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[Migv6 le Frog Fan]

Just drove the car 200 yards and then stopped to unlock a gate and let someone out. I switched the engine off, while doing so and turned the key to restart it a minute later but no joy.
It turned over fine, but wouldn't fire. I opened the bonnet but couldn't see anything amiss, so just wiggled electrical plugs etc.
Previously today I have had a coil pack out and put it back, cleared the usual 3.2 lamda code and then washed the car.
It started fine after each of these jobs.
After a couple of minutes of trying to start it, it fired up as normal.
Plugged Maxscan reader in and it showed no codes.
Im thinking classic crank sensor problem ? Any other possibilities before I replace it.

[Andy B]

Sounds like it could be crank sensor

[TheBoy]

Or its flooded itself.

Full throttle - that's fully full throttle - crank. Injectors shouldn't fire. Then attempt normally.

[Migv6 le Frog Fan]

It had only run a short distance from cold, so possibly switching off for a minute and then on again could have flooded it ?
Will take a chance and wait and see if it happens again I think. Have a spare crank sensor in the boot so can change it in an emergency if need be.

[Nick W]

Absolutely classic symptoms/cause of flooding. That won't throw any fault codes, and if left long enough will 'cure' itself.


If you catch it quick enough, then cranking it with the throttle wide open will probably start it. My preference is not to mess about, but pull the fuel pump fuse, and while the battery is still strong crank it as above several times, replace the fuse and continue the procedure until it does start. If the plugs are nearing the end of their life, this can take a few tries. In a really bad case you'll need to remove them and dry the fuel off them; the gas stove is good for this, or a butane soldering torch. Replacing them is probably a good idea anyway.

Starting it, then turning it off straightaway 'floods' it because it is still running rich due to the cold start. If it doesn't fire on the first few turns, the plugs get too wet with fuel and don't fire. Then it's a vicious circle of more fuel making the problem worse. This can get so bad that you wash the oil from the bores, and it will sound like it has no compression.

So, I don't think you need to buy anything. But I would recommend that you leave the car running whilst opening the gate. If that means removing the gatekey from your car keyring then do it. Your ignition barrel will last longer that way too, so it's two improvements for the price of one.

[Migv6 le Frog Fan]

Key is on a different keyring, and plugs are almost new - but thanks for confirming the flooding option. 
Wont switch it off like that again when its cold. 

[Bigron]

I may be wrong, but it's my understanding that switching off when the ECU is in the middle of its start-up routine upsets and confuses it. Disconnecting the battery for a while can allow it to reset and start normally.

Ron.

[Andy B]

Key is on a different keyring, and plugs are almost new - but thanks for confirming the flooding option. 
Wont switch it off like that again when its cold. 

best to not switch off when it's 'on choke'

[Nick W]

I may be wrong, but it's my understanding that switching off when the ECU is in the middle of its start-up routine upsets and confuses it. Disconnecting the battery for a while can allow it to reset and start normally.

How does that help the unburnt fuel in the cylinders?

[Bigron]

It doesn't, but if the ECU has got ots knickers in a knot, then clearing the unburned fuel is only part of the solution.....

Ron.

[Nick W]

The ECU isn't the problem, as it's working off the coolant temp and air temp sensors(and maybe a time delay). It's operator error, turning it off before the cold start program has finished. That doesn't always lead to a flooded engine, only when it doesn't catch instantly.


I used to see this problem all the time; starting the car, moving it, and turning it off, all within a few seconds. Doing that a couple of times in a row is asking for trouble. Some engines are a complete PITA to restart, more cylinders make it worse like V8 Jags. The simplest solution is to let the engine run a little longer before switching off.

[Bigron]

I think we are saying basically the same thing, Nick. As you said - "cold start programme" - although of course flooding is also a factor. Would I argue with you?   

Ron.

[zirk]

Is this your LPG one?

[powerslinky]

The ECU isn't the problem, as it's working off the coolant temp and air temp sensors(and maybe a time delay). It's operator error, turning it off before the cold start program has finished. That doesn't always lead to a flooded engine, only when it doesn't catch instantly.


I used to see this problem all the time; starting the car, moving it, and turning it off, all within a few seconds. Doing that a couple of times in a row is asking for trouble. Some engines are a complete PITA to restart, more cylinders make it worse like V8 Jags. The simplest solution is to let the engine run a little longer before switching off.

Been there with that one when I first got an XJ8 

[Migv6 le Frog Fan]

Is this your LPG one?

Nah, a thirsty petrol only 3.2.