First track event in Portland went as expected.

[magnusfeuer]

On Friday I was attending my first track event at the Portland international raceway, intent on establishing British dominance once and for all.

And how dominance was established! Once I figured out the basic lines and started honing my brake points, lesser automotive beings were dispatched at a rapid pace. The checkered flag fell as ovulating women were exposing their breasts for me on the ledgers.

All for naught. Halfway through the cool down lap the engine died.

In utter humiliation I was towed back to the pits while now menstruating women hurled used feminine products on me, turning a glorious event into just another daily experience.

Fault search is in progress. Here is the rundown, so far:

No error codes apart from barometric air pressure giving an incorrect signal.
Battery good.
Crank sensor ok - RPM registers during crank.
Cam sensor has been disconnected forever, so 360 mode.
Injectors fire - I took them out and sprayed the garage for a bit.
Ignition relay clicks.
No spark - I've checked all plugs (coil on plug), and they are dead.

While fault searching, I did find a loose ground strap that I tightened down. This means that while the ECU was grounded through its own wire, the engine and chassis did had a flaky ground connection when the car died.

I've just emailed Giles to ask if the ignition driver could have been damaged by the lack of chassis ground?"

[slomove]

Sorry to hear that. As long as all the moving parts are in their proper place you should be fine....I can tell you nothing beats the excitement of seeing a valve stem through the plug hole :)

That said, the ignition driver should not need any ground on the engine side. The coils run from +12 to the ECU driver output. But I am not sure what happens with the COP coil high voltage side and how the spark circuit is closed. E.g. with the Zetec waste spark separate ignition coil it would not matter as well. Did you check the drive side with a scope? And nothing there, none of the coils? If nothing, is it high or low dead?

[magnusfeuer]

Undocumented modifications were made to the harness when it was adapted to coil on plugs, so I will need to buzz the harness to figure out the 12 volt feed to the coils.

If the coils do have power, the T6 is blown. I will then fly down to California, sneak into Doug's house and switch ECUs with him. I'll keep you posted.

/Magnus F.

[Doug Liedblad]

I thought Giles could test and repair them?

What software engineer did the undocumented changes?

How loose was the ground strap? Falling off loose?

[magnusfeuer]

Giles can repair them, although I can probably ask our hardware designer at my office to do it as well. I've borrowed a scope to do some checks.

Adi did the changes, and I was too lazy to update the drawings.

The bold holding the strap to the engine was about 3 turns out, making the strap rattle. Fixed, with Loctite.

/Magnus F.

[magnusfeuer]

I also borrowed a $60(!) oscilloscope to check for signals to the coils.

/Magnus F.

[slomove]

I also borrowed a $60(!) oscilloscope to check for signals to the coils.

/Magnus F.

If this is a cheap and slow digital scope like the little handheld ones, you may not see the typical voltage spike every time when the drive output turns off. That baffled me for a while when I tried to find the reason for ignition problems a few months ago. This pulse (when the spark happens) is so short, a slow scope may just lose it between samples. Was a good excuse for me to buy a new scope.
But you should still see the drive "on" pulse.

If the loose ground strap interrupted the spark high voltage circuit (hard to believe though), the energy stored in the coil's magnet field can not discharge over the well defined plug gap and will backfire into the drive side, leading to a much higher voltage pulse on the drive. I have heard that may damage the ECU.

[magnusfeuer]

Excuse my ignorance. But are you talking about scoping the high-voltage pulse itself, or the signal that triggers the high-voltage pulse?

I would guess that measuring the high voltage bit would fry the scope pretty immediately.

/Magnus F.

[slomove]

Excuse my ignorance. But are you talking about scoping the high-voltage pulse itself, or the signal that triggers the high-voltage pulse?

I would guess that measuring the high voltage bit would fry the scope pretty immediately.

/Magnus F.

Yes, this is a good guess. I mean the drive side that is connected to the ECU. (Exception: if you have a separate ignition coil you can scope the high voltage side with an inductive clamp but that won't work with COP).
But for what I meant:
- When "off" the drive should be at 12V
- When "on" for the specified coil-on-time it should be under 1V
- When turning off at the end of the coil-on-time you should see a very short spike of maybe 200-400V that corresponds to the spark (which may have 30,000+ Voltson on the plug side). But as mentioned a slow scope can miss that pulse.

[magnusfeuer]

Scoped the ignition during the weekend.

12 volt feed is ok and follows ignition.

Signalling is completely dead at 0 volt. I used the very clear 12 volt feed setting as a start and then decreased timing to the micro second range, but there was no indication of life.

I've emailed Giles at Zentec to check if he can service my unit, or if he has a spare one. If that doesn't work I have a hardware designer on my team that may be able to help.

/Magnus F.

[slomove]

Well, does not sound good. But before you do something radical, I would check if you have an old fashioned short to ground in the cable or if the coil itself is burned out (no reasonable resistance). Although, thinking about it...you would need shorts to ground in all 4 cables or 4 broken coils which is kind of unlikely. But then again.... if it is not the cable you would have to burn out all 4 drive transistors in the ECU. Sounds also unlikely but it only means I have no clue what is going on.

[magnusfeuer]

Found the fault. See pic.

I've handed the unit over to one of our hardware developers at Jaguar Land Rover to see if he can fix it.. There are also 5 newly repaired T6 units coming back from England in a week or two. I will probably buy one or two of those to keep as spares.

/Magnus F.

[Doug Liedblad]

Those look to have been on FIRE, not just melted.

All from a loose ground? I will go check mine now.

[magnusfeuer]

The theory is that the gate shorted out and fed full-current 12 volt into the ignition drivers.

/Magnus F.

[Doug Liedblad]

What is the gate?