[ilija.todorovic]

That bucking is the clutch and transmission. Its from dropping the clutch when its trying to revmatch, my advise would be know the gears a bit better, for mine its 6k 1st gear to 3.1k 2nd then 6k 2nd to 3.1k 3rd, then 6k to 4th is 4k

If that doesn't help try to just hold a tiny bit of throttle before lifting the clutch or when decelerating hold the clutch right before bite point so it revmatches, then downshift, hold the clutch, shift, ect. You will literally feel the car click into gear once the clutch and transmission speed matches in the correct gear.

Also theres almost no way to stop bucking in 1st when downshifting from second unless you hold the throttle slightly to keep it at 4k the let off the clutch. The way i do it wears on the clutch more but i find it safter in an emergency then rev matching the traditional way.

Fair enough, and I know exactly what you are referring to as I've been running manuals since I learned driving, but I am pretty confident this is not due to the way of shifting gears. Again, there is no issue with jerking after disconnecting the battery. Also, it's very inconsistent, sometimes jerking is very subtle and other times more intense.

 

[arathol]

Could be something as simple as a bad throttle position sensor, or even a pedal position sensor.....

 

[Derpx2]

Fair enough, and I know exactly what you are referring to as I've been running manuals since I learned driving, but I am pretty confident this is not due to the way of shifting gears. Again, there is no issue with jerking after disconnecting the battery. Also, it's very inconsistent, sometimes jerking is very subtle and other times more intense.

In that case sounds far more reasonable to be air fuel mixures. As the user above stated could be throttle sensor issues.

We have ruled out gearing.

Wiring maybe? But by the sounds of it theres no issue other then the ECU doings its job properly.

Maybe try, If you can afford it, to run your car on 98, and if it runs better its to do with the air fuel ratios.

Does it buck when you just let off the throttle abruptly/ tap it? Thats a sign of lack/abundance of air in the mixure.


When shifting does it go as follows:

floor the gas little to nothing happens? Sign of VVT retarding too far to keep the mixures in check

1st gear, rev it, shift to 2nd it goes, stumbles stumbles comes good and slowly builds its speed back up? probably too much fuel..

Floor the gas in 1st it goes, you feel the VVT kick, 1, 2 , 3 then good till higher revs, shift to 2nd , stumbles slow acceleration feels lacking comes good at 3-3.7k VVT is over compenating for lack of power

turn on the AC it stumbles, low RPM it feels like it could and sometimes/does stall without throttle when lifting the clutch from idle VVT kicks in, cars dumping too much fuel in.

Dropping the clutch @ 3k-4k from a stop just spins the wheels or you feel like your drifing but the clutch is engaged probably a slipping clutch.

I honestly don't know too much about the technical side of how the newer engines function, but what i do know is that when it comes to VVT its good at hiding basic problems and turning them into seemingly impossible ones.

 

[arathol]

Octane has nothing to do with AFRs. AFR (Air Fuel Ratio) is the percentage of fuel mixed in any given volume of air. Doesn't matter if its 85 or 95 octane, if the percentage of fuel is the same you still get the same AFR numbers.
AFRs as reported by the sensors are simple to check with any decent OBD reader by the way. Also, if the AFRs are far enough from what the ECU sees as "normal", a code will be generated and the CEL will illuminate.
You can also read throttle position, timing, etc with an OBD reader. You might want to locate a decent one, it would help immensely in diagnosing problems with the car....

 

[Derpx2]

Octane has nothing to do with AFRs. AFR (Air Fuel Ratio) is the percentage of fuel mixed in any given volume of air. Doesn't matter if its 85 or 95 octane, if the percentage of fuel is the same you still get the same AFR numbers.
AFRs as reported by the sensors are simple to check with any decent OBD reader by the way. Also, if the AFRs are far enough from what the ECU sees as "normal", a code will be generated and the CEL will illuminate.
You can also read throttle position, timing, etc with an OBD reader. You might want to locate a decent one, it would help immensely in diagnosing problems with the car....

i wasn't saying that the octane rating effected the air fuel ratios. Its more to do with the fact that if there is too much or too little of either in the mixure the engine will be less rough with a higher octane rating due to the reduction in pre-ignition/detonation howerver small it may be. But i definitely agree.

 

[theisaaclibby]

Thanks. How would I know what the correct data is? Is there a reference table to refer to? It's a very logical step, but might be above my level of expertise...

I would clear the mappings by resetting the battery and driving in a way that would cause the issue (you said it shouldnt happen when ECU is relearning) and write down what you see, then do the same when the issue starts again and look for differences. It’s a shot in the dark but yes it’s very hard without an engine code.. if there is no error code you can rule out a large number of things.If I’m not mistaken most vacuum and emissions leaks would cause a CEL

make sure there are no cracks or holes in the intake and the intake manifold, for instance, it could be taking in unmetered air. One time on my friends 6 we ended up finding the accordion part of his intake was split and allowing unmetered air in the side. Rule out everything easy because your about to fall down the rabbit hole soon.

also check AFR as someone above said. I didn’t have the SkyActiv engine in my ‘12 so I don’t know what your normal AFR should be but you can also compare it to your reset mappings

 

[zero_gravity]

I'd grab a copy of the service manual and start testing resistance range on all sensors in question. As mentioned, a good OBD tool and do some data logging. If it starts acting up, maybe we'll get lucky and see the problem.

Seems like some sensor is not working correctly but not bad enough to throw a code.

If all else is eliminated, hate to say it but it could come down to a faulty ECU....even if unlikely.

 

[Derpx2]

Just a question, how long has it been since you changed the filter (Km/miles) if its been 10-30k then its due for a change.

Has the air filter gone hard? if so its bad.

Trace amounts of water can come into contact with the filter and also make it go bad in some cases.

This might seem obvious but a bad air filter choking the engine ain't gonna chuck any engine lights, but it will sure as hell mess with its performance once it learns. In extreme cases Refuelling will cause it to relearn which mine had. Btw as a reference looking at how Dirty an airfilter is, isn't a reference to how Used/Worn it is. Mine looked basicly new and only small amounts of fine dust, but it was completely bad.

Its just a quick $20 check and nothing but good will come from it. Im just going back to it simply because you said that it should be getting changed by the mechanics, from my experience they won't even touch it unless specified, and at best the MAF cleaner oils the filter.

 

[ilija.todorovic]

Just a question, how long has it been since you changed the filter (Km/miles) if its been 10-30k then its due for a change.

Has the air filter gone hard? if so its bad.

Trace amounts of water can come into contact with the filter and also make it go bad in some cases.

This might seem obvious but a bad air filter choking the engine ain't gonna chuck any engine lights, but it will sure as hell mess with its performance once it learns. In extreme cases Refuelling will cause it to relearn which mine had. Btw as a reference looking at how Dirty an airfilter is, isn't a reference to how Used/Worn it is. Mine looked basicly new and only small amounts of fine dust, but it was completely bad.

Its just a quick $20 check and nothing but good will come from it. Im just going back to it simply because you said that it should be getting changed by the mechanics, from my experience they won't even touch it unless specified, and at best the MAF cleaner oils the filter.

I replaced an air filer with an OEM one no more than 2 months ago. I'll take another look if by any chance it went bad/dirty, but highly doubt. It's an easy check...

 

[ilija.todorovic]

Could be something as simple as a bad throttle position sensor, or even a pedal position sensor.....

Agreed. There could be so many small things that are throwing it off just slightly to become a nuisance but not throw any CEL. I'll have a chat with my mechanic tomorrow what he thinks how to approach this, as I really don't want to throw any more money in guessing what the issue is...If I was a betting man, I would bet it's A/F ratio that goes off the chart. Now what's causing it, that's a million dollar question without CEL to narrow the search.

But I do like the idea of comparing OBD reading between before and after battery reset, and I will bring this up tomorrow.

 

[ilija.todorovic]

In that case sounds far more reasonable to be air fuel mixures. As the user above stated could be throttle sensor issues.

We have ruled out gearing.

Wiring maybe? But by the sounds of it theres no issue other then the ECU doings its job properly.

Maybe try, If you can afford it, to run your car on 98, and if it runs better its to do with the air fuel ratios.

Does it buck when you just let off the throttle abruptly/ tap it? Thats a sign of lack/abundance of air in the mixure.


When shifting does it go as follows:

floor the gas little to nothing happens? Sign of VVT retarding too far to keep the mixures in check

1st gear, rev it, shift to 2nd it goes, stumbles stumbles comes good and slowly builds its speed back up? probably too much fuel..

Floor the gas in 1st it goes, you feel the VVT kick, 1, 2 , 3 then good till higher revs, shift to 2nd , stumbles slow acceleration feels lacking comes good at 3-3.7k VVT is over compenating for lack of power

turn on the AC it stumbles, low RPM it feels like it could and sometimes/does stall without throttle when lifting the clutch from idle VVT kicks in, cars dumping too much fuel in.

Dropping the clutch @ 3k-4k from a stop just spins the wheels or you feel like your drifing but the clutch is engaged probably a slipping clutch.

I honestly don't know too much about the technical side of how the newer engines function, but what i do know is that when it comes to VVT its good at hiding basic problems and turning them into seemingly impossible ones.

"Does it buck when you just let off the throttle abruptly/ tap it?" - Yes, exactly as you described. Other thing is withgas pedal to the floor, it's a bit sluggish to pick up the power and speed.

 

[Derpx2]

"Does it buck when you just let off the throttle abruptly/ tap it?" - Yes, exactly as you described. Other thing is withgas pedal to the floor, it's a bit sluggish to pick up the power and speed.

only other thing i can think of currently is eaither your engine mount is worn or your suspension is worn/soft, but these things are more on the extreme end of WHAT COULD IT BE! thinking.

 

[ilija.todorovic]

only other thing i can think of currently is eaither your engine mount is worn or your suspension is worn/soft, but these things are more on the extreme end of WHAT COULD IT BE! thinking.

Right, but that would not be affected by battery reset. i.e. after the reset car works like it came out of factory for couple of days...

 

[arathol]

If I was a betting man, I would bet it's A/F ratio that goes off the chart. Now what's causing it, that's a million dollar question without CEL to narrow the search.

As I said before, if the AFRs are that far off you would a get system too lean or too rich error code. If you aren't seeing the CEL come on or codes being set, probably not AFR related.....

 

[Derpx2]

As I said before, if the AFRs are that far off you would a get system too lean or too rich error code. If you aren't seeing the CEL come on or codes being set, probably not AFR related.....

While this is correct the tolerances for a CEL can be quite high.

I feel like a CEL would indicate a failure of some kind while no CEL would prove that everything is functioning but not at 100% or properly.

I know for a fact that the CEL limits are high for some things simply proven by my 1st post, engine was basicly choked by the air filter to the point it had no power but no CEL. How bad was it? Well judging by how it runs now, id be lucky if i was running at 1/4 of what it should be, But still Within spec.

Hell my engine was overheating pinging to hell and back even on 98 just due to intake heat, No CEL... could just be bad sensors but if tolerances were too low i suspect a car company would get bad rep for being unreliable.

I do not trust my car to throw a CEL, regardless of whats wrong, i was getting missfires non-stop before i replaced my sparkplugs, had to run it like that for 3 weeks not a single code or CEL. I rev the crap out of my engine too so its not like its Being babied

If you have feedback for me on this that would be nice, but this is more or less just an explanation as to why even if something is wrong with his engine its probably not showing.

 

[ilija.todorovic]

While this is correct the tolerances for a CEL can be quite high.

I feel like a CEL would indicate a failure of some kind while no CEL would prove that everything is functioning but not at 100% or properly.

I know for a fact that the CEL limits are high for some things simply proven by my 1st post, engine was basicly choked by the air filter to the point it had no power but no CEL. How bad was it? Well judging by how it runs now, id be lucky if i was running at 1/4 of what it should be, But still Within spec.

Hell my engine was overheating pinging to hell and back even on 98 just due to intake heat, No CEL... could just be bad sensors but if tolerances were too low i suspect a car company would get bad rep for being unreliable.

I do not trust my car to throw a CEL, regardless of whats wrong, i was getting missfires non-stop before i replaced my sparkplugs, had to run it like that for 3 weeks not a single code or CEL. I rev the crap out of my engine too so its not like its Being babied

If you have feedback for me on this that would be nice, but this is more or less just an explanation as to why even if something is wrong with his engine its probably not showing.

I agree, I had a misfire on cylinder 3 & 4 for a few days without any CEL being displayed. So what was exactly wrong with your air filer, was it that clogged? Was it the OEM?

 

[ilija.todorovic]

So thanks everyone for your input, it's greatly appreciated.

In the end I have decided to get rid of my mazda 3 and to trade it in for another vehicle. It became endless pursuit to find the solution, and without the CEL i could not get any resolution to it without wasting too much money and time. Even my mechanic said he'd be hesitant to take it again for diagnostics as he could not guarantee it could be fixed. Service at the dealership also failed to find what the issue is. Last thing I did was using injector cleaner and resetting my battery, so the car worked great for the following 4 days and then started choking again.

Thank you all for your input, it was a very good discussion and exchange of opinions. Cheers.

 

[Derpx2]

I agree, I had a misfire on cylinder 3 & 4 for a few days without any CEL being displayed. So what was exactly wrong with your air filer, was it that clogged? Was it the OEM?

the material itself went hard, had no flex in the fibers and felt kinda sharp. Definitely seemed clogged, at the time of removal it was way less black so i presume having it out of the car has let the fibers stretch back out showing how bad it really was. I'll show a pic.

 

[zero_gravity]

So thanks everyone for your input, it's greatly appreciated.

In the end I have decided to get rid of my mazda 3 and to trade it in for another vehicle. It became endless pursuit to find the solution, and without the CEL i could not get any resolution to it without wasting too much money and time. Even my mechanic said he'd be hesitant to take it again for diagnostics as he could not guarantee it could be fixed. Service at the dealership also failed to find what the issue is. Last thing I did was using injector cleaner and resetting my battery, so the car worked great for the following 4 days and then started choking again.

Thank you all for your input, it was a very good discussion and exchange of opinions. Cheers.

Sorry to hear that it didn't work out for you. Hope you're happy with whatever car you get next. Wish I could have gotten my hands on it to take a stab at diagnosing it.

 

[arathol]

the material itself went hard, had no flex in the fibers and felt kinda sharp. Definitely seemed clogged, at the time of removal it was way less black so i presume having it out of the car has let the fibers stretch back out showing how bad it really was. I'll show a pic.

That not nearly bad enough to impede proper operation of the engine. The filter flow capacity is far greater than the engine can draw. The filter needs to be something like 90% obstructed before it stops working.....