Volvo 2006 2.5T benzine
I want to sell a car but i have a problem:
Long engine cranking before starting (like 4-6 seconds) when cold and was sitting for a day or longer.
When it is warm was driving 2-6 hours ago its starts in 1 sec of cranking.

Here are the car problems i know:
1. Misfire Cylinder 1 - i have switched the spark plug and coil with cylinder 2 and wires seem to be good still misfire cylinder 1.
2. Rear heated oxygen sensor bank 1 - signal missing. (is it dead? i dont know. Can it be the cause of bad start?)
3. Car has LPG system When running on benzine engine rpm is stable when switching to LPG u can feel that sometimes engine misfires and slight twitch in rpm needle. (LPG is more sensitive for any problems for what i know).
4. Car seem to start better in cold air (Winter) then warm air.
5. When air is very humid and wet like fog everywhere and i start my car that has not been driving for atleast 12 hours for first 10-15 min it drives well. Then it just starts stalling and if i dont touch accelerator it just shuts down. I also get error ENGINE POWER REDUCED. If i try starting again its the same shuting down or dont even want to start...... but if i leave it for 1 hour (i assume maybe something dries up from hot engine maybe) it start good and runs good for the rest of a day.

Where do i begin to make it cheap as possible. I want to sell a car but bad starting is a price killer.

Can it be compression?
Can Crankshaft sensor be the cause? (I had once error incorrect crankshaft position during staling, I aslso have constant chek engine light on).
Injectors ? (But its the same on LPG and Benzine)

 

low fuel pressure is a common cause for long cranking on cold starts - A leaky fuel pressure regulator or check valve or a leaky injector can allow the residual fuel pressure to slowly bleed off and the car needs the extra crank time to build the pressure back up. Start by testing fuel pressure at the rail prior to the cold start, then again for a warm start. The issue may also contribute to a problem regulating fuel pressure during drive time - which will generate a random misfire CEL code. The fact that your car's driving changes with temperature suggests you may also want to test your engine's coolant temp sensor (aka ECT sensor - located under the thermostat housing cover). The rear o2 sensor is used primarily to measure the efficiency of the catalytic converter. The front sensor does the lambda control for fuel mixture - the rear compares oxygen before and after the cat to see if the cat is working properly. No signal suggests the sensor or wiring has failed but should not impact the driveability. This is a pretty straight forward repair (easy for a shop with a lift since the sensor plugs into the exhaust pipe after the cat). Nothing here seems to be very expensive (say as compared to a failed head gasket) but does require some testing and investigation to avoid replacing parts on a guess.