2019 CX-5 2.5T Misfire

[GTEyes]

It took my dealer a few tries to figure it out.
Just an FYI, the dealer who replaced my engine said they had a CX9 with a similar issue and they ended up replacing that engine, too. That was a year or so ago...so Mazda is aware of these issues whether or not they are doing anything about preventing it is another story. My engine replacement was well over $5k not including the rental I had for weeks while they diagnosed and replaced engine.

 

[FrozenApple]

It took my dealer a few tries to figure it out.
Just an FYI, the dealer who replaced my engine said they had a CX9 with a similar issue and they ended up replacing that engine, too. That was a year or so ago...so Mazda is aware of these issues whether or not they are doing anything about preventing it is another story. My engine replacement was well over $5k not including the rental I had for weeks while they diagnosed and replaced engine.

For sure, a brand new long block is easily $10k or more, especially if you engine was already at 100k i would say its absolutely worth it.

 

[yrwei52]

haha of course, let the "factory trained" technician do their job right? Im just a nobody who loves cars and have too much time.

Actually there’re a few good master mechanics in some Mazda dealerships. I have talked to a master mechanic at my Mazda dealer after a “factory trained" technician screwed up half of the 10 jobs during the last visit for warranty service. The guy seemed very nice and very knowledgeable. He overruled the technician’s opinion and performed a TSB for EPB dragging issue which requires a pair of new revised rear calipers with new rotors and pads. Even better, he did it by himself after I asked. That’s why I have no problems to ask my dealer to do some major work, as long as it’s under warranty (free) !

 

[FrozenApple]

It took my dealer a few tries to figure it out.
Just an FYI, the dealer who replaced my engine said they had a CX9 with a similar issue and they ended up replacing that engine, too. That was a year or so ago...so Mazda is aware of these issues whether or not they are doing anything about preventing it is another story. My engine replacement was well over $5k not including the rental I had for weeks while they diagnosed and replaced engine.

oh really? so these 2.5T does have some problems then, the cx9 had this engine since 2016, i guess most people wont go to forum to post and stuff. Well maybe this time they will look into it further, i would laugh if they tell me they ordered coils and plugs for it

 

[FrozenApple]

Actually there’re a few good master mechanics in some Mazda dealerships. I have talked to a master mechanic at my Mazda dealer after a “factory trained" technician screwed up half of the 10 jobs during the last visit for warranty service. The guy seemed very nice and very knowledgeable. He overruled the technician’s opinion and performed a TSB for EPB dragging issue which requires a pair of new revised rear calipers with new rotors and pads. Even better, he did it by himself after I asked. That’s why I have no problems to ask my dealer to do some major work, as long as it’s under warranty (free) !

That is very nice of him, keep in mind tho, dealership is a flat rate world, the more cars they can bang out the better pay, so they tend not to go into details, and the thing is warranty time usually blows and techs has to go out of their way to diagnose a problem sometimes.

A good dealership would want to fix it right the first time, dealerships rating is based on surveys and if the technician can solve the problem and fix them the first time.

 

[yrwei52]

That is very nice of him, keep in mind tho, dealership is a flat rate world, the more cars they can bang out the better pay, so they tend not to go into details, and the thing is warranty time usually blows and techs has to go out of their way to diagnose a problem sometimes.

A good dealership would want to fix it right the first time, dealerships rating is based on surveys and if the technician can solve the problem and fix them the first time.

Like you said, most “factory trained” technicians suck! But dealers do have hard time to find young people who are interest in doing car service nowadays. It usually makes your hands dirty, and they’d much prefer to stay in an air-conditioned room typing the keyboard!

 

[AVC]

I'd imagine they don't want to do an engine swap at warranty rates, if the P0303 was possibly caused by something less serious. Or to pull the plugs and do a compression test at warranty rates, when they have plenty of $59.95 oil changes and $400 per axle brake pad slaps that need to be done.

 

[youri]

Interesting thread, lower compression in one cylinder is strange, but wouldn’t necessarily cause misfires. I’d be interesting to see what are the specs for the engine, and what are the correct compression values for the engine are. If anyone has acces to the service manual it might be worth a look. Tons of good info in there.

I also think the 2.5T can run on an atkinson cycle ( lower compression ratio by keeping the intake valve open longer during the compression cycle). Not sure when and how often it does, but wondering if this could be the culprit in this case ( very unlikely but food for tought).

Edit: the reason i say that i think it can be run on an Atkinson cycle is because the last time i had access to the service manual it contained the definition and description of an Atkinson cycle engine, but i couldn’t find more. Definitions are rarely explained if they are not relevant to the car referenced, but didn’t find anymore info.

 

[AVC]

Reading tech literature, they do run Atkinson, but seems to be at light throttle cruising, where reduced compression and wide throttle angles reduce pumping losses. At idle, it's all typical; low throttle angle, high vacuum. And yes, with a low contributing cylinder, idle miss and especially rough idle in D o R is common. What threw most of us is the very low mileage, which nudges you towards plug/coil or fuel delivery for the P0303.

 

[youri]

Thanks for the atkinson cycle confirmation. Very interesting thread and hopefully we get decent information back from mazda.

 

[MyFirstMazda]

I wonder, if you poured some oil in that cylinder if the compression would go up, to help identify the cause of the lost compression. Maybe the valves aren't sealing? Head gasket issue? Having cylinder/piston ring failure at such a low mileage doesn't leave one with a good feeling.

 

[CX5Nut]

Hey Op.....You mentioned you had to take the hitch off the car. Have you been pulling heavy loads? Can pulling a load damage an engine?

 

[bluegrass]

I Plasti dipped the oem rim, looks pretty good if u ask me.

Why would you do all of these modifications on a leased vehicle?

 

[FrozenApple]

Hey Op.....You mentioned you had to take the hitch off the car. Have you been pulling heavy loads? Can pulling a load damage an engine?

Initially plan was to pull a droplet trailer but since covid 19 hit plan was cancelled so no, never towed anything. Also i doubt the engine will be damaged if u exceed tow rating, i woulf say the transmission would suffer abit

 

[FrozenApple]

Why would you do all of these modifications on a leased vehicle?

Honestly wanted to buy out the car in the end, so i took care of the vehicle, installed and did everything i wanted

 

[FrozenApple]

I wonder, if you poured some oil in that cylinder if the compression would go up, to help identify the cause of the lost compression. Maybe the valves aren't sealing? Head gasket issue? Having cylinder/piston ring failure at such a low mileage doesn't leave one with a good feeling.

If i had to guess, im gonna say prob valves seals, because well one of the noticable problem with a engine that has piston ring issue is it will burn alot of oil and of course misfires, I always check my oil level prior to oil change and it was always up to level.

Also i noticed mazda has an oil level sensor on the bottom of the oil pan, so i believe... if the oil is low to a certain point, either it will illuminate check engine light or it would prevent vehicle from cranking over.

 

[FrozenApple]

Update (June 25th)
Dropped my car off today since cel came on few days ago, after few hours got a call from the advisor called and told me they need to replace #3 injector, so i thought i will be nice and give them the answer since im trading the car in anyways. I asked if they checked the compression for the engine and they said they will replace injector first before any further diag, and injector is on ordered and will arrive next monday (June 29th).

I asked ok i will swing by after work to pickup vehicle, and the advisor said the vehicle is no longer driveable, so i was like what? i dropped it off this morning it was fine, im driving with the same problem for the past weeks and it was fine, the advisor did not say much and only told me they needed to do the injector because its misfiring badly, anyways they offered me a loaner and that was it.

what i think happened today was.... well they prob swapped coils and realize the misfire is still at cyl#3 and i guess they tried swapping injectors and maybe damaged the injector LOL.

 

[yrwei52]

Update (June 25th)
Dropped my car off today since cel came on few days ago, after few hours got a call from the advisor called and told me they need to replace #3 injector, so i thought i will be nice and give them the answer since im trading the car in anyways. I asked if they checked the compression for the engine and they told me no, they will replace injector first before any further diag, and injector is on ordered and will arrive next monday (June 29th).

I asked ok i will swing by after work to pickup vehicle, and the advisor said the vehicle is no longer driveable, so i was like what? i dropped it off this morning it was fine, im driving with the same problem for the past weeks and it was fine, the advisor did not say much and only told me they needed to do the injector because its misfiring badly, anyways they offered me a loaner and that was it.
what i think happened today was.... well they prob swapped coils and realize the misfire is still at cyl#3 and i guess they tried swapping injectors and maybe damaged the injector LOL.

Wow, even with all the Mazda computers and factory service bulletins, this Mazda dealer can’t really handle more complicated problem like yours! Did you bother to ask if they have assigned a Master Tech to work on your CX-5’s problem?

Since you’ve got a loaner car, no need to hurry them up to fix the problem. Keep us posted.

 

[FrozenApple]

Wow, even with all the Mazda computers and factory service bulletins, this Mazda dealer can’t really handle more complicated problem like yours! Did you bother to ask if they have assigned a Master Tech to work on your CX-5’s problem?

Since you’ve got a loaner car, no need to hurry them up to fix the problem. Keep us posted.

I tried to give them the answer to the problem, but hey they rather try to spend time to take out injector then to perform a simple compression test, so what can i say? I'm just a nobody right? let the technicians follow their procedures.

 

[yrwei52]

I tried to give them the answer to the problem, but hey they rather try to spend times to take out injector then to perform a simple compression test, so what can i say? im just a nobody right? let the technicians follow their procedures.

From the experience dealing with a Master Tech at my Mazda dealer, he really knows lots of things and almost every TSB and Service Alert. And the guy was open minded to discuss all the questions I had to my CX-5. And I really felt comfortable to let him work on my CX-5 without hesitation. I guess not every Mazda dealer would have a qualified Master Tech easily available to the customer.