M56xS weird shifting (dead pedal)

[knelson]

Help

I have made no engine mods or exhaust, only aesthetic to my car.

recently at low speeds, 20-35 mph upon average acceleration my car seems to severely lag. All the sudden i will depress the pedal and it feels like no response at all. the power seems to stop and then all the sudden kick in. when it does finally kick in, it takes off. I was able to actually press the pedal all the way to the floor and no response at all, then after about a second or longer delay it kicks in and responds. Ive been to the dealership twice and they cant find the problem. They reset the ECM and say there's nothing wrong. At first when they reset it, the problem was corrected, but it came back in two weeks. I'm not sure what to do. The car isn't running right.

Any tips?

[knelson]

This is only in full auto mode, standard mode is fine.

[Ilya]

Mine hasn't been completely dead, but there has been a few times where I've given it 90% throttle expecting it to move like a beast and it pretends to act like a Geo Prism instead. Usually when the weather is hot. Where you from?

[knelson]

Dallas. And it is warm out, but not THAT warm. Temperature doesn't effect what's happening.

It's always between 15-30mph, feels like 2nd-3rd gear.

It's always during upshifting. It just delays for a crazy long time before responding to pedal pressure. Then it jumps.

No way this is how it's designed to perform. It's just started doing this.

[knelson]

I'm taking it to a different dealership tomorrow to see if anyone there knows what it could be.

[knelson]

I've been reading online on various forums, but it's like an endless search. Apparently this has happened to others with an X all wheel drive and it can be ecm, or traction control or torque converter. I'll tell the dealer. But weird how two trips in and they say it's driving normal.

[Ilya]

I don't think it's the torque converter. Mine was replaced by the previous owner (I have all of the cars history prior to me buying it) due to a 'shudder' upon acceleration (which I have faintly but dealer said it was fine so I have it in writing, etc.) and that's why they changed it.

[DFW2011M56S]

Dallas. And it is warm out, but not THAT warm. Temperature doesn't effect what's happening.

It's always between 15-30mph, feels like 2nd-3rd gear.

It's always during upshifting. It just delays for a crazy long time before responding to pedal pressure. Then it jumps.

No way this is how it's designed to perform. It's just started doing this.

Mine acted similar before I reflashed the ECU and TCU at work and then Uprev tuned it. Response got even better after I cleaned the cabon out of my intake ports and valves. Mine still has a delay when you downshift though. Most of the time it will be coasting along with an ulocked torque converter, when you first get on it, it locks, bogs then downshifts a couple of gears and GOES. I usually just drive in Sport mode and Paddle shift to keep it shifting when amd where I want it to. Now at 20-25 mph even in 2nd gear I tend to break the tires loose.

[knelson]

Found this thread about the issue.

m56x-hesitation-t550494.html

Problem is I think the dealer DID reset my Ecm and it seemed to fix the delay, but it came back.

I'm going to another dealer right now to talk to them.

[Snake31]

Mine delays too(M56x). I'm starting to thing torque converter is bad on mine. When in manual mode cruising in say 3rd gear at about 1.5k rpm if I punch it, the RPMs spike but the car goes nowhere for a second or two then the RPMs drop back down and the car takes off. Does anyone else experience this?

[knelson]

In standard mode I haven't noticed the delay.

In auto mode it's inconsistent, but when it DOES happen it's always 15-30mph, feels like 2nd gear.

And it has nothing to do with downshifting, it's during normal acceleration. It just goes dead. It'll be dead 1.5-2 seconds and then come back.

Once I had the pedal all the way down (floored) and it did nothing. Then kicked it.

[Snake31]

I tried to make a video of my slippage but this is hard to do while driving. I will have someone help me next time. The video can be seen at: https://youtu.be/msQLqxVFJr8
The RPMs spike for a moment then the transmission engages and the RPMs drop down. This is in manual shift mode in fourth gear.

[knelson]

That might be similar to mine. Hard to tell from the video. Mine usually occurs 15-25MPH.

It's not consistent. But when it happens, basically my car just won't shift, it delays, and then it finally keeps going. It allows me to push the pedal but no response. Multiple times I can push the pedal all the way to the floor, and nothing. I read in the thread on this site from a couple of years ago, that someone said he has time to curse at his car. Same here. It just won't go.

But I believe my car has had all the upgrades to the ecm, software, etc. and it is still doing this.

[Snake31]

Mine was slow to accelerate from a stop for a long time. It didn't seem to be running right. I found a procedure online for resetting the long term fuel trims which helped with the sluggish starts for me that felt engine related. Now my performance issues seem to be more transmission related.

Instructions for LTFT reset:

1Start engine and warm it up to normal operating temperature.
2Turn ignition switch OFF.
3Disconnect mass air flow sensor harness connectors, and restart and run engine for at least 3 seconds at idle speed.(should run rough)
4Stop engine and reconnect mass air flow sensor harness connector.
5Make sure Detected Trouble Code (DTC) P0102 is displayed.
6Erase the DTC memory.
7Make sure no codes are stored in the ECM.
8Run engine for at least 10 minutes at idle speed.

[DFW2011M56S]

I tried to make a video of my slippage but this is hard to do while driving. I will have someone help me next time. The video can be seen at: https://youtu.be/msQLqxVFJr8
The RPMs spike for a moment then the transmission engages and the RPMs drop down. This is in manual shift mode in fourth gear.

I just duplicated this about 10 times in a row. It is the torque converter coasting unlong unlocked and whem you step on the throttle, it locks shortly after. It seems that they tend to keep it locked up as much as possible.