Rough iddle / engine shaking after wash

[lorensiuswlt]

Hello bimmer fellows,

I have problem with my e36 MT 1994. My car sometimes shakes like hell, like some of the plugs are dead after washing the car. Sometimes it happened right after drying and starting the car but sometimes it happened after one or two hours the car was off. The car will run normally after +/- one mile driving. Btw I didnt wash the engine bay, just a normal body wash at home with tap water. What causes the problem? Thank you.

[ultimatetester]

This issue has been discussed multiple times. Most likely your firewall cover at the left side of the engine bay (passenger side) is failing and letting water through resulting in shorting your modules.

[Eric93se]

Could also be your cowl drains that are cloggged, the excess water gets into your DME compartment and fucks with it. You should vacuum out your cowl, fix the drain problem, remove your DME and check both sides of the circuit board for oxidation damage.

[n3985]

Check the last 2 spark plug chambers for water and soak it up as needed

[lorensiuswlt]

This issue has been discussed multiple times. Most likely your firewall cover at the left side of the engine bay (passenger side) is failing and letting water through resulting in shorting your modules.

Thank you ultimatetester, i'll try to check that part.

Could also be your cowl drains that are cloggged, the excess water gets into your DME compartment and fucks with it. You should vacuum out your cowl, fix the drain problem, remove your DME and check both sides of the circuit board for oxidation damage.

Thank you Eric93se, i'll try to check that, maybe some leafs that caused that.

Check the last 2 spark plug chambers for water and soak it up as needed

Thank you n3985; i 'll check the sparks also.

[JDStrickland]

You can look into the last two plug wells to see if there is water. If yes then you can pull the plugs and turn the engine over several times to blow the water out. Actually, with one plug removed, the engine will start. Let it run for a few seconds to blow out the water, then move on to the next plug.

You don't want to take out both plugs then start because while you are taking the second plug out, the water in the first cylinder will be draining into the oil -- this is undesirable. Take a plug out and start the engine. The water that falls in will be blown out of the open spark plug hole. Repeat for the second spark plug.

The $64,000 question is, why is there water in the spark plug wells? The engine cover should prevent this. Not to mention, the hood should prevent it. If the act of washing the car fills the plug wells with water, then driving in the rain will do the same. If your washing the car with the hood raised, this is a bad plan that you should not be repeating.

[lorensiuswlt]

You can look into the last two plug wells to see if there is water. If yes then you can pull the plugs and turn the engine over several times to blow the water out. Actually, with one plug removed, the engine will start. Let it run for a few seconds to blow out the water, then move on to the next plug.

You don't want to take out both plugs then start because while you are taking the second plug out, the water in the first cylinder will be draining into the oil -- this is undesirable. Take a plug out and start the engine. The water that falls in will be blown out of the open spark plug hole. Repeat for the second spark plug.

Thanks JDStrickland. I will check the last two plugs and cowl drain for the possible causes.

The $64,000 question is, why is there water in the spark plug wells? The engine cover should prevent this. Not to mention, the hood should prevent it. If the act of washing the car fills the plug wells with water, then driving in the rain will do the same. If your washing the car with the hood raised, this is a bad plan that you should not be repeating.

LOL..i never do that, maybe that was caused by clogged cowl drain