Airbox engine cover flap valve (engine pinking when hot)

Chat about your 9n Polo (inc GT and Fun)
RUM4MO
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Re: Airbox engine cover flap valve (engine pinking when hot)

Post by RUM4MO » Sat Jul 28, 2012 6:59 pm

I've now refilled the car with Shell Super Unleaded and a dose of Redex and have used the car over 20 miles, prior to refilling it had been pinking a bit, after loading up with the higher octane petrol and Redex, it drove "better" - ie better/sharper pickup and no pinking, though I was trying to provoke it. Normally, after stopping the car for an hour or so after it was heated up, it would pink a bit when loading it up, but today nothing after refueling. One thing I did learn (wife had heard about it though) was, that Shell now offer to do the filling up at their service stations - I rejected that offer, I also rejected what was normally the "do you want a VAT receipt?" - that was actually "do you want a receipt" - ah well that's progress, the paper saving will probably pay for the fuelling person!

Anyway, before I did this, I had a look through Halfords and see that with the exception of one Granville product, namely 10K Boost, the only products for fuel/engine cleaning are all for use in the fueling system and not the actual coke in the engine - the 10K Boost being the only one that claims to be a non invasive decoker - though I'd reckon as it needs repeated every year that will not be very effective - though maybe better than nothing - I should have worked that out a long time ago. Anyway, I'd think that the reason for the lack of "decokers" will be down to the thinking that engines don't need that nowadays combined with the complexity or variety of ways that you can introduce this decoker into the engine without causing problems.

Right:- emissions results 28/09/10 Fast Idle Test CO 0.07% HC 38PPM Natural Idle Test CO 0.05%
emissions results 28/09/11 Fast Idle Test CO 0.03% HC 30PPM Natural Idle Test CO 0.04%

littlepolo
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Re: Airbox engine cover flap valve (engine pinking when hot)

Post by littlepolo » Wed Aug 01, 2012 2:19 pm

Just a quick update on the post-Wynns EGR treatment. Although the weather has cooled, I've not heard any pinking whilst running around these past few days. I've tried to provoke pinking by pressing the accelerator repeatedly around the 1500-2000rpm mark. The engine also appears to be running a little better. I'm going to give it the EcoTek treatment as soon as time allows, to clear out any remaining gunge, and see what happens when the weather hots up again. I think if it does recur, that might be a fuel issue so will dose with octane booster.

RUM4MO
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Re: Airbox engine cover flap valve (engine pinking when hot)

Post by RUM4MO » Sat Aug 11, 2012 9:45 pm

Re my statement about refilling with Shell super unleaded, I was wrong there, what I have been using over the past 3 refills is Shell V-Power unleaded - and there is no statement made on the pumps as to what this stuff really is, ie no BS spec or Octane rating, and I have not been able to find out any hard facts other than it cleans the fuel system etc - and actually it has not improved MPG but has improved driving "feel" as well as stopping pinking other than the odd rattle when the engine's ECU possibly backs off the timing. Over this same period of buying higher speced petrol, I am using Esso super unleaded or what ever it gets called in my old B5 Passat V6 and it is rated at 97 Octane as opposed to the 95?Octane of normal unleaded - or is it called Regular unleadd, that stuff does improve MPG and driving "feel" - but that car is suitable for 95>98 Octane fuel whereas the 9N Polo is suitable for 92>95 Octane fuel.

littlepolo
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Re: Airbox engine cover flap valve (engine pinking when hot)

Post by littlepolo » Sat Aug 11, 2012 10:17 pm

Today, and a couple of days ago (both very warm days) I noticed a distinct onset of pinking at 1500 rpm, and to a lesser extent, 2200rpm. At 1500rpm it is very distinct, and easy to throttle past. In the former case, its under light load, and at 2200rpm occuring on an incline (have been using the A/C). Not sure what to do next, but fuel Octane rating might be an issue. I suspect it will fade with cooler weather expected over the coming days, but will try a higher rated fuel, or octane booster when its hot. Planning a long distance trip later this month, so want things to be as good as they can before setting off.

littlepolo
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Re: Airbox engine cover flap valve (engine pinking when hot)

Post by littlepolo » Sun Aug 12, 2012 5:35 pm

Whilst shopping at ASDA today I noticed Redex Octane Booster on the shelves. On close examination, it claims to boost octane rating by 'up to 1.5' which I though is not a great boost, especially if fuel quality is poor to start with. Also, at 7.50 per 500ml (treats one tank/50l) I thought it would be cheaper just to use a higher rated fuel at the forecourt. So that is what I intend to do tomorrow.

RUM4MO
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Re: Airbox engine cover flap valve (engine pinking when hot)

Post by RUM4MO » Mon Aug 13, 2012 10:03 am

I have never got round to doing the sums, but from what you've discovered, that Redex stuff does seem to offer very little at a cost that is higher than UL+ at the pumps. So it Esso "good" stuff or Texco 99 stuff etc.

littlepolo
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Re: Airbox engine cover flap valve (engine pinking when hot)

Post by littlepolo » Mon Aug 13, 2012 11:18 am

I've just been out this morning, on a short journey. Mild pinking (very brief) at 1500rpm. From trawling the Web about pinking problems in general, some people swear by BP Ultimate - adding that it improves mpg also. I'd be surprised if I see much difference in mpg on my auto, but will try BP Ultimate at the nearest filling station tomorrow. People are saying it takes a couple of hundred miles for the ECU to adapt to the higher octane (and return the best mpg, etc.). I might have guessed there was no cheap solution to this problem...

RUM4MO
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Re: Airbox engine cover flap valve (engine pinking when hot)

Post by RUM4MO » Mon Aug 13, 2012 10:43 pm

My only issue with using BP is that it is normally the most expensive option near me, I reckon that you will notice the improvement immediately and the ECU will not be able to advance to make proper use of UL+ fuel, as the car is designed for 92>95 octane. To sum it up, as soon as you fill the tank with BP UL+ you should notice the differance.

littlepolo
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Re: Airbox engine cover flap valve (engine pinking when hot)

Post by littlepolo » Wed Aug 15, 2012 10:48 pm

I added just over 1/2 tank BP UL to just under 1/4 tank of remaining supermarket fuel. It feels like a completely different car, as the engine now runs so smoothly. But yesterday (which was very warm) I did experience very light pinking, which seemed much more under control and short-lived. UL is 97 octane, so not sure what the overall effect of the mixed tankful would be. I did some quick math on the Redex octane booster vs. UL and found the latter cheaper. There was some Wynns (IIRC) at Halfords for 4.99 (treats one tank) but I do not recall any mention of the octane rating boost capability. I'm doing a lot of short journeys at the moment, so have no idea on UL's mpg performance. On a long trip coming up next week I might put it to the test. The pinking that does now occur seems to occur mainly when coming from near closed/very light throttle, to very light throttle. But it is negligible.

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Re: Airbox engine cover flap valve (engine pinking when hot)

Post by littlepolo » Mon Sep 24, 2012 5:54 pm

As you might have expected from the silence, things had been going well - until now.

I made a 750 mile round trip to Wales in August, having filled up with BP Ultimate beforehand. Despite a loaded vehicle, and the ups and downs of driving around the Welsh landscape, I never heard any pinking from the engine. Whilst in Wales, the fuel ran low, and due to the cost of fuel there I refilled with regular unleaded at Tesco. Due to fine weather, the ambient temp was high, but I heard only a trace of pinking.

After returning home, and refilling on supermarket fuel, pinking occurred again, and quite often - even though the temps were not much more than 20C.
For that reason, I intended to refill with BP Ultimate, just to review the effects, but I did not get around to it before another problem occurred.

Yesterday I made a 60 mile round trip, and due to an early start and cooler weather I turned the heater dial from cold (where it has been for months) to warm. It might be pure co-incidence, but within a very short space of time I had an engine check light on, with a misfire, so I nursed it along to our destination. It seemed to clear after a while, but occurred again on the return journey.

The code was 17772 - Cylinder 4 Ignition Circuit: Open Circuit

Having Googled this again (on SEAT/VW/AUDI keywords), I found more references to a TSB that requires the coil ground wires be rerouted to an earth point under the battery tray. I think I mentioned this above, somewhere. I'm not sure how the heater control could have caused this recurrence to occur, so I'm inclined to think its due to an underlying gremlin. The Internet is full of tales where owners are advised to change the offending coil packs - but this does not seem to have worked.

I'm going to review the TSB requirements, and see if its a straightforward job. I can't see that re-routing the ground wire is going to cause any harm, so might try it. Oddly, the 17772-related misfire occurred last August (quite seriously) whilst driving to Wales, and it did not recur until yesterday.

RUM4MO
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Re: Airbox engine cover flap valve (engine pinking when hot)

Post by RUM4MO » Mon Sep 24, 2012 8:18 pm

Hum, pity you don't have access to a know good coil, just to see if that coil was indeed the root cause of that problem.

I've - or at least we, have driven about 2,000 miles using Shell V-Power exclusively with very little pinking, other than the occasional rattle when taking off - but I've heard many other non-VAG cars making that noise when moving off from being stationary. Curiously, or something, the oil consumption was dropped - especially over the past 3 weeks - if this is factual then it is part of what I would expect if the fuel is cleaning up the engine internals a bit. As stated before, there is no improvement in fuel consumption - but that is expected as these engines can't make full use of the higher octane fuel - its only the added resistance to pinking and engine cleaning that I am aiming for, and soon I will revert to fuelling with proper 95 octane - never supermarket fuel. MOT next!

littlepolo
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Re: Airbox engine cover flap valve (engine pinking when hot)

Post by littlepolo » Mon Sep 24, 2012 8:56 pm

Fuel quality seems to a major factor.

I guess I can swap the coil to another cylinder and see if the code moves to the same cylinder respectively.

Did you ever try any third-party coil packs, as on eBay?

Painful though it is, I'm going to fill up with BP's best tomorrow.

One other minor point, I lost a wheel trim at the weekend. It was the older type, that clips into the outside
face ('spokes') of the road wheel. A cheap(er) replacement version I ordered from eBay has a sprung ring on
the outer edge, and the trim clips in (needs to be banged in) on the outside rim of the wheel. But it stands
proud of the wheel by a few mm.

littlepolo
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Re: Airbox engine cover flap valve (engine pinking when hot)

Post by littlepolo » Mon Sep 24, 2012 10:29 pm

Have just ordered some new Iridium plugs as the current ones are a few years old, and maybe past their best.

Looking through the Owners manual engine data, it states unleaded fuel Super 95RON / Normal 91 RON - the
latter with a footnote:

"with a slight reduction in output, slight increase in consumption and slight pinking until the knock control starts"

I wonder what rating supermarket fuel really is? I think the footnote is an understatement!

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Re: Airbox engine cover flap valve (engine pinking when hot)

Post by littlepolo » Tue Sep 25, 2012 2:06 pm

Went out this morning to go shopping and a serious misfire developed. So I called in at the VW shop and picked up a new coil pack (39.62)for cyl no. 4. Refilled with BP Ultimate on the way back. I swapped out the coil pack, and had a look at the plugs at the same time - the gaps seem excessive, so I think they are worn too. Anyway, engine ran fine with the new coil pack. I was going to have a look at the earth terminals under the battery box but rain stopped play.

Incidentally, I did get hold of a TSB related to the earth issue (though it does not specifically mention the Polo I cannot think why it would not apply - given the same conditions).

I'll put in the new plugs when they arrive, and stay on top grade fuel for a while, maybe alternating tankfuls/half tankfuls thereafter.

Do you think I need to swap out the remaining coil packs? Or just get one and keep as a spare?

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Re: Airbox engine cover flap valve (engine pinking when hot)

Post by RUM4MO » Tue Sep 25, 2012 6:50 pm

As far as the coils are concerned, maybe buy just one as a spare, I think that you did the right thing buying new from VW, I bought a single NOS (same P/N as fitted to engine in factory, used it, bought a new newer type NOS, used it and bought a "good" secondhand one - all from EBAY - the two new ones used to replace two original failed coils with maybe three years between them. Maybe, write down the full part numbers of the latest coil and look for one on ebay instead of buying new - if the price is okay. By the way what is the latest part number - both on the box and on the top of the coil, and who makes them (I prefer the Italian ones as originally fitted to the car Eldor). I don't think that you should now expect another failure - if it happens its a fluke, in general terms, these coils, fitted during that period to these engines do seem to be "not too bad"!

I will need to check the handbook as I've never noticed these commentsn - notice under fuel flap does mention advised fuel grade. I still think that there is an obscure software update that we are missing that would sort out a few issues. By the way, Seat automatically check for software updates when they service cars - I bumped into this while checking something else on the Seat site - maybe get a couple of Seat badges!!??

Fuel quality, I thing that the octane ratings will be okay in supermarket fuel - or the Trading Standards people would hammer them - what is wrong with supermarket fuel is that there is either no, or very little cleaning additive packages in that fuel - and I'd say that its extra cleaning that these VAG engines need, short term the higher octane rating is helping you and me avoid pinking, but I'm banking on the extra cleaning agents that you get will V-Power and Ultimate etc to clean up the engine internals and reduce pinking enough to go back to running lower grade "quality" fuel through winter.

If your plugs are badly worn that might have caused the coil to fail as the EHT would get a lot higher than normal before it arced across the gap - but always remember that these plugs do start off with a big gap and modern plugs do not erode quickly like in the past - so maybe the gap you say was not an issue - though Iridium plugs will keep cleaner and last longer.

Back to fuel quality, I think that all our fuel is getting doped with "bio-fuel" and that is mandated by Europe - there is a ground swell rising amongst users to force fuel companies to state the bio-doping levels on the pumps so that we can choose to pick which we want to use, ie high levels or low levels as it seems that some engines will like this bio stuff and some will not!

I'd think, that while the VAG TSB about the wiring is relevant to Golfs, it could be that this issue either was got rid of when designing the Polo wiring cables - but I could be wrong.

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