It just died for a few hours?

[Boothy]

Following a 7 hour drive to the forest of Griffin this weekend to compete in the Scotia Winch Challenge I returned home with a failure.

Problem 1 I forgot to take my spare ECU which has just been returned to me from Nige, but in panic forgot to put it spares box.....

Right 8.00am start and we're off perfect running superb (as always for the last few years) and suddenly 2 hours into comp a bit of a cough and splutter and dead, no go, check fuel pressure and yes it's fine backed up by taking pipe off rail to confirm and yes there's fuel there, checked sparking with a spare plug and it's sparking good and strong and consisitent, but no go, feel injectors and cannot feel a pulse.

The engine is spinning over fine but no a sign of life.

Long tow back to pits and check 12volt +ive and its present on injector lead. Then suddenly try it again and its running perfect.

I did not touch the ECU etc because it's sealed up in a box on the bulkhead.

Perfect for about 2 hours more without a hiccup and suddenly cough splutter and dead again, exactly the same as before.

2 hour recovery back to the pits and dead as a doornail winch it on trailer and home.

Out this morning to unload trailer and hey ho perfect, so what will stop it from injecting after a few hours of use, dry joint, component breaking down? but it only appears to be injection side only.

The only thing that could possibly be (but I doubt it) is the serial lead is always left in situ and sealed in a bag for ease of connection and 1 wire was off it's terminal and could possibly have touched something else, but if that was the case why when it was still on the pits did it suddenly start to work again with plug being moved or rattled around.

I didn't have the laptop with me for diagnostics (being used to not taking it anymore) and it's not a road going vehicle so it would be very difficult to let it run for 3 or 4 hours until it fails.

Suggestions please

I have spare ECU for a few upcoming events including King of the Valleys but want total realiability.

Thanks Guys

[zim]

for you Chris. It was a long way to go.

James even mentioned to me on Thursday to ring you to ask about taking the spare ecu, hindsight huh I'm currently running on my spare - Nige has my main.

It's too late now, but i had my laptop with me.

G

[elbekko]

How hot does it get in said sealed box?

[FridgeFreezer]

There are very few things that will kill it dead - since you didn't mention checking for sparks, or if the ECU was firing the fuel pump up or flashing LED's during cranking... I would guess VR sensor.

If the VR sensor dies (they can become intermittent with heat, a bit like ignition amps on RRC's) then the EDIS sees nothing, so no sparks, so the ECU hears nothing from the EDIS = no squirts either.

[zim]

It was sparking, we checked that.

The fuel pump was also priming which i'm assuming is controlled from the ecu like normal.

G

[Cynic-al]

i would plug in laptop and check that your getting realistic looking temperature readings incase its flooding or starving it and check the RPM is looking something like. Might be worth checking the map looks ok incase you have a leak somewhere and the TPS, mine somestimes goes full open when i've been in water and i have to press the pedal in and out to get it to work ok.

Otherwise i guess its just testing inputs & outputs or look for something mechanical. Fuel filters, air leaks etc.

[Boothy]

The spark was present when it was cranking and refusing to run as was the fuel (there's a gauge on the fuel rail and the pump was clearly heard) and to confirm this I split the pipe at a union and it certainly was present. There was also as previously stated 12 volts poitive on the injectors.

After an hour of so (on both occastions) it will run perfectly normal, as though nothing ever was wrong.

The ECU and EDIS8 are mounted on the NSF bulkhead in a waterpoof enclosure where the heater unit once lived, this has been the case for four or more years, so I don't believe it is caused by heat due to the wrong location etc, it's certainly been hotter in the past during competitions and never suffered any problems.

I have a problem where I live letting it run for long periods because of annoying the neighbours but yesterday it ran for 10 minutes or so with the laptop plugged in and all appears perfectly normal on the maps and readings etc.

It's a full on off road challenge motor and is not taxed MOT'd or insured so it's difficult to warm it up really unless there's a play day coming up.

Spare ECU is now in place and the suspect one is being posted to guess who Nige, for a looksy...

[Davecrx]

Hi

You problem sounds almost the same as what I had.

It turned out to be the Lamba sensor was overheating which then sent the ecu a signal telling it that it was running rich, the ecu responded by leaning out the fuel mixture to the point that the injectors were only just opening. Resulting in a the engine stopping and not restarting until the Lamba sensor had cooled.

I swapped the sensor and it hasn't played up at all now (touch wood)

Dave

[Bowie69]

You probably want to change the controller authority to just 5%, that won't over fuel so much then, and kill your plugs.

5% is plenty for trim using a Lambda.

[Boothy]

I actually have mine on 0 so if it gets a good dunking on a event chances are it will in a poor state anyway.

The ECU's being looked at by experts (I hope) so all should be revealed.

But thanks for airing thoughts and idea's, it keeps us all informed.

Chris