Spark plug gap argument thread

[V8weight]

I spoke with Kyle last night at length on the subject of spark plug gaps. It's critical on a tuned forced induction car to close up the gap to prevent the spark from "blowing out" under increased cylinder pressures. Being up north where ambient temps are down to about 0-10F, we both seem to be experiencing problems with spark blow out, in varying degrees of severity. With lower ambient temps come higher air densities, and in theory, higher cylinder pressures. I can hear my car stutter and fart out of the exhaust at the onset of full boost, where timing advance is at it's highest. This is a rare event for me, usually when the car is not fully warmed up (pre-heatsoak, when air density is at it's highest). My plugs are currently gapped to .028-.029. Kyles car seems to suffer worse, same symptoms only far more often and all across the boost curve. He believes his plugs may be opened as far as .040. I think this may be less of, or even a non issue for our southern friends in warmer climates, as this was never an issue for me in the summer months.

I'm heading out to the garage today to take my gap down to .024, maybe .025 to see if this helps. For reference, the stage 1-3 S4 owners are running .022-.024 on their cars, and theirs call for a stock .032 gap just like ours. I think Kyle is doing the same, so hopefully this works out for his car. If anybody has any thing to add to the subject, feel free.......

[MaxRS6]

Would it be worth a call to the APR techs to determine if they have a recommended gap setting?

My experience with APR suggests they would be happy to discuss possible issues/resolutions and review some logs. I ocassionally get a misfire code through Vag-Com but it is rather rare.

Less than .03 worth but u get watch u get...;0

[V8weight]

Would it be worth a call to the APR techs to determine if they have a recommended gap setting?

My experience with APR suggests they would be happy to discuss possible issues/resolutions and review some logs. I ocassionally get a misfire code through Vag-Com but it is rather rare.

Less than .03 worth but u get watch u get...;0

They may have a suggestion, if only I knew someone that probably has their number memorized by now, that could give them a call and pick their brains. I know that they participate on some of the larger national forums, it's too bad they don't swing through here every once and a while.

[MaxRS6]

I'll certainly give them a call on Monday and see if I can pick up any pearls. If you have anything specific other than the spark gaps, let me know and I'll be glad to ask the questions.

[speedtrapped]

Hmmm, very interested, turns out on cold start again I sputtered and misfired, misfire code, lean, rich code....and I fixed MAF connections, it's been prevelent ever since temps have been 20-25 degrees. Tech pulled only one plug randomly and gap was .28, all coils and plugs new, looking forward to your results Pat

[4everRS]

for anyone who read the 2nd page of my "early xmas" thread, this was one of the first things I could think of after putting the ecu on program 2. Of course like many of us, I though worse thoughts like TC failure. Haha

Max, its not really an issue of a misfire as no codes are thrown when it happens. The coil is still sending the signal and its not predetonating, just not detonating at all due to blow out. At least this is my theory.

I'll be closing the gaps a little later today. Scraping grout right now, yeah!

[V8weight]

for anyone who read the 2nd page of my "early xmas" thread, this was one of the first things I could think of after putting the ecu on program 2. Of course like many of us, I though worse thoughts like TC failure. Haha

Max, its not really an issue of a misfire as no codes are thrown when it happens. The coil is still sending the signal and its not predetonating, just not detonating at all due to blow out. At least this is my theory.

I'll be closing the gaps a little later today. Scraping grout right now, yeah!

I think you're correct Kyle, as far as the ecu is concerned, detonation is complete, and no fault will be registered in this event. Almost done here, I'll check back in after a test drive.

[JSRS6]

I am in the middle of this process(literally). I will be gapping mine but forgot the torque requirement on the plugs. Anyone got the specs?

[speedtrapped]

So pat if gap is to wide and ambient temp very low, hence air denser and psi stronger?, the ECU won't throw codes? I am get misfire codes ......I am curious and my question should be a diff thread, But could aces be effecting my start up? I have only run 1.5 tanks of the aces, and I know brian said it may run funky in beginning? I am only curious and not suggesting BND fluids is to blame.

[V8weight]

I am in the middle of this process(literally). I will be gapping mine but forgot the torque requirement on the plugs. Anyone got the specs?

Torque spec for the plugs is 30Nm, or 22ft/lbs, or 264in/lbs.

[V8weight]

So pat if gap is to wide and ambient temp very low, hence air denser and psi stronger?, the ECU won't throw codes? I am get misfire codes ......I am curious and my question should be a diff thread, But could aces be effecting my start up? I have only run 1.5 tanks of the aces, and I know brian said it may run funky in beginning? I am only curious and not suggesting BND fluids is to blame.

I think that you are experiencing a large un-metered air leak myself. Re-gapping the plugs surely won't hurt, but you either have an air leak around your MAF sensors, or some kind of vacuum leak. Find a local shop with a smoke tester. Don't bother with the driveway mechanic pressure testing method, a proper smoke test should isolate a leak pretty quickly. Or, you still have a problem with the MAF sensors themselves, or the wiring. Good luck.

[speedtrapped]

Ty, I will have it smoke tested

[V8weight]

Done, and test driven. This was a relevant experiment. No more silly business on acceleration (though it didn't happen very often anyhow), just smooth gut wrenching acceleration. Have fun, going driving!

[JSRS6]

Ha! I just finished too! About to go driving as well. I regapped at .025.

[V8weight]

I set mine at .024", seems to have smoothed out not only the power band, but the idle as well. I'm thinking that anybody with a tune on their car should think about running a .024 gap, and maybe .028 for stock.

[V8weight]

There is a such thing as having your plugs gapped too tight. This is easily checked by connecting a vacuum gauge and monitoring it at idle. If the gap was too narrow, the gauge will fluctuate about 2 inches of vacuum. I checked mine and it's a steady 20 inches, no fluctuation. This is the only way I could think to check and make sure I hadn't gone too far.

[JSRS6]

It feels fine at idle now.

[JSRS6]

And the power does feel smoother.