M50 turbo ignition related problem , Megasquirt 2

[haCR]

Hello there guys,
i´ve been running BMW m50 turbo for two years (b20NV just for now - ive been working on m50b28) with holset hx35. The ECU is kDFi (based on MS2). I have some ignition related problems under boost for a long time, and i cant get it figured out.
After few minutes running at wot, at high RPM, and boost more than like 0.5 -0.7 bar, it start make misfires. At first - just ocational, but after a while it makes so heavy misfires that turbo isnt able to make presure at all. After i let the car cool down on idle, it goes awesome for another like 2 minutes at wot in boost, but then the problem appears again.

Ignition is sequentional (COP) before that it was wastedspark. I switched to COP, because i had a feeling that my IGBT´s are overheating. IGBTs in kDFi arent BIP373´s , but some GS14C40L ones. After i changed wiring it was good for a while, but it started doing again after like a month. I dont know if they are overheating or so ? (They dont have any heatsink at all)
I use ngk bkr8eix spark plugs and before these i used bkr7e´s (problem was the same ). I rechecked grounds, wire and extra cabel to each coil to each to ground.

I think it could cause my coil pack. It sounds like overheating to me...But coils are good heatshielted from the turbo or downpipe... I ´ve checked the boots impedance, 5 of them said around 1.8-1.9 kOhm, one around 1.55kOhm , then i checked coils and all said around 0.8 - 0.9 Ohm . But ive seen some little haircracks on the coils. I´ve already tried another coil pack, but old original one aswell. But same behaviour!

In tunerstudio i have tried set up 1.5ms - 3ms of dwell. The more dwell the sonner problem occurs. Under 2ms engine dont want to go to boost. Spark duration is 1ms.

Now im thinking about to buy set of VAG coils which should gave stronger spark and have integrated igniters or set of new stock ones. Still not decided..And maybe install some heatsink to IGBT´s
Any other thoughts ? What to measure, what to check ?


Is there any MS2 (kDFi) hardware guru ? After i switched from wasted spark to COP, i had to turn on cam signal (output JS10 - which was used for tacho out to instrument rpm gauge before). So i´ve tried to reconnect to IAC1 and gauge doesnt move at all. I tried to wire a wire from ms output to motronik pin for rpm gauge, which didnt work, so i´ ve tried use a resistors and 2N2222A transistor circuit, and it doesnt work aswell.

Thank you for your help

[dkech]

hello!i have a similar build with kdfi ecu stock coils bkr7 gapped to 0.022 and it never misfires hot or cold,can you send me your map,maybe i can help if the problem is not mechanical related

[someguy2800]

That does sound like the coil IGBT's are overheating but its strange that they would be overheating with coil on plug. The old IGBT's they used on megasquirt about 10 years ago used to have the same behavior when they would get hot but that was only when running a single coil with alot of dwell.

For your tach circuit were you using 5 volts or 12 volts with the transistor?

[dburt86]

First thing i would do is record a composite log and see if the crank circuit gets any errors. You could be correct on something over heating, but it may be the crank pick up and not the drivers.

[haCR]

Sorry for my late answer. So i did some changes. I instaled small heatsinks on the ignitors and i changed coils + boots for another pack and for a while it worked like a charm. When is huge rain in space of the 6th (5th) sparkplug water appears and the car missfires. After i clean and dry it sometimes it runs ok, sometimes still start to make misfires.

I will send you my map in a minute.

And for the tacho circuit. Should it be 5V or 12V ? 12V i guess. Is there possible to wire a wire straight from the rpm sensor to instrument cluster (bridge the ECU)? Or what pin from the ECU i should use to make it work? What is the stock circuit in stock motronic for the tacho ?
I found just this circuit, but i dont know where to take +12V ignition wire :
http://msextra.com/doc/ms1extra/MS_E.../LowVTacho.GIF

Thanks for your help

[haCR]

hello!i have a similar build with kdfi ecu stock coils bkr7 gapped to 0.022 and it never misfires hot or cold,can you send me your map,maybe i can help if the problem is not mechanical related

HERE is the video of the problem : https://youtu.be/wYIQd0QFc80
Here is my log from the last ride(take a look on the boost areas above 170-180kPa): http://s000.tinyupload.com/?file_id=...14005261289988
HERE IS MY TUNE FILE: http://s000.tinyupload.com/?file_id=...38331927718548


Last few thoughts that came to my mind, what could be wrong:
-Poor quality of E85 - water in e85 or sthg like that
-Some noises at boost levels to rpm signal or so - i have noise filters off
-Small boost leak - unllikely, maybe around BOV
-broken map senzor

If you take a look on it dkech or the others i would really appreciate it
Thanks

[haCR]

Small update. Temp gauge is working, I´ve bridged the electrical circuit from pin JS10 to IAC2 and it worked.

But my main problem is still here. When i went on a ride when the weather was sunny and warm engine went ok, but at night, 10degrees colder air, car behave exactly bad as ive described.

When i´ve reduce boost using MBC to 0,6 - 0,7bar, car went allright