I have a problem with my IS300 Mk1 sportcross.

When I start the car, cold, in the morning, the car needs 2 or 3 crancks to start running. But it starts fine when the engine is hot. My battery is new, contacts are fine, the iginition coils are new.
I read myself throught different forums and threads on this, and this problem could have different origins. One with the fuel pump, one with some kind of special part that works for riching up the mix by cold starts, or one with the 02 censors.

How can I isolate the most possible culprit ?

 

It's not O2 sensors - those are completely out of the picture for cold starts.

A weak fuel pump, or improperly functioning engine coolant temp sensor or inlet air temp sensor are most likely.

You should get a scan tool (such as the Launch) that allows you to monitor the engine. After car sits overnight, compare ECT and IAT to actual ambient temp and make sure they agree. If not, replace the faulty ones. If those all look good, you should check fuel pressure.

 

Thank you for your kind reply. It helps me a lot and I will do exactly as you said in short.

 

I'd try cleaning the maf first..... then check your fuel pressure.