spark plugs - factory plugs not at proper gap

[NJTom]

I have a 2009 V6 with 83k miles. Changed the spark plugs this weekend with the recommended NGK plugs. Driver's side took 10 minutes! Easy! Passenger side took a bit longer since the manifold needed to be removed. All in all, it took me about 2 hours total for the whole change (with hand tools). It was actually easier than expected once I figured out which bolts/nuts to remove.

Anyway, i gapped the new plugs to the recommended 0.044" and afterwards checked the old plugs which were original from the factory. The old plugs didn't look as bad as I expected but I was surprised their gap was between 0.038-0.040".

The engine runs smoother at idle and appears to be a bit more responsiveness. I'm hoping the gas mileage increases a little too.

 

[balfor]

interesting as normally the gap would increase with use so you expect old plugs to be a bigger gap than new. good that you re-gapped as a bigger gap is better to a certain point.

 

[NJTom]

that's what I expected too. I wonder what gap they were when new. I was meticulous when gapping them. All 6 plugs are now 0.044". I rechecked them a few times to confirm, using two different types of spark plug checkers.

 

[Mark_888]

Here is info from the 2009 Shop Manual for the 3.8L engine:

 

[NJTom]

Thanks for the info Mark_888.
The attached is for the plugs needed for cars manufactured previous to 5/1/2008. The plugs out of my 2009 (manufactured Nov 2008) are SILZKR6B11 and are to have a gap of 0.044".

 

[Mark_888]

Thanks for the info Mark_888.
The attached is for the plugs needed for cars manufactured previous to 5/1/2008. The plugs out of my 2009 (manufactured Nov 2008) are SILZKR6B11 and are to have a gap of 0.044".

I was wondering where you got that information? I was not aware that any US models were made before 5/1/2008.

I used the online version of the 2009 shop manual, which does not mention anything about manufacturing dates. I also looked at the 4.6 V8 spark plug gaps and they were the same (1.0 - 1.1 mm), although the V8 spark plug was different.

- - - Updated - - -

I went out to the NGK website, and I do see that the NGK SILZKR6B11 has a gap of 0.044 in. But my understanding is that those plugs come pre-gapped to that size, not necessarily that it is the correct gap size for the Hyundai Lambda V6 3.8L built after 5/1/2008. That same spark plug was also used in some 2011-2012 Hyundai Elantra engines (obviously a completely different 4 cylinder).

At the same website, I do see that the NGK ILFR5B11 is specified for 3.8L built before 5/1/2008. But those plugs come gapped the same as the ones above (0.044 in), so it appears that the NGK website lists the gap size for the plugs out of the box, not necessarily the gap size recommended by the engine manufacturer. As balfor mentioned above, it is very unusual for plug gaps to decrease after they have been used.

But if you have some Hyundai documentation that specifies a gap 0.044 in for the 2009 3.8L, I would be interested in seeing it.

 

[dougmcp]

No real need to split hairs here, there will be no real difference in performance or fuel economy if you set them at .040 or .044.
These iridium plugs hardly grow in gap over 100,000 miles so if where ever you set them they will be close to that until you change again.

 

[Mark_888]

No real need to split hairs here, there will be no real difference in performance or fuel economy if you set them at .040 or .044.
These iridium plugs hardly grow in gap over 100,000 miles so if where ever you set them they will be close to that until you change again.

Yes, 0.044 is pretty close to the upper limit of the specs I found (assuming the ones I found are the correct specs), but I would like to know what the official specs are in case I need to change the plugs myself.

 

[dougmcp]

The specs you originally quoted are correct. I also checked my service manual and it was the same as yours. I have a 2013 3.8.

 

[NJTom]

Mark, as you said, the info was found on the NGK website and also I found the same information from rockauto.com for the 2009 Genesis. Well, I guess the gap from factory would be correct. The NGK came gapped at about .040 and I regapped them to 0.044. My car does run smoother so I'm happy.

Thanks for the feedback guys!

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