2013~2016 13 GT Cold and Low RPM Misfire

13 GT Cold and Low RPM Misfire

I bought my 13GT about 2 years ago and have a long highway commute so its at about 122k miles now. With about 60k on it, one of the coils failed completely- replaced it and all four plugs and no more issues. At about 115k, I started noticing an inconsistent shake at low RPM under heavy load (which occurs a lot during my commute). Recently, I began noticing that it inconsistently sounded rough during a cold start up as well, and last week it began throwing P0300 and P0303 codes. Knowing the issues I had in the past, I tried to diagnose and ended up replacing the plugs and the coil pack- no dice. Since it only occurs when the engine is cold and warming up or under heavy load at low RPM (aka running rich), my next thought is fuel. My code scanner is a little cheap one that wont give live info, so its hard for me to prove injectors vs fuel pump, etc.. The other thing that came to mind is I recently replaced my exhaust mid pipe due to a progressing exhaust leak. I dont hear a leak from the header, but I also cant see it since its covered in heat shields- anyone have any experience with a failed 2.0 exhaust manifold? How about a fuel pump or injector? I feel like I need more information from the car to truly diagnose- anyone have a code reader that does good freeze frame/live data that theyd recommend for reasonable money?

Sorry for the long post, trying to make sure I didnt miss anything. Thanks in advance for any advice.
 

rsvinylgraphics

2008.5 MGM MS3
Contributor
:
2008.5 MS3
P0303 is misfire on cylinder 3, since you say the plug and coil packs are good it is likely a dirty or faulty fuel injector.

You could try swapping the cylinder 3 fuel injector to a different cylinder and if the code follows, it will tell you the fuel injector was the issue.
 

Chris_Top_Her

Banned
Moderator
Contributor
:
San Antonio, Texas
:
'15 CX-5 Miata AWD
Possibly bad plugs.. failing coils at 60k kinda odd, possibly driving habit or cheap gas/plugs. Try a quality fuel cleaner or at least look at the plug condition (bad plugs can mess up coil). P0300 is random misfire. Workshop manual has plug/coil as the big cause, lists specific sensor signals as possible cause. PM me an email address I'll send you a copy and you can see the ecu detection conditions along with factory remedies for your reference
 
:
13' CX-5 and 16' Mazda6 both Touring w/Tech/Bose
Had a similar code/s on my Mazda6. I forgot to seat my oil dipstick in all the way and I was low in oil (Error on my part during an oil change). Added oil and seated dipstick correctly. Codes never came back.

FYI Check if your air filter housing is closed and sealed correctly.
 

madar

Contributor
:
2016.5 CX 5 Touring AWD, 2015 SCION XB
P0303 is misfire on cylinder 3, since you say the plug and coil packs are good it is likely a dirty or faulty fuel injector.

You could try swapping the cylinder 3 fuel injector to a different cylinder and if the code follows, it will tell you the fuel injector was the issue.
I've had this. A good injector cleaner (Techron) cured it. Cheapest and easiest thing you could try.
 
:
2014 Mazda CX-5 GT AWD w/Tech
Try cleaning the mass Airflow Sensor too. Not sure it's the same on the 2.0 as the 2.5, but early 2.5 MAFs had some issues the cleaning didn't help. The part was upgraded to a new part number. Don't know what the changes were but it solved the small driveability issue I was having with my 2014 2.5.
 
Updates thus far- ran a couple bottles of injector cleaner- no dice. Got a better code reader that will output graphs and stuff and thought I saw something in the MAF, so I cleaned it and no change. Have a new MAF coming but I dont think thats it. The code reader shows how many misfires on each cylinder since start (which I found yesterday). All have 0 except 3, which varies but tends to be about 5 per minute on average. If the MAF doesnt fix it (and Im thinking it wont), Im going to order a full set of injectors, seals, etc. and hit that next... well see.
Nice spot on the plugs- mine are Mazda from the dealership.
 
Last edited:
Problem not solved yet, but boy do I have a good story to go along with this.

I began looking for ways to troubleshoot since its intermittent and noticed that my computer and a number of other things specified California. Then, i saw the emissions warranty and since I had parts specified California I figured I'd ask if i was PZEV. Shenanigans ensued. Note that name is changed and VIN covered to protect the rep and myself.

Agent: Thank you for contacting Mazda Customer Experience Center, my name is Agent. How may I help you?
Joel : Hi Agent, Just wanted to check if my car is PZEV or not- can you look that up for me via VIN?
Agent: Hi Joel, I'd be happy to help with this! In case we get disconnected, can I email you at email Also at the end of our Chat I will have a reference number I can email to you as well.
Joel : that would be great.
Agent: I sure can, whats the VIN?
Joel : J-------------------------------------------
Joel : I cant tell if its a zero or an O in the vin, hopefully you know
Agent: Joel the vehicle is not a PZEV vehicle it is a federal emissions vehicle. Any other questions I can help with? The letter O is not used in VIN numbers only the number 0 FYI.
Joel : Alright, thanks for the clarification. I didnt realize there were California emissions vehicles that werent PZEV- I thought that was a legal requirement.
Agent: There are, and your vehicle is not a CA emissions vehicle either.
Joel : Thats interesting. My PCM is a California version and the hood shows a California ULEV II LDT certification for emissions.
Joel : If my vehicle isnt a California emissions vehicle why does the emissions certification show a Cal cert?
Agent: Hmmm, I do believe MA is a CA compliant state, I wonder if the vehicle was originally sold in a different state?
Joel : I know the original owner was in New Hampshire, but I dont see how that would change the California emissions certification.
Joel : Regardless, if the vehicle isnt PZEV then the point is moot. Certainly a bit frustrating but moot.
Agent: It was in NH which is not an CA emissions state. The vehicle may have been made compliant with CA standards when sold in MA but warranty wise and in Mazda's system it shows as a Federal emissions vehicle.
Agent: I apologize to deliver the unfavorable news.
Agent: The states that have adopted the California standards are: Colorado, Connecticut, Delaware, Maine, Maryland, Massachusetts, New Jersey, New Mexico (2011 model year and later), New York, Oregon, Pennsylvania, Rhode Island, Vermont, and Washington, as well as the District of Columbia
Joel : Okay, so that just adds more confusion to me. I dont understand how if the vehicle is manufactured in the same way with the same parts that depending upon where it was originally sold is whether you honor the warranty.
Joel : The vehicle still needs to pass emissions in Massachusetts regardless of where it was originally sold. It seems odd that if i purchased the exact vehicle in Mass then moved to NH that the warranty would apply but since i went the other way it doesn't.
Joel : or is that irrelevant to the 150k emissions warrant?
Joel : ty
Agent: not all parts and vehicles are the same. essentially the vehicle was not intended to be sold in the CA emissions state so the vehicle was not equipped with the CA emissions equipment. The CA emissions and PZEV are very limited in scope.
Joel : But thats not true- the vehicle has a california emissions certification on the hood.
Agent: CA and PZEV warranties are limited on scope.
Joel : if it doesnt have the california emissions equipment then how did it get the certification?
Joel : They are, but per the warranty booklet that came with the car it includes all of the parts that i can imagine would contribute to the problem i am having.
Agent: It could have been brought up to spec, in your state. I know when vehicles come to CA they have to go through testing and brought up to code, otherwise the vehicle cannot be registered in CA. I can only assume it is the same in your state
Agent: that may be why you have the sticker, the vehicle was brought up to code to pass your state laws.
Joel : I would expect not- but wouldnt Mazda have records of performing that sort of work?
Joel : if the car was sold in NH and that was the residence of the last owner I dont understand why they would upgrade the emissions system.
Agent: We may or May not, if the work was done at a dealer we would if it was done (we have STAR stations here for specific emission testing) at a 3rd party no. I understand your thought, I would not know either, It is also possible the level of emissions was within tolerance and passed the inspection. I truly cannot say for sure, this is just speculation as we don't have all the facts. We have a big gap in the service records 45947 miles to 120540 (last month).
Joel : I purchased the vehicle with about 50k miles on it and due to the miles you can see I drive I do not use the local dealer due to cost. I know I havent upgraded the emissions system, so your theory is that either a station did emissions testing and put a Mazda motor corporation vehicle emission control information sticker on my car without Mazda knowing or that the same thing happened between 45947 miles and when i purchased it with about 50k?
Joel : Does Mazda allow other vendors to put Mazda brand stickers for emissions compliance on their vehicles?
Joel : I hope you understand that this sounds far fetched at best to a customer.
Joel : If i could, I would send you a picture of the sticker I am talking about to clarify- but i dont see how to do that in this messenger
Agent: can you take a photo of the sticker for me? At can understand your point of view, even more interesting is the last service I see at a Mazda dealer was at Naples Mazda in FL, Emissions stickers can be purchased at a parts counter, body shops do this all the time, hypothetically someone could have done this outside Mazda. I wonder if the vehicle was ever in an accident? I will send you an email to reply to with a photo.
Agent has disconnected.
The story that he concocted to explain why it doesn't qualify but has the sticker is hilarious, and then the time between the last message and him disconnecting was under 5 seconds.

Unfortunately if this is the type of "standing behind our product" I can expect with Mazda then this will be my last one, which is a shame because other than this intermittent issue I really like the car. It just sucks that all the parts are expensive and at least the injectors are going to be a pain to get to (behind the dynamic resonance chamber), but I can deal with stuff like that if I feel like I'm not getting stiffed. This just seems like a really easy way to avoid warranty costs and make customers unhappy.
 
Last edited:

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
:
Plano, Texas, USA
13 GT Cold and Low RPM Misfire

Updates thus far- ran a couple bottles of injector cleaner- no dice. Got a better code reader that will output graphs and stuff and thought I saw something in the MAF, so I cleaned it and no change. Have a new MAF coming but I dont think thats it. ⋯
I believe your intermittent misfire problem with P0303 code is electrical. I feel the same that the new MAF wont resolve the issue for you. Id try the easy and simple way again starting with spark plugs. Get some cheaper but correct NGK plugs and replace your OEM ones from Mazda. In the mean time check the part number on your old OEM plugs and see if theyre the right ones.

P0303 Cylinder 3 Issue

If the coil pack for cylinder #3 has never been replaced, try to swap it with the one which you replaced before.

Then check the condition of the ignition cables; replace them if necessary.

Fuel injectors? IMO highly unlikely and too much work (and cost)!

BTW, which parts the California 150K-mile emission warranty covers? Spark plugs? Coil pack? MFA? Or fuel injectors?
 
Ill start at the end- the 150k warranty covers PZEV vehicles sold in certain states, and includes all emissions affected system including injectors, PCM, coils, etc. with the exception of spark plugs. If you check your warranty booklet with the cars manual, it should be in there.
The coil pack on cylinder 3 has been swapped and replaced. No change to speak of.
All 4 spark plugs have been replaced with Mazda plugs.
When you say ignition wires, are you taking about the wires that go from the PCM to the coil or the coil to the spark plug? The coil to plug wire is included with a new coil is why I ask.
The reason I am at injectors is because Ive run out of electrical ideas- I suppose it could be a bad PCM but beyond that there isnt much electrical to look at.
 
Another piece of potentially relevant information- when warm, the fuel trims at low loads (STFT+LTFT) are power than at high loads. Typical low load will be about 7%, whereas high load varies between 10.5-12.5%. Note that its high load- pretty much doesnt care about RPM, its more related to the engine load.
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
:
Plano, Texas, USA
13 GT Cold and Low RPM Misfire

Ill start at the end- the 150k warranty covers PZEV vehicles sold in certain states, and includes all emissions affected system including injectors, PCM, coils, etc. with the exception of spark plugs. If you check your warranty booklet with the cars manual, it should be in there.
The coil pack on cylinder 3 has been swapped and replaced. No change to speak of.
All 4 spark plugs have been replaced with Mazda plugs.
When you say ignition wires, are you taking about the wires that go from the PCM to the coil or the coil to the spark plug? The coil to plug wire is included with a new coil is why I ask.
The reason I am at injectors is because Ive run out of electrical ideas- I suppose it could be a bad PCM but beyond that there isnt much electrical to look at.
So you had swapped coil pack and spark plug on cylinder #3 with another cylinder? And the spark plug and coil pack are new for cylinder #3 now? I guess you can re-check the part numbers on both coil pack and spark plugs you replaced making sure they're correct. And you can check the gap of spark plugs to see if they're within specs. If not, I'd try to adjust the gap carefully although it's not recommended. Checking ignition wires / cables that I did mean checking the wires and connectors from PCM to coil pack making sure there's no loose or bad connections. Finally, check the grounding of the coil pack itself to cylinder head. Hope you can find something from all of these tedious work of checking.

Per 2.0 liter out of the service manual, can't imagine why it wouldn't hold true for 2.5 liter:

2013 - CX-5 - Engine
SPARK PLUG INSPECTION [SKYACTIV-G 2.0]
Specification
Spark plug type
PE01-18-110, PE02-18-110, PE5R-18-110, PE5S-18-110
Plug Gap Inspection
CAUTION:
1. To avoid possible damage to the tip, do not adjust the plug gap.
2. To prevent damaging the tip, use a wire type plug gap gauge when inspecting the plug
gap.
1. Measure the spark plug gap using a wire type plug gap gauge.
1. If not within the standard specification, replace the spark plug.
Spark plug gap (PE01-18-110, PE02-18-110)
Standard: 0.751.10 mm {0.0300.043 in}
New spark plug (reference): 0.750.85 mm {0.0300.033 in}
Spark plug gap (PE5R-18-110, PE5S-18-110)
Standard: 1.051.40 mm {0.04140.0551 in}
New spark plug (reference): 1.051.15 mm {0.04140.0452 in}
This holds true for these plugs as well. DO NOT USE A ROUND COIN STYLE GAPPING TOOL

There is an iridium pad attached to the underside of the ground electrode. Using the wrong method, or the wrong gapping tool can disturb or destroy the iridium / platinum pad.

ah, all good points, I'm used to the old style coin types, those are bad as mazdadude points out, the wire type as shown in video seems to work better, no actually contact with the sensitive parts of the spark plug..... still think it's a good idea just to double checked they're gapped right per OEM spec just for peace of mind....

https://www.mazdas247.com/forum/showthread.php?123852711-Spark-plug-replacement-surprise

 
So you had swapped coil pack and spark plug on cylinder #3 with another cylinder? And the spark plug and coil pack are new for cylinder #3 now? I guess you can re-check the part numbers on both coil pack and spark plugs you replaced making sure they're correct. And you can check the gap of spark plugs to see if they're within specs. If not, I'd try to adjust the gap carefully although it's not recommended. Checking ignition wires / cables that I did mean checking the wires and connectors from PCM to coil pack making sure there's no loose or bad connections. Finally, check the grounding of the coil pack itself to cylinder head. Hope you can find something from all of these tedious work of checking.
Yes, coil pack and plug replaced, then swapped with working cylinder- no dice. After the swap I moved the coil pack back to where it was. I pulled the #3 spark plug and checked the gap with feelers- just a bit over 0.040 inches (which I believe is in spec for the PE5R-18110s I have installed). I didn't check the other plugs gaps.
As far as the ignition wires- since all of the wires are encased chasing them will be a tough one, but I'll check all I can. Also, in the wiring diagram the ground wires look fairly accessible, hoping that's the case.
 
Problem solved. Injector 3 looked nearly completely plugged upon removal. Replaced it and car runs like a top. Definitely some carbon build up in the intake runners and the head but not terrible, and a couple of pieces of buildup on the intake valves as well. Probably look into sea foam or something like it sometime soon. Thanks for the advice guys.
 
Top