[Midnightsky228]

Ive noticed more recently that my 2017 Mazda 3 GT 2.5L manual likes to rev hang. I swear when it was new it never had this bad of rev hang, like it's getting rediculous. Ive poked around on here and have not found any conclusive evidence of a solution to this problem. A tune would help some but I feel like this is more mechanical, like maybe my clutch is already going on it. Just clicked past 30,000km and there was a few times I may have been not so nice to my clutch when I was stuck in the snow. The possibility that I have partially smoked the clutch is definitely there. Im early enough to possibly claim warranty but at this point Id like to gather more information before I go any further down this path. Is it possible a partially smoked clutch would create abnormal rev hang? Would a light-weight flywheel help discourage rev hang? A stronger clutch and pressure plate? Or is this likely all because of the factory tuning and I won't see any decrease in rev hang without a tune from OV? Id really like to avoid the tuning but if that becomes the solution then I might go down that rabbit hole. What do you guys think?

 

[Rdrokit]

Not sure you could have fried your clutch if you only missed used it a couple times. Could have heated up the clutch plate and glazed it over. Have the dealer diagnose the problem.

 

[arathol]

Does it still shift ok, as in no grinding or anything that would indicate that the clutch isn't fully disengaging?

 

[Midnightsky228]

Does it still shift ok, as in no grinding or anything that would indicate that the clutch isn't fully disengaging?

nah nothing like that, takes the shift nicely, just that rev loves to hang for what feels like an eternity.

 

[Midnightsky228]

The other thing I guess I should mention is that 2 weeks ago I swapped out my custom axleback exhaust to go back to my oem factory axle-back. Which Im already regretting and might switch it back tonight lol.

 

[Nateness]

Sounds like you’re noticing the OEM dual mass flywheel. Going with a single mass or lightweight flywheel would help. Haven’t seen any lightweight flywheel options for our 2.5L so far, but am hoping that eventually Exedy provides their chromoly lightweight flywheel.

 

[Midnightsky228]

Sounds like you’re noticing the OEM dual mass flywheel. Going with a single mass or lightweight flywheel would help. Haven’t seen any lightweight flywheel options for our 2.5L so far, but am hoping that eventually Exedy provides their chromoly lightweight flywheel.

Seriously? My 2003 Elantra had lightweight flywheel options, and our Mazda 2.5L doesn't? Da FUNK!?

 

[Nateness]

My feelings, exactly. I’m hoping that will change soon since the BM generation has been out for a few years with another year or two left before the next generation. Hopefully by then the market will be large enough to entice manufacturers to offer a LWFW product.

 

[kickin81]

My car acts the opposite. I cannot get the revs to stay up in between shifts causing the passengers to jerk forward when I upshift. Maybe the previous owner installed a lightweight flywheel without my knowledge.

 

[curvyroads28]

My car acts the opposite. I cannot get the revs to stay up in between shifts causing the passengers to jerk forward when I upshift. Maybe the previous owner installed a lightweight flywheel without my knowledge.

I experience both rev hang and faster rev drop under different conditions. I have a feeling it has something to do with how the ECU adapts to driving styles. Also, you may notice that if you drive with the A/C on, the revs tend to drop faster due to the added load on the engine. At least that is what I have experienced. There are times when I am doing a hard pull on a freeway on-ramp and the revs will hang from 4th to 5th to 6th. Other times the revs drop much faster and it makes it seem as though I haven't driven stick before because I seem to miss the right RPM when shifting. I have also noticed that the throttle can have a slight delay between up shifts, also causing issues with catching the right RPM. So there is a lot going on with what the computer is controlling versus what your feet are telling it to do. I find that I have to adapt how I am moving my feet in order to adapt to how the car is trying to adapt to my driving. :blink 1: I miss driving a car with a cable throttle and no nanny systems.

 

[Dittobox]

Totally crazy thought...do you have MRCC on? If it's on, and engaged, it'll hold revs for you and (sort of) rev match.

I've noticed that the revs in this car take an eternity to drop. So much so that I'm afraid to pull out in traffic at times because dropping 4000 RPM from 1 > 2 takes so damned long. I drove a friend's '99 Boxster the other day and the cabled throttle was like a light switch.

 

[zero_gravity]

Rev hang is very common in modern cars, ours just show it worse. Not many notice it because almost everyone drives auto now. Hell, less and less cars are even coming with a manual option.

I did read somewhere that the rev hang is a side effect of the newer emissions systems. I do notice it on my 2.0L/ MT 3, but I also tend to shift quite quickly so it doesn't bother me much.

I think this is one of those things we'll have to live with. Maybe the OV tune helps? You'd have to ask members that have done the tune and drive stick. I'm sure they could help the hang if you were to ask for it.

 

[Madazaspeed]

And with the rev hang is it from stock intakes mostly that have baffles an noise suppressors that all slow the air speed down or is same with pod filters an short ram intakes?..i also think advancing the timing to make decel sharper is the best option if a pod doesnt help after a week or so driving

 

[Cdn17Sport6MT]

It is all controlled by the pcm actuating the electronic throttle. Usually cars have an rpm below which throttle hang does NOT occur, by way of pcm programming. That rpm may be as low as 1500 tho.

 

[arathol]

And with the rev hang is it from stock intakes mostly that have baffles an noise suppressors that all slow the air speed down or is same with pod filters an short ram intakes?..i also think advancing the timing to make decel sharper is the best option if a pod doesnt help after a week or so driving

There are no baffles or noise suppressors in the intake so thats not an issue.
Changing the timing advance is not an option because A- its not something you can just "do" like in older cars, and B- its got nothing to do with the rev hang issue.
The reason for rev hang is to reduce emissions. When you lift your foot off the throttle at speed in an older car, the throttle plate closes and the rpms fall quickly. This sudden throttle closing causes a rise in crankcase pressure which in turn causes an increase in oil vaporization. In addition, when the throttle is closed quickly as it would when shifting, the fuel mix has a lean spike. This results in an increase in NOx emissions. Keeping the throttle plate open a bit instead of closing completely significantly reduces the amount of oil vapor created and helps keep NOx levels down. The throttle plate not closing completely is what causes the rpms to stay elevated.
Rev hang is something you can eliminate by retuning the throttle calibrations.

 

[gregersonke]

Underdrive pulley should help too as it will reduce the rotating weight of the motor inertia going to the clutch.