First Start on Ignition & Running On Fix

Day 8/9

Well… spent all of yesterday afternoon trying to get it started after I finished looming and connecting the sensors; sorry no pictures.

Symptom were no spark, except once when it backfired. Using the TunerStudio ignition logger/tooth logger under the diagnostic tab, I ascertained that it was a trigger problem. After much cranking to look at the problem, my battery went flat. Autobarn had a special on 600, 900 & 2400 Amp jump starter packs; I opted for the 900A (I think its 450CCA) and put it to good use for the rest of the arvo.

I got real techo and pressed my DSO (Digital Storage Oscilloscope) into action. Looking at the waveforms it was very apparent the VR sensor was not sensing the missing tooth properly, in fact it was getting 2 missing teeth instead of 1, hence the MS ECU was not firing the coil pack because it was not being indexed properly i.e. 1 missing tooth 35 teeth and repeat.

Fast forward to this morning. Had a look at the VR sensor and how it was positioned. The VR sensor was slightly out by around 2.5mm in the Z /axis (looking from front of pulley Z is in out, X left/right and Y is up/down) and around 3mm in the X axis. Also re-adjusted the air-gap back to 1mm (Y axis).

Back to the diagnostic “tooth logger”, things looked a lot better, but it was getting an occasional missing tooth. I adjusted the Zero-Crossing Setpoint and Hysteresis (R56 & R52) multi-turn potentiometers in the MS ECU whilst cranking and monitoring the output of the voltage comparator U7a with the DSO, and as they say, “bingo!” a perfect waveform.

I also noticed now that the red ignition LED was lighting when cranking, so now I should be able start her up… so I thought. Screwed the spark plugs in, and gave it a crank… nothing.

Connected the DSO to one of the ignition outputs on the MS relay board (there are 2 for a wasted spark coil on a 4 cylinder engine) and it was toggling as it should. Had a look at the 12V going to the coil… not there. Looks like I blew it yesterday whilst fiddling with the wires on the Relay board.

Replaced fuse, surely (don’t call me Shirley) it will start now… nope, nothing, SFA. Brainwave, maybe I have the two coil wires transposed? Changed the wires around and then crank… Vrooooooom, Vroooooooom, it runs!

Let car warm up so I could test thermostatic fan. I’m controlling this from the MS ECU via an relay mounted on the bulkhead. Got the temp up to the turn on point (initially set to 85C with 5C hysteresis) but no fan… bugger. Looking at the voltages to the relay, it was soon apparent that I had stuffed up again. On the relay board I’m using the “Fast Idle Relay” to control my fan relay. It has a jumper that allows you to either supply 0v or 12V, for some reason I choose 0V. Removed and re-soldered link ito the 12V position. Kalamazoo, shabam, we now have a thermo fan that works under ECU control very well!

Car Running On

Nearly forgot, the car would keep running when I turned off the ignition! Long story short, I had to put a diode (1N4001) in series with the alternator ignition idiot light. I just plumbed one into the lead that went to the alternator.

What an unexpected difference the new ignition has made to the performance and ‘feel” of the car. It starts easier, seems to have more low down torque and revs more freely. I’m only using a best guess map until I can get some on the road time to tune it a little better.

Stay tuned for further updates. The car is now all wired and ready for the EFI, all I have to do is put in the EFI fuel tank along with a fuel return line, and then I’ll have a TBI Mini! Hope to do all of this in early January, so stay tuned.