CELLryuu

Not sure what is wrong with my transmission, but i took the car out today to burn some of the rubber off my tires and all of a sudden it started.

I had the car in S and the traction control was on Sport. Just before redline at wot the transmission make a ridiculously bad shift. Its kind of like the transmission slips for a moment or the engine shuts off for a split second and then it shifts.

It also make a faint whining sound above 5500 rpm. could it have anything to do with the ecu tune?

any ideas?

impr

how full was your tank? I encountered a similar problem a few years ago when my tank was about 1/4 full I just gunned it and the transmission started skipping and felt like the engine was rapidly shutting down.

Anywa I took it in and they replace the fuel pump and it was fine until.. a year later now, everytime I"m at about 1/4 tank I make sure not to go WOT cuz the car starts clunking around again.

CELLryuu

full tank of gas

xtyper

How long have you had the updated V3 version of the tune? Did you ever experience anything similar before then?

CELLryuu

Ive had the v3 for a couple months and no i havent had had any problems. I did just remember that i accidentally filled up half of my tank with 87. so it is half 93 half 87. i dont think thats the problem though cause that wouldnt explain the faint whining sound?

xtyper

That roughly equates to the 91 octane us CA boys are running around with, and I've never had any issues like that. I doubt it's tune related since the general consensus seems to be that it has minimal (if any) impact to the TCU and transmission.

How many miles do you have? Although I'm sure not required at this point, you may want to consider flushing your transmission fluid. Otherwise just drive the car to see if the problem gets worse and more frequent, at which point the dealer should be able to easily diagnose and fix it.

SonnyakaPig

I hate to say it, but dealerships are weak at diagnosing these days.

I'll throw out some ideas. First, the ecu or tcu (who really knows?) shuts the engine off near redline sometimes and if you keep the throttle pinned the engine will revive itself. It can seem like a delayed shift but I think its the ecu either pulling massive timing for a moment or just killing power all together.

This can occur due to numerous reasons (I imagine). Its the ecu protecting the engine. So it may be hard to figure out what exactly caused it to happen on a given occasion. Even when this does happen there may not even be any stored codes for the event, which would be a good thing because nothing got damaged.

I suspect octane and traction are the culprits here. CA 91 octane is inconsistent as ****. The car doesn't like it. And here, part of the tank has 87 which, even when mixed with 93 may still be below 91. The ecu may be protecting the engine at high rpms at wot.

Also, regarding traction, for some reason our cars will present this strange shift event described in the OP when there is good traction. If the tires were hot and sticky maybe that contributed to the loss of power or delayed shift.

But I don't know beyond that.

BerBer63

Mine would do the same every blue moon but only in 1-2nd gear....you can't really tell what the transmission is doing tho at WOT with traction control ON. turn it off and see if it's slipping or sliding

drawde

Subscribing. I also have a faint whining sound at higher RPMs sometimes. It's very intermittent for me. I took it to the dealer, could not reproduce and I took it to an indy shop and I was driving around with the owner like a madman and was still unable to reproduce. I still get it every now and then though.

As far as the issue going WOT.. I have the same thing. I'm very excited to have someone else with the same issues I've been having. However, these did not start at the same time. I rarely drive WOT, I actually cannot remember the last time. I assumed that the "cluck" (as you referred to it) was just the ECU/TCU not being used to me driving that way and I assumed it'd go away when I stopped driving like a grandma.

SonnyakaPig

I agree, 1-2nd shift.

mthis

When this is happening does it sound like it's bouncing off the rev limited and when it shifts is it hard?

CELLryuu

ya, something like that, but its never done it before.

also, i just got back from going out for dinner and it was doing more weird stuff. under some aggressive acceleration it shifted at 3000 rpm and almost bogged. ugg. got an appointment at the dealership on Thursday, so ill let you guys know how it turns out.

mthis

You might want go put u car back to stock if u bring it to the dealer.
Good luck.

bluejae

hope you find out what's wrong... although i don't do a lot of WOT runs, i haven't run into any issues... but if it's primarily in 1-2 shift, i guess i'll test it out.

jims5

I had the same problem this year (2009 with a tune, problem at 6k miles). Shifts were 'clunky', like power was killed for a second during the shift but only at WOT. Your head would bounce forward. When cold, it would do it at partial throttle and I could make it happen. I had the whining also but didn't know it was related.
Had tune taken out, took it to the dealer and they caught a code so they rebuilt the transmission. Problem fixed and now shifts are quick and smooth. Whining went away but dealer said the noise was unrelated (strange coincidence). They replaced the 4th gear "disc", alhought it happened in the lower gears too so i don't understand it. They said disc was "burned" and "discolored". Took a week.
But now I still have the clunky shift at 1-2 WOT. Only 10-15% of the time and only WOT. No other symptoms. Dealer can't fix it since there are no codes. So far I have to live with it but I WOT quite a bit. I haven't put the tune back in yet.
I look forward to hearing what your dealer says since mine made no sense to me.

GHAZAN

I think the transmission either slips or torque limiters kick in if the shifts are "adapted" for city/traffic driving. Because if you run it 10 times at a track it might do it the 1st or 2nd run, but it won't slip on 1-2nd or any shift after it adapts. But then on some random WOT in the suburbia when your transmission is adapted for short shifting half-*** traffic shifts it'll slip up.

BTW I do only notice it mainly in cool environments when the engine is at peak power. Also more so when I go WOT from ~3k+ and not from 1k. With all this being said it has maybe happened 5 times in 3 years.

drawde

Agree with above. There's a road on my daily commute that lately I've been dropping to the lowest gear it'll let me and letting it run through multiple gears.. Every time I'd get on it and it let it shift through, shifting slowly got better and better each time. I'm thinking definitely an adapting issue.

I do still get the whine every now and then and it's annoying. Awaiting to see what the dealer says to you OP.

GMW

I have a tune and I've noticed if I switch Octane ratings when filling up the car, the transmission can initially hold the gear at the red line before changing up to the next gear, on full throttle acceleration runs. However, after one or two tankfuls of the same Octane rated fuel and a couple of full throttle runs it's as smooth as it can be....till the next time I put different Octane rated fuel in it. :-) Moral of the story is try to keep using the same Octane rated fuel all the time.

CELLryuu

thanks everyone for your input. im going into the dealership tomorrow morning and you guys have given me some extra fire power to help the service department out with my problem. lol, i need all the help i can get considering the past performances by their service department.

btw, ive been driving around pretty tame lately but have been laying into her in manual mode. things are worlds better in manual mode but there are still some hiccups. C mode the other day had a horrid shift at about 3000 rpm. wtf i said. i wasnt even trying.....i was just accelerating normal? oh well, she goes in tomorrow.

thanks again everyone

4ramin

keep us posted please and good luck

CELLryuu

ok, went to the dealership and they said that it could be a torque converter flare or needs an upgrad in the ecu. i have a tune on my car and i told them this but they said that they are unable to reflash my ecu for the upgrade because there is a firewall preventing them from accessing the programming.

does this make any sense?

propain

They are blaming the tune and don't want to touch it from what it sounds like. They should be able to flash over your tune with no problem.

drawde

OP any updates?

mdmbc63

No, I am not an expert on cars or AMG, but they are using "lingo" (that they must have heard in a movie). Embedded Devices like ECU's don't have firewalls. That's a networking concept (this is where I try not to nerd out) or actually...a fire-wall, ya know to prevent fires from spreading. Again I am not merc expert but my first inclination would be to have them document the "firewall" issue. Their reaction should speak volumes.

Mort

The file may be encrypted and/or password protected by the tuner and they don't have the password or key to break the encryption. Some tuners do this to protect their code from being read and stolen by other tuners.