Dreaded Pinging

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I just wanted to think aloud in the event anyone is able to shed light on what my car is experiencing.

Mechanically, I just have a GIAC 98 octane tune and a new diverter valve. Under high load, low rpm situations, particularly a 1st/2nd/3rd squirt changing around 3,500rpm, I very rarely experience pinging.

Now these cases haven't neccisarily been in high temp situations (ie. car idling for a long time, or stuck in traffic etc.) nor have they been on hot days (21 degree's outside today). That led me to think it's fuel, but after getting all the injectors professionally cleaned, the fuel filter replaced, and a bottle worth of Nulon injector cleaner run through the car it still hasn't resolved this.

The more I look at the fuel system, the more I suspect heat being the issue. Particularly seeing it's normally 1st/2nd/3rd runs... whereby I come to a brief stop before accelerating, giving heatsoak a chance to set in.

Anyone had anything similar? I'm really not up for forking out for an intercooler upgrade, and beside pulling the front wheel well lining up and checking the air flow to the intercooler and possibly giving it a rear vent into the wheel well, anyone up for any ideas (besides the obvious 'turn the boost down', which is a little hard with nothing but a GIAC tune running at ~20.5psi peak)

Edit: One other thing I'm about to try is cleaning out the MAF to see if that helps. Is there a way to identify a faulty MAF other than VAG logging?

[h100vw]

You can buy a new MAF and see if it is better. I think you have wasted money up to now. Any time you have something amiss with a car like yours, you have to get it scanned for faults. Randomly replacing parts can get costly. Have you looked at the sparkplugs?

If there's no faults, you need to look deeper and ask yourself why it would be pinking. It shouldn't be pinking in response to heatsoak, the ECU should be retarding the timing to prevent that.

As you are in Brissy, I'd get hold of Jimmy and get it looked at. You will save money in the long run.

[noone]

I have not done conclusive logging, but changing the spark plugs to the NGK BRK7E's stopped some seemingly random (to my inexperienced eyes) timing pull on my car. Whilst Pinging is often associated with heat, I don't think that the Heat alone will be causing the issue. If you had serious issues in summer, then I would understand, but what you are likely experiencing could be picked up by Vagcom

I don't know if this relates to a little carbon buildup, a damaged plug or the colder plugs working a little better with the tuned engine, but seems to have made a difference. The plugs were <$20, so if you have the tools, its worth a check.

If you have a serious concern and want some short-term protection, you can use a Vag-com cable and one of the Adaptation Tuning applications (eg Lemmiwinks) to retard your boost.

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You can buy a new MAF and see if it is better. I think you have wasted money up to now. Any time you have something amiss with a car like yours, you have to get it scanned for faults. Randomly replacing parts can get costly. Have you looked at the sparkplugs?

I see where you're coming from, but most of the parts have been required as park of the 60k service. Plugs have already been done (nearly 10k ago) to BKUR7ET's.

But yes, I'm also baffled why the ECU isn't retarding the tune... MAF certainly could be a cause of such a fault, but like you said... without proper VAG logging I won't know for certain.

Oh, as for carbon build up, I'm running some Subaru upper engine cleaner through it next weekend (have some lying around anyway).

[noone]

Has the issue only been since the last service? Could be the Plug was bad?

The ECU can retard timing, but if the issue is not consistent, then it does not know how to stop it from happening.

Ebay Vag-com cable can get you some info for not much...

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Has the issue only been since the last service? Could be the Plug was bad?

The ECU can retard timing, but if the issue is not consistent, then it does not know how to stop it from happening.

Ebay Vag-com cable can get you some info for not much...

Do the 16pin VAG cables all support the Polo MKV?

But yeah, the issue has been very rarely (three times over 30,000km now), first time before new plugs... second and third time after.

Edit: I've also checked for any leaks post MAF to see if somehow there is extra air being drawn in post MAF reading, and I can't see anything obvious.

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Quick Q on the upper engine cleaner, on my old WRX I ran it through the vacuum line... but I've read mixed reports if it should be done through the vacuum line or just rip off the airbox and put it through the intake (ie. straight into the MAF essentially).

Thoughts?

[h100vw]

NOT THROUGH THE MAF. They don't want to be wet, like Mogwai's .

A vacuum pipe should work. Never done one but have read about them on the internet.

Gavin

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NOT THROUGH THE MAF. They don't want to be wet, like Mogwai's .

A vacuum pipe should work. Never done one but have read about them on the internet.

Gavin

Yeah, having a quick look we have the break booster line just underneath the intercooler pipe leading up into the plennum with a re-usable clamp on it, that looks like the best point of entry for it, particularly seeing it's past the throttle body as well.