RS7 Tune: APR recommends a spark plug gap of .024" +/- .002" for best results

[jb1970]

How important / what difference does this spark plug gap make?

What is the factory gap?

[sciblades]

Apr can answer this better than I can, in the cold they were getting missfires so this was the fix.

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[eyeloveteeth]

yeah happened to Kiku i think

[Kai@EliteMS]

If the car is misfiring it needs to be gapped. Some cars do and some don't from our experience but best is to gap them so the spark/flame doesn't blow out with the added boost on the factory gap.

[HeelBuff]

It's likely not worth the pain and expense of removing your plugs and re-gapping them. My car was throwing misfire codes after I tuned it a year ago and it was suggested I have the plugs re-gapped. I did and it didn't make a hill of beans' difference. Once APR released their revised software I began seeing improvements.

[kiku]

Agree with Heel on this. Besides pulling plugs on these cars is labor intensive.

[DrBeerMD]

I'm about to swap plugs on mine in the next 5K miles or so. Figured 23-25K miles on tune it might be time.
Curious how many hours you guys got billed for such a service?

[Jake@JHM]

More boost = more compression. Having more compression makes it harder for the spark to jump the gap of the spark plug, and also makes your coil packs work harder. By reducing the gap you eliminate this issue.

[Nabizzy]

I'm about to swap plugs on mine in the next 5K miles or so. Figured 23-25K miles on tune it might be time.
Curious how many hours you guys got billed for such a service?

23-25k miles on tune.....man....that is impressive.

[Brooklyn]

First time this has been explained in terms this knuckle dragger could understand. So this is an issue for tuned S6/7 owners as well? I'd imagine so based on your description, but I haven't heard of this being an issue with the S cars.

More boost = more compression. Having more compression makes it harder for the spark to jump the gap of the spark plug, and also makes your coil packs work harder. By reducing the gap you eliminate this issue.

[Jake@JHM]

First time this has been explained in terms this knuckle dragger could understand. So this is an issue for tuned S6/7 owners as well? I'd imagine so based on your description, but I haven't heard of this being an issue with the S cars.

Not sure to be honest. APR would know more about this as they have more experience with this platform. I happened to see the thread title so I clicked on it and explained the reasoning behind reducing gap when adding more boost.

I would have to see stock compression ratios and spark plugs used vs how much boost.

[DrBeerMD]

23-25k miles on tune.....man....that is impressive.

Well I've had the tune since day 3 of it's life. Right now it has about 19K on her. Lots of road trips all over the place. The only issue ever with this car has been a leak on my windshield washer fluid reservoir. Things a reliable beast.

[Clubba117]

This happened to me in a big way. I unfortunately listened to someone on YouTube that said to gap my plugs to .055 on a stage 2+ tune (RS7 performance turbos) and it misfired like crazy! This weekend I will bring them to .025 and see what happens. DS1 box tune by the way. I ordered a @kyletunedit custom tune but I don’t want to send out the data until I see if I can resolve the misfiring with the new gap.

[jeff351]

This happened to me in a big way. I unfortunately listened to someone on YouTube that said to gap my plugs to .055 on a stage 2+ tune (RS7 performance turbos) and it misfired like crazy! This weekend I will bring them to .025 and see what happens. DS1 box tune by the way. I ordered a @kyletunedit custom tune but I don’t want to send out the data until I see if I can resolve the misfiring with the new gap.

I just put APR plugs and coil packs in and thankfully googled what to gap them first because pulling plugs on a 4.0 is a pain in the ass. The stock plugs were at .028 and I was getting misfire on cylinder 5, which is a totally different cause than spark plugs but my shop suggested plugs first instead of shimming the valve springs and I will say that I have felt a slight improvement at higher rpm's just before a shift... car feels like it still has power instead of falling off and rebounds a little quicker after the shift

[Clubba117]

I just put APR plugs and coil packs in and thankfully googled what to gap them first because pulling plugs on a 4.0 is a pain in the ass. The stock plugs were at .028 and I was getting misfire on cylinder 5, which is a totally different cause than spark plugs but my shop suggested plugs first instead of shimming the valve springs and I will say that I have felt a slight improvement at higher rpm's just before a shift... car feels like it still has power instead of falling off and rebounds a little quicker after the shift

Yes! cylinder 5 on mine too! I'm getting ready to re-gap them right now. So there might be a different reason for the mis-fire?
I only noticed it right after the stage 2 install and "stupidly" leaned on it a little too hard before it was completely warmed up. I'm just playing it safe and going with the 0.024 gap.

[jeff351]

Yes! cylinder 5 on mine too! I'm getting ready to re-gap them right now. So there might be a different reason for the mis-fire?
I only noticed it right after the stage 2 install and "stupidly" leaned on it a little too hard before it was completely warmed up. I'm just playing it safe and going with the 0.024 gap.

there is a manufacture defect on certain batches of RS7's where the factory incorrectly made the cylinder head and when the engine is not warm enough the exhaust valve on 5 can float, the first step is to reprogram the ecu to help prevent overboosting when the engine is not at proper temp, if that doesnt work and the plugs are fine then the solution is to shim the valves causing more spring pressure on the valve so it closes properly. Once mine got reprogrammed it was quite a while before i had a misfire, I dont floor it when its cold but there are a few times when it gets right at 5k before a shift and that would cause the misfire. since i replaced all plugs and coil packs its been a lot smoother