Awkward gear change?

Not sure if anyone has noticed this... but this problem has happened to me on numerous occasions.

After starting up the engine, I accelerate moderately. Gear jumps from 1 to 2. Around 3000RPM (or maybe a tad higher?) the dash shows gear change to 3, but suddenly my RPM drops to ~1500RPM and my Mazda 5 lurches forward! It feels like when the car reaches 3rd gear, the trans suddenly drops to 1st gear and you feel the sudden jolt, except the dash still says that I'm in 3rd gear.

It is very unnerving and I've noticed that it typically happens when I drive with a cold engine. Once the engine warms up, it seems to disappear.

Anyone else living in a winterey climate noticing this as well?

dracore said:

Not sure if anyone has noticed this... but this problem has happened to me on numerous occasions.

After starting up the engine, I accelerate moderately. Gear jumps from 1 to 2. Around 3000RPM (or maybe a tad higher?) the dash shows gear change to 3, but suddenly my RPM drops to ~1500RPM and my Mazda 5 lurches forward! It feels like when the car reaches 3rd gear, the trans suddenly drops to 1st gear and you feel the sudden jolt, except the dash still says that I'm in 3rd gear.

It is very unnerving and I've noticed that it typically happens when I drive with a cold engine. Once the engine warms up, it seems to disappear.

Anyone else living in a winterey climate noticing this as well?

Click to expand...

Sorry, I drive a manual. But that just doesn't sound like it's normal. My only thought is this...

Does anyone know if the automatics have a lockup torque converter? In what gear(s) can it lock? I notice a lot of newer cars have converters than can lock in gears other than just top gear (as used to be the case, I think). This gives the powertrain engineers the ability to 'create' the equivalent of more ratios than just the four fixed gear ratios of the transmission (an unlocked converter allows slippage and a variation of the ratio of input to output speeds, but when locked becomes a 'direct drive' 1:1 throughput for engine torque). Thus if your transmission is locking in 3rd and 4th, you might feel like you're experiencing six different ratios:

1st gear unlocked
2nd gear unlocked
3rd gear unlocked
3rd gear locked
4th gear unlocked
4th gear locked

My weak hypothesis is that your 'jerking' sensation is the torque converter locking up. Yes the transmission is staying in 3rd gear. Yes, the effective gear ratio is changing when the converter locks and engine speed is tied directly to wheel speed.

Usually this process is so smooth that it's barely noticable, and the converter locks at steady speeds and will unlock with acceleration, but that depends on how the computer is programmed.

dracore said:

Not sure if anyone has noticed this... but this problem has happened to me on numerous occasions.

After starting up the engine, I accelerate moderately. Gear jumps from 1 to 2. Around 3000RPM (or maybe a tad higher?) the dash shows gear change to 3, but suddenly my RPM drops to ~1500RPM and my Mazda 5 lurches forward! It feels like when the car reaches 3rd gear, the trans suddenly drops to 1st gear and you feel the sudden jolt, except the dash still says that I'm in 3rd gear.

It is very unnerving and I've noticed that it typically happens when I drive with a cold engine. Once the engine warms up, it seems to disappear.

Anyone else living in a winterey climate noticing this as well?

Click to expand...

Yup felt the same exact symptom as you mentioned but not sure what gear it was in ( I was making a left ).