Tq limiter 65536 and car goes in to limp. What causes this?

[Kahuna]

I have almost changed all parts around the engine, some even twice to get the car not to go into limp and throw cel when doing wot-runs. Often it happens around 5300rpm, but also close to redline. Car pull timing mostly on spool but almost never up in the rev-range. Does someone know why this would happen. Tq lim 65536 when it happens, no stutter or anything, just shuts down cyl. Mostly cyl 6, but sometimes cyl 4 or 5. Even changed the flywheel if it was false knock.
Log example here.

datazap.me | kahuna

datazap.me

Edit:
List of some things i have changed -
New Eldor coils (had new Delphi)
Ngk 97506 (tried different gaps)
New Boost control solenoid
All vacuum hoses to solenoid and checked the whole vacuum-system that holds vacuum perfect
New turbo, wastegate, dv
New Stage 2 lpfp
New fuel regulator
New valvetronic actuator
New dmf flywheel (Holds up to 1200Nm)
New 7.5" intercooler

Things i have also checked:
Pcv
Pressure tested system to 28psi
Leak-down test, both 30psi and 100psi
Compression test ,195-205 on all cylinders
Shifted the map-sensors
New n20 map sensor
Cleaned the maf-sensor
Cleaned the vanos valves
Walnut blast intake valves
New tank breather valve (leaking boost to tank)
New oilfiller cap

 

[Kahuna]

Tried a new DME and new o2 sensors last week. But it didn't help. Still shut down on cyl.6.

 

[carabuser]

I know this is an N55 but the N54 shares a lot of logic so it could help knowing the cause for an N54.

That torque limiter activates due to an error condition from the HPFP, VCV or intake valves. So maybe on an N55 that could also be related to valvetronic.

Those error conditions won't necessarily trigger an error code.

 

[carabuser]

Low pressure fuel control errors can also trigger this. What's the low pressure side looking like?

 

[Stokes]

I know this is an N55 but the N54 shares a lot of logic so it could help knowing the cause for an N54.

That torque limiter activates due to an error condition from the HPFP, VCV or intake valves. So maybe on an N55 that could also be related to valvetronic.

Those error conditions won't necessarily trigger an error code.

Thank you for sharing... I think I might be able to confirm valve-tronic also causing 65536 on an E-N55 as well. Nothing concrete yet, because I have so many other possible reasons (like factory fueling and ignition). lol

My non-definitive story:

• PS2 DCT setup with factory fueling and ignition but engine was replaced by BMW in 2015, so dual mass might be improved... could reach 24# before having 65536 limit around 5xxx rpm or right after a shift
• Upgraded to Pure750 and then was having limp limit issues at 18# boost about 5500 rpm
• Car sat for a couple months getting 1M body work finished and painted
• Picked car up and valvetronic started clicking (sensor connection failed)
• Replaced valvetronic motor/senor assembly and now can hit 23# with no issues (on 93 oct and low timing)
• Need to add some ethanol and raise timing to see how it does
• Only difference was new valvetronic unit and temperatures went up, so 23# @ 98*F could be like 18# @ 62*F.

 

[onedirty5]

Tq limit 65536 means limp mode. It doesnt specify what is causing it. Every N55 E series with DCT that I've encountered, has had this problem under high boost. Heck, I parted and sold my big turbo N55 E series DCT because there was no tuning support for this issue. Nothing that any tuner was willing to work on and decipher. I too changed many parts and tried many things. Only recently has Houtan been able to go around this issue by disabling knock detection altogether.

 

[Stokes]

I forgot about this post. I took have disabled misfire protection after 5k rpm and am pushing way more boost than I should be able to on a factory flywheel. Will get it dynoed soon to see how much on factory fuel, ignition and flywheel. Hoping to get close to 500 wheel on all that just to defy the interwebs . Lol

 

[wheela]

Tq limit 65536 means limp mode. It doesnt specify what is causing it. Every N55 E series with DCT that I've encountered, has had this problem under high boost. Heck, I parted and sold my big turbo N55 E series DCT because there was no tuning support for this issue. Nothing that any tuner was willing to work on and decipher. I too changed many parts and tried many things. Only recently has Houtan been able to go around this issue by disabling knock detection altogether.

Wow, you got rid of your e-chassis n55? Did you replace it with anything, if you don't mind my asking?

 

[CalvinNismo]

Tq limit 65536 means limp mode. It doesnt specify what is causing it. Every N55 E series with DCT that I've encountered, has had this problem under high boost. Heck, I parted and sold my big turbo N55 E series DCT because there was no tuning support for this issue. Nothing that any tuner was willing to work on and decipher. I too changed many parts and tried many things. Only recently has Houtan been able to go around this issue by disabling knock detection altogether.

Sorry to read this, your 135i looked really well set up!

 

[onedirty5]

Wow, you got rid of your e-chassis n55? Did you replace it with anything, if you don't mind my asking?

I have stuck with the N55, just moved onto the more supported M235i. Carried over most of my setup that was in the 135. Currently going through the dialing in process with tuning, but so far so good. No misfires and no false knock and that's with 24-25psi. Waiting on tuner to dial in the stfts some more and increase boost ceiling before attempting more boost. Can DM more info and video clips if interested

 

[wheela]

• Replaced valvetronic motor/senor assembly and now can hit 23# with no issues (on 93 oct and low ttiming

If you don't mind my asking, what kind of timing were you running on 93 octane and 23 psi? When I get my big turbo on, I'll be sticking with 93. I thought around 20 psi would be the limit, nice to see you were able to go higher

 

[Stokes]

If you don't mind my asking, what kind of timing were you running on 93 octane and 23 psi? When I get my big turbo on, I'll be sticking with 93. I thought around 20 psi would be the limit, nice to see you were able to go higher

I'll need to find a log to confirm, but I recall it was low like 3* ramping up to 6* at the top end. I feel more ignition timing is better than more boost, but it was a fun experiment.

I also messed with injection timing, but didn't dyno to verify a clean ignition timing log with a different injection timing was better than stock inj timing and less ignition timing.

 

[Stokes]

If you don't mind my asking, what kind of timing were you running on 93 octane and 23 psi? When I get my big turbo on, I'll be sticking with 93. I thought around 20 psi would be the limit, nice to see you were able to go higher

I recently went back to 93 octane, so here's a work in progress log. I can't believe we can run so much timing on E30 or lack of timing with 93 octane.

Log-02-28-2024-02-33-52

Uploaded by API.

www.spoolstreet.com

I don't remember how to put a log inline, so you'll have to click the link.

Also, it seems my memory was fairly accurate on timing... I target 220 load (around 22# boost).

I'm also using the M2 N55 injection timing table which is a bit more aggressive than the standard N55 table and running out of fuel at this boost level even running 93 octane and ramping up the HPFP duty cycle into the 90s.

 

[Stokes]

I recently went back to 93 octane, so here's a work in progress log. I can't believe we can run so much timing on E30 or lack of timing with 93 octane.

Log-02-28-2024-02-33-52

Uploaded by API.

www.spoolstreet.com

I don't remember how to put a log inline, so you'll have to click the link.

Also, it seems my memory was fairly accurate on timing... I target 220 load (around 22# boost).
View attachment 91779

I'm also using the M2 N55 injection timing table which is a bit more aggressive than the standard N55 table and running out of fuel at this boost level even running 93 octane and ramping up the HPFP duty cycle into the 90s.

And if you want to compare to timing on an E35 mix:
- stock LPFP,
- stock HPFP,
- stock DCT flywheel

Probably not the best example, but shows the PS2 maxed out. Running less vanos overlap than factory must have cylinder pressures to high for the E35 octane. Dropping to factory vanos would most likely clean up the correction in the top end (I have the PS2+; exhaust manifold from the pure 750 that flows much better). There's no way I could add more ethanol when running the HPFP at around 95% duty cycle already.

here's a link

Log-02-18-2024-23-08-41

Uploaded by API.

www.spoolstreet.com

I'm super happy I can run some real power with the misfire detection disabled now. One day I'll grab a 100-200 kph time.

 

[wheela]

Thanks for the follow-up on this, much appreciated!

 

[houtan]

@Kahuna did you ever figure this out? Who is your tuner?