RPM dip in 3/4/5 gear (AT)

[Craig]

I'll start this off with info:

FRS purchased mid august
Perrin Drop in filter installed 10/8
Zeta intake pipe installed 10/12
Car has approximately 4.2k miles on it today (12/3/12)
Car has 'crickets' and will be brought to dealership to address both that and the rear tap from the trunk

This problem has been occurring prior to both 'mods,' and I have removed them to test to see if the problem persists, and it does.

When driving in paddle mode, I find my car exhibits a strange RPM dip in 3/4/5 gear during acceleration. Example: Pull behind tractor trailer in 6th, slow down momentarily, check other lane, downshift once into fifth, then again into fourth, and proceed to accelerate into the next lane in order to overtake said truck. Whilst pulling through fourth, around 4k rpm, the car loses a noticeable amount of power, (Torque dip I presume) and the RPMs will drop anywhere from 200-500 rpms, then continue to climb as normal afterwards. This is noticed not only through watching the tachometer, but also the engine loses a noticeable amount of sound through this range.

This would also occur if I'm in slower traffic, shifting into 3rd to pass someone or pull into traffic etc.

Happens in 5th if I'm driving at a higher speed in sixth, and drop into fifth to pick up a couple MPH for whatever reason.

I attempted to take a crappy cell video of it today to show here, but traffic was s**t so I was unable to 'open her up'.

Was wondering if anyone had any idea what's going on here, also if I should bring it up when I go to have the TSB on the crickets taken care of.

Thanks ^_^

~Craig

[OrbitalEllipses]

Something similar happened to me in my WRX; I could reproduce it on the same stretch of road flawlessly. Never figured it out, but I'm interested in what you find out. Yes, my WRX was automatic.

[Craig]

Originally Posted by OrbitalEllipses

Something similar happened to me in my WRX; I could reproduce it on the same stretch of road flawlessly. Never figured it out, but I'm interested in what you find out. Yes, my WRX was automatic.

I'll be sure to post here when I find something out. Doesn't make much sense that I'd be losing RPM at all.

[Moshpit37]

Pretty sure you answered your own question: it's gotta be the torque dip. I have experienced the same issue but just assumed it was a product of that terrible torque curve and didn't think much more about it, other than "damn that torque dip sucks!"

[Craig]

Wow, that's honestly pathetic if the torque dip is that bad. I'm going to end up having to get a tune to smooth it out cause it pisses me off that much... I'm still going to bring it up at the dealership when I go in for the crickets, and if anyone else in here has any other ideas...shoot ^_^

[Lytheum]

wait so the rpms are going down while accelerating? if so that shouldnt happen. around 4k i think you should be coming out of the torque dip. around 3-4k youll notice the car doesnt have as much get up and go(rpm's will climb, but slowly)

[Freeman]

It's been my understanding that the torque dip happens from 3-4k revs.

Sent from my Nexus 7 using Tapatalk 2

[Craig]

Originally Posted by Lytheum

wait so the rpms are going down while accelerating? if so that shouldnt happen. around 4k i think you should be coming out of the torque dip. around 3-4k youll notice the car doesnt have as much get up and go(rpm's will climb, but slowly)

That's what I thought, the Torque dip shouldn't drop the RPMs. Even if I open the trottle more through this area the problem persists, so it's not an issue of throttle response, I can't imagine why the RPMs would fall during a climb unless there's an underlying issue.

[BRZranger]

I get this too if I drop one gear to overtake or pass. Whenever I pass or need to accelerate I drop two or three gears.

[Lytheum]

is it shifting back up a gear on its own?

[developer]

Maybe you have confused the ecu with your intake and filter mods. If it were me I would leave them off and reset the ecu by disconnecting the battery for 15 minutes. Then let the car idle for 15 minutes. Then drive it for about 50 miles before reassessing the RPM drop. This should allow the ecu to relearn. Good luck!

[normanb21]

My car did this a few times to me also. while accelerating in 3rd around 4k it felt like the car would cut out for a split second and then continue to accelerate. After I switched to non ethanol gasoline,(at 600miles) it has not happened since and the crickets are gone too.(now at 1400miles) Im guessing it has something to do with the USA ethanol gasoline.

[normanb21]

Forgot to add that my car has no mods and also wondering if this only happens with the auto trannys then could it be a transmission problem? Maybe some type of slippage?

[CircuitJerk]

I've had a similar experience but it's not consistent. It catches me off gaurd and I generally attribute it to the torque converter and transmission related logic programming. It's like the computer's not sure what to do and it's not in total lockup.
I think it may also have something to do with throttle position. Does that make sense?
What is the approximate throttle position?
Be interesting to get some logs. Now that I've seen this, I'm going to be more conscious of it and will look to see if I can duplicate. If so, I may run some EcuTek logs. That is, if I have time. The car will be garaged once the first snow/salt hits which could be any time now.