VW Vortex - Volkswagen Forum banner
41 - 60 of 70 Posts

·
Registered
Joined
·
1,703 Posts
Thank (almost) everybody for the information listed here. My 2005.5 has had random misfires over the years, often seemingly depending on humidity. I replaced the knock sensors twice before realizing that wasn't likely the problem. As well as professionally cleaning the injectors, I plan on trying plugs other than oem. I've never researched spark plugs beyond part number lookup, so this thread really helps.

Please help me clarify: If I run a cooler plug, will this reduce my chance of knock? My engine is a BGQ from 2007, swapped from the original BGP. The knock can happen whether or not I have my stock intake or my short ram cold air intake. I may also replace the coils, it's been a few years since my last set.
Try upping your octane. Remember, the owners manual says for best performance, use 91 octane.

Try 89 and then move up to 91 if the knock is till there.


Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
152 Posts
Try upping your octane. Remember, the owners manual says for best performance, use 91 octane.

Try 89 and then move up to 91 if the knock is till there.


Sent from my iPhone using Tapatalk
Thanks, I've already been all over that, plus octane boosters sometimes. It's really fickle, and I have my theories. It seems to happen more while rounding tight corners, so maybe the electric steering is pushing voltages just past certain points? I'll soon replace the coils and plugs, and probably upgrade the ground wires, if not do the big 3 (my sound system dims the lights, so this is on the list anyway). I'm still debating which plugs to run, but will make the choice soon. Lots to consider.
 

·
Registered
Joined
·
1,703 Posts
This is the story of one VW-loving man's quest to find the perfect NGK standard copper (nickel-alloy!) spark plug for our beloved 2.5L inline-5 cylinder engine...read on friends!


So the only recommended COPPER spark plug (aka standard aka NOT platinum or iridium tipped AKA nickel-alloy outer electrode...remember all spark plugs have copper cores so it's kind of a misnomer!) for our 2.5L inline-5's is a Denso plug, K16GPR-U11, which I have not been very impressed with after 2 sets of 30k and 20k miles. Don't get me wrong, they were decent especially for the money ($3.07 per plug), but meh...

The alternative? Just buy OEM 2.5L plugs and be done with it you say? :screwy: No way, what am I made of money?! $12/plug is absurd, and Platinum tipped never seems to run as good (and that is backed up by electrical science...go look up conductivity of metals).

And since I've never had a poorly performing NGK plug in any application ever....the obvious next step was to spec out the Denso K16GPR-U11 plug, crossreference to NGK and BOOM, sexy electrical magic! ❤

I came down to 3 NGK plugs that matched the Denso's specs (and as a check, they are all in the base family of the OEM platinum plug, PZFR5Q-11, hooray! 👍):

ZFR5D-11, ZFR5E-11, and ZFR5J-11

So these are all the same-spec'd plug, with the variable letter denoting "special firing-end design" which of course NGK does not explain anywhere. Initially I was set on the "J" version, thinking that since the original OEM platinum plug was a "J" plug (PZFR5J-11), however I found some info indicating the "J" copper plug had a shorter insulator than the other coppers and the OEM platinum plug.

With that said, I chose the ZFR5E-11.

No real reason over the "D" version...I thought I saw that the "D" was a non-V groove electrode so that was my reason against it...wouldn't hesitate to try the "D" or the "J" though, but as always your miles may vary/do at your own risk yadda yadda...I can only comment on the ZFR5E-11 ...

... and let me say...THEY ARE AWESOME. Now of course these are not "official" OEM spark plugs for our engine, so just remember that...but the results speak for themselves. I'll say it again for effect...


THE NGK ZFR5E-11 STANDARD COPPER SPARK PLUGS RUN GREAT IN VW 2.5L INLINE-5 CYLINDER ENGINES !!!!!!!


Just had to gap down to .040"/1.0mm. The butt-dyno says YES, idle is smoother, MPG's are up (couldn't get more than 28 highway before, recorded multiple highway cruises on the NGKs at 72-75mph in the 30.X range!), and, oh yeah, did I mention they cost $2.50 per plug? The wallet also says YES.


So run along now to your local auto parts store, where they are literally ALWAYS in stock (part #4435) and rejoice at the thought of walking out with 5 quality NGK copper plugs for less than $13. Boom shakalaka. Y'all are welcome! ☮
So far, the OP is on to something. I’m using these plugs and that are great.

Next I’m going to try the NGK ZFR6T-11G Copper Nickel. These are OEM for later 2.5 motors. I have early 2.5. I’m curious how these slightly bottler plugs will run and especially since I run premium at all times.

I’ll report back. But good find OP. These work great.


Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
278 Posts
So far, the OP is on to something. I’m using these plugs and that are great.

Next I’m going to try the NGK ZFR6T-11G Copper Nickel. These are OEM for later 2.5 motors. I have early 2.5. I’m curious how these slightly bottler plugs will run and especially since I run premium at all times.

I’ll report back. But good find OP. These work great.


Sent from my iPhone using Tapatalk
When you run higher octane gas than the car is designed for, the ECU adjusts the ignition system so that it runs like it would on regular octane. This made a difference in older cars but you're wasting your money for the more expensive gas.
 

·
Registered
Joined
·
1,703 Posts
When you run higher octane gas than the car is designed for, the ECU adjusts the ignition system so that it runs like it would on regular octane. This made a difference in older cars but you're wasting your money for the more expensive gas.
Oh no, you haven’t read the owners manual.

It says for best performance use premium, but minimum requirement is regular.

This was also covered by a few auto magazines in the 2000’s with dyno test and fuel economy test. Premium really improved power and economy.

The car was was designed to take advantage of premium. It’s also pretty well known that modern VW ecus have aggressive timing software compared to others.


Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
1,703 Posts
Ok, I found a set of Bosch copper nickel FR7HE02 which are OE for 170hp 2.5, but wow, the best plug I have ran yet. So far the worst plug was the NGK laser platinum.


Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
278 Posts
Oh no, you haven’t read the owners manual.

It says for best performance use premium, but minimum requirement is regular.

This was also covered by a few auto magazines in the 2000’s with dyno test and fuel economy test. Premium really improved power and economy.

The car was was designed to take advantage of premium. It’s also pretty well known that modern VW ecus have aggressive timing software compared to others.


Sent from my iPhone using Tapatalk
I wasn't aware of that. It looks like I've got to go back and read my manual again. I'm usually pretty good about that. Still, I can't complain about the performance. I have NGK coils and iridium plugs in my 2008 2.5. It runs fantastically. It has the 09G automatic transmission and I only run "D" on the interstate. I use "S" or manual mode for everything else below 70 mph. It consistently gets great gas mileage - upper 20's around town and upper 30's on the highway - with the rpm's always well above 3K. In spite of the low end torque, I do not run it like an old Buick at low rpm's. This car loves to scream. With over 153K miles on it, it burns no oil and has no leaks (no vacuum pump). I keep all fluids changed regularly with premium quality.

On the subject of premium gas, I used to have a Miata NB2 which required premium. The owner's manual said it would run on regular octane but not it was not recommended. Any savings at the pump was sacrificed in performance AND gas mileage. I always ran top tier premium in it.

I've been running top tier regular octane in my Rabbit but I'll try the top tier premium and see if I can notice a difference in performance.

Thanks.
 

·
Registered
Joined
·
278 Posts
I wasn't aware of that. It looks like I've got to go back and read my manual again. I'm usually pretty good about that. Still, I can't complain about the performance. I have NGK coils and iridium plugs in my 2008 2.5. It runs fantastically. It has the 09G automatic transmission and I only run "D" on the interstate. I use "S" or manual mode for everything else below 70 mph. It consistently gets great gas mileage - upper 20's around town and upper 30's on the highway - with the rpm's always well above 3K. In spite of the low end torque, I do not run it like an old Buick at low rpm's. This car loves to scream. With over 153K miles on it, it burns no oil and has no leaks (no vacuum pump). I keep all fluids changed regularly with premium quality.

On the subject of premium gas, I used to have a Miata NB2 which required premium. The owner's manual said it would run on regular octane but not it was not recommended. Any savings at the pump was sacrificed in performance AND gas mileage. I always ran top tier premium in it.

I've been running top tier regular octane in my Rabbit but I'll try the top tier premium and see if I can notice a difference in performance.

Thanks.
UPDATE: I read my owner's manual for the fuel octane recommended for my 2008 2.5. It said IF premium fuel is recommended, it would be printed on the label inside the fuel filler "flap" (door). I checked the label and it listed 87 and 91 both, without a preference. This tells me the premium is not recommended but will work. I still plan on trying it out for a comparison and I will be objective. I would definitely like even better performance than I already have, although it is great right now. If it turns out to be the same, I'm still happy.
In spite of the weird German engineering, I still love the car....electrical gremlins and all.
 

·
Registered
Joined
·
1,703 Posts
UPDATE: I read my owner's manual for the fuel octane recommended for my 2008 2.5. It said IF premium fuel is recommended, it would be printed on the label inside the fuel filler "flap" (door). I checked the label and it listed 87 and 91 both, without a preference. This tells me the premium is not recommended but will work. I still plan on trying it out for a comparison and I will be objective. I would definitely like even better performance than I already have, although it is great right now. If it turns out to be the same, I'm still happy.
In spite of the weird German engineering, I still love the car....electrical gremlins and all.
The fuel door is just listing the min requirement, the 91 you see is RON. In AKI it’s 87. AKI is used in most of NA and RON is used in other places. Both are 87 octane.

There is a section in the manual that talks about fuel grade.


Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
278 Posts
The fuel door is just listing the min requirement, the 91 you see is RON. In AKI it’s 87. AKI is used in most of NA and RON is used in other places. Both are 87 octane.

There is a section in the manual that talks about fuel grade.


Sent from my iPhone using Tapatalk
You're right, I went back to the label and it does mention AKI 87 and RON 91 as being the minimum requirements. I've gone through the whole Section 3.2 of the many volume owner's manual and the only other details I've found are in regard to alcholol and methanol. There is nothing in there about the car running better on premium AKI 91. I will try it out, just out of curiosity.
 

·
Registered
Joined
·
1,703 Posts
You're right, I went back to the label and it does mention AKI 87 and RON 91 as being the minimum requirements. I've gone through the whole Section 3.2 of the many volume owner's manual and the only other details I've found are in regard to alcholol and methanol. There is nothing in there about the car running better on premium AKI 91. I will try it out, just out of curiosity.
I will find it my manual and take pic for you.


Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
1,703 Posts
You're right, I went back to the label and it does mention AKI 87 and RON 91 as being the minimum requirements. I've gone through the whole Section 3.2 of the many volume owner's manual and the only other details I've found are in regard to alcholol and methanol. There is nothing in there about the car running better on premium AKI 91. I will try it out, just out of curiosity.



Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
706 Posts
I replaced the spark plugs for wife's 2010 Golf 2.5 @ 30K with Autolite APP5224-4PK Double Platinum Spark Plug. It's now 130K still running great but it's got 100K so I wanted to change. Did a research and found this thread. I think I will stick with Autolite but the only thing is they changed the design and I kind of wanted to stick with the old one because it's been working great for me...
 

·
Registered
Joined
·
290 Posts
I was using the Autolite XP5224 at a 40K service because they were on a terrific sale and *Iridium * mmmmm. Left them in for 6K and took them out for the NGK, ZFR6T-11G (5960) and found a slight improvement in mileage around town and to my butt dyno, better idle smoothness. The removed 5224's metered 7K-8K ohms on removal. The 5960's were all around 1Kohm going in. I'll use the NGK's at the next service interval.

Edited to correct plug model #
 

·
Registered
Joined
·
1,703 Posts
I was using the Autolite XP5224 at a 40K service because they were on a terrific sale and *Iridium * mmmmm. Left them in for 6K and took them out for the NGK, ZFR6T-11G and found a slight improvement in mileage around town and to my butt dyno, better idle smoothness. The removed 5224's metered 7K-8K ohms on removal. The 5224's were all around 1Kohm going in. I'll use the NGK's at the next service interval.
I’m also using the 5960. Very nice plug. The best one I’ve ran yet.


Sent from my iPhone using Tapatalk
 

·
Registered
2008 VW Rabbit, MT, 3-door
Joined
·
169 Posts
I’m also using the 5960. Very nice plug. The best one I’ve ran yet.


Sent from my iPhone using Tapatalk
What's the gap?
1.0 mm?

I came across different values here... anywhere from 0.8 mm to 1.1 mm.
 

·
Registered
2008 VW Rabbit, MT, 3-door
Joined
·
169 Posts
41 - 60 of 70 Posts
Top