[4coupe440i]

I am quite new to tuning my gen 1 B58. I was under the impression running the standard MHD OTS maps are considered conservative and thus safe to run.

Currently I am running a stock engine with MHD ST1 93 map. With this map my engine gets into an overboost scenario between 3000-4000 rpm. The DME responds to this using throttle closure.

This can be seen in this log: https://datazap.me/u/mkldz/log-17005...-15-18&solo=18

Just recently I learned about LSPI. As I understand high boost at low rpm is thought to be the primary cause of LSPI.

Now my worry: is my recurring overboost scenario a possible sign/cause of imminent LSPI?

More questions:

I am about to have a catted downpipe installed, after that I plan to flash MHD ST2 93 map. Will that setup increase chance of LSPI?

What can I do to decrease my chances of LSPI (besides going back to stock map)? Does running the 91 octane map while using 93 octane fuel help in preventing LSPI?

[4coupe440i]

Anybody aware of LSPI with OTS maps?

In this Youtube video (from a respectable German engine builder/tuner) they suspect a 340i with 80000 miles running BMW's own MPPSK tune had a broken piston due to LSPI.

[M2C]

Nope. Only in case of several uncommon factors happening at the same time like too late oil changes, bad oil, bad fuel and full throttle at high gears with very low rpm etc. (all at the same time).

[4coupe440i]

As I understand I can do the following to decrease the chance of LSPI.

* regular oil changes
* use oil which addresses LSPI (spec: API SN Plus and/or GM Dexos 2)
* use high octane fuel
* prevent high load scenario's at low rpm

What I haven't been able to determine:

1) does it help to run a tuning map for a lower octane fuel? I mean: run MHD octane 91 maps instead of their octane 93 maps while using octane 93 fuel?

2) when doing a datalog run you are supposed to go full throttle in 4th gear starting from 2500rpm, is this considered a dangerous LSPI scenario?

3) my overboost issues occur in the 3000-4000 rpm range, I guess this rpm range is outside the LSPI low rpm range?


Update:
The following images suggest LSPI can occur in rpm ranges below 3000rpm.





So this seems to suggest I am safe with my overboost issues. It does seem to suggest doing datalogs starting from 2500rpm is in the LSPI zone...

[G.Newt]

LSPI is not an issue on these cars (or really most cars made in the last 20 years) unless you're in 7th/8th gear flooring it from under 2k rpm type of scenario.

Your overboost issue is caused by the tune's poor boost control.