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 » Wed Jan 25, 2012 10:34 pm

littlepolo wrote:Sounds promising. Do you think I can take off/clean the EGR valve assembly, refit new gaskets,
etc., without any special tools? What is re-adaption exactly? Is that something you are doing with software?
Adaption is done with software, though it has been said that if you switch the ignition on and do nothing, the TB will perform adaption. One way to try this would be to remove the aircleaner/cover thing, switch on the ignition and go back round to the front of the car, if this theory is true, after some time (how long?) if you look down the throttle body, it should get driven shut (which it will be almost already) - then fully open then back to closed, it is not a silent operation so you will hear it happening, even from inside the car if its in a quiet garage.

As you have already had the Throttle Body off, you know how to do that, after that, hopefully you can leave it to one side without disconnecting the control/power lead, as your car is the same age as my wife's, you will see the interface plate below that - its only about 1/2" thick - maybe before you remove the Throttle Body, unbolt the EGR pipe on the (your) RHS of the interface plate - and save the gasket for later use, twist off the crankcase fumes pipe that is on the other side of the interface plate. Once the Throttle Body is out of the way, the interface plate just lifts off, it has a retained steel top gasket and there is a "rubber" ring gasket that should stay in its recess on top of the plastic inlet manifold. If I were you, I would look at the interface plate and see if you can see in through the EGR pipe port - on my car it was blocked inside the interface plate. Now using carb cleaner and rubber gloves and ??? clean up the interface plate totally, leaving the top gasket alone. This is the only part that you should clean in the first place - refit everything.

I can give you the complete list of gasket p/ns and screw/bolt torques, for the torques its 20NM for the big bolts and 10NM for the small ones. These gaskets will probably need to get ordered in (generally two days).

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

Post by littlepolo » Wed Jan 25, 2012 10:44 pm

Thanks, that sounds worth a try. It would be great if you have the part nos.

When I asked at a VW dealer for a parts diagram, an dpart nos for other parts they
said 'we can't give that information to customers...'

How long do you think I need to do the work, unhurried?

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

Post by RUM4MO » Wed Jan 25, 2012 10:51 pm

littlepolo wrote:Thanks, that sounds worth a try. It would be great if you have the part nos

How long do you think I need to do the work, unhurried?
Top cover off (one pipe to pull off) > Fume pipe to pull off I/F plate + EGR pipe to unbolt and recover gasket > 4-off cap headed bolts holding Throttle Body on lift to one side > lift out interface plate > etc.

Maybe 15>30 minutes to get things off, cleaning the interface plate using carb cleaner and things to poke down the EGR port on the plate another 30 minutes followed by 15>30 minutes to put it all back together.

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

Post by RUM4MO » Thu Jan 26, 2012 8:13 am

Okay, numbers etc:-

Gasket Throttle Body to Interface Plate 036 133 161C Gasket Interface Plate to manifold 036 133 073 Gasket EGR pipe to Interface Plate 036 131 550A - cost must be about £7 inc VAT as I bought another 3-off gaskets for £12.41 inc VAT. Any VAG dealer will order this in for you within two days.

Torques, all 10NM so not very tight at all - take care!

Strange to note, VW supplied me with what ended up being 3-off steel gaskets for the Throttle Body to Interface Plate joint - I only discovered that after having a spot of bother fitting what was supplied - what came off was roughly 0.28mm, what was supplied was roughly 0.84mm and when worked on fell apart into 3 packs of shims each roughly the correct thickness. If this happens to you, the first thing that you will notice is that you can not easily get the new gasket to snap in place over its retainers on th top of the Interface Plate!

If you have difficulty easing the EGR pipe away far enough to clear the Interface Plate, then work your hands back along the side of the pipe towards the front and about a third of the way back from the Interface Plate, you will find a bolt securing the pipe to the big plastic lump with all the pipes - probably the thermostat hides in there, remove that small bolt (self taper into plastic so treat with care when putting it back in!).
Edited to sort spelling!

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

Post by RUM4MO » Sat Feb 11, 2012 10:37 am

littlepolo, no progress to report yet?

My wife's car is still throwing up a "load cross calculation error - lower limit exceeded" once a week or so, but it always happens when the car engine is fully warmed up and she has lifted off to change gear! As the EGR valve is a possible source of extra "free air", I've decided to replace it as cleaning old one up might might not help, or even make it worse (I've no experience of cleaning up a petrol engine's EGR and I got "the real thing" new on ebay for about £90) - there seems to be plenty pattern parts available as well, VAG tend to use Pierburg devices. Thinking about this second problem a bit more, and hoping to finally stop this "load cross calculation error - lower limited exceeded" for once and for all, I've broken my own rules and bought a secondhand thrust sensor (its this engine's equivalent of a MAF/MAP device and it lives in the inlet manifold), my logic is that this second, and long term intermiitant fault (well in the past only in winter) is either due in the ingress of unmeasured air via the EGR, or the thrust sensor is losing senstivity due to getting covered with gunge in the inlet manifold. Time will tell as long as the one I've bought is still usable!

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

Post by littlepolo » Sat Feb 11, 2012 10:59 am

No progress due to weather, seasonal ailments, etc.

Sounds like you are on track to solving your problems!

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

Post by RUM4MO » Tue May 22, 2012 8:42 pm

littlepolo wrote:No progress due to weather, seasonal ailments, etc.

Sounds like you are on track to solving your problems!
Any update on this issue yet?

I have yet to fit the new EGR valve, I am waiting until the weather is really hot before doing that just in case I get a better EGR adaption!(?)

One thing though, as I now have an intermittant O/S/F indicator bulb that means that I MUST get the bumper off, I have been reading my copy of ElsaWin and discovered that if a car shows up with repeating logged faults that include:- 17550 035 & 16407 035 & 17584 & 17586, then a flash update is available and its on a CD supplied to the dealer by VW with acticle number 000 5001 22 00 - it is only meant to cover cars built 29/01/03 > 7/04/03 and only concerns engine ECUs with the p/ns 036 906 034AK + CE + DD + DM + EM + FH + FJ + FL + S . My wife's car was built late August/early September 2002 as a 2003MY car and its engine ECU is 036 906 034DD - so I'd expect that rightly or wrongly, it is included with that need for a flash update as it regularly, in winter weather, comes up with the first two listed fault codes.

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

Post by littlepolo » Mon Jul 02, 2012 3:55 pm

I have just gone through the cleaning procedure for the throttle body and spacer plate as you outlined above. I had previously cleaned the TB around 12 months before, yet it was still quite gummed up. What I missed before was the spacer plate - and I found a lot of oily deposits/gunge around the inlet flange of the EGR pipe, and also near an inlet to what I assume is a crankcase breather. There was also a light coating of gunge around the flange/upper plenum. The breather pipe inlet, and EGR pipe inlet were not blocked, although the latter had a layer of gunge around it. I cleaned everything using q-tips, carb clearer, and kitchen towel. I used a small 'bottle brush' in the EGR pipe, but found only light powder deposits. I pulled No 4 and No 1 plugs and found the former had burnt light (oil?) deposits on it, but the latter was fine.

I started the engine and had to get away on a 100 mile journey, and straight away I noticed that the throttle snapped shut when lifting off. Idle was OK, but the throttle body must have been slightly sticky before due to deposits. On a run at speed, I found no evidence at all of pinking across the range - there is an ascent on the way where even at 3000rpm I experienced pinking before (though it was not a loaded vehicle today). Overall, the throttle response and engine pull seemed better.

At the end of my journey, in start-stop traffic, and around the neighbourhood at 20-25mph, I did hear some pinking around 2000 rpm. It seemed to be less than before, but I have not driven enough to say with certainty. It does seem to appear though, after a long run (when slowing down), or prolonged about town driving in hot weather, as if heat soak is a factor. I think I need more time to review the outcome.

It was only the sudden increase in pinking due to recent warm weather that made me set to the work this morning -- in the rain! It was annoying to hear pinking again, but it does seem to be less than before. Incidentally, I did take off the EGR but could not see much.

I think you were referring to a sensor that is on the manifold opposite end to the TB? I did change that over 12 months ago for an eBay third-party item, but wonder if that is now gummed up again. For moment there, it really felt like a new car. I'll let you know in a week or so as to how things are with the pinking problem. Not sure what I can do beyond what I've already done.

One other matter that needs attention is the Climactic thermostat/switch. The heater tends to blow how and cold of its own accord. I usually turn it full on, then back down to cold and after a while it seems to go cold. Similarly, when I want heat, sometimes it seems there is a delay for warm air to come through - usually after I've manipulated the dial.

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

Post by littlepolo » Mon Jul 02, 2012 3:59 pm

I'll have to check also, to see if my Polo is in the range for that flash update.

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

Post by RUM4MO » Mon Jul 02, 2012 9:33 pm

Good to hear that you have had some improvement. My wife's car does pink lightly in warmer weather now and again - though I have not replaced the EGR valve yet - will do soon. Any pinking now is momentarly and not the same hard pinking that you could not drive through prior to cleaning things up. That sensor at the opposite side to the TB is known as the thrust sensor, and according to some posts for this engine, the design has been changed quite a bit - I still have the secondhand original type to try out. I have even replaced the brake servo vacum hose as the "passing" one way valve has always annoyed me (vacum lost as soon as engine has been stopped) - but other than fixing that issue no other change.

Your Climatronic temperature issue, that sounds like a flap motor positional feedback is a bit dirty - it will be the one for temperature regulation. I had that on my 2000MY Passat and eventually replaced that motor, originally working the demanded temperature to HI and back to LO a few times allowed it to behave for a while. Most of the flap motors on my wife's Polo do complain now and again, and it lost "basic settings" a few days ago - it was flashing when the engine was started - that is Climatronic's way of says "I've got a problem" - but it eventually gave in to a few demands of "basic settings" and now seems to be okay.

I would not worry too much about burnt oil on one plug I'm sure that it is not helping anything but should be bearable. On the subject of plugs, do you replace them every few years and only use NGK ones? I replace them every four years or 30,000 miles.

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

Post by littlepolo » Mon Jul 02, 2012 10:42 pm

I replaced the plugs a couple of years back when I started to try and sort out the pinking problem, and a few other issues at the time. IIRC they are some kind of Iridium or Platinum plugs (probably NGK). I must check the gap spec - though I know they use a larger gap, I'm not sure they haven't worn.

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

Post by RUM4MO » Tue Jul 03, 2012 8:12 pm

From my experience of VWs with NGK plugs, the gap does not change by any measurable ammount over 4 years 30,000 miles - not like things were like 20 or so years ago.

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

Post by RUM4MO » Sun Jul 08, 2012 9:00 pm

Having had a bit too much light pinking, I just went and replaced the EGR - and after two 6 mile journeys with significant engine loading (hillls) - no pinking, though the A/C was accidentally on AUTO and cooling the car (so that was what the slight noise was and the probable reason for poor economy today), I'd think that in the main, the "no pinking" is a flook as I can't see anything that I could fail the old EGR valve for - but will clean it up using something serious, although maybe it was sticky while moving. I'd think next is to fit the secondhand MAP sensor and clean up the original one.

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

Post by littlepolo » Sun Jul 08, 2012 9:26 pm

Interesting. I was out on two long journeys since decoking the throttle body plate, and noticed
very little pinking. As usual, it occurred at the end of a long run, and whilst about town with
the engine warm (after parking, shopping, and a restart). But it is much, much, better, and where
in the past pinking continued until changing down, or flooring the gas, it is now much better
contained/managed. I also experienced similar light pinking at 3000rpm uphill under load, but
that was also contained/short-lived. I added some Redex to the tank, and not having reset
the ECU (via battery disconnect) wonder if the system has adapted, or if I should reset it.

However, if an EGR replacement would fix the remaining light pinking I'd swap it out for sure.
I suppose its possible that the EGR looks OK, but might be sticking, or otherwise not operating
incorrectly? That said, I see none of the fault codes that you reported.

Did I ask earlier, did you ever use that Ecotek PowerBoost decoke foam? On a previous vehicle
I used it to good effect. It needs to be injected downstream of any sensors though.

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

Post by RUM4MO » Sun Jul 08, 2012 10:54 pm

No, I've never tried any decoke stuff - yet, these engines look like they do get carboned up inside from looking in through the sparkplug holes. I did give the higher octane petrol a quick look when I refuelled today though. Redex, the older stuff seemed to be quite good, I might start using the newer stuff again, there is some really expensive Redex stuff around but I've not heard too much about if its any good.

You re-adapting your cleaned up TB, I thought that it would re-adapt itself if you left the car with just the ignition switched on for a few minutes - you could listen under the bonnet to see if you could hear TB activity it would just fully open and close and that would be all it would need to do to find its endstops.

It could be quite hard to justify replacing your EGR valve - but maybe your engine needs that done. I paid £80+ for mine - which was a bargain I reckon for a genuine VAG part. Seems like oven cleaners are good for cleaning these things up, so I might try that on my old one - although as I said, it seems to "be" like the new one, ie when out of the car the I/L is closed to the O/L, the small air I/L does pass air through to the O/L.

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