Cranking car with plugs out
Discussion
Had a problem with car not starting, possible oiled up plug. Anyway, last time this happened, my audi technician said before he replaced with new plugs, cranked the engine over with the plugs out. Today, had the same problem after 6 months, so I replaced the plugs and nothing. Still not starting. Then I removed the plugs and cranked it a few times, replaced plugs and it fired on 3rd attempt. Now starts first time. Looked online but can't find why cranking the engine with plugs out would get the car started? Also just read that I could damage the ignition system if I crank it without plugs, what is the correct method to do this? Kind regards, Mark
Back in the days of carburetors one could clear a flooded engine by cranking with the plugs out. Not sure if you can flood a modern engine with fuel injection but I can't think of anything else that can be achieved by cranking with the plugs out.
Yes you can damage your ECU by cranking with the plugs out. The high tension spark that would have gone to the plug has to go somewhere else and there is a danger it will spike your system. The correct thing to do is to disconnect the low tension feed from the coils so that they are inoperative. This may throw up a fault light on the dash but you can clear that.
Back in the days of carbs etc that stray spark was not a major worry because there was no computer stuff in cars. However, you still needed to be careful because in certain circumstances it could do harm. For instance if you had a metal bracelet on your watch you could get burned and if you were wearing a pacemaker it could be fatal. (That still applies today)
Yes you can damage your ECU by cranking with the plugs out. The high tension spark that would have gone to the plug has to go somewhere else and there is a danger it will spike your system. The correct thing to do is to disconnect the low tension feed from the coils so that they are inoperative. This may throw up a fault light on the dash but you can clear that.
Back in the days of carbs etc that stray spark was not a major worry because there was no computer stuff in cars. However, you still needed to be careful because in certain circumstances it could do harm. For instance if you had a metal bracelet on your watch you could get burned and if you were wearing a pacemaker it could be fatal. (That still applies today)
Its always wise to remove the multiplying from the coils(s) and the injectors before cranking with the plugs out. On most after market systems, speed site 0, maximum load site is usually zero fuel to facilitate a cylinder clean out, hold foot to the boards while cranking and only air goes into the cylinders.
Dave
Dave
If only I understood that Dave! It's an audi A2, so remove lead "to" the coil or after it? Christ, don't even know where to look or what the coil looks like on this thing and renove injectors? If only it was as easy as working on my old skool TVR, i know the coil is the cylinder thing, has a distributor cap and rotor arm .......
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