my M30 turbo engine/VEMS GenBoard 3.3 build page
After some piston-replacement, new turbo and cam, head studs and other slight mods, the car is running again.
I was experimenting with power shiftcut function with nice results in boost and ugly in engine internals.
I've got two broken rocker arms, intake valves hit the pistons and more interestingly exhaust valves hit intake valves.
I've got a burnt airfilter also.
I'm not sure that all this has related to powershift but very suspicious.
If you're also using powershift, please write your experience here!
Launch problems: As I'm using wasted spark, at launch I need to retard well after TDC to spool the turbo. This also means that the other plug of the coil will fire in well in the induction stroke of an opposite cylinder.
As there's no possibility to set fuel injection to the end of this stroke, sometimes it ends up in a blow-back to the intake.
How can I cure this problem? Can we develop optional use of ALS-style (igncut) launch instead of heavy retarding?
My attempts to use shift-cut always ended up in engine stall even from high rpms, and serious white smoke (excess fuel in exhaust).
I'm running the same wiring, firmware version (1.1.26) and config as last year, so it's a mistery for the moment.
Did some bench-testing on same fw+conf with another ECU. Besides the function seemed to work OK generally, there are some problems here:
If shiftcut switch is activated for more than the timing for the cut, releasing of the button _sometimes_ (no wander, depending on inputprelling) also results in a similar cut. Log: http://quasar.dynaweb.hu/%7Elezsi/bmw/200809/desk-shiftcut-test-cut_fuel_and_spark.xls
- the behaviour was changed recently (neglectnoise period after shiftcut active state), and also indefinite-long shiftcut time possible if shiftcut_time=FF
Another problem (?) that spark cut didn't happened here, however both fuel and spark cutting were enabled. It might be related to low RPM (ALS settings?)
- as logs at higher rpm showed spark cut
- yes, old behaviour was to not cut below (iac_coldRPM+launchRPM)/2 ... a shiftcut_minrpm was added recently
These made with ALS enabled, but the case is the same when it is disabled.
A config for the test: http://quasar.dynaweb.hu/%7Elezsi/bmw/200809/megasquirt200808311840.msq
Car is mapped up to 1.5-1.7bars of boost (which is reached only in 5th gear)
Got boost control also, but not in everyday use, just preparation for dyno run planned today evening.
Knock experiments made.
Details going to be here: MembersPage/GergelyLezsak/BigSixTurbo/KnockSense
Car is mapped up to 1.2-1.3 bars of boost, probably around 450 BHP on the crank.
- I've got slight missfire problem at the high-rev low-map area (50-60kPa, 3000-5000rpm), don't know the cause.
- This is know considered to be too lean lambda, which was around 1.05-1.07 -not extremely lean but maybe low compression engine doesn't tolerate it well
- Found a strange behavior with mixture: Saturday it was mapped around 0.75lambda in the high-boost area, and the same untouched map (and config) resulted ~0.95lambda monday.
- The only change I can recognize is around -15 degC difference in ambient temp. -Which was not really reflected on MAT sensor's temp.
- that suggests the MAT sensor placement is not good
- -15C is appr +5% air density. So even than, the change is too big
- It is solved, a vacuum line popped from the fuel pressure regulator. Very dangerous to have 3 bars of pressure instead of 4-4.5bars. And hard to notice as lambda and idle control corrigates values in normal cruising, no big signs of problem.
Can you check the wideband parameters? pumppw_zero and nernstdc_target (according to the values you got from WebShop via email, and maybe the values you had inside the ecu when shipped), and redo free-air calibration. Maybe misfire also contrinuted to the lean reading.
I had serious troubles with ECU #378: S259 and P259 outputs didn't work at all. INJFET and I259 seemed OK.
Lambda heater value on LCD didn't start to raise at MDE02 command. However later the sensor got hot somehow -not every time. Could this be a config problem?
- Roland reported it as a config problem which means configured Narrow-Band lambda instead of Wideband, which looks Wideband in megatune! -It can easily kill the engine if not detected. Which config variable needs to be checked?
Later I started the car with another ECU. No tuning yet.
- I plan to use MembersPage/GergelyLezsak/COP ignition
- Just another option: MembersPage/GergelyLezsak/WastedSpark
- I'll need MembersPage/GergelyLezsak/CamTrigger? to use them sequentially
- More to come...