2016~2023 Little help

[Mazdaratti4]

I have a 2018 cx9 touring with just over 30k. Twice now after a long trip when I get home or just before, the car almost acts like it has a fuel or spark issue. Rough idle, surges and no codes. After a few minutes ill start it up and everything is fine.. Any ideas? The local dealer is kind of a joke but that's a whole lot to explain. I am mechanically inclined but new to these cars so just seeing if anyone has experience in this.

 

[s0n1c]

This sounds like what I experienced before they found the crack in my engine block. I did eventually get misfire codes and they replaced one plug and ignition pack. I managed to resolve the rest by replacing the spark plugs, which are recommended every 37.5k miles anyway, but that only temporarily fixed my issue.

I’d suggest replacing plugs first, but keep your eyes open for coolant leaks or burning

 

[PTguy]

Start with the easy stuff. Water in the gas can cause something like what's described. Put in some Heet gas line antifreeze at label dosage. If that works, great. If not, you're only out a coupl'a bucks. Then on to the next possibility. Looking at the spark plug tips can be a clue--if one looks different from the others, there is a reason.

 

[Mazdaratti4]

Start with the easy stuff. Water in the gas can cause something like what's described. Put in some Heet gas line antifreeze at label dosage. If that works, great. If not, you're only out a coupl'a bucks. Then on to the next possibility. Looking at the spark plug tips can be a clue--if one looks different from the others, there is a reason.

Yeah im well versed in spark plugs language as I own a tenth gen f150 with a 5.4 lol. The water in the gas I'd have trouble buying into as it only happens after long drives and gas from these drives where states away from each other. But I was planning looking into the plugs. Thank you

 

[Mazdaratti4]

This sounds like what I experienced before they found the crack in my engine block. I did eventually get misfire codes and they replaced one plug and ignition pack. I managed to resolve the rest by replacing the spark plugs, which are recommended every 37.5k miles anyway, but that only temporarily fixed my issue.

I’d suggest replacing plugs first, but keep your eyes open for coolant leaks or burning

Where did they find the crack? Any oil loss or milky coolant?

 

[s0n1c]

Where did they find the crack? Any oil loss or milky coolant?

It was near the exhaust manifold. I found the leaking coolant myself and then took it in for them to look more. No oil loss or milky coolant. Just misfires, hesitation, then coolant loss. In that order is how it showed up. Mine usually happened after long drives or first thing in the morning but I was never able to get it to happen in front of the techs. One morning I got it to throw a code so I drove it there and left it running until they could scan it. They did pressure tests and other evaluations and determined at that time it was a bad ignition pack. The problem didn’t go away, so I replaced the other three plugs (since they only replaced the one listed by the misfire). Things were cool for a few weeks after that but slowly the hesitation came back and the coolant leak surfaced.