Unburnt fuel = injector loom shorting, thus holding injectors open permanently; OR if you have a Marelli ignition car, the ignition system not sparking one bank of the V.
If the first, a new injector loom is absolutely needed, do not use the car until done. If the second (and please let us know) one of the Marelli ignition experts will tell you what to do. Raw fuel into the exhaust will blow out all sorts of collected carbon from the silencers.

 

The loom, although after market, is new and when i did the injector test all were kicking out the same amount of fuel, although it was hard to tell if they were injecting properly. I have tested the loom and can't see a fault on my multi-meter? As far as i can see each group of three injectors have their own earth wire totaling eight wires at the block connector. Is there a common earth further back down the main engine loom?

 

I have just re-read the thread. Please put the car's build date and details on your signature. It seems from your first post that the original symptoms have not gone away at all. Is this correct?

Assuming so, and assuming there is now a STRONG blue spark (not clear from the thread if the weak yellow spark was ever sorted) the over-fuelling could be caused by a stuck open WOT enrichment valve, a malfunctioning TPS, or far too high fuel pressure (notwithstanding your new FPR).

As after the overfilling with oil there may be loads of oil in the exhaust system and inlet manifolds, I suggest:

• Clean out the inlet manifolds and airboxes
• keep the crankcase breather disconnected for now
• remove all plugs and clean them up/change them
• check the WOT switch and its loom. It should be open (ie NOT pass current) at tickover
• check the TPS for smooth voltage change as the capstan is moved and for the correct voltage at closed throttle
• check the vac signal tube to the ECU in the boot holds vac
• if this all seems OK, borrow an ECU and see if an ECU change does anything.
• if all this checks out, measure fuel pressure in the rail.

 

Further to the above post, it is worth checking to see if you have a 6CU version of the ECU. If so, this is the early version and it is not nearly so reliable as the later 16CU - which is a direct swap requiring no changes whatsoever.

 

Geez, Digger22, can we get a Picture or two of your engine... and possible a link to a Vid (with sound) of the problem

 

That's right, still no change. As you suggested i have been checking everything again today, in search of a ground and have found the following. My after market wiring loom appears to have been wired differently to my car, even though the different coloured wires all line up. I have identified the connectors for each injector group and the pins are not in the same order on the cars loom multi pin, (by checking for a common circuit)! I have also found that in testing the cars multi pin connector, i have high resistance, which i presume is the resistor packs work, on four of the connectors. However one of the resistors seems lower (7.5)than the other three (14.6). But it gets more weird, as one group has no resistance and one has resistance on both connectors. Does this show i need a new resistor pack, before i start rewiring the injector harness, or could this be caused by a ground/short between the multi pin and the resistor pack? I have the old harness, although cut in two, and decided to replace it because the insulation was crumbling. I will put it back together to check against the new one. May be getting somewhere at last. Fantastic advise from all. I will report back.

 

Hi Jonathan, thanks for your advise. I will post a video if i have no joy with that wiring loom issue i found today. Thanks again.

 

Mmm, having put my old harness together, my new harness is the same! The odd readings i'm getting from the cars loom disappear when i disconnect the ECU. With the ECU connected i get two sets of two earth and two sets of two live connectors joined in the same circuit, although these groups make no sense, as they don't correspond to the harness in any way. Without the ECU connected there are no grounds or shorts in the loom. I don't know enough about the ECU, but i'm guessing it's shot? Its part number is DAC3062, not sure if this is the earlier or later ECU?

 

DAC3062 is the early 6CU unit.

There appears to be more and more of these units doing weird things as age creeps in.

 

Will carry out a comp test as planned, if that is Ok i will replace the ECU.

 

Can you draw a diagram of the ECU pins and wiring and show me how you are measuring the circuit.

If you measure the injector driver via the ECU pins and swap + & - meter leads the readings will change...............

Your resistance of 7.5 rather than 14.6 seems odd as 2 15ohm resistors measured in parallel will read 7.5 ohms

 

I will try and put together my test in a format I can put on here although I.T is not my thing. I disconnected my fuel pump to see if the over fuel would compensate for no pump pressure allowing her to run for a few seconds. Didn't work, she didn't start at all. I presume that means I have no overfuel after all, just poor spark? checked my coils and found my primary coil had primary resistance of 1.8 ohms, secondary winding was 7500. Is that right? Secondary coil had 2.0 in the primary, can't test the secondary? Still trying to comp test her although struggling to find one that fits.

 

That 2.0 is a tad high but not off the scale.

Leave the secondary coil unplugged from teh primary, and give it a try. The 2nd coil really only "kicks in" above about 2500rpm. The engine wills atrt and run just fine on teh primary coil only.

The expected primary for each coil is about 1.6 - 1.8, giving a 0.9ish when connected together. The module in the amp prefers under 1.0ohms, in the long term, but as a try out with that 1 coil, will do no harm.

That front coil has been known to reek havoc more so that the one in the V with all that heat, odd but fact.

 

Tried her without the 2nd one connected and no difference. Is the 7500ohm secondary winding on the primary coil a little low?

 

Sounds it, but I will dig out a coil and measure later today.

 

Ohm testing a coil is not a very effective way of verifying operation.

If the coil has been replaced then the new one might have thicker wire = less ohms or thinner wire = more ohms, but still do the job. As the turns ratio is what is important.

Try shorting your meter leads and measure the ohms of the meter cables, this will be somewhere around 0.5ohms for a good set of Fluke leads, Did you null this out before measuring the coil?

Best way to test the primary of a coil is to Measure voltage on positive terminal, then disconnect the Negative terminal and measure voltage from Negative terminal to ground, this should be the same as the positive terminal.

 

I can't draw what i'm doing well enough, so will explain. I disconnected the injector harness and by unplugging all the injectors i was able to work out which wire was the live and earth for each set of injectors at the multipin. I then disconnected the resistor pack and looked for a circuit that mirrored the injector harness on the cars injector harness multipin, if that makes sense, in an effort to find a short in the cars wiring, however this resulted in the odd result i mentioned previously. I talked to AJ6 and they don't think that result is possible without the ECU being re-wired which it hasn't been, therefore my 'test' looks irrelevant!

 

I'm all over the place with this, i'm going to test the comp as soon as i can find an adapter that fits, and if all OK i'm going to test the lot again, and while i'm comp testing i'm going to see if the spark is in time with compression as best as i can. Is there a more scientific test for that other than just trying to observe spark against comp on the gauge?

 

To find a short in a loom you MUST disconnect it at BOTH ends. If you leave it connected at the ECU you will be measuring through the ECU to ground and it should measure different continuity if you swap the leads around

 

My way for many years.

Screw in comp tester, readily available down here, and cheap enough.

I would then go back to bare bones, since the plugs are out, it will be very simple.

2 people will be handy, but its 1 person do-able.

Socket on the front crank bolt, thumb/finger over #1A plug hole, Hand rotate (clockwise only) the engine, and when the comp "pushes" the finger, STOP. Thread a soft wire probe (an opened and cut wire coat hanger is my probe), down the hole until the end sits ON the piston top, and continue rotating whilst watching the wire rise. When that rise stops, STOP rotating. You are now at TDC Compression Stroke #1A.

Look at the rotor arm, and where it is pointing. It should be pointing at the #1A post of the cap. Some caps have a #1 cast into them at this point, some dont.

If it is pointing at that position, the timing, and the distributor is deemed OK.

Look under the front of the engine at the timing plate. See if the timing marks line up with TDC, or VERY close. The timing "ring" on that pulley can slip, and that makes using it to time the engine utterly useless.

Then its simple to plug the HT leads in an Anticlockwise direction into the cap in the correct sequence.

NOT scientific, but mistimed distributors, and out of sequence V12 HT leads will drive ya to drink, and that is my VERY simplistic way of establishing a base setting to work up from.

That setting will get it running, and then the timing can be fine set by ear in the advance direction, until that "Sweet spot" is reached, usually about 12deg BTDC at idle, with all the junk plugged in, just as you will drive it anyway.