Mazda CX-3 Forum banner
1 - 4 of 4 Posts

·
Registered
Joined
·
1 Posts
Discussion Starter · #1 ·
Hey everyone, new member and first post. I've got an issue and am hoping someone can help me out. I have a 2016 CX 3 Grand touring AWD that I bought new, have 95,000 miles on it. When the engine is hot and I'm in drive with ac off and foot on the brake after a few seconds my RPM's drop to 550 and the car shakes. When I let off the brake RPMs go back up to around 700 and the engine runs smooth again. The check engine light was on for a day then turned off on its own but got the p0300 code random/multiple cylinder misfire. Dealer couldn't work me in for a couple weeks when I got there they charged $125.00 to run the diagnostics and told me I needed new spark plugs so I replaced them and it didn't fix the problem, so a short time later I replaced the coils, still didn't fix the problem. Last time I talked with the dealer they told me it's normal for the engine to shake and RPM's to drop, but this only started in January and I've been dealing with it since. Any Ideas and recommendation will be greatly appreciated.
 

·
Registered
Joined
·
586 Posts
Two other things to checkout, see if theres any cracking on the intake tube. The rubber is ridiculously terrible and fades/cracks easy as has happened on previous mazda vehicles and still has not been corrected to this day smh. The other, although not sure how relevant it could be, possibly something with the fuel system. I would suggest running about 1.5x the amount of seafoam through the engine in the fuel tank. (add in when almost empty, add in the '1.5x amount of what should be added for a full tank, drive around for a mile or two and then fill up at gas station). I would suspect maybe a dirty injector didnt spray enough and caused preignition? iirc our mazda has a higher compression ratio than average vehicles and its been an occasional problem for cars which havent been periodically cleaned through.

As unfortunate as it is to say, dealers are pretty bad at fixing anything once its out of warranty and you enter the 'trial and error phase' where they will basiclaly try random things, bill you for it like its gonna fix the problem, then when it doesnt which is very likely, repeat the process all over again


edit: Now that I remember, your issue feels awfully similar to an old coworkers bmw (manual) that would struggle and stall out when he put it in neutral after dumping rpms out of a gear. We ran some extra concentrated fuel system cleaner and maintained high revs to force it through (not recommended on auto transmission in neutral) and it fixed the issue.Fuel pump was working perfectly and this issue was noticed a while before the stalling when the engine would struggle whenever in neutral (or in our case braking to a stop) it got progressively worse to the point he couldnt leave work because turning the car on would go crank, fire up rpms in the initial rev then drop out to a stall. May or may not be relevant here but couldnt hurt to pursue this route of maintanence,
 

·
Registered
Joined
·
586 Posts
Last time I talked with the dealer they told me it's normal for the engine to shake and RPM's to drop,
this is also code for we dont know what else to charge you for because you will notice we are just billing random service we dont know what were doing so we say its 'normal' 👀
 
1 - 4 of 4 Posts
Top