Anyone experienced a loss in HP after downgapping the plugs?

[doughboy17]

I just replaced my stock gapped (.032) NGK plugs with 39K miles on them with the same plugs but gapped to .026 per EPL's recommendation for my Stage 2 tune (via 179mm crank pulley). The car feels considerably less responsive. I was absolutely surprised when I drove it because I expected zero difference.

Has anyone experienced this after downgapping plugs? Thanks for sharing your experiences and advice.

I realize emotions are running high after EPL's exit from the industry but respectfully request that replies made to this thread remain on topic.

[0mn1]

Did you buy from a reputable location? eBay and Amazon have been noted to sell fake plugs. I find that .026-. 028works beautiful for me. Never had a loss of power but be sure to torque them to spec and ensure the coil packs are firmly inserted.

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[doughboy17]

Did you buy from a reputable location? eBay and Amazon have been noted to sell fake plugs. I find that .026-. 028works beautiful for me. Never had a loss of power but be sure to torque them to spec and ensure the coil packs are firmly inserted.

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Thanks for the advice. These were from FCP Euro. Although I did use a torque wrench, I got nervous about the torque being applied and set it to - 2 lbs. off the recommendation. I inserted the coil packs after adding a bit of dielectric grease and am confident they are seated.

It does idle smoother. Could the lower torque spec. and dielectric grease cause such a decrease in power?

[BucDan]

Thanks for the advice. These were from FCP Euro. Although I did use a torque wrench, I got nervous about the torque being applied and set it to - 2 lbs. off the recommendation. I inserted the coil packs after adding a bit of dielectric grease and am confident they are seated.

It does idle smoother. Could the lower torque spec. and dielectric grease cause such a decrease in power?

No. Those won't make the decrease in power occur. 2lbs of torque is about only an extra 10 degree throw of the wrench short. That shouldn't affect anything at all.

I'm using the NGK Iridiums based off of APRs Stage 2 recommendation for my 034 stage 2+, stock gap, they've been installed before I went 034. Too lazy to gap down since it's been running ok.

[EvolutionArmory]

What did you gap them with and is it accurate?

Too small a gap won’t ignite the fuel properly worse than running a bigger gap.

If your car ran fine with your original gap there no need to run lower. You really should run the biggest gap your car/tune will allow you to run without misfires under heavy load for cleanest ignition.

Also, are you running the correct heat range for your state of tune?

[MSq5]

.026" is what EPL runs for stage 2. That's what I run with no problem. Either that or .028". No wider. Perhaps OP gapped them incorrectly.

There is an issue with .032" with higher boost than stock. If you gap them that open, they will run fine for a while. But as they wear, when the gap open to about .034-.035" you start getting boost spark blow-out. Stage 2 boost can actually blow out the spark at wide open throttle! Yes, its a thing. It will be an abrupt power cut under full throttle, bucking. When you let up on throttle and boost drops, power returns. Very distinctive sign of too wide a gap.

There are guys here with higher power levels than single pulley ratios running ethanol blends with gaps as small as .024".

Another thing OP: are those NGK plugs the proper heat range 8? At single pulley level 9s may be too cold. Are the the OEM type platinum tip or are they iridium fine wire. I run iridium now for longer plug life, but that tip is easily damaged with a gapping tool, so it should not be scraped or wedged against.

OP: can you log for misfires? Do you have a way to measure your 0-60 or 60-100 mph times? Sometimes butt dyno can be misloading. Smooth might seem slower when its actually quicker. You might not really be losing power.

I hate to ask you to pull them, but do. Inspect to see if any of them are improperly gapped, any sign of tip or insulator damage. If too tight use care to open then. If too tight use a tool with a pry arm to gently lift the electrode while not touching the tip or insulator. Avoid using the coin type gapping tool.

This is the correct NGK platinum plug:



Gapping:



This is for a Kia Optima, but the principle is the same. Just set at .026", no wider than .028. I use feeler gauges and just the adjustment arms on the gapper to gently pry as most of those don't give enough wire diameters. Often they go from .025" to .030". A feeler gauge set is dirt cheep and will not harm the tip. If too open, I tap the electrode strap on a block of wood.

[BucDan]

.026" is what EPL runs for stage 2. That's what I run with no problem. Either that or .028". No wider. Perhaps OP gapped them incorrectly.

There is an issue with .032" with higher boost than stock. If you gap them that open, they will run fine for a while. But as they wear, when the gap open to about .034-.035" you start getting boost spark blow-out. Stage 2 boost can actually blow out the spark at wide open throttle! Yes, its a thing. It will be an abrupt power cut under full throttle, bucking. When you let up on throttle and boost drops, power returns. Very distinctive sign of too wide a gap.

There are guys here with higher power levels than single pulley ratios running ethanol blends with gaps as small as .024".

Another thing OP: are those NGK plugs the proper heat range 8? At single pulley level 9s may be too cold. Are the the OEM type platinum tip or are they iridium fine wire. I run iridium now for longer plug life, but that tip is easily damaged with a gapping tool, so it should not be scraped or wedged against.

OP: can you log for misfires? Do you have a way to measure your 0-60 or 60-100 mph times? Sometimes butt dyno can be misloading. Smooth might seem slower when its actually quicker. You might not really be losing power.

I hate to ask you to pull them, but do. Inspect to see if any of them are improperly gapped, any sign of tip or insulator damage. If too tight use care to open then. If too tight use a tool with a pry arm to gently lift the electrode while not touching the tip or insulator. Avoid using the coin type gapping tool.

This is the correct NGK platinum plug:



Gapping:



This is for a Kia Optima, but the principle is the same. Just set at .026", no wider than .028. I use feeler gauges and just the adjustment arms on the gapper to gently pry as most of those don't give enough wire diameters. Often they go from .025" to .030". A feeler gauge set is dirt cheep and will not harm the tip. If too open, I tap the electrode strap on a block of wood.

The gap reliability is usually a concern primarily for WOT as you stated right? I was running 034 Stage 1 tune on .032" stock NGK Iridiums with dual pulley, no WOT ever, just a test drive for a few weeks, but it drove ok.

Maybe I need to go WOT to see if I get that spark blow out you're talking about.

[EvolutionArmory]

Why are you running dual pulley on stage 1 software?

Trying to diagnose something with conflicting software and hardware is much harder than when the software matches the hardware.


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[BucDan]

Why are you running dual pulley on stage 1 software?

Trying to diagnose something with conflicting software and hardware is much harder than when the software matches the hardware.


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Currently I am not. Currently on their Stage 2+ tune as a daily.

Tested their Stage 1 CARB tune for smog purposes here in CA, works just fine for that purpose. Not intended for daily, just enough to get the readiness ok and smog done when the time comes.

But concerning MSQ5's post, I meant running the stock NGK gap iridum on Stage 2+ at WOT as a test. Because APR never said anything about gapping for their stage 2 software when I was running it for a bit, granted I only did spirited driving, no launches or heavy WOT.

[EvolutionArmory]

Are you running the colder plugs with the stage 1 tune? Maybe you need to switch back to stock 8 heat range plugs for smog too?

APR’s stage 2 dual pulley is meant for 9 heat range plugs gapped to .026.

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[BucDan]

Are you running the colder plugs with the stage 1 tune? Maybe you need to switch back to stock 8 heat range plugs for smog too?

APR’s stage 2 dual pulley is meant for 9 heat range plugs gapped to .026.

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Yes. I ran and smogged with ngk heat 9 plugs on APR stage 1 after 20K miles. Worked fine and passed, this was back circa 2020. Then I went EPL Stage 2 with pullies, same plugs but new, no gap, worked fine. Then I went 034 Stage 1 CARB, no gap, same spec plugs, worked fine, for 2k miles or so. Now I'm on 034 Stage 2+ no gap, running ok. I will test the WOT theory that MSQ5 spoke of.

Sorry, long winded, but I've been on a dumb journey. I know I won't get the advertised results, but if I can get 95% without having to pull plugs every 2 years to re-gap or change plugs for the tune, I'll be happy for my purposes. Maybe a gap to .30" or .28" heat 9 plugs will work for stage 1 as well, idk, but I'm not there yet to test that. I don't do WOT through every gear, just spirited driving for freeway on ramps and pulling.

[MSq5]

Currently I am not. Currently on their Stage 2+ tune as a daily.

Tested their Stage 1 CARB tune for smog purposes here in CA, works just fine for that purpose. Not intended for daily, just enough to get the readiness ok and smog done when the time comes.

But concerning MSQ5's post, I meant running the stock NGK gap iridum on Stage 2+ at WOT as a test. Because APR never said anything about gapping for their stage 2 software when I was running it for a bit, granted I only did spirited driving, no launches or heavy WOT.

The timing tables and fueling for dual pulley tunes are all wrong for a stage 1 map. I'd not want to go WOT at all.

As to your DP tune, APR will have a preferred plug and gap. Follow their advice.

[BucDan]

The timing tables and fueling for dual pulley tunes are all wrong for a stage 1 map. I'd not want to go WOT at all.

As to your DP tune, APR will have a preferred plug and gap. Follow their advice.

I thought boost bleed off compensates for it anyway? I mean, I never had an issue in regular driving.

[EvolutionArmory]

I thought boost bleed off compensates for it anyway? I mean, I never had an issue in regular driving.

It’s bleeding off boost but still asking for dual pulley fuel and timing. So the ECU is pulling all of those things to compensate for you spinning the supercharger up too fast.

It’s more than just boost. Not that simple. It is a bad idea to run such a high pulley ratio on a stage 1 tune.


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[BucDan]

It’s bleeding off boost but still asking for dual pulley fuel and timing. So the ECU is pulling all of those things to compensate for you spinning the supercharger up too fast.

It’s more than just boost. Not that simple. It is a bad idea to run such a high pulley ratio on a stage 1 tune.


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Duly noted. I just never heard someone having actually cause an issue before doing that. But hey, if it can go long enough for the computers to set in ready state for smog with easy driving after a week or so, that's good enough for me.

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[MSq5]

Duly noted. I just never heard someone having actually cause an issue before doing that. But hey, if it can go long enough for the computers to set in ready state for smog with easy driving after a week or so, that's good enough for me.

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Because the fuel and timing tables will be wrong, be very careful. While the bypass valve can blow off the extra boost, you might feel safe, but that's a false hope. The ECU will be asking for less fuel with a stage 1 tune loaded. But, the supercharger will be needing more because it is spinning faster.

The ECU will try to compensate to maintain a proper air-to-fuel ratio by richening up the mixture. There is a fuel trim range that it can operate in. You may max out what the ECU can command. I'd be afraid of a lean out. In theory, if that happens it would lead to detonation. Detonation can severely damage an engine.

There are safety protocols the ECU would try to execute - pulling timing if it senses detonation, maybe cutting fuel or spark completely making the car buck and jerk, un-drivable. Maybe execute a limp mode. Maybe not. Risky.

If you stay out of the throttle you might get by. Very risky. It just does not seem a good plan for a DP car.

I'd at least put the stock crank pulley and belt back on for what ever time period you try this. Only takes 45 minutes to an hour for the swap and the mismatch would be far less.

[BucDan]

Because the fuel and timing tables will be wrong, be very careful. While the bypass valve can blow off the extra boost, you might feel safe, but that's a false hope. The ECU will be asking for less fuel with a stage 1 tune loaded. But, the supercharger will be needing more because it is spinning faster.

The ECU will try to compensate to maintain a proper air-to-fuel ratio by richening up the mixture. There is a fuel trim range that it can operate in. You may max out what the ECU can command. I'd be afraid of a lean out. In theory, if that happens it would lead to detonation. Detonation can severely damage an engine.

There are safety protocols the ECU would try to execute - pulling timing if it senses detonation, maybe cutting fuel or spark completely making the car buck and jerk, un-drivable. Maybe execute a limp mode. Maybe not. Risky.

If you stay out of the throttle you might get by. Very risky. It just does not seem a good plan for a DP car.

I'd at least put the stock crank pulley and belt back on for what ever time period you try this. Only takes 45 minutes to an hour for the swap and the mismatch would be far less.

Hmmm... Interesting. I'll remember that. The car didn't feel weird when I was testing the Stage 1 tune for a few weeks with DP hardware. Granted, I wasn't really ever on the throttle. The more insight the better! Thanks!

[doughboy17]

What did you gap them with and is it accurate?

Too small a gap won’t ignite the fuel properly worse than running a bigger gap.

If your car ran fine with your original gap there no need to run lower. You really should run the biggest gap your car/tune will allow you to run without misfires under heavy load for cleanest ignition.

Also, are you running the correct heat range for your state of tune?

I am using the OEM NGK plugs gapped to .026 (per EPL's advice) using a feeler gauge. I tried to be very careful when gapping them. I thought it ran quite well with the stock gap.

.026" is what EPL runs for stage 2. That's what I run with no problem. Either that or .028". No wider. Perhaps OP gapped them incorrectly.

There is an issue with .032" with higher boost than stock. If you gap them that open, they will run fine for a while. But as they wear, when the gap open to about .034-.035" you start getting boost spark blow-out. Stage 2 boost can actually blow out the spark at wide open throttle! Yes, its a thing. It will be an abrupt power cut under full throttle, bucking. When you let up on throttle and boost drops, power returns. Very distinctive sign of too wide a gap.

There are guys here with higher power levels than single pulley ratios running ethanol blends with gaps as small as .024".

Another thing OP: are those NGK plugs the proper heat range 8? At single pulley level 9s may be too cold. Are the the or are they iridium fine wire. I run iridium now for longer plug life, but that tip is easily damaged with a gapping tool, so it should not be scraped or wedged against.

OP: can you log for misfires? Do you have a way to measure your 0-60 or 60-100 mph times? Sometimes butt dyno can be misloading. Smooth might seem slower when its actually quicker. You might not really be losing power.

I hate to ask you to pull them, but do. Inspect to see if any of them are improperly gapped, any sign of tip or insulator damage. If too tight use care to open then. If too tight use a tool with a pry arm to gently lift the electrode while not touching the tip or insulator. Avoid using the coin type gapping tool.

This is the correct NGK platinum plug:



Gapping:



This is for a Kia Optima, but the principle is the same. Just set at .026", no wider than .028. I use feeler gauges and just the adjustment arms on the gapper to gently pry as most of those don't give enough wire diameters. Often they go from .025" to .030". A feeler gauge set is dirt cheep and will not harm the tip. If too open, I tap the electrode strap on a block of wood.

The plugs are OEM type platinum tip. I am really trying not to pull them, if possible. Unfortunately, my ability to log misfires is limited. The most annoying part is there seems to be a pause (I hesitate to say bog) when you first apply the throttle below 1500 rpms. That was never there before.

I appreciate everyone's feedback.

[01northernS4]

I am using the OEM NGK plugs gapped to .026 (per EPL's advice) using a feeler gauge. I tried to be very careful when gapping them. I thought it ran quite well with the stock gap.




The plugs are OEM type platinum tip. I am really trying not to pull them, if possible. Unfortunately, my ability to log misfires is limited. The most annoying part is there seems to be a pause (I hesitate to say bog) when you first apply the throttle below 1500 rpms. That was never there before.

I'm in the same boat with unitronic stage 3... feels like a bog/pause when I first apply the throttle... same thing new plugs gapped down but ran pretty good iirc at stock gap .32 before I changed...

the hesitation/bog bothers me but I run a decent 0to60 of 3.5sec w/1 ft roll out w/launch control...

don't really feel like going back to stock plugs and gap... unless it can eliminate the bog/pause under 1500rpm when first applying throttle... thoughts?

[EvolutionArmory]

Duly noted. I just never heard someone having actually cause an issue before doing that. But hey, if it can go long enough for the computers to set in ready state for smog with easy driving after a week or so, that's good enough for me.

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I would never run dual pulleys on a stage 1 tune but I get what you’re trying to do and why.

A stage 1 tune might have enough flexibility to adjust to a lower single pulley but not dual pulley.

I think something like a mild 179mm lower pulley would be fun on a stage 1 tune. Just a little more low end torque but probably still safe enough for the safety monitors.

The hoops you guys gotta jump through for smog sucks


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[EvolutionArmory]

I'm in the same boat with unitronic stage 3... feels like a bog/pause when I first apply the throttle... same thing new plugs gapped down but ran pretty good iirc at stock gap .32 before I changed...

the hesitation/bog bothers me but I run a decent 0to60 of 3.5sec w/1 ft roll out w/launch control...

don't really feel like going back to stock plugs and gap... unless it can eliminate the bog/pause under 1500rpm when first applying throttle... thoughts?

Is that really a decent 0-60 for dual pulley with 1 foot roll out? I can get that with APR’s stage 1 pretty regularly. With launch control though, not without.

If you’re not cutting low 3 second dual pulley 0-60’s something ain’t working. Especially with 1 foot roll out. Maybe it’s the tune, maybe it’s tires, not sure about your set up.


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[doughboy17]

I'm in the same boat with unitronic stage 3... feels like a bog/pause when I first apply the throttle... same thing new plugs gapped down but ran pretty good iirc at stock gap .32 before I changed...

the hesitation/bog bothers me but I run a decent 0to60 of 3.5sec w/1 ft roll out w/launch control...

don't really feel like going back to stock plugs and gap... unless it can eliminate the bog/pause under 1500rpm when first applying throttle... thoughts?

Just to confirm, are you saying you ran stock gapped plugs on Uni Stage 3 beforehand and then noticed the bog/pause after downgapping?

Although something else could have gone wrong, I just think the plug gap and new plugs is the only thing I changed. If I knew a .032 gap would bring back the prior acceleration/ behavior, I would have to consider changing the plugs back.

[Midnight_Rider]

usually it means the spark plugs are fouled. I'd do a visual inspection of the plugs to make sure it's not fouled.

[01northernS4]

Is that really a decent 0-60 for dual pulley with 1 foot roll out? I can get that with APR’s stage 1 pretty regularly. With launch control though, not without.

If you’re not cutting low 3 second dual pulley 0-60’s something ain’t working. Especially with 1 foot roll out. Maybe it’s the tune, maybe it’s tires, not sure about your set up.


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I agree... have to figure it out... logs look good... fooled around with the tire pressures... I feel a little bog/hesitation off the line which is why I posted here... that's probably it...

[01northernS4]

Just to confirm, are you saying you ran stock gapped plugs on Uni Stage 3 beforehand and then noticed the bog/pause after downgapping?

Although something else could have gone wrong, I just think the plug gap and new plugs is the only thing I changed. If I knew a .032 gap would bring back the prior acceleration/ behavior, I would have to consider changing the plugs back.

Yes and this is what I will be exploring next... I do believe the new plugs and smaller gap exasperated an existing pause/bog... definitely didn't help... but as with yourself I found the car to be much smoother and possibly more top end power?... I will investigate when time presents itself. I guess it's all a balance.

[01northernS4]

usually it means the spark plugs are fouled. I'd do a visual inspection of the plugs to make sure it's not fouled.

agreed and will do... I think I should be in the low 3's on dual pulley 0 to 60 and hopefully this is the issue or gap, etc...

[Izzyz28]

There's some smart folks in here so I'll ask. I moved from sea level to 7,000 feet last year, so my DP car now produces 12 PSI instead of 18-20. Would it behoove me in any way(increased timing, whatever) to knock my DP tune down to Stage 1 or Stage 2? Car runs great, but if it can take a bunch more timing, why not? I would like to think the ECU has optimized timing at 12 pounds, 15 pounds, 18 pounds, 22 pounds, etc....., but who knows what the guys at 034 did when the maps were created.

[Thugmeet]

There's some smart folks in here so I'll ask. I moved from sea level to 7,000 feet last year, so my DP car now produces 12 PSI instead of 18-20. Would it behoove me in any way(increased timing, whatever) to knock my DP tune down to Stage 1 or Stage 2? Car runs great, but if it can take a bunch more timing, why not? I would like to think the ECU has optimized timing at 12 pounds, 15 pounds, 18 pounds, 22 pounds, etc....., but who knows what the guys at 034 did when the maps were created.

You’re better off switching to a higher pr ratio and your car will never be as fast as it was at sea level. Superchargers don’t do as well as turbos at elevation

[RoofRails]

There's some smart folks in here so I'll ask. I moved from sea level to 7,000 feet last year, so my DP car now produces 12 PSI instead of 18-20. Would it behoove me in any way(increased timing, whatever) to knock my DP tune down to Stage 1 or Stage 2? Car runs great, but if it can take a bunch more timing, why not? I would like to think the ECU has optimized timing at 12 pounds, 15 pounds, 18 pounds, 22 pounds, etc....., but who knows what the guys at 034 did when the maps were created.

You will not be better off downgrading your tune. If you want to get some of that lost power back you could raise your pulley ratio or port your blower. I'm not sure where all the talk about timing maps came from in this thread but on a tuned ECU peak timing target is based on the fuel / octane of the file you have loaded up and not the stage / boost. At least that's what I have seen looking at a bunch of logs. A STG 1 E40 file will target a peak timing advance of 30 degrees and a STG2 + targets the same peak timing. It adjusts in real time based on the feedback it's getting from the various sensors. A custom tuner may try to dial in a few more degrees of peak timing on a file running less boost but that's not how these OTS tunes do it. They have to build in a layer of safety so the tune works safely where you are at 7000ft and where I'm at sea level in a -3000 DA (boost season).

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[EvolutionArmory]

If you’re at 7000 feet no matter what you do your car is going to be way slower than you were used to before you moved.

There’s not really anything you can do about it except accept it.


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