Something blew causing injector to stay open hydrolocking engine

[se7ensport]

My ECU is off to Rob for a check over following an incident on a rolling road earlier. 

About 3hours in to a rolling road session, ignition is complete and getting towards the top end of the fuel table, we had just mapped 4000rpm and were halfway through 4500 when the engine stuttered and the car died. The mechanic shut the engine down immediately, we tried to restart but engine wouldn't turn, strangely we could hear a bubbling sound, taking the plugs out number 1 cylinder was full of fuel.

Looks as though a circuit blew on the ECU keeping the injector open, so we span the engine with the plugs out to clear the fuel and changed to another injector circuit and went to re-start. At this point the smoke decided to escape from coil number 2, something is definitely wrong with the ECU as its putting out a constant 12volts to just one coil. Having no spare smoke available we called it a day and I took a low loader home.

As I'm running large injectors on a low PW will this have put additional load on the circuit causing it to blow?  The injectors are 440CC High Impedance (~12/16 OHMs) on a 2.0 Duratec, at 1000rpm the PW is 2.7Ms.

http://vems.hu/vemstune/sharingcenter/reports.php?cmd=view&key=79IcbX

[Denmark]

I have had the same problem with one injector fet blowing on a Car that is getting used hard, this have happend 3 times and the last time i changed All injectorfets for ign fets, and the problem have not happend since

/Skassa

[se7ensport]

That's interesting, does changing to ign fets change have an impact on any of the VE map i.e. increased or decreased resistance meaning PW would need to change?

[Denmark]

The one i made did not need a change on the ve table , and its still going strong for even more hard use,
And for longer time now that ever, so i belive the problem vent away when the All Got changed to ign fets

[billman]

I had a rich running issue last weekend and also considering posibilities (checked FPR ect) and now I came across this.

Car is an RS2 running VEMS since 2008. At some time I used Siemens Deka 630 injectors (idling at 1.5ms).

Can you post what parts did you used?

How can I test if the injectors are working with the test mode? schwitch fuel pump off, choost test mode and then ON? Ca nI hear them clicking then?

[mattias]

billman: In case you have a check-valve at the fuel pump, it can taka quite a while and a lot of fuel in the cylinder before the fuel pressure drops.

If you have fuel injectors handy, plug those in and only press ON then OFF quickly to not overheat the solenoid.

What has been described here is when the output shorts to ground permanently, which means you will never hear a click from the solenoid, only when you power up the solenoid (turn on the ignition, typically) will you hear a click as it opens and never closes until you remove power. If you slowly insert a free injector into the connector you will feel and hear it turn on.

[mattias]

se7ensport:

If your coils died it's the same procedure, the IGBT for the coil that died is shorting to ground permanently which kills the coil pretty quickly as it gets severly cooked from the high and lasting current. Reasonably sized fuses helps a lot here, max 10 A for the common power to the coils is a good start.
Is 3.8 ms a normal ignition dwell for your coils? Seems high and when run in dual-out mode it will punish them twice as hard as far as heat load goes. If the coil dies from shorting out within itself from over-heating it can take the IGBT with it if you haven't got proper fuses in place (which is rare to have actually).

Your ECU is relatively old (sn 807), and has the old injector FETs. New ones are much harder to kill, it is said that poor grounding and flyback issues can cause the old ones to die and short out, but I'm not sure - some have lived "forever" too.

[billman]

Thanks for the reply. My ECU is sn 1441. Should I go ahead and change the Fets or leave then if I pass the test? I would not like to cause harm to the engine if simply by changing FETs I have extra safety.

[mattias]

If you pass the test I would leave it alone.

[se7ensport]

se7ensport:

If your coils died it's the same procedure, the IGBT for the coil that died is shorting to ground permanently which kills the coil pretty quickly as it gets severly cooked from the high and lasting current. Reasonably sized fuses helps a lot here, max 10 A for the common power to the coils is a good start.
Is 3.8 ms a normal ignition dwell for your coils? Seems high and when run in dual-out mode it will punish them twice as hard as far as heat load goes. If the coil dies from shorting out within itself from over-heating it can take the IGBT with it if you haven't got proper fuses in place (which is rare to have actually).

Your ECU is relatively old (sn 807), and has the old injector FETs. New ones are much harder to kill, it is said that poor grounding and flyback issues can cause the old ones to die and short out, but I'm not sure - some have lived "forever" too.

I was using one 10amp fuse when the unit froze keeping the channel open and it didn't blow instead taking out the coil.  The unit went to Rob for testing; I concluded the best option was to start again and bought a new unit number 4869.  This time I have a 5amp fuse for each COP and dwell is reduced to 2.5.  I'm having difficulty getting all ignition channels to operate in test, but that is the subject of another thread.


Alex

[se7ensport]

Back on the road, new ECU fitted and rolling road successful; 216BHP with 170lbft at the flywheel, not bad for a 2.0 Duratec with no internal mods!

[rob@vems.co.uk]

That's good news then.  And thankfully the car is ready in time for the sunny weather.