Rattle under load when engine is hot

[Golf Loon]

If you read all the posts, it says the timing has been checked.

I re-checked it and recommended he change the knock sensor.

[jmystaki]

OK

Knock Sensor ordered from the US....

Already in shipping... should get it this week....

[jmystaki]

Brand new Knock Sensor installed, still pinging........

[jmystaki]

ok, flushed the tank and check the fuel filter (new one installed in the last 12 months - genuine Bosch).

Just did 2000km (return the Melbourne from Sydney) thought it may clean up the engine...(possible more carbon in the head, causing high compression, therefore causing pinging....)

Still pinging !!!

Despite the temp gauge in the middle of the range, I think it is running a little hot, and therefore a bit lean.....

Suggestions?

[sydVR6]

Ok.

When plugged into a VAG COM scanner, is it throwing you any codes?

Other than that, If it's leaning out enough to ping, there must be an obvious reason as to why... somewhere. Even with the new knock sensor, your bosch system isn't retarding the timing enough to stop the pinging. I'm wondering if the ECM is reading ok.

I think it might be time to talk to the EFI gurus, whoever they are : )
I know of a good bunch (Petroject.com.au) who consult on this type of thing.

Have you tried seeing what happens when you run a (Wynns, Nulon) Octane Booster with your tank of 98 octane fuel? Theoretically, that should at least help it to stop pinging.

Have you done a check of your fuel pressure regulator or had the injectors cleaned at all?

BTW What happened when you went to have the head de-carbonised? Was that done for you in the end? If you want to try something like that for yourself, you could do the tablepoon of brake fluid in the chamber trick.

It's pretty easy - remove the plugs, spoon or syringe a tablespoon of brake fluid into each cylinder through the plug hole, crank by hand for a cycle or two, then leave overnight. Replace the plugs, fire up engine, watch the masses of smoke pour out for a (scary) minute or two then take the car for a spirited drive. This recipe is sometimes recommended for bore glazing and the like, but also removes a lot of crap from your upper cylinders and plenum chambers, so, it could be worth a go (if you haven't already had the de-carb). Of course, be it at your own risk, but plenty of pretty safe minded heads have tried it over the years and had good success with gunged up cylinder heads. The brake fluid won't harm anything inside the bores, but sure does get rid of any crap!

Sorry for the lack of 'structure' in this reply, here, but it's late : )

[DubSteve]

[jmystaki]

Hi sydVR6

VAG Showing no codes.

I have been running 98 octane fuel, with an additional octane booster... I think this has a major improvement, but still not enough...

Injectors and head have been cleaned with Petroject machine. I also decarbed the head a few times myself..

I have been using all sorts of injector cleaners products....

no luck.

I cannot see any clear way to tell how effective the knock sensor is with VAGCOM.... I guess it is working as i usually have reduced performance when the engine is really hot...(retarded timing)...

[Bug_racer]

how about posting some logs ?

Injector duty cycle and lambda values as well as ignition timing and intake air temp ?

[h100vw]

How tight is the bolt on the knock sensor? I forget the setting but it's only like 10-15 lbs.

Gavin

[jmystaki]

Hi Bugracer - please check out post 42 of this thread... I have attached logs there.

If you need more data I would be happy to log some more... just let me know what you need.

H100vw - yep, the Knock Sensor is set correctly at 15 foot pounds of torque.

Cheers

[Bug_racer]

Hi Bugracer - please check out post 42 of this thread... I have attached logs there.

Ive gone through the logs and they arent very helpful .

there is only one time where you actually go above 2000rpm , and the intervals are like almost 5 seconds apart !

When you log an old car you can only do 1 channel at a time so you can keep the frame rate above 1.1-1.2 . Do those same channels again , this time logging 1 at a time !

(why do I get the feeling no-one else knows how to read logs???)

[sydVR6]

Well, I'm going to throw something new into the mix here.

A non-functioning EGR valve could be causing your ping problem. You could check that the valve opens properly and the ports under the valve are clear.

Bit of an explanation here;

http://autorepair.about.com/od/glossary/gr/def_egr-valve.htm

I don't think this has been suggested yet and I've seen blocked EGR valves cause similar problems on a few Jap cars, so worth maybe looking at...

[Bug_racer]

MK3 doesnt have EGR valve as far as I know .

Well, I'm going to throw something new into the mix here.

A non-functioning EGR valve could be causing your ping problem. You could check that the valve opens properly and the ports under the valve are clear.

Bit of an explanation here;

http://autorepair.about.com/od/glossary/gr/def_egr-valve.htm

I don't think this has been suggested yet and I've seen blocked EGR valves cause similar problems on a few Jap cars, so worth maybe looking at...

[sydVR6]

I know the VR6 does. I'm pretty sure the 2.0 does (without the Bentley manual in front of me) but could be wrong.

GAP stocks them for the 8v:

http://www.germanautoparts.com/Volkswagen/Golf/Engine/317/1

[Bug_racer]

Show us a picture , Ive never seen one on a Australian VR6

US cars are different to ours dont forget

I know the VR6 does. I'm pretty sure the 2.0 does (without the Bentley manual in front of me) but could be wrong.

GAP stocks them for the 8v:

http://www.germanautoparts.com/Volks...f/Engine/317/1