DCT Missed Gear?

[rjsiciliano]

Alright guys I'm freaking out right now. This all happened so quickly so I will try to explain to the best of my ability. My car is a 2013 DCT 33k miles with Alpine stage 2/GTS tune.

On my way out of the gas station I pulled out and hit it full throttle in 1st. Right as I was about to hit redline I clicked the paddle to shift into 2nd. What happened next scared the shit out of me. The car slammed harder than I have ever felt and shifted into what I thought was 2nd. I thought the transmission was literally going to explode. But then instead of going into 2nd gear like normal the car missed the gear? Next thing I know the RPM's jump almost like when you money shift a manual. Then all the sudden i'm in 3rd gear and everything was normal.

Like I said this all of this happened so quickly I may have missed something but I am positive this is exactly the turn of events. WTF is wrong with my car?

[amrazM]

could just be your shift paddle or you gave it a double tap without knowing. if something was wrong with your dct youd know, this car doesnt keep secrets.

[DrFerry]

Originally Posted by rjsiciliano

Alright guys I'm freaking out right now. This all happened so quickly so I will try to explain to the best of my ability. My car is a 2013 DCT 33k miles with Alpine stage 2/GTS tune.

On my way out of the gas station I pulled out and hit it full throttle in 1st. Right as I was about to hit redline I clicked the paddle to shift into 2nd. What happened next scared the shit out of me. The car slammed harder than I have ever felt and shifted into what I thought was 2nd. I thought the transmission was literally going to explode. But then instead of going into 2nd gear like normal the car missed the gear? Next thing I know the RPM's jump almost like when you money shift a manual. Then all the sudden i'm in 3rd gear and everything was normal.

Like I said this all of this happened so quickly I may have missed something but I am positive this is exactly the turn of events. WTF is wrong with my car?

With the engine running check the voltage across the battery charging terminals under the hood and see if the alternator is charging properly. In my experience, IF the voltage regulator/alternator is going out (failing) hard shifts (and even just bumps in the road) can 'upset' the voltage regulator and the DCT can begin to shift "all on its own" as the voltage spikes and voltage interuptions play havoc with the DCT DME.

Some alternators fail spectacularly on the E9X M3 platform with intermittent power (like limp mode) reduction, ghostly shifting, clicking from underneath the DCT shifter boot and other totally odd error messages such as "Increased Emissions" and "Service Engine Soon" and "Battery Discharge/Disconnected" iDrive warning messages. The voltage across the under-hood terminals with the engine running should be about 13.4V if I recall correctly. Search "alternator failing" on this forum to find more information and symptoms. PS: Your battery could also be failing. Report back and let us know what voltage you measure across the terminals under hood when the engine is running.

[M3SQRD]

If you were at redline in 1st there could not be a large jump in rpm because there’s no lower gear (numerical higher gear) below 1st. So it could not have been something similar to a money shift to cause an over-rev condition. Any chance the engine stayed in 1st and abruptly bounced off the rev limiter before harshly selecting 2nd then 3rd OR it incorrectly selected 3rd, then did a large throttle blip to select 2nd and then suddenly shifted back to 3rd again?

[Helmsman]

Originally Posted by DrFerry

The voltage across the under-hood terminals with the engine running should be about 13.4V if I recall correctly.

Below 13.5V I'd say indicate either a very discharged or broken battery, possibly a bad alternator. Should be more like 14V or above. Reasonable charged battery, voltage will be around 14.2-14.4V, if AGM even tad more. Cold outside will add a couple of tens of volts.

[omgzirra_exe]

Originally Posted by M3SQRD

If you were at redline in 1st there could not be a large jump in rpm because there’s no lower gear (numerical higher gear) below 1st. So it could not have been something similar to a money shift to cause an over-rev condition. Any chance the engine stayed in 1st and abruptly bounced off the rev limiter before harshly selecting 2nd then 3rd OR it incorrectly selected 3rd, then did a large throttle blip to select 2nd and then suddenly shifted back to 3rd again?

I don't think the RPMs bounce off the limiter if you don't shift. In my experience, it tends to hold at maximum RPM until I shift. (DCT)

However, it could be that bad engine mounts are causing the shifts to be less crisp and smooth. The same could be said for the transmission and differential mounts. If the engine is moving around due to bad mounts, it could lead to the transmission behaving awkwardly.

so you can just jack the car up and see if the oil pan is sitting on the reinforcement plate. if it is, then your engine mounts went poof.

[rjsiciliano]

Originally Posted by DrFerry

With the engine running check the voltage across the battery charging terminals under the hood and see if the alternator is charging properly. In my experience, IF the voltage regulator/alternator is going out (failing) hard shifts (and even just bumps in the road) can 'upset' the voltage regulator and the DCT can begin to shift "all on its own" as the voltage spikes and voltage interuptions play havoc with the DCT DME.

Some alternators fail spectacularly on the E9X M3 platform with intermittent power (like limp mode) reduction, ghostly shifting, clicking from underneath the DCT shifter boot and other totally odd error messages such as "Increased Emissions" and "Service Engine Soon" and "Battery Discharge/Disconnected" iDrive warning messages. The voltage across the under-hood terminals with the engine running should be about 13.4V if I recall correctly. Search "alternator failing" on this forum to find more information and symptoms. PS: Your battery could also be failing. Report back and let us know what voltage you measure across the terminals under hood when the engine is running.

I will check this and report back

Originally Posted by M3SQRD

If you were at redline in 1st there could not be a large jump in rpm because there’s no lower gear (numerical higher gear) below 1st. So it could not have been something similar to a money shift to cause an over-rev condition. Any chance the engine stayed in 1st and abruptly bounced off the rev limiter before harshly selecting 2nd then 3rd OR it incorrectly selected 3rd, then did a large throttle blip to select 2nd and then suddenly shifted back to 3rd again?

Definitely the latter situation, there was a large throttle blip then all the sudden the car is in 3rd.

Originally Posted by omgzirra_exe

I don't think the RPMs bounce off the limiter if you don't shift. In my experience, it tends to hold at maximum RPM until I shift. (DCT)

However, it could be that bad engine mounts are causing the shifts to be less crisp and smooth. The same could be said for the transmission and differential mounts. If the engine is moving around due to bad mounts, it could lead to the transmission behaving awkwardly.

so you can just jack the car up and see if the oil pan is sitting on the reinforcement plate. if it is, then your engine mounts went poof.

Just had rod bearings done and they replaced motor mounts at the same time. Trans and Diff mounts have not been changed to my knowledge.

I am starting to think this might be a DCT fluid issue. After reading around someone reported having the same issue when their fluid was low. I cannot see any leaks but the I know for a fact it has never been changed since 2013. Thoughts?

[omgzirra_exe]

Originally Posted by rjsiciliano

I know for a fact it has never been changed since 2013. Thoughts?

if there was no sign of leaking, then it's safe to assume it's hasn't leaked. otherwise you would notice once you remove the little cover and dct overheating warnings.

although doesn't hurt to do after 10 years. $700 and a weekend.

[M3SQRD]

Originally Posted by omgzirra_exe

I don't think the RPMs bounce off the limiter if you don't shift. In my experience, it tends to hold at maximum RPM until I shift. (DCT)

However, it could be that bad engine mounts are causing the shifts to be less crisp and smooth. The same could be said for the transmission and differential mounts. If the engine is moving around due to bad mounts, it could lead to the transmission behaving awkwardly.

so you can just jack the car up and see if the oil pan is sitting on the reinforcement plate. if it is, then your engine mounts went poof.

I have two e92 M3s and one has the redline raised to 8600 rpm with a 3.62 FD DCT diff. When I drive the one with the stock redline and diff, I always get into the rev limiter because I’m used to pulling the shift paddle at about the stock redline on the car with the raised redline. The car definitely bounces off the rev limiter just like in my s2000s and e46 M3. I’ll pay closer attention the next time it happens but it definitely doesn’t feel, or sound, like it’s just holding a constant rpm rather than bouncing off the limiter.

I have PF engine mounts which raise the engine ~1/16” higher than new oem mounts.

[omgzirra_exe]

Originally Posted by M3SQRD

I have two e92 M3s and one has the redline raised to 8600 rpm with a 3.62 FD DCT diff. When I drive the one with the stock redline and diff, I always get into the rev limiter because I’m used to pulling the shift paddle at about the stock redline on the car with the raised redline. The car definitely bounces off the rev limiter just like in my s2000s and e46 M3. I’ll pay closer attention the next time it happens but it definitely doesn’t feel, or sound, like it’s just holding a constant rpm rather than bouncing off the limiter.

I have PF engine mounts which raise the engine ~1/16” higher than new oem mounts.

yeah i have a 3.45FD 8,7rpm i've never noticed it bounced it just tends to just sit at the red line.

and i rev out my car a lot so ill pay more attention.

when i hear redline i expect it to redline like my S2000 / evo / sti lol just BABPABPABPPBAPBPPBAPBAPBAPBAPBPBPAPB noises

[M3SQRD]

Originally Posted by omgzirra_exe

yeah i have a 3.45FD 8,7rpm i've never noticed it bounced it just tends to just sit at the red line.

and i rev out my car a lot so ill pay more attention.

when i hear redline i expect it to redline like my S2000 / evo / sti lol just BABPABPABPPBAPBPPBAPBAPBAPBAPBPBPAPB noises

The sound from an f20c and f22c as it bounces off the rev limiter could wake the dead!

The fuel cutoff is 100 or 200 rpm (can’t remember which it is, I think it’s 100 rpm) above redline so there’s a small window to get it to bounce off the limiter.

How do you like your 3.45 FD diff + 8700 rpm redline? I absolutely love my 3.62 FD + 8600 rpm redline. It’s by far the best mod you can do for the s65!

[omgzirra_exe]

Originally Posted by M3SQRD

The sound from an f20c and f22c as it bounces off the rev limiter could wake the dead!

The fuel cutoff is 100 or 200 rpm (can’t remember which it is, I think it’s 100 rpm) above redline so there’s a small window to get it to bounce off the limiter.

How do you like your 3.45 FD diff + 8700 rpm redline? I absolutely love my 3.62 FD + 8600 rpm redline. It’s by far the best mod you can do for the s65!

the slight pause you hear after you shift into the next gear just to repeat the rev limiter again is to die for.. before snapping an axel or breaking the ever so fragile diff on the S2K LOL.

The 3.45 FD is a great from canyons to streets to track days. If I need to tweak the gearing further, I can play with tire sizing.

On the track, I don't always rev out to 8,700 RPM. Typically, I tend to short shift around 8,300-8,400 RPM. However, on the street, I don't mind occasionally revving out to 8,700 RPM, especially when entering the highway in 1st gear.

Having that extra 3-400 RPM depending on my shift points allows me to avoid shifting up to the next gear if I'm about to brake and downshift anyways. On my local canyon roads, I usually stick to 3rd or 4th gear since I don't need to shift into higher gears with the extra revs.

for a street car is damn near perfect with a DCT. cruising RPM is a few rpm's higher but nothing crazy.

sorry for de-railing the post @ OP LOL.