Airbox engine cover flap valve (engine pinking when hot)

[littlepolo]

Agree, although I'm spending too much time on it. I'll have a garage check it, and determine if it can be fixed or not, hopefully early in the new year.

[RUM4MO]

I've now had a VAG fault code 16785 which could mean that at 80,000 miles, the EGR valve and pipes need cleaning out - accompanied by VAG fault code 17550 (this one shows up every few months). Now, I've read on a VAG forum, that on Fabia with BBY engine, the original engine ECU P/N was 036 906 034 - as indeed mine is, and when fault codes 18081, 17550 and 16704 "turned up" - especially in the first months of the car's life, an engine ECU flash upgrade was made available, round about 24/01/03 the ungrade available changed the engine ECU P/N to 036 997 034, next round about 7/10/03 a new service action known as "24H2" was rolled out covering Fabias within VIN range 3533045 > 7630269. The search tag that unearthed that was "EGR fault on BBY". Now niether your car or mine is new, but are these engine ECU upgrades relevant and/or needed? I think that it seems most dealerships know very little about all engine ECU updates, you would need to demand, at your expense, that they plugged their VAS machine into your car, then using their latest ECU flash update disc, they would need to let the VAS machine compare what s/w standard the car's engine ECU currently is and from that it would know if a flash update was desirable and/or necessary, it seems that by doing this, the "local human knowledge" is removed from the equation. This might be the smart way forward!? Note, just in case you do not know it, that the current engine ECU s/w standard is obvious from its current p/n.

[littlepolo]

I've had 17550 code before. Interesting that there is a flash update early 2003. My Polo is late 2002, and you'd think
that at the first service/oil change a competent dealer would have picked up on it (or maybe the TSB was not made
known). I have found a good third-party VW specialist (I used once before and they picked up lots of tiny niggles -
but not the fault we are investigating), and intend to go back to them with this specific problem (and maybe ask
first if they know about it).

I did mention earlier one problem that occurred at the end of a long journey, climbing a hill (full car, engine loaded)
in the rain. Serious misfire. And that led me to another TSB (Seat or Audi, I think) to correctly earth No1(?) ignition
coil by running a new wire under the battery box or something like that. I think that is another matter, and not
related to the pinking around 2000rpm.

I might have asked before but I just had to buy 4L Castrol Edge (35.00 from ASDA), but because the Polo uses oil (as
mentioned above) by the time 12 months passes (we drive about 7K/year) I've already put in over one new 4L bottle.
So I'm wondering if its worth using the 'long life' 0W 30 rated Edge, and what alternative oil I could use?

[RUM4MO]

Oil, I used to use Quantum Gold 5W-40 from VAG or online, I stopped that when the price before crazy and VAG changed that oil to be Quantum Platinum. The oil I have been using is Fuch Titan Supersyn 5W-40 from GSF - but they have stopped stocking it. So, after emailing Fuchs, they directed me to some local motor factors first, but none of them held the Supersyn 5W-40, then Fuchs suggested Unipart (?!). This kind of tied up with what I had "heard" on some VAG forums, ie that Unipart Protec(?) 200 or 400 was same as Fuchs Titan Supersyn 5W-40. So off I went to my local Unipart place (they took over the Quiton Hazel outlets), and bought the Unipart oil, I asked if it was same as Fuchs Titan Supersyn 5W-40 and was told, while it is indeed supplied by Fuchs, as are all their oils in this group, it is not quite the same "quality" as the Supersyn oil. One other thing, Fuchs have superceded the Titan Supersyn range and Unipart also sell that as Fuchs brand - pity Fuchs UK had not told me that! Anyway, after buying the Unipart oil, I went ahead and watched ebay for getting the Supersyn 5W-40 at a reasonable price, which I did and so have enough Supersyn 5W-40 to last for another year or so. So, maybe you want to check out at your local Unipart place to see what the "non flexible servicing" oil costs and compare that price with what they are selling the new equivalent Fuchs oil for. Personally, I would stick to using 5W-40 fully synthetic in that engine and just live with the high oil usage.

I'd reckon that you are right about the wiring/coil issue, never had that problem, just needed to replace two of the original coils.

I just wish that there was a data base held at VW main dealers workshops with engine ECU S/W issues and why/what the changes were need for etc, and a quoted price to flash later s/w issues if it was thought to be of benefit to the car owner. I'd reckon that the cost will be the usual "connect VAS" to the car plus ? to down load the later version of engine ECU S/W.

[RUM4MO]

One other thing that I've seen commented on, the EGR valve might not be closing completely and so letting "fuel free" air back into the engine, and so leading to under fuelling under certain conditions that exceed the "movement" allowed by the ECU's advance/retard settings. Now that I have had one EGR low flow fault code - intermittant, I should really get this valve out and clean it - or if it is still a bit sticky replace it.

[littlepolo]

Where is the EGR located, and it is easy to take off and clean?

Not sure how that works exactly, but I'd guess problems would be less specific than at 2000rpm only.

I cleaned the throttle body (didn't seem to bad considering the car was used previously for
mainly short runs) in situ, as I read that when its removed, it has to be re-calibrated.

[RUM4MO]

EGR valve assembly "seems" to be as easy to sort out as the throttle valve - its mounted on the "front/gearbox" end of the engine. Now I've never taken either of these bits of this engine yet - but feel the need to do some thing soon. I'd reckon that there are guides out there for removing the EGR valve assembly, though most of the ones that I've seen are for the TDI engines - seems fair enough as the TDI engines will put out more soot than the petrol ones.

[RUM4MO]

Ten days and 300+miles later from previous event, car has thrown up fault codes 16785 and 17550, that means EGR system - insufficient flow and load calculation cross check - lower limited exceeded. Time to order in all "maybe" required gaskets and seals associated with the EGR valve and TB - by the way, both these assemblies need adaption if they have been removed from the car. Instructions are contained within "Ross-Tech Wiki". There are 2-off gaskets/seals required for the TB and 4-off gaskets for the EGR valve.

[RUM4MO]

Okay, I've now removed the EGR valve, Throttle Body and Interface plate. The EGR valve was not very dirty and any cleaning that you can do to it will be mainly cosmetic, really same thing for Throttle Body although it was a bit more curded up. The Interface plate, that is the bit between the Throttle Body and the inlet manifold - and also the bit where the crankcase etc fumes get drawn into the inlet along with the EGR valve's exhaust and metered fresh air - the port where the EGR gasses connects to this plate, was clogged up and it would have been that, I'd expect, that was causing the "EGR low flow" fault code - the port opposite, ie the crankcase fumes inlet, was clear, but I'd reckon that it would be its oily fumes that have been causing the exhaust gasses to clog up its port. All cleaned up, all new gaskets fitted, Throttle Body and EGR valve "re-aligned" - now car runs okay under load, but feels a bit "fluffy" under low throttle openings. I did check the throttle pot over its full range by monitoring it on VCDS - and it seems okay. I don't really know if the engine's ECU will now take some time to alter some settings to become "used" to the changes that have been made, I'll see what my wife thinks of it over the next few days. If I'm being negative, I could suggest that my EGR valve is faulty but the clogged up gas inlet at the inlet manifold was masking this, time will tell! EGR adaption is meant to be done while the engine temperature is between 10C and 50C and battery volatge is greater than 11.55 volts (I think) - I made sure that I satisfied that criteria - but maybe I'll do another adaption on both units soon. I have the original min and max for the EGR, but forgot to look at the Throttle Body original min and max.

[littlepolo]

Interesting.

Similar to what I found on my TB.

Are you saying its not now pinking?

[RUM4MO]

Interesting. Similar to what I found on my TB. Are you saying its not now pinking?

Too early to say that I'd reckon, I've only been out in it once (today roughly 16 miles) since I put it back together last night. Remember, like your car, we seem to get some "good days" with no pinking.

Did you remove the inteface plate and clean out the ports?

[littlepolo]

No, I haven't had time. I'm hoping to get a full diag done at a third-party VW specialist next month...

[RUM4MO]

Right, maybe an update, wife says car still feels "fluffy" on light throttle, also, it has logged yet another "16785" which is P0401 - 35 - 10 EGR insufficient flow - now either I messed up clearing the stored faults (were originally two so why one left behind?), or after cleaning up a fully blocked EGR port at the manifold adaptor plate, there is still no exhaust gas intermittantly getting recirculated. Could this now mean that he EGR is faulty and has been faulty for some time, maybe getting too hot due to lack of movement of exhaust gas through it into the inlet manifold - speculation, but, sniffing around the internet throws up:- "If the EGR valve is stuck closed, emissions of nitrogen oxides will rise, and the car may start to knock. Spark knock happens when the fuel mixture in the combustion chamber ignites before it has been reached by the explosion in the cylinder, resulting in a disruption of the engine timing. In this instance, the engine should be warmed up and revved to see if the EGR valve will move. " Or am I seeing what I want to believe. The thing is, when performing alignment on the EGR using VCDS, you don't really hear any movement like you do when aligning the Throttle Body - but that does not mean its faulty as it does claim to successfully pass the alignment test. Questions questions!

[RUM4MO]

Interesting. Similar to what I found on my TB. Are you saying its not now pinking?

After three days of use, and a TB & EGR re-adaption after the first day, my wife reports that where it would pinking a few times every day, it is not pinking at all! Also the re-adaption seems to have cleared the light throttle "fluffyness" at appeared after I had it apart for cleaning. Interestingly, I've read on the web, that faulty TBs can lead to this light throttle "fluffyness" as can a EGR valve that is passing slightly. One thing to note is that the EGR "min value" did increase after cleaning and re-adapting, which would suggest that the valve is no longer, as it aged, able to return to its original "closed" position - I would think that it would need soaked in a suitable liquid for a few hours with frequent switching to free it up back to as new. Carb cleaners just don't hang about long enough to do that though the frequent operating is possible using VCDS on "output testing".

I'm really just dumping any facts that I've found here as I'd reckon that lots of cars will have this problem.

[littlepolo]

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?