Reading Spark Plugs While Tuning? 2024 CX-5 Turbo

[AL Cx5]

I'm working with DRT tuning our '24 CX 5 Turbo. I understand, DRT is an accomplished tuner. I have confidence in his tune for upping the power a bit for our DD CX-5.

I've been "reading" spark plugs on drag racing motors to confirm the O2 sensors AFR, timing, knock and heat range. We compare this to our O2 AFRs, timing and such. We have an EGT per cylinder to compare as well. We can tune each cylinder fuel and timing independently. We have picked up 20 to 30 HP at WOT changing heat range, gape along with fuel and timing. After melting holes in a new set of pistons, relying on O2 sensors, we confirm by reading plugs.

I'm considering putting a set of new plugs in the 2.5l T in a parking lot. Make a WOT 2nd through 3rd, cut the ignition, coast to the shoulder and pull the plugs. Install the originals. Then photograph the test plugs and read them in the shop. Then I'll have a base line for a healthy engine and confirm if AFR/Timing/Heat Range are happy with the tune. Four plugs seems like a piece of cake compared to changing 16 plugs in the race motor!

Each cylinder gets a different amount of air through the intake manifold. The exhaust back pressure is different on each "hole" as well. Injectors input fuel slight differently as well. On a DD tune, this should not be critical but could yield some info for the tuner.

I'd be interested to know if others have done this exercise and what they found. Each engine, fuel and spark plug combo have a different plug signature. I'd like to compare my test to another.

Thanks

https://honda-tech.com/forums/forced-induction-16/***-basics-reading-spark-plug***-3063102/

 

[skid00skid0]

In the '70's and '80's, I did it on two-strokes...

You won't be able to account for lean at part-throttle, or specific rev ranges, though.

 

[AL Cx5]

In the '70's and '80's, I did it on two-strokes...

You won't be able to account for lean at part-throttle, or specific rev ranges, though.

Agreed. It's a snap shot when the ignition is turned off. Partial throttle is less likely to melt a piston or have sever KR vs. Wot.

It can confirm if that cylinder is lean or rich and timing vs what is commanded.

This info works hand in glove to cofirm the logged values. And since we get an average afr it would be nice to have another reference.

 

[sm1ke]

I haven't done this, and as far as I can recall I haven't seen anyone else do this either (on these forums, at least). Maybe if you can provide a step-by-step procedure of what needs to be done, someone nearing their spark plug replacement interval can run through the exercise and post the results?

Make a WOT 2nd through 3rd, cut the ignition, coast to the shoulder and pull the plugs. Install the originals.

It sounds simple and straightforward enough, but are there any other factors to note? Use 91+ only? OEM plugs only? Etc.

 

[AL Cx5]

I haven't done this, and as far as I can recall I haven't seen anyone else do this either (on these forums, at least). Maybe if you can provide a step-by-step procedure of what needs to be done, someone nearing their spark plug replacement interval can run through the exercise and post the results?



It sounds simple and straightforward enough, but are there any other factors to note? Use 91+ only? OEM plugs only? Etc.

It's straight forward. I will use the fuel that I'm tuning to. The hardest part is dealing with a hot plug. I have pliers, gloves and rags for this step.

Another point of interest, as the engine management sensors age, they don't send the Ecu correct info. I've tuned around old sensors that was a waste of time and money.

As an example, as the O2 sensors age they read lean so the Ecu adds more fuel and it runs rich. We think all is well because we trust the electronics.

A $25 plug is a cheap way to cross check the above. Our O2 is reading an average of 4 cylinders. It doesn't give any indication of if it has the correct timing and plug heat range. Power maybe available with this simple test.

I change out engine management sensors on my gas burners at a 100K. It's like doing a major tune up. My gas mileage increases 2 MPG and it's way more fun to drive. There is a pay back to have fresh sensors.

Note: only buy Mazda or Denso/NTK from a trusted source. There are a lot of counterfeits floating around.

I run with the fuel the tuner and I agreed to use. In my case we tune with 93 octane.

 

[AL Cx5]

I made a WOT pull today with a new spark plug today. Ran out to +5000 rpm in second and lifted. I don't have enough open road to run out 3rd and avoid getting a ticket.

This is my first test and I've already learned more about these 2.5l. I'm convinced there is power to be gained on our 2.5l buy reading plugs, changing gap and maybe plug heat range.

First, on WOT pull doesn't get enough heat in the plug. Next test I'll make 2 pulls back to back.

Second, our ignition will not turn off while rolling. I slipped the trans into neutral. I don't think it impacted results.

Third, these 14mm plugs are fragile. I cracked the ceramic on the OEM plug putting it back in the engine on the side of the road. I need to own a magnetic 14mm spark plug socket....

What I learned. My tuner is tuning way on the safe side so as not to burn a piston. Or I'll see if I can run one heat range hotter. SO we are a good deal of power on the table. I would like to see the ground strap have a line in the middle to lower part of the bend. This is still a safe tune. This could be 20 to 30 HP, min. On my race engine, one degree of timing is 30 HP. So it's a big deal to get safely get the most timing possible.

My Mazda respected tuner is flying blind without seeing a spark plug to confirm if the engine needs more or less timing. Same goes with air to fuel ratio. SO he errors on the safe side. I appreciate that! AND, I have a tuner work around if he disagrees...

The next test, I'll make two WPT Pulls back to back and get more heat in the plug. I'll cut this plug down to confirm air to fuel ratio.

Here is a video from Steve Morris, who is one of, if not the, most respected engine builders around. What I like about Steve he doesn't sugar coat his opinions.

https://www.youtube.com/watch?v=MecCoercp-s

 

[skid00skid0]

"changing gap and maybe plug heat range."

NO.

Unless the gap is so small or so large that ignition doesn't happen, there will be negligible change to power.

Plug heat range ONLY controls how hot the center electrode gets. You have to keep it hot enough that combustion deposits don't accumulate, and not so hot that pre-ignition occurs. Power won't be affected at all.

 

[AL Cx5]

"changing gap and maybe plug heat range."

NO.

Unless the gap is so small or so large that ignition doesn't happen, there will be negligible change to power.

Plug heat range ONLY controls how hot the center electrode gets. You have to keep it hot enough that combustion deposits don't accumulate, and not so hot that pre-ignition occurs. Power won't be affected at all.

In drag racing gap and heat range impact HP. Reading the porcelain is invaluable if the fueling is correct. This applies to DDs as well. There is a range between deposits and pre ignition, knock retard, that is optimum.

Most manufacturers error on the safe side so their engines will live in a wide range of conditions.

We run standalone ecus racing that are lightening fast and are way more feature rich than a DD ecu. We run 2 up to 8 O2 sensors, 1 to 8 egt sensors, dome pressure sensors and such. Still we read spark plugs and fuss with gap and heat range. Our engines make north of a 1000 HP and those that look for 30 HP gain with the right gap or other means win races.

An extreme example, when we changed to burning methanol, we had to close the gap or the engine would brake up above 6000 rpm.

We rented a chassis dyno and closed the gap up to 20 thou, made a pull. Opened up to 25 thousands, engine ran smooth but lost 30 HP. We run at 20 thousands and make more power than our competitors. We did the same tests with air to fuel ratio. We found out what the engine liked. We knew the correct heat range going in from previous tests.

We have invested in high energy coil packs. It takes 16, 1 per plug. This will allow us to open the plug gap and make more power.

Did simular tests with e85 before we went to 100% methanol. A change in gap was saw 15 HPgain. Getting the right heat range was another 15 HP.

Finding the right gap and heat range for the engine combo makes more power. Same goes for timing and afr.

In the how to read spark plug video, Steve Morris talked about gap, timing, heat range and fueling. He assumed the viewer knew that getting each one of these right makes more power.

Looking at my Mazda plug with 5k on it, it's running too cool. The base ring is not discolored. I'll try one heat range hotter and read that plug.

If you have any A to B tests you have run on your 2.5 t or na, please share and save me some time.

I will come up with a safe way to test on the street at WOT and partial throttle. I'm not invested in the outcome. No gain fine. I'll have fun and learn something trying.

I'm willing to try something new and may fail.

 

[Antoine]

Just a friendly reminder for everyone...Please remember to keep it friendly, civil, informative and On Topic (at all times and throughout the entire site).

Thank you.

 

[N7turbo]

Looking at my Mazda plug with 5k on it, it's running to cool. The base ring is not discolored. I'll try one heat range hotter and read that plug.

Interested in your findings to optimize these engines.

 

[skid00skid0]

In drag racing gap and heat range impact HP.

Motor Trend's Engine Masters show dyno runs proved that is not true.

You ~might~ make the claim that a larger gap results in a larger flame kernel, which will ignite the entire charge earlier. But that falls under having the correct ignition timing...

I know for a fact that a 1976 Honda Civic ~started~ MUCH easier with a huge gap, powered by what I think was called an Accel Super Coil.

What is your logic that a slightly hotter or colder center electrode produces more power? Please tell me that you DON'T think the spark plug's heat range controls the combstion/engine temp!!!

We rented a chassis dyno and closed the gap up to 20 thou, made a pull. Opened up to 25 thousands, engine ran smooth but lost 30 HP. We run at 20 thousands and make more power than our competitors. We did the same tests with air to fuel ratio. We found out what the engine liked. We knew the correct heat range going in from previous tests.

We have invested in high energy coil packs. It takes 16, 1 per plug. This will allow us to open the plug gap and make more power.

Did simular tests with e85 before we went to 100% methanol. A change in gap was saw 15 HPgain. Getting the right heat range was another 15 HP.

OK, I should have read further. You are talking about ~misfires~ due to too small/large a gap. Very high compression, and maybe crappy/old/abused plug wires, and a tired/shorted out coil. And a V8 engine with poor mixing of air and fuel, and who knows how the head flowed into the combustion chamber.

Running pure methanol, it won't start to burn as easily as gasoline. But that has nothing to do with a CX-5.

 

[AL Cx5]

Motor Trend's Engine Masters show dyno runs proved that is not true.

You ~might~ make the claim that a larger gap results in a larger flame kernel, which will ignite the entire charge earlier. But that falls under having the correct ignition timing...

I know for a fact that a 1976 Honda Civic ~started~ MUCH easier with a huge gap, powered by what I think was called an Accel Super Coil.

What is your logic that a slightly hotter or colder center electrode produces more power? Please tell me that you DON'T think the spark plug's heat range controls the combstion/engine temp!!!



OK, I should have read further. You are talking about ~misfires~ due to too small/large a gap. Very high compression, and maybe crappy/old/abused plug wires, and a tired/shorted out coil. And a V8 engine with poor mixing of air and fuel, and who knows how the head flowed into the combustion chamber.

Running pure methanol, it won't start to burn as easily as gasoline. But that has nothing to do with a CX-5.

The referenced na V8 had COP ignition. It made 2 hp/ci displacement. It has state of the art EFI, far better than DD ecus. It holds the Gen3 Hemi NA record.

Before racing off to Google, 2.0 cu/ci is just a stout na race engine. The complete package resulted in record setting 1/4 time. Inline with Engine Masters engines.

Our 2.5l na make 1.63 hp\ci. This about average for a street engine. Fwiw, less efficient at WOT than a 392 ci old tech, push rod Hemi.

I still like and respect this little engine as a DD. I was surprised with high cr it didn't make more hp/ci.

With out a misfire the v8 gained power by changing the gap. We were at max timing and not willing to chance melting the pistons. Alcohols, E85 and methanol have a wide tuning window but once past it, there is little to no warning. Resulting in catastrophic failure. Been there, once is enough.

Quoting from a Motor Trend is fine. Motor Trend has never won an Engine Masters completion. The folks who won know way more about plug heat range and gap. If I followed Motor Trend reports my engines would be like the reset of the herd. Fun but not cutting edge. Real world results can be found on forums like Yellow Bullet. This forum doesn't protect the feelings or ban folks for calling one out. They eat up and spit out keyboard experts daily.

I'm fortunate to be personal friends with the tuner and engine builder who have won several Engine Masters competitions. Every detail is considered including spark plug gap and heat range.

In the spirit of this forum, I respectfully reframe from discussing this with keyboard experts who quote from generic sources. I encourage these type to lift there hands off the keyboard and turn a few wrenches before quoting run of the mill sources with an attitude. Looking forward reading personal results.

Back to topic:

Reading the Mazda plugs suggest 1 step hotter heat range. I can't find this plug so HR is off the table.

I have a second set of plugs ordered and will try a couple different gap settings. If Mazda got it right, WONDERFUL. I'll know. With the general attitude on the forum, I'm not inclined to report.

The biggest take away so far, my 2.4l engine can take more timing and make more power. One would NEVER know looking at data logs from a computer.

Pic of 429 Hemi making +2 hp/ci and 1.4 second 0 to 60 mph car it powers.

 

[sm1ke]

One more reminder for everyone..

The forum doesn't issue warnings or ban for disagreements, debates, or healthy back and forth discussion. All that is asked of you, as a community, is to keep it friendly and be civil.

If the conversation degrades to petty comments, veiled insults, personal attacks, etc., mods may get involved. But we're all adults with the ability to self-moderate. Let's keep it positive!

If you have an opposing opinion, or if you want to present some data that conflicts with what is being posted, please do so respectfully.

 

[AL Cx5]

One more reminder for everyone..

The forum doesn't issue warnings or ban for disagreements, debates, or healthy back and forth discussion. All that is asked of you, as a community, is to keep it friendly and be civil.

If the conversation degrades to petty comments, veiled insults, personal attacks, etc., mods may get involved. But we're all adults with the ability to self-moderate. Let's keep it positive!

If you have an opposing opinion, or if you want to present some data that conflicts with what is being posted, please do so respectfully.

Thank you @sm1ke

I know that I'm at fault. Just for me, reporting petty comments, veiled insults and personal attacks feels like tattling. I'm doing my best to push back on perceived judgmental comments without enlisting Moderator support within in the guidelines of this forum.

If I have offended sid00sid0, I apologize.

Before I get banned, I'm cutting way back on posting on this fine forum. I appreciate many of the tech articles and have learn so much about my CX 5.

I'll find another place folks are more open to testing and exploring moving our platform to another level.

Cheers!!

 

[sm1ke]

Thank you @sm1ke

I know that I'm at fault. Just for me, reporting petty comments, veiled insults and personal attacks feels like tattling. I'm doing my best to push back on perceived judgmental comments without enlisting Moderator support within in the guidelines of this forum.

If I have offended sid00sid0, I apologize.

Before I get banned, I'm cutting way back on posting on this fine forum. I appreciate many of the tech articles and have learn so much about my CX 5.

I'll find another place folks are more open to testing and exploring moving our platform to another level.

Cheers!!

I'll say it again @AL Cx5, you're not doing anything wrong, and you don't need to be worried about getting banned. Nobody needs to worry about that at this point. Typically we give users plenty of leeway, and only issue warnings when things really start to spiral. Bans are usually only issued after multiple official warnings.

I can assure you that sharing information is what this forum is all about. I hope you won't let a couple of less-than-ideal interactions sour your experience here.

 

[N7turbo]

Before I get banned, I'm cutting way back on posting on this fine forum. I appreciate many of the tech articles and have learn so much about my CX 5.

I think you're misinterpreting. I don't think you're under fire. But I hope I can speak for many that info on how to optimize these engines is interesting reading.

 

[AL Cx5]

I'll say it again @AL Cx5, you're not doing anything wrong, and you don't need to be worried about getting banned. Nobody needs to worry about that at this point. Typically we give users plenty of leeway, and only issue warnings when things really start to spiral. Bans are usually only issued after multiple official warnings.

I can assure you that sharing information is what this forum is all about. I hope you won't let a couple of less-than-ideal interactions sour your experience here.

I'm not use to so much interaction with Moderators. You guys take your job seriously.

On other social media pages, I can handle myself with some less than ideal types. On this forum, I'm not clear what is considered civil, encouraging and friendly.

I value many of the posts on Mazdas247, and follow "take what I need and leave the rest" attitude.

As a moderator on a racing page, guys are a hands on group. Keyboard opinions and judgements are pushed aside very quickly.

I appreciate not everyone is turning wrenches, data logging tests or interested in this stuff.

It's frustrating and constraining for me, being encouraging, civil and friendly, around self proclaimed experts quoting stuff they Googled and never done the work.

I'm looking for the GIFT dealing with these less than ideal interactions. "Teachers" bring it on!!

I think you're misinterpreting. I don't think you're under fire. But I hope I can speak for many that info on how to optimize these engines is interesting reading.

Thank you @N7turbo. I interpreted "everyone" posted by a moderator just below my post pertaining to myself. Like I've step over a forum boundary. I never have interacted so much with Moderators in the past and interpreted this as I'm about ready to get the boot.

I'm a bit of "fish out of water" here. I feel a need to defend ideas and concepts that have worked on other platforms and work on CX 5s. Pass on methods that help none wrencher/racers improve their rides...

I find it amusing for awhile dealing with finely crafted "NO THAT WON'T WORK" comments.

This is not unlike some other forums I have chosen to leave. It was fun for awhile to banter with closed minded, judgmental folks ON THESE FORUMS. Then it wasn't and I left.

 

[skid00skid0]

"With the general attitude on the forum, I'm not inclined to report."

Just because you and I disagree, isn't cause for this...

I was building engines in 1975. A lot of what you are suggesting was already debunked then. I would have just come out and said that, but then you mentioned methanol. I don't know meth. Haha.

There certainly are things I need to learn. And I'm willing to. I hope to also learn from YOU.

I think your last post was quite out of line. Maybe you are having a bad day. I have MORE than my share, and I apologize when I see I went over the line.

 

[N7turbo]

I'm no stranger to engines. Like the Legos I grew up with, I took apart and put back together the mystery small block Chevy in my high school car, then drove it to school. All because I wanted to view the engine block code and measure the bore and stroke. Turns out it was a 283 block from a Chevy Nova with a 327 crank, making it a Frankenstein 307ci.

Then I was active during the LS1 F-Body days.

Now I just want to get the most out of my daily driver, the car I've determined to be the best for my needs & wants. What really intrigues me is the potential to get 400 lb feet of torque out of these engines, the same as my LS1.