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Help Please!


stuck

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Hi all,

Need help with a new problem please.

Last night my 4.6 was running fine but now it isn't :ph34r:

When I crank the engine it starts as normal (& sounds normal) but it cuts out within a couple of seconds.

As soon as the engine has cut out I can hear the two relays click & the fuel pump prime.

Does this mean the ECU is loosing power or would it do that in the event of a stall any way?

In the few seconds that the engine is running it doesn't respond to the throttle, RPM is showing, as is manifold & coolant temperature.

Any ideas?

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The ecu should be powered whilst the ignition us on. Easy to check, put a volt meter on the 12v supply pin and see what happens.

If the engine stalls the fuel pump should run on for a few seconds then shut off until you turn the ignition off and on ready for another crank.again easy to check with a volt meter at the fuel relay output pin.

to check the throttle is working go to the tps calibration page with the ignition on but engine off and press the throttle up and down. The bar graph should go up and down smoothly.

The last time I had a problem with the engine cutting out it was a rotten fuse only letting a few volts through to the ecu. Took me hours to find as I was using am auto probe without a volt reading! Good luck!

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Was it running properly beforehand? I had the same thing with running for a couple of seconds and dieing when I was getting it running the first time. The cranking pulse was enough to get it to fire but the VE map / warmup enrichment was too lean. The other problem I had was the ecu resetting due to noise on the VR sensor wireing from the HT leads, this also killed the engine but if it had statrted it would be pretty random when it would happen.

Edit: Im not using EDIS so the last bit may not apply if you are

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Don't assume it is MS...

Physical issues crop up when MSing, but very easy to blame everything on the new bit of kit, when in reality it could be something else...

Are you sure the pump is priming after a cut out? It shouldn't prime then, but it should of course click to turn off the fuel supply.

Sounds like maybe the fuel pump relay is being incorrectly triggered somehow? i.e. only when MS is not running?

Test for this would be to run 12V directly to fuel pump, and start it.

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Scratching my head here chaps.

As above my 4.6 is starting but cuts out after a second or so, it doesn't cough & splutter it just dies as though you've turned the ignition off.

When you turn the ignition on you here the fuel pump hum for a second or so & the PWM valve click under the bonnet.

Engine starts & I have a constant 12v supply to the EDIS module & to the ECU (these are constant & aren't dropping off)

Fuel pump keeps running until a second or two after the engine dies.

TPS has been calibrated, engine is showing RPM, air temperature & coolant temperature.

Any ideas?

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I would try reloading the firmware then reload the Msq obviously making sure you have saved the Msq before rebooting the ECU... :ph34r:

Ehm,

How do I do that then?

TunerStudio is detecting version 29V is installed in the CPU at the minute but I can't see how to flash a new version of the firmware nor do I know where to find one.

Where can I find a firmware file?

Thanks for all the help.

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If you think it's fuel pressure I would check the pressure with a gauge before throwing parts at it. You can check with an oil pressure gauge if you have one. I think it should be 2.5 bar above manifold pressure.

Does it still stall if you start it with the throttle a bit open so it revs straight away?

Have you checked plugs and injectors?

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Hi Al,

The only thing I know I've done is run the engine whilst the regulator vacuum hose was dislodged, not sure if that would bugger it up or not.

I've checked the injectors as in measure the resistance, not sure what else I can check.

The engine does start & while it's running it sounds normal so I can't see it being plugs.

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