ME7 M-Box (5120 hack and 4bar MAP) with Tial 770R's. The wastegates crack at about 22psi, so the ability to control the boost in low-throttle, high RPM situations is limited and is resulting in 17963 Charge pressure: Maximum limit exceeded. Closing the throttle plate and retarding ignition are limited mitigations, i.e I have seen 20PSI+ with ~25% throttle.

My approach so far has been to increase KFMIRL (and generate the KFMIOP inverse), in areas where I essentially cannot control boost, to something that (kind of) follows the boost profile. The result is that mimax_w has been raised to something that looks reasonable. Unfortunately, mifa_w has not come along with it which eventually results in my requested load/boost being to low. One of the torque monitor interventions in MDFAW must be limiting mifa_w.


Following from wped_w, mrfa_w is requesting enough torque. I don't have the memory address of mivbeg_w, but I don't think mivbeg_w is the problem unless there is something very strange happening with mrfa_w(mimax_w - mimin_w) as MDIMX = 99. mivbeb_w is not the problem assuming mivbeg_w is reasonable since mimax_w is not the limiting factor.

DMFABEG has a number of potential interventions.

• SAWE: Change limitation during overrun fuel cutoff and reinsertion
• DASHPOT: Change limitation with negative load changes (Dashpot)
• MISMEUS: Change limitation with fast torque intervention for operating mode changeover
• LSD: Change limitation during positive load changes (load impact evaporation)
• MDBG: Momentary gradient limitation

Only MISMEUS, LSD and MDBG seem like candidates.

• MISMEUS: Not clear to me what is happening here (and very little information). I do not have the memory address for B_mismeus. Can anyone elaborate?
• LSD: I can log B_lsd and it is 0 so not a factor.
• MDBG: KFMIFABG looks interesting, but it looks like SY_CVT = 0, so it isn't used (?). I do not have the memory address for B_mifabg. Can anyone elaborate?

Any help is greatly appreciated.

KFVPDKSD/KFVPDKSE for setting base spring pressure. Setting these properly will allow the ecu to control boost with the throttle for values under the wastegate spring pressure

If 20% throttle is not enough to prevent overboosting, I'd reconsider the wg setup :/

The turbos are set up the way Johnny recommends. This is the reality of a 20PSI WG crack pressure and my intention from the beginning of the build was to be able to make around 40PSI. I knew what I was getting into and I was aware that tuning part throttle at high RPM might be interesting, but I was expecting to be able to do more with limiting the throttle. Maybe I can do a better job of closing down the throttle, but tuning for an arbitrary torque request limit is silly.  I am really more interested in what the mystery torque intervention is.


a) rl is not much lower than rlsol.
b) See above. The configuration is no different than most Tial setups, i.e. the WG's won't start to crack until 20psi.

The forum is refusing to upload the CSV. https://drive.google.com/file/d/1ZHahZk2lD7ozHtq-y7CuqP_Lxx5cpHnu/view?usp=sharing

I appreciate you looking at them, let me know if you suspect I have done something ridiculous.

You are talking about the 710s?

As an aside, is there a way to feed the single wg n75 signal to an external wg and external dual wg solenoid?

N249 has not been deleted. I have new Forge DV's that replaced old Forge DV's during the build. I just looked and they appear to have the 15-23PSI spring instead of the 5-15PSI springs. You are likely onto something here (can't thank you enough for helping). I will replace them and report back.

The lighter spring has not helped. From the design of the Forge DV's, it is clear that a positive pressure differential in the charge path relative to the intake path will only push the valves closed. They will only open under vacuum (or if for some reason the intake path had a positive pressure differential relative to the charge path). I am not sure if 710's are also designed in this way, but from what I can tell from reading the documentation the N249 was not intended to be used as a boost limiter. Only as a turbo bypass under vacuum and re circulation coming off boost.


They do. They are quite soft (it doesn't take much vacuum to get them to compress) and those numbers are presumably an (arbitrary) conversion to boost pressure. Although, based on my comments above, I don't see why you would need a stiffer spring in the first place.

Logs: https://drive.google.com/open?id=1pcFiR09vHxvMN9J_I_kOhsEPIoFWS_7i

Haven't had a chance to look at them really closely, but on the last pull (the interesting one) I had TM 2 and it shut down the ECU. It was't immediately clear to me why.

If you install them backwards they will be held closed with spring pressure as the force from the inlet is the same as the boost force (since the throttle plate isn't a restriction).

If it is, the boost will blow it open.  As far as my understanding goes.