Firstly, I got my Zetec engine started on the first turn of the key yesterday, using Megasquirt, which was a great feeling!

However I'm puzzled over something going on when using the Fuel Pump Relay to power the Edis and Coilpack as recommended. Basically on power-up the relay comes on and the pumps run for the 2.5 seconds and then switches of as it should, however after another second or so the relay starts switching on and off at about 1 second intervals and the injectors click each time as well. If I start the engine before this happens then there is no problem and if I change the point where the +12V supply is picked up for the Edis/Coilpack then again there is no problem. Has anyone got any idea what is causing this?

I've asked over on msefi.com this morning but no answers so far????

Many thanks
Chris

MS1, V3 PCB, Megatune 2.25, 024s13.

Where did you get that the EDIS should be powered from the FP relay?
I have powered mine from the same switched ign supply that powers the MS.
It is common to power the lambda sensor from the FP relay.
It sounds like you may have a wiring fault somewhere.
Are you using the relay board?
It sound as though when you are connected to the FP relay you are sinking too much power from MS and it is re-setting.
I would connect the EDIS to the main MS supply relay and be sure you are not pulling other voltages down too low.
MS is not very tollerant of low voltage supply.
Below about 9V it craps out completely.

[Edited on 21-5-06 by BKLOCO]

No, I'm not using the relay board, it's all my own work.

I read that it is recommended that the Edis and coilpack are best powered by the FP relay so that during long periods of fiddling about with the MS powered up, you are not powering or damaging your edis/coilpack as it shuts it off after a couple of secons of no rpm.

Weird thing isI can use a scrap piece of wire to jumper the edis/coilpack wire to another +12V source and everything works as it should but if I put the same lead onto the FP relay output then the cycling thing starts on the next power-up. It's as if the edis is somehow triggerring the ecu to reset when the FP relay turns off or something, Weird

Chris

Chris,
I wouldn't worry about burning out the coil pack or EDIS.
My system is wired with EDIS direct to an IGN supply and I have left it switched on for over 24hrs more than once with no ill effect.
As I said it sounds like there is a volt drop somewhere associated with the FP wiring that is causing MS to re-set and fire the priming pulse each time.

I've just read your post again. I reckon it's the back emf as the FP switches off thats re setting the MS.
You could try putting a flyback diode across the fuel pump. banded end to +ve supply.
1N4001, 1N4002, 1N4004. If you don't have anything suitable give me a U2U and I'll bung something in the post.

[Edited on 21-5-06 by BKLOCO]

Thanks BKLOCO but it still does it with the fuel pumps disconnected! Like you say at the moment I'm tempted to just wire it up to the main ECU relay but it's annoying me not understanding what it is trying to do at the moment!!!

Chris

I cant help with the reason for the fault but found that when I tried to use the Tacho output from my Edis it caused the same fault. I solved it by taking a tacho output from the megajolt tacho output instead.
Paul.

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Originally posted by Chris_G
Thanks BKLOCO but it still does it with the fuel pumps disconnected! Like you say at the moment I'm tempted to just wire it up to the main ECU relay but it's annoying me not understanding what it is trying to do at the moment!!!

Chris

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quote:

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Have you just disconnected the fuel pump?
If the relay is still pulling in it could be spikes from that feeding back to pin 37 on the MS connector. Try a diode accross the relay coil.

It could also be an earthing problem. It is easy to get different earth potentials on a car, due to wire resistances. Make sure that everything pertaining to MS and the associated components is earthed as close to the battery as possible and preferably to the same point.

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Running the ignition drivers off of the fuel pump relay is more of a necessity for MS'n'S users rather than EDIS, it's to stop the possibility of the ignition output being held at an 'unsafe' place during things like code flashes. EDIS should be pretty safe though, the EDIS module is sensible enough not to fry it's coil pack and will shut down if it doesn't recieve a PIP or SAW signal.

The problem you are having is that MS relies on the EDIS module to provide it with an ignition signal to activate the fuel pump realy, and the EDIS module relies on MS activating the fuel pump relay to give it power, catch 22. MS is probably seeing a falling edge on the input from the EDIS module as it powers off, interprets this as an ignition event and activates the FPR relay again for a second (turning the EDIS module back on), doesn't see any more so turns it back off, gets another ignition event, and so on. I had a similar problem, although with my setup I wouldn't see it oscillate, I just didn't see an rpm signal at all after the ignition module had been powered off.

There is an omission in the instructions really, it should tell you that if your ignition input signal relies on the ignition module being powered then you have to run the module from a switched 12V supply not the fuel pump relay.

Hi Martyn,

Thanks for your reply and welcome aboard!

Your post is very interesting and I think you have hit the nail on the head!

I have been going round in circles a bit on this as the FPR clicking every second is also a condition occurring when there are some sofware conflicts as described HERE
That lead me to looking for the conflict with Miniterminal and then updating to the very latest firmware, but still the problem persisted.

Having read your post I have gone back to the statement made on the MSnS Set-up page which says:

"Ignition module and coil power supply
You are strongly advised to connect your ignition module and coil via the fuel pump relay so they only receive power when the engine is running. This will prevent unwanted sparks or modules overheating as you load in new code or change settings.
For EDIS and HEI7 the modules need power when the ignition is on. Any modules used as VR conditioners also need power."

I think the way the comment about the EDIS power is written is misleading and should be more like "However, for EDIS and HEI7 the modules do need power whenever the ignition is on and so should not be wired to the FPR"

Anyway, time for a minor bit of rewiring and hopefully that will see things sorted. Thanks for your help.

Chris