1-2 misfires on 2014 CX-5 2.5L - Should I be worried?

[weitau]

I have a 2014 CX-5 2.5L with 158k miles. All four of the cylinders appear to have a handful of misfires (live data in pic below).
One of the coils is bad. There is a DTC: "P2311:00-2F Secondary Circuit Of Ignition Coil D". It also looks like it was a replacement coil, as it looks different than the other 3.

The misfires were present when I bought the car. I just replaced the spark plugs with Denso 3532 aka ZC20HPR11 today, and still get these minor misfires.

The defective coil I will replace but does anyone have experience with aftermarket coils? I would replace the other 3 coils as well, but NGK's are $85 each.

I assume the gas in the tank is regular unleaded, and the intake valves have never been cleaned. The condition of the fuel injectors is unknown. The engine appears to be healthy otherwise. Steady idle and decent acceleration with no hiccups. The onboard computer showed 24 mpg overall in mixed city/highway driving in suburban Connecticut when I bought the car.

Should I be concerned with just a handful of misfires that don't appear to increase as I'm driving?
Maybe it's something related to engine startup and it goes away?

 

[weitau]

I'm suspecting carbon buildup in the intake manifold, given my high miles. This video also explains why cold engines has higher chance of misfires.

Tsi cold misfires explained

In this video i explain why a tsi engine with carbon build up has cold misfires.For business inquiries; Diagnosedan@gmail.com (not for technical questions)

youtu.be

Based on this theory, I don't need a new set of coils, but I should focus on cleaning out the carbon.

 

[madar]

Try a bottle of Techron fuel injector cleaner, maybe with a tank of Mobil or Shell super unleaded, do the easy stuff first. Dirty injectors might be doing this and the Mazda ones have a rather elaborate spray pattern.

 

[Lazy2.5]

try the fuel system cleaner.

dont worry about the intake valves.

change those ignition coils. be sure to replace spark plugs while you're in there.

 

[yrwei52]

I have a 2014 CX-5 2.5L with 158k miles. All four of the cylinders appear to have a handful of misfires (live data in pic below).
One of the coils is bad. There is a DTC: "P2311:00-2F Secondary Circuit Of Ignition Coil D". It also looks like it was a replacement coil, as it looks different than the other 3.

The misfires were present when I bought the car. I just replaced the spark plugs with Denso 3532 aka ZC20HPR11 today, and still get these minor misfires.

The defective coil I will replace the defective coil (any suggested brands?). I would replace the other 3 coils as well, but NGK's are $85 each.

I assume the gas is regular unleaded, and the intake valves have never been cleaned. The condition of the fuel injectors is unknown. The engine appears to be healthy otherwise. Steady idle and decent acceleration with no hiccups. The onboard computer showed 24 mpg overall in mixed city/highway driving in suburban Connecticut when I bought the car.

Should I be concerned with just a handful of misfires that don't appear to increase as I'm driving?
Maybe it's something related to engine startup and it goes away?




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Is your 2014 CX-5 a 2.0L or 2.5L?

OEM PE5R-18-110 (NGK ILKAR7L11 / 94124) or PE5S-18-110 (Denso ZC20HPR11 / 3532) spark plugs can’t be $85 each but it’s about $35 each. You can get aftermarket NGK equivalent plugs for about $15 each. Search the forum.

Honestly using Denso ZC20HPR11 / 3532 plugs should be fine and can’t be your problem of misfire unless you got counterfeit plugs.

You should replace the questionable aftermarket ignition coil first with an OEM coil. IMO cleaning the intake valves should be done at 158K miles with something like CRC GDI IVD Intake Valve & Turbo Cleaner. Or better to take the intake manifold down and clean the valves.

Well, fuel system is seperate. Valve build up issues is more of a vacuum/pcv system factor. You should be using a head cleaner sprayed into a vacuum line and in the fresh air hose attachment on the intake/airbox hose (past the MAF). It's easy enough to do and can be done before an oil change. Importantly when used in the vac lines it's good for cleaning the pcv valve and the vacuum pump.

CRC gdi valve cleaner is what I like to use because it doesnt stall the engine, therefore it can be done by 1 person. A cheap fuel system cleaner is HeeT with fuel injector cleaner.. or if you want good s*** that will clean into the cat, G2P (guaranteed to pass) but it's like $10. But fuel additives *do not* clean valves on a direct injection engine

 

[acidbug]

Best off taking the coil packs from Cylinder three and four, and moving them to banks one and two. Move coil packs 1 & 2 and moving them to cylinder 3 & 4 (basically swapping them). This way you can see if the problem follows the coil pack or not. This will save you money on purchasing new coil packs if they’re not needed. Secondly, as others have mentioned, while you’re in there, it might be wise to pull the plugs, and at the very least check the gaps, making sure they’re gaped properly and look good.

Whatever you do, don’t cheap out on the coil packs. Stick with the NGK’s as that’s what this engine is designed for and using the cheaper ones may cause performance loss and or check engine lines/miss-fires/etc down the road.

For replacement parts I use rockauto and their prices are competitive versus Mazda Dealer Parts Department/other places.

 

[TotalMazda1]

Rule out a head gasket leak. Amazon has a color change tube inserted into the radiator neck. Recently had a misfire code on a high mileage toyota... Tried plugs , coils....ended up being a head gasket leak..... just enough to affect coolant level slightly and show up as bubbles in the radiator coolant Good luck.

 

[weitau]

Thanks for all the replies! I didn't get any notifications, will need to check my settings.

 

[weitau]

Is your 2014 CX-5 a 2.0L or 2.5L?

OEM PE5R-18-110 (NGK ILKAR7L11 / 94124) or PE5S-18-110 (Denso ZC20HPR11 / 3532) spark plugs can’t be $85 each but it’s about $35 each. You can get aftermarket NGK equivalent plugs for about $15 each. Search the forum.

Honestly using Denso ZC20HPR11 / 3532 plugs should be fine and can’t be your problem of misfire unless you got counterfeit plugs.

You should replace the questionable aftermarket ignition coil first with an OEM coil. IMO cleaning the intake valves should be done at 158K miles with something like CRC GDI IVD Intake Valve & Turbo Cleaner. Or better to take the intake manifold down and clean the valves.

$85 per plug would be outrageous indeed! I was talking about NGK coils for $85 each at Rock Auto. This is what I settled on, after trying $40 coils (a set of 4) from eBay.

 

[weitau]

Best off taking the coil packs from Cylinder three and four, and moving them to banks one and two. Move coil packs 1 & 2 and moving them to cylinder 3 & 4 (basically swapping them). This way you can see if the problem follows the coil pack or not. This will save you money on purchasing new coil packs if they’re not needed. Secondly, as others have mentioned, while you’re in there, it might be wise to pull the plugs, and at the very least check the gaps, making sure they’re gaped properly and look good.

Whatever you do, don’t cheap out on the coil packs. Stick with the NGK’s as that’s what this engine is designed for and using the cheaper ones may cause performance loss and or check engine lines/miss-fires/etc down the road.

For replacement parts I use rockauto and their prices are competitive versus Mazda Dealer Parts Department/other places.

Yes, that's exactly what I did. Swapped the coils. Used my scan tool and saw the error code move to the new cylinder. I settled on a single NGK coil, and it fixed the DTC code I was getting.
I don't think the OEM coils are NGKs (read this somewhere else - and CX5 coils seem to be problem as supplied by the factory). But the misfire problem still exists on all cylinders, even on the cylinder with the new NGK coil.

Rock Auto rocks! Autozone wanted over $100 for a Duralast.. go figure.

 

[weitau]

Rule out a head gasket leak. Amazon has a color change tube inserted into the radiator neck. Recently had a misfire code on a high mileage toyota... Tried plugs , coils....ended up being a head gasket leak..... just enough to affect coolant level slightly and show up as bubbles in the radiator coolant Good luck.

I had Camry with 226k miles. It had a small head gasket leak, which was "fixed" with a silicon head gasket sealer. Worked nearly instantly. Sorry to hear about your troubles!

 

[weitau]

Try a bottle of Techron fuel injector cleaner, maybe with a tank of Mobil or Shell super unleaded, do the easy stuff first. Dirty injectors might be doing this and the Mazda ones have a rather elaborate spray pattern.

I used both octane booster and Supertech gas treatment. At the same time. Only one misfire at startup, but that's probably because the additives did not make it to the engine yet

Coming from working with turbo motors, high compression engines need high octane gas. Mazda did an amazing job getting 14:1 compression on regular unleaded, but with carbon building on the intake, I suspect this caused a lean condition. The ECU is adding the right amount of fuel, but it doesn't realize that not all the fuel is making it to the combustion cylinder.

 

[weitau]

It was 76 degrees in NYC yesterday. It was do the carbon clean up today or wait until spring. Started at 2:30PM and finished at 2AM. Yeah, I'm crazy, but I'm working outside, and it was going to rain the next day.

There was a lot of carbon in the intake side of the head. Took 4 soaks/brush cycles with Berryman B-12 to get 90% of it off valves and 100% off the ports. I also cleaned the ports on the intake manifold. Cleaned the throttle body as well since I had it off.

The results were well worth it! The accelleration and noticeably quicker based on the butt-dyno. Gas mileage most likely better too. I have to wait until the next gas fill up to know whether it's my octane boost/gas treatment or the carbon cleanup that eliminated the misfires. Nevertheless I highly recommend a carbon cleanup, especially if you get a reputable shop to do it.

 

[TotalMazda1]

I had Camry with 226k miles. It had a small head gasket leak, which was "fixed" with a silicon head gasket sealer. Worked nearly instantly. Sorry to hear about your troubles!

A friend's Toyota Matrix had a slight diagnosed head gasket leak , we attempted the Bars HG-HG1 head gasket sealer and as of about 1.5 months ago.....the stuff seems to be working. So far so good. Based on the original poster's post below, looks like its no head gasket leak.

 

[weitau]

A friend's Toyota Matrix had a slight diagnosed head gasket leak , we attempted the Bars HG-HG1 head gasket sealer and as of about 1.5 months ago.....the stuff seems to be working. So far so good. Based on the original poster's post below, looks like its no head gasket leak.

Bars has a few different HG sealers. I used this one. $28 at Walmart and I used only half. I need to find another car with a hg problem to use the other half. LoL

 

[TotalMazda1]

Bars has a few different HG sealers. I used this one. $28 at Walmart and I used only half. I need to find another car with a hg problem to use the other half. LoL

And, what was the result and how long has it been effective or ineffective and how bad was the leak prior to adding the sealer?

 

[weitau]

The hg leak wasn't that bad, but there was some white smoke even after the engine was warmed up. No milkshake coolant, oil looked fine. But the O2 sensor was shot, and the cat probably wasn't too far behind. I drove it for a month or two before plans changed & someone made me an offer I could not turn down

 

[madar]

I used both octane booster and Supertech gas treatment. At the same time. Only one misfire at startup, but that's probably because the additives did not make it to the engine yet

Coming from working with turbo motors, high compression engines need high octane gas. Mazda did an amazing job getting 14:1 compression on regular unleaded, but with carbon building on the intake, I suspect this caused a lean condition. The ECU is adding the right amount of fuel, but it doesn't realize that not all the fuel is making it to the combustion cylinder.

Yeah, I agree with that. I run mainly 89 with occasionally 93 mixed in there especially in the warmer, drier times of the year. 87 is ok, but the higher octanes do it justice, and over time and many miles the problems start to show up.

 

[weitau]

To follow up, I got a P0421 DTC immediately after completing the carbon cleanup. I had to crank the engine for a few minutes before it slowly came back to life. I'm guessing I left too much Berryman B-12 in the intake manifold, and perhaps some seeped into the combustion cylinder. I've since driven to 100 miles and changed the oil today.

Before I start changing the O2 sensors, I'll try the Scotty Kilmer laquer thinner trick. Dump 1 gallon LT per 10 gallons gas and drive at highway speeds for 150 miles or rev at 2500 RPM for 30 min.

Before my oil change, I also still have some occasional misfires, but a Ford Focus website said 1 misfire per 1000 RPMs is not bad. On the way back from buying LT from Home Depot, I had zero. Go figure.

 

[TotalMazda1]

To follow up, I got a P0421 DTC immediately after completing the carbon cleanup. I had to crank the engine for a few minutes before it slowly came back to life. I'm guessing I left too much Berryman B-12 in the intake manifold, and perhaps some seeped into the combustion cylinder. I've since driven to 100 miles and changed the oil today.

Before I start changing the O2 sensors, I'll try the Scotty Kilmer laquer thinner trick. Dump 1 gallon LT per 10 gallons gas and drive at highway speeds for 150 miles or rev at 2500 RPM for 30 min.

Before my oil change, I also still have some occasional misfires, but a Ford Focus website said 1 misfire per 1000 RPMs is not bad. On the way back from buying LT from Home Depot, I had zero. Go figure.EW

What are the options to have someone else do the intake / exhaust valves professionally cleaned, like w walnut shells blown into the valves area? What would the fee be at a dealer or shop?