[s5s]

Hi all,

I'm having a problem with my e90 330i with N53.

After a drive, if I stop and switch the engine off, wait 5-10 minutes then try to start it,
there is a long crank and a mechanical rattle at 200rpm but ultimately after a few seconds it dies - it can't get higher than ~200rpm. If I wait another 10 or so minutes, then the engine is able to start. The longer I wait, the more likely the engine will start but usually 10-15 min is enogh. Also, if I turn the engine off and switch it back on immediately, then there are no issues - it's only if I switch the engine off, wait 5-10 minutes then I have problems starting it back up.

Spark plugs were changed 3k miles ago. The exhaust pipe has black soot on it (running rich - although this could be due to a NOX sensor issue - the previous owner had fitted a Chinese knockoff, I put an OEM + reset adaptations but I'm not sure it works correctly).

Anyway, I am almost certain this is due to fuel injectors leaking. I'm on index 7. I suspect when I switch the engine off, the residual pressure in the fuel line leaks fuel onto the spark plugs and they can't produce a spark? Waiting 10 min means the leaking has stopped because the pressure in the fuel line has dropped and the fuel on the spark plugs has evaporated so they can produce a spark.

Any thoughts on my theory? Other suspects are crankshaft position sensor, camshaft position sensor, MAF, fuel pump but given the symptoms (only happens when engine is warm and then goes away) I feel this sounds exactly like leaky injectors.

If I remove the injectors, can I clean them in any way? It wouldn't make sense to buy new ones. Otherwise, I've not had issues with the car.

[Phil325i]

I would find yourself a good indy who can read your engine's fault codes. The symptoms you have could have a number of causes. Most experiences I've read about say it's impossible to successfully clean piezo injectors. As N53 injectors are now at issue 11 and N54 (which I've successfully used in my N53) are at version 12, yours are getting old...