Technical 899cc Not Starting!

[Bagpuss23]

So we have purchased new coils and still no difference.

Checked the spark plugs and there resistance was way out of tolerance. So we have fitted new ones, as they were way past there due date.

But still no luck.

Even tried a spare HT lead and plug direct to earth and still new spark.

But we do have power to the primary side of the coil.

Also tried these things with the other ECU we purchased.

Anyone want to buy a P reg white Cinq with 18000 miles on the clock?????

 

[Ivan MadGyver]

The only thing left to check then is the cable harness.It might show OK with connectivity test but it can still have problems.
Been there with my motorcycle after changing and reconditioning all the ignition components and with an already rebuild cable harness.
No more suggestions to throw.
Only 18000 miles!!!!wow!!!

 

[Prawny12009]

Is the key code light going out? Fuel pump priming etc? Do your power relays test ok?

For both coils to have power but no spark or could be an ECU earth issue, check and clean all the earth points, iirc there are some down by the headlights that give problems.

 

[Prawny12009]

What make and model is your diagnostic machine?

So that others know for future reference.

 

[Bagpuss23]

The diagnostics is an Autel MaxiDAS DS708

The key light does go out after a couple of seconds of turning the key and the fuel pump primes.

The relays have been bench tested and seem to be fine. They also click when key turned.

We have cleaned all the earth points (both sides)

We have checked continuity on the earth side to the coil which showed low resistance and on cranking it switches to open circuit (which we believe to be correct, as it is coming from the pulse width modulation in the ECU)

We replaced the crank position sensor as we didn't have any fuel or spark, now we have fuel back but still no spark.

 

[Bagpuss23]

After spending some more time scratching our heads we thought we would see if we could run live data.

So we ran an individual components test, here are the results:

Injector: Pulses
Fuel Pump: Relay clicks
EVAP: Solenoid activates
Coil 1 and 2: Car tried to start - Removed a spark plug from each coil and earthed to block resulting in both coils sending a spark.

So in summary everything seems to be in working order but the ECU doesn't seem to be getting the signal to fire the plugs.

New crank position has been installed so not sure where to go next.

Any ideas??

 

[Bagpuss23]

Anyone know what the voltage should be at the Crank Sensor?

 

[Prawny12009]

Check for continuity back to the ECU plug

 

[Bagpuss23]

We have checked the continuity and everything is fine.

So we went back to the diagnostic's live data and got the below picture.

I know it's not the best picture but the engine speed comes out at 228 RPM and this is with the engine not even cranking just ignition on, then when cranking it still reads 228 RPM.

Another thing we have tried is holding the crank position sensor in 1 hand, having it plugged in, with the ignition on and waving a metal object across it (to mimic the crank pulley) and the ECU seems to receive a signal, and then click the relay then the fuel pump and the injector. But then after doing that for sometime there was only 1 random time it tried to spark.

So I'm guessing this can only really point to an earth issue.

 

[Bagpuss23]

Just thought we would give you an update on this.

So we have found a partial short to ground. Which is affecting the entire positive feed circuit. But not causing any fuses to blow!

Because of the short to ground, the signal from the crank position sensor is being disrupted.

We think the reason why it fired with the diagnostic's was because the diagnostic's was using its own positive and negative feed, so it wasn't affected by the short. Therefore, allowing the spark plug to fire perfectly.

We have chased the short around the engine bay and into the cabin, and we think we have narrowed it down to a few components, but it will still be a big job to find the actual culprit.

 

[Ivan MadGyver]

Any update on the issue?

 

[Bagpuss23]

Only real update is that it is affecting every single wire in the car, so every wire has become a positive and an earth, but no fuses blown

It's looking more live a short to ground on the permanent live but not enough amp draw to blow a fuse.

Already removed some of the dash, but it is a full dash removal and a loom strip, to locate the problem.

Got a bit on at the moment, but when we get back on it we will add an update.

 

[Prawny12009]

could be your alternator regulator or rectifier diode pack backfeeding or shorting to earth

there should be a diode and resistor in the dash to prevent a backfeed through the battery warning light too.

try disconnecting the alternator wiring

other likely culprit for backfeeds is the stereo head unit

 

[antonis132]

No just open ecu read 68hc11 chip and send it to my email, [email protected]
Immobilizer will turn off and start the engine

 

[Bagpuss23]

We have tried disconnecting the alternator and the starter motor and still get the fault.

The ECU we bought has already had the immobiliser 'deleted', so thanks, antonis132, but it isn't that.

We also thought the immobiliser was at fault but after getting a wiring diagram for it we tested the lines and that is when we found out the earth is live and the positives are also earth's!

So till we find the short he car won't start.

We are getting continuity to ground on every cable (be it a live or ground)

 

[antonis132]

Needs remove immobilizer module in the car, there is a case bad used ecu or bad immobilizer delete on used ecu. Connect through multiecuscan live data ''engine start up'' should be ''allowed''