Deceleration during attempted acceleration

[sbowden99]

Hi all,

I've done a search for this, but no-one else seems to have this particular problem.

Vehicle: 2007 Mazda3 5DR, S-Touring, AT, 40k miles.

Scenario: I'm driving along at around 25 - 30 mph, and floor the accelerator. 90% of the time this prompts a quick downshift to 2nd or 1st and life is good.

10% of the time, however, the car decelerates rapidly for about 1 second, as though I've actually put on the brakes.

I've only experienced this once, and it's proven impossible to reproduce, so I don't know 1.) exactly what gear I'm in and 2.) what the RPMs do.

My theories:

1.) Fuel cut-off somehow activated.
2.) Tranny upshifting instead of downshifting, causing severe engine bog. (I just did the dealer recommended tranny flush, so my fluid is good.)

Anyone else with this problem?

cheers,
--Seth

 

[lucaspl88]

i would say try TB ground MOD, it eliminates a lot of trans shock and helps smoother and faster shifts...
other then that.. its an auto trans... sometimes it gets confused.. its normal

 

[joshritger]

I get this sort of thing happening in my 07 5 door with the automatic also. I did the throttle body ground this spring and it helped a little bit. I do notice that the AT coasts very bad and also I get a pulling feeling as it down shifts from 5th to 4th while coasting. I had my transmission replaced last summer also at around 15,000 miles due to some other issues. I have been thinking about having my tranny fluid changed over to either redline or amsoil synthetic, but have to find a shop to change it first. Is it a bad idea to have the tranny flushed when I do get the fluid changed, I have heard mixed info on that? Oh and I am around 35,000 miles now.

 

[sbowden99]

Is it a bad idea to have the tranny flushed when I do get the fluid changed, I have heard mixed info on that?

Tranny flushes are a controversial issue: set aside a few hours and do a google search.

To summarize the relevant points of contention:

1.) Some folks claim that when your car is hooked up to the machine, you'll get a dose of the previous car's dirty fluid. I asked my service guy about this, and he said that was impossible.

2.) Some folks also claim that the flush forces metal particles in the fluid into nooks and crannies in your transmission; nooks and crannies that, under normal operation, would never experience such a thing. I couldn't find a definitive answer to that one.

3.) There are claims that the high pressure of the flush can damage your transmission (not sure how). Couldn't find a definitive answer.

4.) Perhaps most damning of all, the Mazda3 owner's manual does not specify any transmission service AT ALL. I recently bought a Mazda Extended Protection plan (out to 100K miles), and thought that settled the case. If it's not in the owner's manual, I don't have to do it, right?

Well, not quite. Many reps at Mazda informed me that if my tranny were to fail during the warranty period, in order for the warranty to cover tranny replacement, I would have to show evidence that I had followed dealer recommendations and changed the fluid.

5.) Instead of a flush, some folks recommend draining and replacing the fluid multiple times. Unfortunately, (at least according to my service guy), the fluid is quite expensive and that method would be very costly.


So, in conclusion, I could find only unsupported evidence against the flush. In favor of the flush, however, my fluid was quite dark and needed changing. Also in favor of the flush was the fact that I trust my service guy.

So, I got the flush. Expensive, but perhaps worth it.

Anyone else care to contribute to the flush versus anti-flush thread?

More importantly, anyone else have the problem I described above?

cheers,
--Seth

 

[joshritger]

Thanks for the feedback Seth, I haven't changed to synthetic fluid yet because the transmission shop where I live, supposedly very reputable, said that they didn't recommend a flush. They said that it moves around debris, but my thought was well my transmission only has 15,000 miles on it, how much debris can there be in it. They wouldn't even give me a quote on changing the fluid. I also asked them about synthetic fluid and they didn't recommend it unless it specified that it was to mazda's spec, which I know now redline and amsoil are.

Hmm, what to do?

Josh

 

[sanblaster]

I mentioned that in my old 3 thread as well. Something we have to deal with.

http://www.mazdas247.com/forum/showthread.php?t=123737244

I took it in the dealership a week after I bought it and they said they didn't feel anything.

 

[sbowden99]

I mentioned that in my old 3 thread as well. Something we have to deal with.

http://www.mazdas247.com/forum/showthread.php?t=123737244

I took it in the dealership a week after I bought it and they said they didn't feel anything.

I don't think what I'm experiencing is exactly what you're experiencing, but who knows.

Here's a pic from some recent "off-roading" in Phantom Canyon, Colorado. Love the car!

 

[sbowden99]

Thanks for the feedback Seth, I haven't changed to synthetic fluid yet because the transmission shop where I live, supposedly very reputable, said that they didn't recommend a flush. They said that it moves around debris, but my thought was well my transmission only has 15,000 miles on it, how much debris can there be in it. They wouldn't even give me a quote on changing the fluid. I also asked them about synthetic fluid and they didn't recommend it unless it specified that it was to mazda's spec, which I know now redline and amsoil are.

Hmm, what to do?

Josh

It's possible that a new transmission would have more debris than an old one. My theory would be that when metal is new it has all kinds of microscopic ragged edges, and those edges gradually wear down (and shed particles) over the life of the transmission.

I think the same theory applies for new oil in a new engine. That first oil change may get rid of a substantial amount of metal particles.

However, not being an engineer, I'm just guessing. Any smart folks out there want to enlighten me?

cheers,
--Seth

 

[TheDoc]

I think it's way too soon to think it's trans-related.

I would start checking at the TPS and work from there. Make sure it's functioning properly/not getting any unexpected feedback.