Hydrolocked on rolling road
se7ensport - 14/5/12 at 05:25 PM
Having a very expensive day.
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, but 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 (the ECU has 8 available) 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.
ECU is off for a full inspection tomorrow, new COP ordered, having hydrolocked the engine what damage can I expect and how should I check for it?
guessing compression test, but anything else?
Description
motorcycle_mayhem - 14/5/12 at 06:13 PM
I guess you're hoping that someone will say that you haven't washed the bores with fuel and picked up on a ring, bent a rod, or experienced
similar flooding induced maladies.
I guess you either run the motor as is, watching and hoping that the engine grim reaper isn't hiding around the corner, or you have an internal
look first. I didn't see how abrupt the halt was on the crankshaft, you did.... decisions.
se7ensport - 14/5/12 at 06:21 PM
We shut down on the misfire, rather than the engine locking solid on the rollers. I have no idea how much fuel was in the cylinder while it was
running or if it filled while we had the ignition on looking to restart it.
Regarding internal look, would a boroscope down the plug hole be sufficient to show damage to bores and valves etc I'm not aware of the extent of
damage I should be looking for?
MikeRJ - 14/5/12 at 06:29 PM
If it didn't actually lock up during running, but only when you went to turn it over on the starter it's probably fine. Might want to
change the oil however.
Which ECU were you running?
se7ensport - 14/5/12 at 06:34 PM
I'm using VEMS.
mark chandler - 14/5/12 at 06:51 PM
Output transistor blew on my megasquirt ECU, it then put a full earth on the injector so full flow.
My problem was PWM not wide enough so the resistance of the injector blew the circuit, if you have blown one output the chances are the rest will
follow in short order, you need to shunt the injectors via resistors or whatever VEMs requests or open up the pulse width.
Regards Mark
MkIndy7 - 14/5/12 at 06:52 PM
quote:
Originally posted by se7ensport
We shut down on the misfire, rather than the engine locking solid on the rollers. I have no idea how much fuel was in the cylinder while it was
running or if it filled while we had the ignition on looking to
Just to pick up on this point and the blowing of the coils...
On Megasquirt the fuel pump on only runs to prime on initial startup and then stops until it sees the crank move, and the coil(s) should be fed the
same... Might be worth checking the same is/isin't/should be true for your setup.
se7ensport - 14/5/12 at 07:43 PM
quote:
Originally posted by mark chandler
Output transistor blew on my megasquirt ECU, it then put a full earth on the injector so full flow.
My problem was PWM not wide enough so the resistance of the injector blew the circuit, if you have blown one output the chances are the rest will
follow in short order, you need to shunt the injectors via resistors or whatever VEMs requests or open up the pulse width.
Regards Mark
That's interesting, I'm using large injectors which are High Impedance (~12/16 OHMs) and the PWM is low (2.7Ms at 1000 rpm) where we spent a
fair amount of time mapping.
se7ensport - 14/5/12 at 07:44 PM
quote:
Originally posted by MkIndy7
quote:
Originally posted by se7ensport
We shut down on the misfire, rather than the engine locking solid on the rollers. I have no idea how much fuel was in the cylinder while it was
running or if it filled while we had the ignition on looking to
Just to pick up on this point and the blowing of the coils...
On Megasquirt the fuel pump on only runs to prime on initial startup and then stops until it sees the crank move, and the coil(s) should be fed the
same... Might be worth checking the same is/isin't/should be true for your setup.
Pump on is set to 2.1 seconds, we may have done this twice before checking the cylinder. Injectors are 440cc, so they will have flowed a fair bit of
fuel in that time.
[Edited on 14/5/12 by se7ensport]
scudderfish - 14/5/12 at 08:16 PM
About 30cc by my BOTE calculation. Do you know the volume of the combustion chamber?
matt_gsxr - 14/5/12 at 08:48 PM
quote:
Originally posted by scudderfish
About 30cc by my BOTE calculation. Do you know the volume of the combustion chamber?
Maybe slightly more if your fuel system has rubber pipes as they expand under the pressure.
You know how you always get that squirt in the eyes when you need to open up an EFI fuel rail.
ReMan - 14/5/12 at 08:55 PM
Fingers crossed I would like to think its not actually locked up
From an anciant experience of a hydraulic lock you should be ok
Oddified - 14/5/12 at 08:55 PM
If an ecu driver has gone short circuit it doesn't matter what the programming is for injectors/igniton coils, what ever it's connected to
will be full on (or injector open) while the ignition is turned on because the ecu is no longer in control of that circuit.
If the engine just missfired and didn't go clunk/bang, it probably started misfiring and was shut down, then fill up with petrol while you were
scratching your heads!.
Ian
[Edited on 14/5/12 by Oddified]
se7ensport - 14/5/12 at 09:06 PM
quote:
Originally posted by Oddified
If an ecu driver has gone short circuit it doesn't matter what the programming is for injectors/igniton coils, what ever it's connected to
will be full on (or injector open) while the ignition is turned on because the ecu is no longer in control of that circuit.
If the engine just missfired and didn't go clunk/bang, it probably started misfiring and was shut down, then fill up with petrol while you were
scratching your heads!.
Ian
[Edited on 14/5/12 by Oddified]
That is pretty much my expectation, what I'm keen to understand is the potential damage and method of identification. Oil will be changed as
recommended and I'll compression test, in excess of that is there any other tests/checks I should carry out short of a complete engine strip?
matt_gsxr - 14/5/12 at 09:33 PM
quote:
Originally posted by se7ensport
... is there any other tests/checks I should carry out short of a complete engine strip?
You could check your credit limit.
omega 24 v6 - 14/5/12 at 11:00 PM
Personally I doubt you'll have done much engine damage. Bore wash yes and I'd change the oil and filter as a matter of course.
You could do a compression test and see if there are wildly differing results per cyl ( if the rod was bent it'd be quite minimal difference
wise, unless its REALLY BENT) or quite a bit different if the rings have gone . A leakdown test as well could be carried out.
Whatever, keep an eye on it after the ECU is back in.
MkIndy7 - 14/5/12 at 11:04 PM
If your really unsure of what the ECU is upto and don't trust it, you could always get some 12v LED's and try push the legs down the back of
the plugs for the injectors or the coils etc, then you could maybe see whats going on a little better even if it's only for your own piece of
mind
[Edited on 14/5/12 by MkIndy7]
dhutch - 15/5/12 at 08:12 AM
I wouldnt expect the injector to produce enough fuel to hydrolock a runnign engine.
- You shut it down on misfire, and then it filled up with fuel, and was lock so wouldnt start. Rather than locking while running.
Daniel
stevebubs - 15/5/12 at 08:21 AM
FWIW, my dad had a similar issue on his KV6 Rover 75; a chafed wire due to incompetent mechanic meant one of the injectors was permanently flowing. He
drove most of the way from Reading to Birmingham with it like that - sometimes losing power and then it being OK. Around Banbury, it finally conked
out. And wouldn't restart as the cylinder was filling with fuel.
We got it home using the RAC, repaired and rerouted the wire correctly and car started first time and was fine for the next 30k miles until he chopped
it in....
Bluemoon - 15/5/12 at 09:08 AM
quote:
Originally posted by dhutch
I wouldnt expect the injector to produce enough fuel to hydrolock a runnign engine.
- You shut it down on misfire, and then it filled up with fuel, and was lock so wouldnt start. Rather than locking while running.
Daniel
Ditto, think you will be fine.. Quite convinced it filled up after the engine stopped running from your description, but do what you can sensibly do
before running it up again.. To get it to lock at 4000rpm with fuel I would guess you need higher flow rate that the injectors would supply (you could
work this out if worried if you know the compression ratio of the engine)...
Cheers
Dan
