Engine runs real rough when EZ display power disconnected

[Webby]

Engine running pink now has good clean supply. However problem still remains. when power to handheld pulled engine goes rough but sometimes picks up and is ok. If/when engine stalls I hear noise which sounds like relay chatter for a couple of secs then it stops. not sure which relay fuel pump or main as they are side by side in my setup. Could be bad joint in loom where earths are spliced together causing one relay or ecu to earth through handheld rather than complete system.
Will do further checks on loom. I notice that there are 2 earth wires from ecu to to splice on loom. Is there any reason for this? Would be great to get an answer even if it is to give me the name of somebody to ring to discuss problem.

[SoCal]

That sound may be injectors and not relay clatter. As an engine is in the process of stalling, it stops making vacuum and manifold pressure goes way up. To the ECU, this looks like a big increase in load. So the injectors will be open longer. At the same time, RPM is dwindling. So there will be a lot more time between injector openings. One or both of these two changes together may give the injectors an odd sound. The engine will normally be making less racket so noise from the injectors would be more noticable. The engine can seem fat upon recranking after a stall. That would fit with the notion that the noise could be the injectors going to town as the engine is stalling.

Regarding pre-squirting, you probably know that only happens at the first key-on until the engine has started one time and reset that feature. To prevent flooding. Also, with the main relay out, you won't be able to tell if the ECU did or did not pre-squirt. The relay powers the injectors. The ECU may have provided the ground side to the injectors to pre-squirt. But without power on the other side of the injectors, nothing happens.

This does not sound like relay problems to me. But if you don't trust them, you can temporarily bypass the relay(s). Remove them and use jumper wires to connect the power in to the power out. For the main relay, this will mean your injectors and O2 sensor are always powered. For the fuel pump relay, the fuel pump will always be on. Proceed with caution if you try this.

[Webby]

yeah I understand how the relay provides power to the injectors and that presquirt only happens once. I discovered that having removed the relays one of the connectors had pushed out when I replaced them, so fuel pump not running. Engine now runs but problem is still there. The buzzing noise occurs for a second or two after the engine has stalled. I can't tell if it is there whilst engine is running because of the engine noise. It does not sound anything like the presquirt clicking of the injectors. A loud buzz! too fast I would have thought for injectors cycling at 900 rpm. I guess bypassing the relays will prove one way or another if the noise is relay chatter.

[Webby]

However having stalled it is definately very fat. Difficult to start and really rough for a few secs until it clears. So it could just be injector noise. Problem just has to be an earth fault somewhere.

[Webby]

Not sure if anybody is reading this thread let alone able to help.
Problem still remains. Engine runs rough when handheld unplugged.
Main pos and neg do go direct to battery with nothing else connected. They have been tested for resistance and continuity from the neg connections at the ecu plug ie 10 & 28 resistance is negligable (0.02ohms). I have proved that the earth wire to the handheld is making the engine run clean by disconnecting the earth only from the handheld with engine running and sure enough it goes rough. What other tests can I make? At this moment I can only conclude that the ecu must be faulty in some way.

[SoCal]

In that case, maybe your next move should be sending the ECU in to be checked out.

It sounds like you've covered all the basic wiring checks.

[Webby]

Ok RMA no obtained.
But before I send back:
I will connect the handheld power lead to the exact same points as the main pos and neg ie the battery and see what happens

[FASTTECH1]

webby,
When you send in the ECU on the RMA, please send the HandHeld unit back as well. thanks

[Webby]

No difference which doesn't prove that much really.
tried measuring current through neg cables
handheld 0.12amps engine off. 0.12 engine on
ecu 0.3amps engine off. 1.3 amps engine idling.
Handheld neg wire is actually a lot shorter than ecu neg wire becuase this is rear engine car with battery in front. However battery neg wire is a lot thicker so resistance is very similar.
Might try running ecu and hand held from separate battery.

[Webby]

FASTECH1
Yes of course I can send handheld.
Can you just confirm wiring of hand held connector to ecu loom. I took plugs apart to feed through bulkhead.
ECU loom has red white and black wires handheld has red clear/screen? and black.
I have connected red to red. white to clear and black to black. is that correct?
the clear/ screen wire. If indeed it has a screen is it actually in use? How should it be connected?