VW 1.4 Tsi Spark Plug Indexing

[sohccammer427]

Just watched a video over at Youtube detailing spark plug replacement on the 1.4l Tsi engine. Fairly new video dated May 2019.

Anyway the installer states that at least the VW plugs threads are cut to provide the correct indexing when torqued to the factory spec of 22 newton meters.

When ever I replace mine in a few years I am going to compare the thread cut on both the old and new plugs. I wonder if other manufactures are doing this also?

Here's what he states. Any VW wrenches that can verify.

The threads on the spark plug and the cylinder head are precisely cut and they define the position of the spark plug in such a way to place the earthing electrode pointing towards the exhaust valves.

This substantially improves the cooling of the spark plug due to the fresh gas streaming in.

 

[sloinker]

Indexing of plugs in a passenger vehicle is nearly meaningless imo. It has basically undetectable levels on a dyno on race engines where builders trying to squeeze the last portion of a horsepower index the plugs. The depth and angle of the plug for cooling makes some sense, the index of the electrode is probably not so much.

 

[atikovi]

Indexing of plugs in a passenger vehicle is nearly meaningless imo.

First gen Honda Insights had the choice of four different indexed plugs, A to D to match the corresponding cylinder head. I don't think they would have bothered unless it gave some valuable gains.

 

[sloinker]

First gen Honda Insights had the choice of four different indexed plugs, A to D to match the corresponding cylinder head. I don't think they would have bothered unless it gave some valuable gains.

I still doubt it. There are spark plugs that have 2 and 4 electrodes. I don't see any manufacturers using them. If Honda is running the mixture so lean in its lean burn engines that the position of the electrode can cause a stumble because the spark isn't amidst the richest portion of the swirled combustion seems a pretty big reach. It would be interesting to dyno their first generation engine in its lean burn configuration with the four spark plug choices and see if there is a measurable difference. I would suspect heat range and coil joules would have a bigger impact.

 

[nthach]

First gen Honda Insights had the choice of four different indexed plugs, A to D to match the corresponding cylinder head. I don't think they would have bothered unless it gave some valuable gains.

When I pulled the OEM Denso plugs on my old car, Toyota had indexed plugs installed from the factory, they were marked with an A on the terminal end.

The replacements were not indexed and the car ran fine. It’s still a practice limited to racing engines or certain exotics.

 

[Trav]

Just watched a video over at Youtube detailing spark plug replacement on the 1.4l Tsi engine. Fairly new video dated May 2019.

Anyway the installer states that at least the VW plugs threads are cut to provide the correct indexing when torqued to the factory spec of 22 newton meters.

When ever I replace mine in a few years I am going to compare the thread cut on both the old and new plugs. I wonder if other manufactures are doing this also?

Here's what he states. Any VW wrenches that can verify.

The threads on the spark plug and the cylinder head are precisely cut and they define the position of the spark plug in such a way to place the earthing electrode pointing towards the exhaust valves.

This substantially improves the cooling of the spark plug due to the fresh gas streaming in.

This is very important with some GDI engines, follow the FSM for torque spec and use OE plugs not aftermarket even if they are the same brand. This for example is the issue with NGK in a MB.
Indexing is no longer only for racing or exotics, some very small displacement engines are making some serious power for their small size.

 

[sohccammer427]

This is very important with some GDI engines, follow the FSM for torque spec and use OE plugs not aftermarket even if they are the same brand. This for example is the issue with NGK in a MB.
Indexing is no longer only for racing or exotics, some very small displacement engines are making some serious power for their small size.

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Thanks... Spark plugs for the 1.4L Tsi appear to be a unique VW part. It may be possible ( I have not searched) to find Bosch or even NGK replacements. They could very well be an exact OEM spec part, but this will be part that I will definitely purchase directly from the dealer.

My other vehicle is a 2021 Mazda3 with a very high 14:1 compression ratio. Just for giggles I looked on line for plugs for it. The are NGK's available as a direct replacement for the OEM Mazda brand plugs. They even have the ruthenium types available. I suppose one could take an OEM plug and inspect the thread start and length and maybe be able to see if would index in the same position. Tightening torque would come into play too. Interesting stuff on these new engines.

 

[Trav]

Torque within a couple of Nm eg 20-22 Nm is fine to get them in the perfect position (directly facing the injector), the easiest way is to put the plug in the socket and mark the top of the socket with the position of the open end of the electrode. If it gets to the correct spot within a couple of Nm call it good, do not use never seize on these unless lubed threads are specified.

Just one reason for indexing....

Whether the side electrode requires special orientation or indexing within the chamber is controversial. Everyone agrees that it is sometimes necessary to control electrode orientation on extremely high-compression engines using pop-up pistons—not to gain power but to keep the dome from contacting the side electrode and closing up the plug gap.

 

[atikovi]

Thanks... Spark plugs for the 1.4L Tsi appear to be a unique VW part. It may be possible ( I have not searched) to find Bosch or even NGK replacements. They could very well be an exact OEM spec part, but this will be part that I will definitely purchase directly from the dealer.

There are no direct replacements for the four different Honda plugs I posted either, just $20 a pop from Honda. Sure, there are NGK that will fit and seem to work fine but they don't bring the engine to it's full potential.

 

[sloinker]

There are no direct replacements for the four different Honda plugs I posted either, just $20 a pop from Honda. Sure, there are NGK that will fit and seem to work fine but they don't bring the engine to it's full potential.

Is there any actual third party testing evidence to support your claim? Do these Honda engines have pop up or high compression shaped cylinder domes where the electrode can contact the piston if not indexed? Many tuners out there. There must be dyno sheets for plug changes.

 

[atikovi]

Get on the Insight Central forum and you can ask those that know more than I do. Whenever I get an Insight I change the plugs to the indexed Honda ones if not already there, for better resale. Can't really tell that it runs any better, but again, I assume Honda did it for a reason or else why bother stocking 4 different plugs plus measuring and marking each cylinder head. There is a reason they get over 70 mpg and while this isn't the main reason, it probably adds something.