Multiple Misfires without an engine light!

[Jerrouss]

Hello,

Are there any techs out there?

Which originally I thought it was bad gas, after two weeks with it not stopping I hooked up my cheap scanner to being shocked with a reading of multiple misfires at high rpm’s. The engine starts fine and idles fine. Then when I go to pass a vehicle on the highway or when the RPM reaches 4.5 up it starts stuttering but has not popped an engine light. The spark plugs are new from last summer. Can the ignition coils all give a misfire.
Thank you in advance,

 

[edmaz]

Vehicle year, engine, mileage? Is the CEL on, or is your scan tool just showing a pending P0300 or individual cylinder misfire codes? I'm not aware of any current Mazda techs posting here, except for very infrequent drop-ins every once in a while.

 

[Silly Wabbit]

OEM plugs?

 

[Jerrouss]

2016.5 GT TECH with 175 k’s extremely well taken care of.

 

[Jmaz]

Maybe injectors starved for fuel. Partially plugged fuel filter?

 

[Jerrouss]

**UPDATE**

I thought to try putting my old stock spark plugs back in & BOOM that’s what the problem was! My one year old spark plugs failed

 

[Jmaz]

**UPDATE**

I thought to try putting my old stock spark plugs back in & BOOM that’s what the problem was! My one year old spark plugs failed

What brand and model number plugs were problematic at 1 year old?

 

[edmaz]

NGK LASER IRIDIUM

It's highly unusual for 1 of these NGK plugs to fail, and more than 1 going bad is off the charts. I replaced the NGKs on the 2019 a bit late at 80K, and also replaced a set of NGK LI on a KIA at the spec 100K. Every one of those 8 plugs looked like they could have run for another 100K, and there was never a hiccup before or after the swaps. There just aren't very many reports of NGK plugs failing.

Is there any visible damage to any of the replacement plugs? Did you do a resistance test on the replacements and the factory plugs? In any case, I'd be willing to place a hefty bet that NGK would want to take a look at those plugs that you bought and would send you a free replacement set as well.

 

[Koko_Bandit]

where did you buy the new plugs? Unfortunately, there are several online 'vendors' selling counterfeit parts.

 

[yrwei52]

NGK LASER IRIDIUM

The NGK equivalent for OEM PE5R-18-110 is NGK Laser Iridium spark plug ILKAR7L11 / 94124.

CX-5 NGK spark plugs 14mm or 9/16 and torque?

If the gap of your ILKAR7L11 plugs is in 1.05—1.15 mm {0.0414—0.0452 in}, and the resistance is in 3.0 ~ 7.5 KΩ range, I’d agree with @Koko_Bandit, you may havd got counterfeit plugs. You can contact NGK USA and I believe they can help you to verify if your NGK plugs are counterfeit or not.

 

[edmaz]

.... Two of the spark plug tips were red & the other two were normal. ...

Ok, I'll have to retract what I wrote about NGK sending you replacement plugs. Red coloration on the tips means something is going on with the fuel system - either some iron-based additive is being used, or there's rust or iron in the fuel system. IMO you should try to figure out what the specific fuel issue with your vehicle is.

 

[Kedis82ZE8]

Wonder what fuel additive got in there to foul out those plugs?

 

[yrwei52]

Wonder what fuel additive got in there to foul out those plugs?

Well, if the fuel used by OP is questionable, it should do the same to the 175K-mile (or km?) old stock spark plugs which were replaced a year ago and now put them back. We’ll see.

 

[Kedis82ZE8]

If it does end up being simply counterfeit plugs that caused this issue… it just reinforces my personal need to continue with OEM parts and the added parts expense…still a cheaper option doing the work yourself


Even up to 10 years ago I used to entertain eBay and Amazon parts without blinking an eye and then started to see the trends.

IMO: If you do stray from OEM parts then only purchase from authorized resellers

 

[Jerrouss]

It's highly unusual for 1 of these NGK plugs to fail, and more than 1 going bad is off the charts. I replaced the NGKs on the 2019 a bit late at 80K, and also replaced a set of NGK LI on a KIA at the spec 100K. Every one of those 8 plugs looked like they could have run for another 100K, and there was never a hiccup before or after the swaps. There just aren't very many reports of NGK plugs failing.

Is there any visible damage to any of the replacement plugs? Did you do a resistance test on the replacements and the factory plugs? In any case, I'd be willing to place a hefty bet that NGK would want to take a look at those plugs that you bought and would send you a free replacement set as well.

I’m just going to put new OEM Plugs from now on

Ok, I'll have to retract what I wrote about NGK sending you replacement plugs. Red coloration on the tips means something is going on with the fuel system - either some iron-based additive is being used, or there's rust or iron in the fuel system. IMO you should try to figure out what the specific fuel issue with your vehicle is.

two plugs were red and two were normal

 

[Jerrouss]

If it does end up being simply counterfeit plugs that caused this issue… it just reinforces my personal need to continue with OEM parts and the added parts expense…still a cheaper option doing the work yourself


Even up to 10 years ago I used to entertain eBay and Amazon parts without blinking an eye and then started to see the trends.

IMO: If you do stray from OEM parts then only purchase from authorized resellers

They were not counterfeit, it came from Parts Avatar, it’s Canada’s version of Rock Auto

 

[MichalP]

They were not counterfeit, it came from Parts Avatar, it’s Canada’s version of Rock Auto

I have been following this topic and just today I started the new thread but your situation got me worried a little. Here in Canada I just checked Canadian Tire and I found the same spark plugs from NGK. I noticed that on Parts Avatar they are listed under NGK Canada and the clerk at Canadian Tire also told me that they are made in Canada however when he brought me the set of 4 to check, they were manufactured in Thailand. They are significantly cheaper than the one from Mazda dealer (CT - $22, Mazda dealer - $51). It is almost too good to be true. I would like to save money but really don't have time to deal with any complications.

 

[Kedis82ZE8]

I don’t purchase from Rock Auto either.. I’l leave it there

 

[edmaz]

.....
two plugs were red and two were normal

So because 2 of the plugs weren't red, you don't believe there's a problem with iron or rust in the fuel?

 

[Jerrouss]

I have been following this topic and just today I started the new thread but your situation got me worried a little. Here in Canada I just checked Canadian Tire and I found the same spark plugs from NGK. I noticed that on Parts Avatar they are listed under NGK Canada and the clerk at Canadian Tire also told me that they are made in Canada however when he brought me the set of 4 to check, they were manufactured in Thailand. They are significantly cheaper than the one from Mazda dealer (CT - $22, Mazda dealer - $51). It is almost too good to be true. I would like to save money but really don't have time to deal with any complications.

I just went to Mazda and spent $200.00 for my new spark plugs I went and test drove it and it does appear more responsive & peppier ZOOMZOOM RULES

I hope that this helps people that need new spark plugs, strictly buy OEM from MAZDA & it says on the box, Made in Japan