Failed emissions

[moulin12]

Guys, looking for thoughts over a MOT failure today, ahead of a return to the VW dealer on Wednesday, for diagnostics.

My 2011 (11 plate) 160HP went in for a major service today (including spark plugs, air filter) and for its MOT. No known history of engine problems to date (other than that explained below). 30K mileage.

The MOT has failed on emissions.

Fast Idle Test
Engine Speed............Pass
CO <=0.200% (Limits) 7.910% (Actual) ...FAIL
HO <=200 ppm (Limits) 919 ppm .........FAIL
lambda 0.970-1.030 (Limits) 0.742.........FAIL

Fast Idle Test
Engine Speed............Pass
CO <=0.200% (Limits) 8.727% (Actual) ...FAIL
HO <=200 ppm (Limits) 680 ppm .........FAIL
lambda 0.970-1.030 (Limits) 0.725.........FAIL

Normal Idle Test
Engine Speed...........Pass
CO <=0.300% (Limits) 8.703%..............FAIL.

Other info.
- No warning lights re emissions, or other.

-Dealer says that the emissions were 'spiking'. Don't if it was MOT'd before the spark plugs and filter were changed, but presumably not.

- When I first got the car (just over two years old), the idle sometimes appeared a little rough, under both hot and cold conditions. Nothing major, but at worse felt like a definite shudder for a moment. In all other respects, the car has always run very nicely, and quietly. Could be psychological, but it seems to me that after using the recommend fuel additive for a few months (i.e. once a month) and using of shell v-power, the idling issue improved considerably, whilst still sometimes noticeable.

- At the last service and MOT, when the car was still under approved warranty, I mentioned that the car's idle when warming up was sometimes a little rough: I was concerned because of the track record of the tsi 160s. The garage couldn't find an issue, and I left it there.

- When taking the car in today, I again mentioned the slightly rough idle, especially after a mile so from cold.

- I'm now under Mondial extended warranty (comprehensive).

- I do mostly short journeys, but drove down to Cornwall and back last month, and did another longish run a couple of weeks back.

So, I guess I'm looking for some suggestions over possible causes (not sure if the actuals provide any indications?) and for thoughts on my position on purchase rights/aftercare and warranty in any worst case scenarios.

Thanks in advance for your thoughts/suggestions.

[Paddy_R]

Is it burning oil?

[greg7728]

My 160 seems to run a bit lumpy on idle kind of like the revs are too low for comfort, doesn't burn oil or loose any fluid, makes me nervous this. 18k on the clock - wonder if it's something a warranty company will deal with or wiggle out of. I only use v power fuel - mot not due for a while yet though. Let me know if you find anything.


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[moulin12]

Is it burning oil?

No, not at all: check it fairly regularly and has never required a top between services. And as said, apart from the sometimes slight rough idle from cold (which some forums have suggested can result from successive short drives, not allowing the car to warm off and burn efficiently) it drives (and has always driven) very well.

I have a sneaking suspicion in the back of my mind that it may be something to do with the change of plugs, though it's also the case that on the short drive from the garage the driving experience was unchanged. They've booked it in with the chief technician for next Wednesday, so any obvious fault such as this should be hopefully covered off, including not warming it up correctly before taking the measurements.

[moulin12]

My 160 seems to run a bit lumpy on idle kind of like the revs are too low for comfort, doesn't burn oil or loose any fluid, makes me nervous this. 18k on the clock - wonder if it's something a warranty company will deal with or wiggle out of. I only use v power fuel - mot not due for a while yet though. Let me know if you find anything.


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Be sure that I will. Your description sounds just like mine, and which does seem to be vey common on the 160s: I guess it's easy to fear the worse, given the history of engine issues, especially with the earlier units.

[moulin12]

Update. Dealer has had the car two days and the techs are "still going through test plans laid down by VW". Ruled out faulty lambda sensor, but said there was a fault indicating possible sticking valve (???), which they've replaced but which hasn't changed the emissions. Are saying that they may need to have a webinar with a VW technician since they're beginning to feel stumped????

This is a large vw dealer, btw.

So far covered under extended warranty, but somewhat concerned...

[froudeg]

The 1.4 tsi's are prone to intake valve carbon buildup, especially if the car is only used for short runs.

Mine has had a bit of a lumpy idle since i bought it with 30k on the clock. Re-gapped (0.7) new spark plugs helped, along with newer version coil packs however it still occurred occasionally, especially if i hadn't done any long journeys in a while. Importantly though i had no misfires logged when checking with VCDS, nor did the live misfire counter show me getting misfires during driving.

I need to take my intake manifold off and clean the valves, to prove it is the intake valves all clogged up; a month ago i drove down the motorway for 25 mins, keeping the engine at 4000+ rpm at 70mph.

After doing that my idle was perfectly smooth and remained so for weeks although i can now feel the idle is just starting to become a little unsmooth.....pretty much confirms i need an intake valve clean, the prolonged high rpms at speed burnt off a load of carbon but it was a short term fix.

However i wouldn't go driving at 4000+rpm for 30 mins if you have engine/emission problems - a clogged up intake wouldn't cause your emissions to be that far out.
With a lambda of 0.7 your engine is running rich, knocking out the emissions....i would look for misfires being logged, and if on a particular cylinder only swap out the coil pack & spark plug.

These engines are very particular about the spark plugs, a gap of 0.8mm is what the new revised sparks are from VW (they were revised in 2011 to fix misfires and exploding engines). It has been found the engines run better with a gap of 0.7mm (hence me regapping mine). If the wrong sparks are put in it will misfire like crazy and knock your emissions out.

If it's not the coil pack/spark then it could be a leaking injector.

[moulin12]

Froudeg, many thanks for your reply, much appreciated.

I was aware of the coking up issue, and indeed I took the car for a 30 mins high rev run (keeping to around 4000 rpm) before returning the car for its diagnostics.

I earlier had in mind the plug issue (as I recall, ex-poster RW1 had wrote extensively on this, on this forum), especially given that the car had a major service before the mot, which meant of course that they had changed the plugs. Reading a forum yesterday evening I came across a poster who had been put through the mill with similar issues with his Golf (resulting in, effectively, half an engine rebuild), seemingly only to have his issue fixed once the plugs had been carefully looked at.

Think I'll pop in the garage this morning to make sure that they take a good, second look at the spark plugs.

[salsajoe]

Is it burning oil?

And as said, apart from the sometimes slight rough idle from cold (which some forums have suggested can result from successive short drives, not allowing the car to warm off and burn efficiently) it drives (and has always driven) very well.

Had this slight rough idling for a few seconds from cold just before 3 years old and 30k miles. Still under warranty at the time. Dealer said on checking that it was a documented fault and the cure was to reprogram the ECU which they did. No problems since and on 48k. Nearly always use vpower.

I have noticed with the Golf GTI that with v power there is virtually no 'soot' on the chrome exhaust tip but there is with 95 fuels.

Hope you get it sorted.

[moulin12]

salsajoe, thanks.

I think possibly you're referring to the high revving on start, for which I've read before that there's is an ECU update. I did mention this to the dealer last year, when taking the car in for a service, but they couldn't find any TPI on it (probably didn't look too hard). I've read that the update also changes the power curve slightly, with a bit more torque around 4000 rpm and holding onto 6th for slightly longer, but with a lightly flatter response between 40-50 mph.

My slight rough idle issue, however, is when I've travelled about half a mile or so, from cold.

No further update from the dealer as yet, and I'm feeling less than positive on the situation. My quandary is what to do even should they sort the issue. Given the issues that appear to surround the 160s I would like to trade on; but the thought of paying several grand more for a 2.0 of the same age (four years old) isn't an attractive one. So then I find myself thinking of paying out another 10k for a later 2.0, which isn't too attractive either!

[moulin12]

Well, it still doesn't continue to look too good. Dealer's had the car a week, and it's hard getting information out of them second hand through the service advisor, but they've piddled about with the usual things, including injectors, had the head off to change an inlet valve, put the head back on and changed a vacuum pipe and an exhaust valve grommet.

Now it's on to compression tests, though not sure why this test is so far down the list; but then, not exactly sure how compression affects emissions, either.

I fear engine rebuild, and a car (that, to me, was running very nicely) that will never feel the same way again.

[froudeg]

Man i can't believe they have not done a compression test yet! - crazy.

If the diagnostics don't point to anything obvious and you have already fiddled with sparks & coil packs and then next stage would be a compression test, both dry and wet.

Since a compression test is very simple and fairly quick i have no idea why they have not done it yet.

Remember the diagnostics and emissions have already pretty much told you whats going on - lambda is way out, its running very rich which = misfires.
This engine is known to misfire under various conditions, always worst at idle - one of the death knells of this engine is misfires as a cylinder piston is loosing compression, usually cylinder 3.

You check sparks, coil packs and then compression!

No way do you start ripping inlet manifolds off and fuel rails to change injectors and then insanity of all insanities, rip the cylinder head off (with the sheer amount of ancillary stuff to get off first) to change an inlet valve - before doing compression tests!!

I would have also been looking at precat, postcat sensors and MAF sensor well before i start going down injector route and hell, way before i think about ripping the cylinder head off.

It's a pity your dealership appears to be operated by muppets who don't know basic engine diagnostics and rely on a guy on a phone to tell them what to do next.
Sounds like they plugged it into diagnostics, tried a couple of things and then they had to ask mummy for help - resulting in them wildly stabbing in the dark changing pieces hoping it will fix it.

I think you need to put pressure on them as they will hopefully just give up and give you a new engine - that's your best outcome.

[moulin12]

Albeit from a position of very limited (near non existent) understanding of modern cars (i.e. anything after 1979…) I did find it odd that compression tests were so far down the line. They’ve now been done however, and all bores are well within manufacturer’s limits.

Because I wanted to get a feel of the state of progress, I took along a colleague who’s as steeped as any technician in car engine diagnostics (use to set up is own racing engines, and still takes a very keen interest in upgrading his cars).

To say, first of all, regarding the inlet valve, something had gotten lost in translation between the technican and service advisor, since they haven’t had the head off.

Tbh, most of the conversation between the technician and my colleague may have well have been in German, but it did seem – and my colleague was of the view – that they are following a well laid out test plan that exhausts all basic mechanics and engine management.

The main point of interest is that if the car is run, then turned off and then started without throttle, emissions check out okay, but these spike again on throttle. As I left the dealership on Thurday this had led them to question the function of the throttle body opening; but clearly this hasn’t been the answer either.

I should think that they will have exhausted all possibilities by early next week, so then it will be onto the vw network for advice and the start of throwing parts at it.

[moulin12]

another week, another set of injectors going on....

[moulin12]

..and have made no difference. VW have now requested photos of the cat. And so it goes on - dealers now had the car a day short of 4 weeks.

[Irvysan]

I hope you are well compensated when this is all over, what a nightmare.

Sent from my phone

[Roy_01]

Maybe it's a sticking N80 valve?

[moulin12]

VW have confirmed that the cat is okay. They then directed a ECU reset. The result of all of the activities to date has been to bring the CO down from just under 8% to just under 2%: still way out of kilter. The dealer admits to being totally out of ideas and is now simply working to each new directive coming out of VW Germany.

The car has now been at the dealers just short of 5 weeks.

My quandary is that I have agreed a purchase for a 125i, with the Roc as PX. The bmw dealer were /are fully aware of the situation with my car, and my deposit is refundable should the delay with the Roc repair becomes untenable.

I was looking to pay the remainder of the 125i with savings, but have access to a cheap loan, and could purchase the car outright, with view to selling the Roc later. This is not, however, the route I prefer to go down. Of course, the longer it takes to get the car back, the more depreciation will be incurred.

So the question is, how long is reasonable to allow the dealer/mondial/vw time to fix the car before looking at the possibility of compensation, and what procedure do I need to put in place?

[Irvysan]

You need to read your warranty document. There will be a cost/time they define to be reasonable and may be liable to offer compensation as a result of their inability to repair the car in a reasonable timescale.

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[moulin12]

You need to read your warranty document. There will be a cost/time they define to be reasonable and may be liable to offer compensation as a result of their inability to repair the car in a reasonable timescale.

Sent from my phone

I'll have a re-read of the Mondial VW extended warranty document, but I don't think there's any mention.

edit - yup, no mention.