At stop light engine wants to stall when inl. Revs dropping below 500RPM.

[mcf_24]

Hi.

I have 2008 Mazda 3 2.0 AT with ~134,000KM.
Apart from regular wear and tear brakes, tires, transmission flush etc its been flawless still running like new when I purchased it.


Few days ago with really cold temps (-40ish windchill) in Manitoba, car was barely starting even with block heater so I took battery to get tested and it measured 12.5V ~200CCA. It was the original Panasonic battery that came with car. (Crazy it lasted 6 years of Manitoba winters)


So bought new battery and installed it. Car fired up great and I let it run for 5-10 minutes in park.

Then I took it for 30-40 minute drive so ECU relearns itself.

Immediately I noticed on stop lights with car in drive the revs were bouncing below 1,000RPM from 800RPM,750RPM,620ish and then few times below 500RPM car was shaking a lot and was on verge of stalling but it didn't. At one point low power steering flashed on dash for less then second and quickly disappeared.

When I move from D to N the revs jump to 800RPM and the shaking stops. Its been doing that 2 days now.
On old battery I had none of these issues.


Does ECU need long time before it returns to what it was before?


Searching here and other mazda3 forum it seems to be one of the following

throttle body
maf sensor
need dealer ecu update

Tsb on the rough idle.
http://www.miata.net/garage/tsb/01-007-09-2069.pdf

When I took it to local Mazda dealer they said its due to cold weather, problem will resolve itself.
Said they don't do ecu updates.
Had no idea about tsb.


I have cleaned maf sensor myself but throttle body seems bit delicate on what cleaner to use and where you can touch etc. According to diagram above.

Is it something I should do myself or should I take it to Mazda?

Since I am out of warranty anyone know what would it cost to get throttle body cleaned?

Thanks for help.

[danacosta24]

did you get a CEL?

[mcf_24]

did you get a CEL?

no CEL.

[Stathakos]

I have an 09 2.0 AT as well and I experienced the same exact thing. A TB cleaning solved it for me.

[Squisher]

Anyway id try a battery pull Let it sit for over 10 minutes disconnected then connect it and let it idle for 10 minutes..then it will relearn ur driving habbits for the next short while. See if that helps

This was posted in another thread. I read where you switched your battery but did you leave it disconnected for 10 min? Five to ten minutes of idling you said, I'd time 10 minutes. Then drive.

[mcf_24]

I have an 09 2.0 AT as well and I experienced the same exact thing. A TB cleaning solved it for me.

That's what I am leaning on. Did you do it yourself?

There is several good guides on here but I am afraid of messing it up.

This was posted in another thread. I read where you switched your battery but did you leave it disconnected for 10 min? Five to ten minutes of idling you said, I'd time 10 minutes. Then drive.

After taking old battery out I cleaned cable terminals as it had blue foam from corrosion with battery spray.

Spray requires 3-5 minutes to sit on terminals so I am sure I let the car sit for 10 minutes before putting new battery.

Everything reset once I started it with new battery.

I let it run 5 minutes in park turned it off, went to put away tools etc then came back and went for drive 30-40 minutes.

[Stathakos]

That's what I am leaning on. Did you do it yourself?

There is several good guides on here but I am afraid of messing it up.




After taking old battery out I cleaned cable terminals as it had blue foam from corrosion with battery spray.

Spray requires 3-5 minutes to sit on terminals so I am sure I let the car sit for 10 minutes before putting new battery.

Everything reset once I started it with new battery.

I let it run 5 minutes in park turned it off, went to put away tools etc then came back and went for drive 30-40 minutes.

No I got a mechanic to do it. (Jimmy from Street performance) I was watching him do it, it wasn't anything too complicated. I'm sure there is a guide on here somewhere

[Squisher]

Just seems odd timing a maf would go from a battery change? Any reason it would?

[Squisher]

Or sorry meant throttle body, but I can't edit.

[mcf_24]

update:

I seem to have solved my problem for now.


So this morning I unplugged negative battery terminal to reset ECU again. Waited 15 minutes.

Connected negative again.

Let it idle few minutes then went on drive with mix of really slow driving to highway.

And now in drive car at stop light idles at 750RPM without any drops in RPM and no shaking.

Hopefully it lasts for good.

[McGuyver_3]

Glad you managed to straighten things out, but why would your mazda dealer not want to update the ECU? I had the same issue with a dealer not wanting to do an update for me. I simply told them I was willing to pay and that I wanted the update and they ended up doing it for me. Cost me an hour labor for something I guess would take 10 minutes but I wanted the update.
At work we are constantly updating cars and it fixes ALOT of issues. Heck even our testplans tell us to update the car because it knows there is a software glitch

[Canadianbacon]

Update ECU takes 2 minutes with mazdaedit. I have stock/tuned versions very simple

[mcf_24]

Glad you managed to straighten things out, but why would your mazda dealer not want to update the ECU? I had the same issue with a dealer not wanting to do an update for me. I simply told them I was willing to pay and that I wanted the update and they ended up doing it for me. Cost me an hour labor for something I guess would take 10 minutes but I wanted the update.
At work we are constantly updating cars and it fixes ALOT of issues. Heck even our testplans tell us to update the car because it knows there is a software glitch

Dealer told me they would only update ecu if there was something wrong with car. Otherwise you are stuck with what you have.

....I complained to them before when I got the car as my fuel consumption was too high and it still is (city 9L/100Km / 7L/100KM highway)....during winter almost 11L/100Km combined.

Update ECU takes 2 minutes with mazdaedit. I have stock/tuned versions very simple

Agh I wish there was normal dealership in Manitoba that you can actually deal with. These guys here are real aholes.

[sarujo]

That is pretty close to what you can expect from the 2.0L MZR. My 2010 2.0L MZR is "rated" for 5.9L/100km hwy and 8.1L/100 city and I have a standard trans. Given the age of your car and automatic it is in line. If you want ultra gas mileage then buy a Fit or Prius.

Dealer told me they would only update ecu if there was something wrong with car. Otherwise you are stuck with what you have.

....I complained to them before when I got the car as my fuel consumption was too high and it still is (city 9L/100Km / 7L/100KM highway)....during winter almost 11L/100Km combined.





Agh I wish there was normal dealership in Manitoba that you can actually deal with. These guys here are real aholes.