Jerky Acceleration from stopped, Low Idle, Jerky Shift - all related?

[M3Nick]

Hi all,

I just picked up my 05 M3 (auto) in late Oct, and have been driving it for around half a month now.

I'm not sure if this is actually an issue, but I am noticing a slight jerk(iness) when accelerating from 0 to 10-20 km/h when the engine is both cold or warm. The car picks up at a constant acceleration, then seems to jump to a faster rate. I was driving to London last friday on the 401 and was caught in some traffic around Mississauga, and thats when I began to notice it.

The only problem with this is that it is intermittent. Some times I can reproduce the problem, other times I can't. It tends to happen more frequently when the engine is warm - needle in the nominal temperature position.

The problem seems to be similar to the following threads, but not quite exactly what the original post was about: http://www.torontomazda3.ca/forum/showthread.php?t=21259 and http://www.torontomazda3.ca/forum/showthread.php?t=21177&highlight=jerky

I figure maybe this might be just bad gas, but I did read on another Mazda forum about cleaning out an EGR valve to solve low-idle (which is also another problem I seem to be having):

http://www.mazda3club.com/showthread.php?t=41077

As for the jerky shift between 1 -> 2, the second link sums up the issue quite nicely.

And I'm not sure if this (has been done, or) could solve the jerk between 1 -> 2.
http://www.mazda3forums.com/index.php?topic=31143.0

Finally, I'm noticing a low-idle issue, around 600-350 RPM. But it is extremely variable, meaning it will idle at 600-700 RPM, drop to 400 (car almost feels like it's beginning to stall), then kicks up back to 500.

Could these 3 symptoms possibly be related?

[J-Wo]

It is called 1-2 (1st to 2nd gear) shift shock and there is a TSB available for it. I have the same year and model and MOT fixed it for me under warranty and involves a computer program update for the PCM (whatever that is)

[M3Nick]

Might be a long shot, but did you find this also fixed the acceleration jerk problem, or did you even experience that?

[J-Wo]

I'm pretty sure that the jerky acceleration you describe is the 1-2 shift shock. It occurs when the car switches from 1st to 2nd gear, on a properly running AT this transition should be smooth but on many m3 ATs it is very jerky. You can confirm this by looking at your tachometer when you're driving, the rpms should spike high before the car changes gears, giving you a nice jolt/jerk. The tachometer also tells you what gear you're in, there's a digital display so keep an eye when it transitions from 1 to 2.

[M3Nick]

I don't think so, because I knock it into 1st in sport mode and then test 'er out. No go, as she still jerks (maybe buckles is a bette word) when I caress the pedal with my foot... It is very slight application of the throttle, it begins to pick up speed. Low RPM up to 5-6km/h, then spikes to a higher RPM and im up to maybe 10-12km/h, its a weird feeling. I showed my GF last night, too, and before that she thought I was crazy. Not anymore though.

[M3Nick]

All of this in 1st, too I might add.

[M3Nick]

Well, I'm going in for my 72k KM service today, I'll bring up these issues and let everyone know whats going on.

Thanks J-WO for your replies.

[M3Nick]

So - after:

72,000 km service (What I was originally going in for)
Transmission Fluid Change and flush (was told it was burnt)
Brake fluid system flush(I forget the reason the service guy told me I needed this done for)
Fuel Injection System Flush (I wanted this done, it hadn't been)
Fix lose window assembly problem (caused clunking when moving windows)
Broken Engine Mount (warranty thank god)

I'm looking at just over a grand. The bad part is, the only difference I notice is that the shift shock is gone (PCM) and my windows don't clunk. It still cyclically vibrates at stop lights and idles low, and the acceleration jerk is still there. They told me the PCM updates took care of those.

Lesson: If you don't know exactly how to fix the problem you are complaining about, don't tell the dealer, and don't let them convince you to get anything else.

Please read the last line of my sig for how I feel right now... lol

[tinyfist]

I've been experiencing the shift shock too, but my car is under warranty. I don't mind paying to have the PCM flashed, but how much would I be looking at for that?

[Cardinal Fang]

If your car is under warranty it will not cost you anything.

[tinyfist]

whoops, sorry about that. I meant to say that my car is no longer covered under warranty. :(