Ignition problems

[Christo Atanasov]

Hi Ben,
I'm using KG engine with MAC-05A ECU, from what I know it's similar as MAC-07 used in KH engine.
I test with LED RPM and TDC sensors and all is OK.
I didn't check Hall, because I drive this car with an extra ignition system (Hall sensor, regular TCI switching unit, Coil), so I know Hall is Ok, and Coil is Ok.
So I think the only thing that was wrong is this darlington transistor mounted to the coil pack.
I found a friend with similar car and saw that on this transistor is writen HF8311A.
The problem is that I think this must be PNP transistor, because it has only 2 pins, and body of this transistor is solid grounded to the heatsink.
I found some sugest BU931 as replacement, but BU931 is NPN transistor, so I'm a little bit confused about this.
tomorow I'll try to get some info about this HF8311A from local electronic parts shop.
what I may sugest to you:
disconect Ignition booster, then connect only pin 2 of ECU to ground.
after that take some LED and connect negative to pin 2 (ground), and positive to pin 22
crank the engine and watch if it blinks. If blinks it's obvious that ECU try to fire the coil, but maybe this trigger (ignition booster) thoesn't alow this.

  ----- Original Message ----- 
  From: Ben Swann 
  To: chris at maimex.bg 
  Cc: quattro at audifans.com 
  Sent: Thursday, November 04, 2004 4:44 PM
  Subject: Re: Ignition problems


  Christo,

  What engine/ECU system are you using.  I am having (possibly similar) problem with aan MC transplant into an early GT Coupe that I have yet to resolve.  

  See for details:

  http://www.homestead.com/ben_swann/MCWiring.html

  Sounds like the pin/wiring you describe is similar as what I have outlined here.  And your problem sounds similar.  My Hall sender tested OK  - at least by the book, and I seem to have continutity on my wiring, but there is obviously a breakdown in some discrete component somewhere.

  I will be resuming trouble shooting on this next week.  I had to put this problem on the back burner since I was not able to identify the problem with the several days of testing I already did.  I'd be very interested in knowing what you find - anything to help me get this one resolved.

  Where/What is HF8311A?  Is this the darlington transistor that is mounted to the coild pack?  Something inside the ECU?   I already tried swapping both ECU and Coil Pack in my trouble shooting - both were known working units.

  Ben

  [Date: Thu, 4 Nov 2004 13:55:34 +0200
  From: "Christo Atanasov" <chris at maimex.bg>
  Subject: Re: Ignition problems
  To: "Quattro List" <quattro at audifans.com>

  just one little step.....
  last night after make some wiring work I've got a right ignition signal on pin 22 from my ECU when I ground pin 2, and connect test led between pins 2 and 22.. turn on ignition, and try to start the engine and the test led BLINKS :)))

  so at this point I have one problem - how to trigger the coil. HF8311A seems
  to be failed, so I must find a replacement. bad thing - I dosen't have an
  idea what's the spec of this HF8311A.
  Have some one changed this trigger transistor before?

  ----- Original Message -----
  From: "Ti Kan" <ti at amb.org>
  To: "Christo Atanasov" <chris at maimex.bg>
  Sent: Tuesday, November 02, 2004 10:43 PM
  Subject: Re: Ignition problems

  <snip>]