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Did a bit of digging around.
Fuel pressure regulator is built into top of TB.
Now,seeing as I,ve changed that with no difference,I,ve either got 2 fooked TBs or thats not the problem area.
Car drives and runs superbly,none of this makes any sense.
So,I,m going to bite the bullet and take it away from my friend,who is a mighty fine mechanic and take it to one of the specialists in Nottingham.
I think theres one in Lenton,called Auditec or something like that and I,ve been told they have all the latest diagnostic equipment in their workshop.
RALPH
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sensible plan when all obvious stuff fails.
Let us know what happens.
James
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Will do matey.
Just to add to the sum of human knowlege :)
By the way,where is the idle control valve located?
I,m reading cleaning this can produce amazing results :)
RALPH
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The fuel pressure figures I gave are for multi point injection cars.
Single point engines run at 0.8 to 1.5 bar.
Just to clarify.
RALPH
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The Car is Sorted!!
Got a bit fed up with it and lots of "experts" who should know better telling me it was anything from the wrong throttle body to a screwed ecu.
Turned out to be the 4 wires from the lambda plug in.
Thats the plug into the car,not the wires on the lambda sensor.
So,if you have issues with your Mk3 failing on high lambda readings,get those wires checked before you replace a thing.
You,ll save yourself a fortune.
RALPH