Strange 2.5T Engine misfire problem w/multiple choice answer game. Come play.

[Tchman2016]

I eventually started getting codes but it took several months. Codes usually happened in parking lots when I was backing in/out of a spot or other slow maneuvers.

Mazda and my dealer were helpful through the process.

I believe it was only a single cylinder misfiring. Not all of them.

Basically if car was in gear and I’d put the ebrake on and let off the foot brake so there was some load on the engine. You could feel it was running rough and idle would dip down below 500rpm.

Daily driving on the highway you’d never know..it was slow speeds or at a stop where it felt off.

Ahhh! Yes exactly it, you'd never know during normal driving which is crazy. Only doing the standstill idling in drive with foot on brake or slow maneuvers is when it strikes and those exact symptoms show.

I just don't want to drive the car around hoping a code will store or cel pop on dash and do more damage to the cats.

The flip side is the dealer may say well there isnt a code and the money light is not on so come back when it does, all the while having a horrible running engine that they can see but wanting me to go away and do more damage, rather than investigating on their dime. It's ridiculous and manufacturers just hate paying for stuff.

 

[GTEyes]

Ahhh! Yes exactly it, you'd never know during normal driving which is crazy. Only doing the standstill idling in drive with foot on brake or slow maneuvers is when it strikes and those exact symptoms show.

I just don't want to drive the car around hoping a code will store or cel pop on dash and do more damage to the cats.

The flip side is the dealer may say well there isnt a code and the money light is not on so come back when it does, all the while having a horrible running engine that they can see but wanting me to go away and do more damage, rather than investigating on their dime. It's ridiculous and manufacturers just hate paying for stuff.

You could simply pay them to do a compression test. if that is indeed the culprit, that will identify it and give them what they need to open a case with Mazda.

 

[Tchman2016]

You raaang?

I've actually been watching this thread to see what the solution was and to offer help where possible. Unfortunately I've never run into this problem, and I've never seen any other reports on the forum about this. I was planning to try checking idle RPMs in Drive to check for idle changes on and off the brakes, but it looks like that's already been tested and confirmed by others as normal (outside of the misfiring).

@Tchman2016 I'd check the fine print of your extended warranty to make sure you follow the process outlined in making a warranty claim. Sometimes there are disclaimers saying you need to have a diagnosis performed by "X" dealer before the claim can proceed, so it would be a waste to take it to "Y" shop, have it diagnosed there, and then try to file a claim and have it rejected just because you didn't go to the "X" dealer for diagnosis.

If it were me, I'd put the original plugs back in (in the same cylinders if possible) before taking it to the dealer for diagnosis. When they run through their troubleshooting, the plug condition would likely help them figure out the underlying cause.

Haha the all knowledgeable sm1ke has entered the chat! You're a good man thank you.(Actually everyone here is)

Yes, i'm going to do exactly that, put the original plugs back in the same cylinders ( I kept them in order) and make a dealer appt.

The warranty is Mazda OEM Platinum exclusionary with no deductible. So that's a huge plus if they come through.

I'm wondering if I should suggest to the dealer that they boroscope and run a compression test on all cylinders as well as a leakdown test and offer to pay for those services out of pocket as a gesture of faith they will want to try hard to find the issue and not have to depend on warranty diagnostic and rush. What do you suggest?

 

[Silly Wabbit]

If you want I can send you my old set of oem plugs w/ 35k miles. That way you have oem equipment when you bring it in.

 

[Tchman2016]

If you want I can send you my old set of oem plugs w/ 35k miles. That way you have oem equipment when you bring it in.

No way!!!! That is so incredibly generous of you my jaw dropped i'm speechless.

That would so awesome and I can feel so much easier knowing they can't try to blame something on my own plugs. I've played that game before and it's so much aggrevation.

Really, THANK YOU and I will be happy to pay you something for them and of course shipping.

You all rock and I'm so happy to be a part of this community to help when I can as well and feel good that we've all got each other.

I'll send you my address and send me your PayPal or zelle email!

 

[sm1ke]

Haha the all knowledgeable sm1ke has entered the chat! You're a good man thank you.(Actually everyone here is)

Yes, i'm going to do exactly that, put the original plugs back in the same cylinders ( I kept them in order) and make a dealer appt.

The warranty is Mazda OEM Platinum exclusionary with no deductible. So that's a huge plus if they come through.

I'm wondering if I should suggest to the dealer that they boroscope and run a compression test on all cylinders as well as a leakdown test and offer to pay for those services out of pocket as a gesture of faith they will want to try hard to find the issue and not have to depend on warranty diagnostic and rush. What do you suggest?

Lol I'm only as knowledgeable as the community, everything I learned comes from you guys

I think I would trust the process and raise your concerns with the dealer. Have them verify the symptoms and see what they do next. If they try to send you away, explain your concerns about potentially causing additional damage and the uncertainty of having to drive the car in that state, not knowing what could happen and how badly it could damage the car by continuing to drive it. Maybe loop the service manager in at some point in the convo so they're aware of your concerns. Hopefully that's good enough to give you a loaner so they can do a deep dive on the car. And if it's not, and they insist on waiting for things to get worse, consider running it up the chain to Mazda Corporate.

It's hard to say what the best course of action is.. In my experience, the service reps at the desk are service salespeople - they don't actually service the cars, they act as middle men between the customer and the mechanics doing the diagnosis. Which means that talking to them about what you've done and potential further testing could be wasted breath, especially if they simply want to follow their internal policies and wait for check engine lights or whatever.

On the other hand, there are some service reps that have a mechanical background and would be able to discuss the troubleshooting path and diagnosis with you. Those reps are usually more sympathetic and are more open to running those tests, especially if you're offering to pay for them to speed up the repair process and get your car back to 100%.