W168 cold start problem

[area51]

I'm having trouble with starting my year 2000 A160 petrol from cold. Once started it will be ok for the rest of that day.

Cranks over fine, fires up briefly then dies. Usually restarts ok at the second attempt and settles into a fast idle but feels a bit lumpy.

The car will only start normally from cold when the throttle body can be heard initialising, high pitched whine followed by a clunk. The clunk noise almost never happens now.

Any suggestions?
Thanks

 

[mattkh]

Any suggestions?
Thanks

Pull out the relay for the fuel pump.
Put up a picture on here of the pins.
Use a very fine emery paper to clean the relay flat pins to a shine. Push back the relay.

 

[area51]

The fuel pump relay is new. Fuel pressure is a steady 3.6 bar.

 

[mattkh]

The fuel pump relay is new.

Thanks, one thing ruled out.
Now unscrew the air filter cover. Remove the cylindrical air filter. Thru the plastic mesh on the right side, you should be able to see the fiament of the air flow sensor. Attach a small plastic pipe to a can of carburettor/MAF sensor cleaner, and spray onto the filament without touching it. Let it evaporate then test and report back.

 

[area51]

Firstly, my apologies for taking so long to reply. I had to wait for a can of MAF cleaner to be delivered.

The MAF is now spotless. I've only had the opportunity to do one cold start since using the cleaner but it was a huge improvement.

Didn't try to stall, dropped off of fast idle quite quickly (to be expected with a temperature in the high 20s) and running more smoothly.

I need to do more cold starts to properly assess things but this looks promising so far.

Thank you.