[CarJunkie]

Originally Posted by talmadge

I have a 2010 135i with 76,000 miles. Intermittently it has been hard to start. What I mean is hit the starter button and it takes a few seconds of turning over before it starts. Unfortunately this has been increasingly the case. What might be causing this? Fuel pump or maybe injectors? Also sometimes after the first start of the day I hear a quick rattle sound. Don’t hear it when I start after the car is warm.
Any ideas?
Other than this the car runs great!
FYI I replaced the plugs and coils along with the charge pipe. Running MHD stage 1.

You are in the 1M section, which will decrease your responses.

Having said that, when I had failing fuel injectors and a week HPFP, long cranking time was the most noticeable symptom. Fuel leaks out of the injectors, in the long cranking times is related to flooding of the engine. If you restart immediately after shutting off, it will start normally. If you restart a day or so after shutting off, there is no problem. My long cranks would occur when the car had sat for a few hours, got flooded, and there had not been enough time for the fuel to drain out of the cylinders yet.

For the 1M, only the fuel injectors are covered by warranty. I had to shell out money for the high-pressure fuel pump. I believe both are covered with an extended warranty on the 135.

If you use MHD, you can see if your injectors leak. Monitor Lambda bank 1 and lambda bank 2. When the engine is being overrun above about 1200 RPMs (meaning the tires are driving the engine such as when cruising down a hill in gear) the fuel should be shut off. Both lambdas should quickly go to max value (about 255) and stay there. When my injectors were failing, Lambdas would hover in the mid 100 range and move all over the place because there's a small amount of fuel still going through the system. The leaking causes flooding, because the injectors leak fuel when the engine is shut off.

I also noticed that the calculated fuel economy was much higher than actual because the computer had no idea how much fuel was actually flowing. Once the injectors were replaced, it was spot on again.