As expected, the sensor again refused to budge tonight, so tomorrow I will look into sourcing a new downpipe and gasket.

 

While the car was up on stands I cleaned up the linkage as you suggested:

 

Not really sure what purpose the tiewrap is serving to be honest.  There is play in the joints here, but the tiewrap doesn't look like its holding anything together to me.  I've got no previous experience here, so perhaps having some looseness is a bad thing, but to me it doesn't "feel" like its about to fall apart.  What do you think?

Well, yeah... the tie wrap is a feeble attempt to reduce the play in that joint. The plastic bushes inside are probably worn. But for now you can leave it alone. There is no imminent danger whatsoever. When the spring will come, maybe it will worth revisiting the area. Anyway, two thumbs up for taking good care of your car. I know how it's like to clean the mud in that area during winter. It is car owners like you that make me feel my desire to help is worthwile.

In case you are wondering what other people did in that area, here is a preview.

 

 

Try running the engine for 5 mins first to heat the lambda up it may come easier when hot. But the flange is shot and it will start to bend where the springs are soon and start to blow..I'd just get a new one tbh and fit the new sensor in it.

Thanks for the replies guys!  I will add the gear linkage to the list of things to look at when the weather improves.  I wonder what differences removing the play will have on how it feels to select gears, presumably more accurate/easier to find the right gears?

 

I've gone ahead and ordered a new downpipe and sealing ring, should have them on Monday.

 

But the flange is shot and it will start to bend where the springs are soon and start to blow..

 

Interesting, I can see on the photos Ricardo posted that there were springs on the bolts that pass through the flange.  On mine, the bolts seem to just be regular bolts.  Is this a problem? The motor factors couldn't get hold of replacement bolts, so I was just going to get some ordinary ones that were the same size as those on there at the moment.

 

One more question: would it be a good idea to put some high-temperature paint on the downpipe before fitting, to help reduce corrosion?

I wonder what differences removing the play will have on how it feels to select gears, presumably more accurate/easier to find the right gears?

Don't expect wonders just from dealing with that joint. The biggest play is usually found below the vertical gear selector lever

Yeah, the gears shifting will be more precise and the lever stiffer.

 

Interesting, I can see on the photos Ricardo posted that there were springs on the bolts that pass through the flange.  On mine, the bolts seem to just be regular bolts.  Is this a problem? The motor factors couldn't get hold of replacement bolts, so I was just going to get some ordinary ones that were the same size as those on there at the moment.

The springs add to the flexibility of the exhaust system and definitely help. Somebody decided otherwise because it was easier to screw the pipes.

 

One more question: would it be a good idea to put some high-temperature paint on the downpipe before fitting, to help reduce corrosion?

Great idea. I've always wanted to do that. Do a research on various forums to find verified solutions. The weldings and the mating parts are "designed" to corrode. Please share your findings.

Thanks for the reply!  Regarding the catalytic converter bolts, sounds like it would be a good idea to try and get the proper fittings.  I've found this on ebay, does it sound like the right thing to you?  The diagram of the cat looks right to me, and the listed years match, but there isn't a picture of the bolts themselves unfortunately.

 

I will do some reading around regarding exhaust paint; the stuff I had in mind initially was some Halfords Very High Temperature paint that I'd seen before, which is rated up to ~650C.  I suspect that whether or not this would be suitable depends on what metal the outside of the downpipe is made from.

My opinion on eBay is "no real photo, no purchase".

Here are better photos of the coupling.

 

 

Incidently we can see how messy the weldings are and how they 'protect' them. The HT paint should not crack and flake. The real problem is the 'flexibility' of the coating. Vibrations and temperature variations are the main issues. The highest temperature the paint should withstand is met by almost all products.

The bolts should be a shoulder type bolt to stop you over tensioning the springs and wearing out the coupling.

The flange always rusts thru because it's a big heat sink thus runs a lot cooler than the pipe itself yout could give it all a good coat of vht paint

The springs need around 25 mm of preload so as long as you do that with the bolts it will be fine.

Update time:  

 

Finally sourced all the bits and fitted them this weekend.  The first step was to clean up the new downpipe, cleaned up the mess made by the welding and sanded it all down:

 

 

Then painted it with Halfords VHT paint (their website lies, the stuff they sell is actually only rated to 300C but I thought I'd give it a try anyway):

 

 

I put on 3 coats of the stuff, and cured it for an hour in the oven between coats 1 and 2.  The result:

 

 

Here are the fittings I managed to get hold of:

 

 

And the new pipe when fitted:

 

 

I think the angle of the picture makes the springs look more compressed than they are, but regardless I found it extremely difficult to fit these!  I've locked off two nuts to hold it together, as I think otherwise the nut may well work itself loose over time.

 

The old downpipe:

 

 

I had to saw through the old bolts to remove them as the nuts were too rusty.  Also, the old gasket looked more like a solid lump than the wiry thing that replaced it.

 

I've run the engine up to temperature, and the new sensor varies between around 0.8 and 1V so it looks like it is working correctly.  Hopefully my fitting of the downpipe to the catalytic converter will be suitable, it was really tough to find the bits for this!

You did a great job on pipes and flange. Let's see what will tell us the test of time.

 

I've run the engine up to temperature, and the new sensor varies between around 0.8 and 1V so it looks like it is working correctly.  Hopefully my fitting of the downpipe to the catalytic converter will be suitable, it was really tough to find the bits for this!

Actually the voltage output from oxygen sensor should vary between 0.1V and 0.9V...

Actually the voltage output from oxygen sensor should vary between 0.1V and 0.9V...

 

Hmm OK, I will test the sensor properly as I did before when I next have the chance, idling the car up to temperature while logging the sensor output.  All I did today was take the car for a short drive, then check what the sensor was outputting when I returned home (it was up to temperature, though).  Hopefully the new sensor is ok!

Please post the manufacturer and code of sensor.

The manufacturer is Cambiare, it is a VE381085 lambda sensor.

The manufacturer says the sensor is good for both 1.3 and 1.6 engines. Any chance of looking at old sensor's tip?

See http://cambiare-ve.com/wp-content/uploads/2015/06/Cambiare-Lambda-Sensors.pdf

 

The new sensor indicates a rich mixture all the time. Not good.

Edited 23 January, 201610 yr by RicardoM

Thanks for the reply, here are a couple of pictures of the old sensor tip. It's a lot easier to remove the sensor when you can just stick it in a vice and lever on the downpipe!

 

 

 

A bit crispy perhaps, but I don't think its ever been changed so I can understand it having some sooty deposits on it. 

 

The new sensor indicates a rich mixture all the time. Not good.

 

What do you think could be the cause of this? Dodgy fuel injector or restricted air intake would be my uneducated guess, there were no fault codes but perhaps these issues wouldn't throw a fault?

 

I will test the engine tomorrow morning, to see if the behaviour repeats.  I need to drive home tomorrow afternoon, but won't need to use the car after that for a few weeks.  I hope that running rich hasn't caused damage that will give further problems in future!

Edited 23 January, 201610 yr by areed

Yeah, really crispy and showing a rich condition which may be quite old. Rich mixtures usually kill the catalyst. I would be curious if an exhaust test is MOT pass. Anyway, going back to the rich condition. Your two hypotheses are correct for now. Maybe unmetered air too.

Edited 23 January, 201610 yr by RicardoM

Yeah, really crispy and showing a rich condition which may be quite old. Rich mixtures usually kill the catalyst. I would be curious if an exhaust test is MOT pass. Anyway, going back to the rich condition. Your two hypotheses are correct for now. Maybe unmetered air too.

 

It passed the MOT last August, so I can only hope that significant damage has not yet been done.  I will find out in 6/7 months whether or not this is the case I guess!

 

For now, is there anything you recommend to help narrow down the cause of the problem?  

Did you reset the TB? No errors stored is a prerequisite.

I cleared the fault codes before I disconnected the battery to change the sensor; then when everything was hooked up again I turned the ignition on for ~10 seconds before starting the car for the first time.  It was my understanding that this would reset the throttle body, is that the case? 

I would look at the coolant temp reading first to check it's sensible. Valve clearances checked?

Hmm OK, I will test the sensor properly as I did before when I next have the chance, idling the car up to temperature while logging the sensor output. All I did today was take the car for a short drive, then check what the sensor was outputting when I returned home (it was up to temperature, though). Hopefully the new sensor is ok!

Are you reading the voltage with a multimeter?

Lots of digital multimeters are a bit slow to change so may report a higher reading as they miss the changing voltage. If it drives ok now I wouldn't worry about it. The black on the old sensor is from the heating circuit not heating up.

Easy test for the mixture is to pull the servo vacuum pipe off while it's idling and see if the lambda then switches to lean..

I would look at the coolant temp reading first to check it's sensible. Valve clearances checked?

Are you reading the voltage with a multimeter?

 

Read the whole topic and you'll see that 1) he is using a VAG-COM scanner and 2) the coolant temperature sensor is working fine. That is why I didn't mention it as a first obvious cause.

 

areed,

Look at spark plugs after a longer trip with higher speeds on highway. Are all black indicating a rich mixture?

Removing the battery cleared all stored errors. After a few trips check if new errors are set. If no errors, use VAG-COM to reset the TB. There is a specific procedure described many times in this section.

 

Is the engine idling smooth? Are there any hesitation, bogs when driving?

areed

 

Try this free software too. Not 100% sure if it will work with your interface, but it is worth a try.

http://www.motordiag.cz/msm/index.php

Thank you both once again for the helpful replies

 

I would look at the coolant temp reading first to check it's sensible. Valve clearances checked?

 

The temperature sensor gives sensible readings so I assume its working OK.  I set the valve clearances as carefully as I could when I put the engine back together, so hopefully they are correct.

 

Look at spark plugs after a longer trip with higher speeds on highway. Are all black indicating a rich mixture?

Removing the battery cleared all stored errors. After a few trips check if new errors are set. If no errors, use VAG-COM to reset the TB. There is a specific procedure described many times in this section.

 

I drove home today, which is a long journey, so I will pull the spark plugs out this week and take pictures to see what you make of them.  When I do this I will also check for fault codes, and go through the throttle body reset procedure on VAG-COM.

 

I was planning on checking for fault codes and measuring the lambda voltage when I arrived tonight, but the journey was sufficiently traumatic that I didn't feel up to it.  On a related note, I now need to source a replacement alloy wheel :(

 

Is the engine idling smooth? Are there any hesitation, bogs when driving?

 

I think that the engine idles OK, it does seem to me to sometimes lack power when I press the accelerator but I'm unsure of this.  It also had the starting problem again after I changed the wheel on the way home, the engine was firing while turning the key (i.e. you could feel that the engine was turning faster than just the starter motor on its own)  but not enough to keep running after releasing the key.  Massaging the accelerator pedal while turning the engine over meant that it picked up after a few seconds, after which it idled fine.