Shaking/Vibrating while Accelerating

[Eazy_B97]

I'm having some trouble with my 2006 Mazda 3S. There is inconsistent shaking/vibrating while I'm slowly accelerating. If I accelerate quickly or at high speeds, there doesn't seem to be an issue, it's only at lower speeds and generally in 4th gear. The car is a 5-speed automatic with 110km on it. The problem isn't consistent, it may happen once or twice on a 15 km drive through the city.

Any help would be appreciated

[P1TA]

Sounds like you're lugging your engine.

[stock3]

Don't worry about the lugging comment. You can't lug any modern engine mated to an automatic transmission. In fact I can't think of an old car with auto tranny that could be lugged as well.

Vibration during acceleration unfortunately could be many things. It could be motor or tranny mounts, could be torque converter shudder, could be drive shafts or CV joints. If you can't narrow down the problem yourself you have to go to a mechanic or a dealer to get this diagnosed.

[P1TA]

"Automatic"

Whoops... Shouldn't browse when tired. Ignore that

[standsideways]

Don't worry about the lugging comment. You can't lug any modern engine mated to an automatic transmission. In fact I can't think of an old car with auto tranny that could be lugged as well.

you need to rethink your comment.

i have driven enough automatic mazda 3's to know the auto lugs real good....how much experience do you have with the first gen automatic mazda3?

hell i TURBOCHARGED mine, and it could STILL lug quite a bit without downshifting automatically if i were in D, even with the extra 100HP.

:bang

and the fact that he/she said "it happens at low speeds in 4th gear" confirms it is lugging, and just needs a downshift.

[stock3]

you need to rethink your comment.

i have driven enough automatic mazda 3's to know the auto lugs real good....how much experience do you have with the first gen automatic mazda3?

hell i TURBOCHARGED mine, and it could STILL lug quite a bit without downshifting automatically if i were in D, even with the extra 100HP.

:bang

and the fact that he/she said "it happens at low speeds in 4th gear" confirms it is lugging, and just needs a downshift.

How much experience do I have with first gen 3? Oh, I don't know, about 7 years and almost 170,000 clicks. But that's beside the point, because that's not the only automatic car I had over the years. If you take a moment and read up on how the torque converter works you will understand what I mean. Just because you THOUGHT you were lugging the engine, doesn't mean it actually happened because it's impossible with TQ, knock sensors, ignition timing and computer programmed transmissions to lug an engine.
What you most likely experienced with your aftermarket turbocharger was engine knock. You can probably thank your tuner for screwing that up.

Also, I lugged few engines with manual trannys, diesels and gas, and not one of them was shaking or vibrating. So if it did not happen with a proper clutch and manual tranny, I can bet my house that the engine would not shake with torque converter and automatic transmission.