Damaged component in Q16

[habib99]

After getting very excited about the prospect of finally getting my MS'd engine running, purchasing Tuner Studio and installing a wideband O2 sensor, I've (I think caused) a new problem.

The engine stopped starting/running - will sometimes splutter with full throttle but dies out. Not being able to work out what the problem is I've looked into the MS case to find the component in Q16 not looking healthy at all:



Can anyone tell me what this component is/does and what might have caused the fault/damage? Unfortunately I can't actually read the printed data on the component because of the damage.

I guess from reading the megamanual that it is part of what drives the coil pack, but the engine still fires if full throttle is applied during cranking, the PCB is blue V3.0 and the MS chip says MSV30 BG on it (I thought it was a MS1 chip). I am willing to replace the component but am concerned that I don't really know why I blew it in the first place and it will just happen again.

Any advice would be great, thanks.

[cukali]

The reason it still fires possibly is because the curcuit may not be completely disfunctional and the extra dwell full throttle gives may allows a little spark to get through. I had the same issue, mine got very hot many times and I didn't have spark after a while. I believe I had some problems with my VR sensor and got a smaller one (was using a big VR sensor from ford) and replaced the Q16 and lowered my dwell to 2.0ms and spark output to 1.5ms and it barely gets warm and car ran fine.

[racingmini_mtl]

The 2 most likely causes are too much dwell or a wrong output polarity. Both of these will cause a lot of heat in Q16 (and your coil) which can lead to failure.

Jean

[habib99]

Thanks for the replies.

I've been in touch with the original builder - he's going to supply a replacement part (the Bosch version) and I'll solder it in and pay more attention to my Dwell and trigger settings.

How can the VR sensor or a dodgy VR connection cause this problem?

[cukali]

Thanks for the replies.

I've been in touch with the original builder - he's going to supply a replacement part (the Bosch version) and I'll solder it in and pay more attention to my Dwell and trigger settings.

How can the VR sensor or a dodgy VR connection cause this problem?

I believe, if you examine the way the ignition curcuit fires, you will notice that if the VR sensor is backwards (wrong polarity) or the teeth are actually grooves, then as engine speeds up, dwell will increase. With a varying dwell it will overheat the Q16. Now I am ONLY speculating, but my solution worked for me. Also, the VR sensor I had contained a huge magnet...this created something just shy of 200megavolts (just kidding) it really generated about 50+ volts at speed. I had to mount it far away from the wheel which gave me a poor signal. I got a very small more focused VR sensor with small magnet (BMW) and it has not caused an issue since.


There is the great possibility there is something more going on then I deduct, but like I said...my solution fixed whatever was going on.

[cukali]

Thanks for the replies.

I've been in touch with the original builder - he's going to supply a replacement part (the Bosch version) and I'll solder it in and pay more attention to my Dwell and trigger settings.

How can the VR sensor or a dodgy VR connection cause this problem?

Oh, also.. I had a Q16 on another unit arc across to the heat sink. This burned up my coil AND the Q16....make sure there is a good isolation from the Q16 to heatsink. Mine was the mica but it passed across the edge. Go figure.

[habib99]

thanks Cukali, working out why is a bit beyond me so appreciate your thoughts on it.

Interestingly I was running the VR with reversed polarity for a good few days before realising that it was why I wasn't getting a decent trigger signal - although Q16 finally failed with the polarity the correct way round.

Guess I'll be replacing the component, and I'll be much more cautious with the dwell settings (guess I will need to double check the trigger wheel decoder settings too).

[cukali]

thanks Cukali, working out why is a bit beyond me so appreciate your thoughts on it.

Interestingly I was running the VR with reversed polarity for a good few days before realising that it was why I wasn't getting a decent trigger signal - although Q16 finally failed with the polarity the correct way round.

Guess I'll be replacing the component, and I'll be much more cautious with the dwell settings (guess I will need to double check the trigger wheel decoder settings too).

Lower your dwell ans low as possible without misfires. I ran too long at 4-6 dwell and fried several Qs