The old EU2-EU3 Loom modification (again!)

[aliwes]

I've read and re-read all the posts regarding the EU3-EU2 conversion on here but still have a question.

To anyone that has made/bought/borrowed or even stolen a cable to change the MEMS plugs to fit an Emerald.... Could someone please confirm if this pin layout is correct? I have made my own adapter, and confirmed that the pins correspond to this diagram but my engine will not run. It turns over and fires for a couple of seconds before stalling. As I have changed four things all at the same time (Plenum to throttle bodies, MEMS to Emerald, Wiring to EU2 and from standard 1600 injectors to cream ones), I'd like to check each one without reverting to the original set-up and putting the items in one at a time.

Thanks in anticipation!

Ali

http://www.alcester-racing-sevens.com/converter_-_soldering.htm

[david nelson]

would it be easier to find a eu 2 engine  loom?

[aliwes]

Not really. That would involve an engine bay rewire. It is quite an easy thing to make an adapter (I'm an electrical/electronic engineer by trade) - which I have already done. BUT... it does rely on reliable wiring info :-)

[The_ASH]

Do you still have an immobiliser, the engine start and run for a few seconds scenario you describe is what I remember would happen if the plipper wasn’t pressed before starting. As you’ve changed so many things this could be a red herring but worth a thought.

[aliwes]

Thanks for your input The Ash. I had considered that too but, just in case, I have disabled the immobiliser in the Emerald mapping software. I'll double check the lamp though :-)

[oilyhands]

Check that your tbs are flowing enough air, that the map is for the right injectors and that you are set up for a single coil.

Oily

[aliwes]

Cheers Dave, Even if I hold the butterflies open it still won't run. I'm running a 1.6K SS TB's map but I am set to grouped injectors and wasted spark ignition (the engine is EU3 1600).

Today I have removed the fuel rail with the injectors still wired to the harness and sat the injectors in 4 clear plastic cups to see if the injectors were actually triggering. Well, they are not!

So, immobiliser disabled, ignition turned on and fuel pump primes. Turn the engine over and the led on the Emerald turns from red to green (as it should). No fuel out of the injectors. These injectors were fine last week on the MEMS and plenum, but I have changed them, and the rail and FPR and still no joy.

I've also tried a base map for a 1.6 on plenum with a long 4-1. You guessed it... still no fuel.

I think I've tried all of the stupid things like there is fuel in the tank (1/2 full) and that the plugs and leads are all connected and that the immobiliser is disabled.

Ummmmmmmmmmmmmmmm

[revilla]

A recent similar case turned out to be the ECU / engine loom earth. Check that's clean and bolted to a suitable location (in the other case it was attached to one of the heater bolts I think!). Symptoms were the same, ECU appeared to be running happily but it could pull the injectors clean down to ground and they weren't firing.

[aliwes]

Nice one, thank you. I'll try that tomorrow and let you know. I used your most excellent wiring diagrams to wire the adapter loom so there can't be an issue there hehe

[revilla]

Don't say that... You'll jinx them

[david nelson]

Is the injector loom attached to the main engine loom? I spent hours looking for a similar issue only to find I had not concede the two plugs.

 

David

[aliwes]

Hi David, sadly it is. I have tried two fuel rails, two sets of injectors and fuel regulators to no avail. I detached (and refitted) the injector harness each time.

Keep the ideas coming please...

[revilla]

Thinking about it a bit more, if it fires up for a second or two then dies (I assume that's still the behaviour you're seeing?) then it's less likely to be the ECU earth - but check it anyway.

If there's no fuel squirting out of the injectors, I guess there are three possibilities:

1. There's no (or poor) 12V supply to the live side of the injectors.
2. There's no (or poor) ground drive to the switched side of the injectors.
3. There's no fuel pressure behind the injectors.

My initial guess would be 3. Hard to see how it would run for a bit with 1 or 2. If your fuel pump was driven to prime but not when the engine starts, it would run until the fuel pressure in the rail dropped off, then die. The fuel pump is controlled by a relay in the MFRU which is ECU controlled. MFRU internal wiring did differ EU2 to EU3 so there's the potential for something to be miss-wired in that area. 

Easiest place to probe the feed to the fuel pump without wriggling under the car is at the inertia switch on the engine bay bulkhead, assuming you have one? That's just in series with the pump, so if you remove the plug, one pin will be wired to the pump and the other is a switched 12V feed. Easy enough to rig a bulb to ground (sometimes easier to read than a voltmeter when you're trying to work the ignition switch and things at the same time).

If it's not powering the pump when the engine starts, I guess there are two likely explanations for that:

1. The ECU doesn't want to. Which would still indicate an immobiliser issue.
2. There's a wiring fault or compatibility issue around the pump and relay drive somewhere. We can worry about that once you've proved it's a fuel pump issue though.

If it is powering the pump, that leaves an electrical issue with the injectors.

As I see you're an electronic engineer, any chance of getting a scope on one of the injectors? If so, below are voltage and current traces from mine (which is apparently healthy!) for comparison. Exact values will vary between types of injectors but yours should in theory be pretty similar in terms of the key features. Inductive spike when the driver turns off is large - close to 70V in my example but could be more so you may need an attenuator to protect the scope. If they just aren't firing, something is going to look markedly different. So what you can see there is:

1. Driver turns on, pulls the switched side of the injector close to 0V.
2. Current starts to ramp up more or less linearly as the inductor is "charged" with current (you know what I mean!).
3. Driver voltage remains close to 0V - if this ramps up you have a ground impedance issue.
4. The kink in the current ramp is the "pintle hump", caused by the injector physically opening. If this is missing, it isn't opening.
5. Current ramp falls off and reaches saturation as the coil resistance starts to dominate over inductance. Should be somewhere around 0.9A peak current.
6. Driver turns off. Inductive flyback is capped by a Zener diode in the driver to protect the electronics (the flat top to the spike), in my case around 70V. Emerald may differ here.
7. Current falls sharply to zero. If it's sluggish, there's a driver fault.
8. Voltage decays back to supply voltage.
9. There's a similar "pintle hump" in the decaying voltage trace.

Does the Emerald have a configuration option for "High Impedance" or "Low Impedance / Peak & Hold" injectors? If so you want the high impedance option. The low impedance injectors use current limiting strategies in the driver electronic after initially ramping the current up fast. Not sure what the Emerald supports here, I'm used to MEMS3.

If you can work out which of the options in bold is causing the issue we can go from there.

Cheers,

Andrew