Long Cranking Problem, Hard to start..
 

Ok I've searched a lot and couldnt find the exact problem with the same car that I was having. Pretty much for like a week now the car will take foreverrrr to crank. I thought it was due to the cold but the lowest it gets is around 30 degrees. It did not do this last year with lower temps. I got the battery, alternator and starter tested and the machine said it was all good.
It is seriously annoying me to have to crank the car 3-4 times for like 10 seconds each time. The engine also stumbles just before it finally starts.

The only thing I have recently done like 3-4 months ago is new spark plugs and a fuel filter both oem. The car has 68k miles.

I need help with this since I dont want to mess up my starter or something with all this cranking or get stuck somewhere :/.

CPS maybe but that is a shot in the dark but does fail often.

CPS is a good guess - If not see if the car is storing codes with an OBDII scanner. Could be dirty MAF or O2 sensors lazy. Mileage is low for O2 sensor problems. Could also be temp sensor sending wrong data to ECU & not enriching mixture adequately at cold start.

I thought the CPS only failed often on the older w203s? I haven't cleaned my MAF ever but not sure its that. What are signs of temp sensor going bad? My temp gauge works fine. I read on here that it could be some check valve in the fuel pump but I'm not sure that its relevant to my car? There is no check engine light on but ill scan it to see if there is codes.

CPS's fail on ALL Benz engines. They get cooked because of where they are mounted.

Thanks Glyn. Well last night while driving the check engine light came on. And 2 hours later when I tried to restart the car it was nearly imposible the engine kept stumbling and the rpm wouldnt go above 900. I tried to put it in gear and step on the gas but the car would just shake so I shut it off and kept trying to start it. After a few tries it turned on and function normal. This morning I scanned the codes and got P0171 and P0171 pending which it says is system too lean, bank 1. Are you still thinking its the CPS. Could it be dirty air filter? I havent changed that yet and I had to take the front tube off because the fabric thing broke so im driving without that.

I would say MAF (Mass Air Flow) sensor is the problem. Try cleaning the MAF with CRC cleaner. If that doesn't help, you may just have to buy a new MAF sensor.

i had the same issues and it was the maf

I'm trying to take out the maf to clean it but those stupid clamps they used on the plastic tube are so hard to get to with the tools I have that I just put everything back together since it was getting dark. Is there a way to test the maf?

OK I guess you can check MAF by unplugging it since car will run on default map. I unplugged it and tried to start it. It still took a while to start but started on second try.. It runs so nice even with the MAF unplugged lol.. What would happen if i just drove around without it

Take time and understand how MAF comes out of your car. At minimum, you will need to remove and clean. Worst case scenario, you will need to replace MAF. Either way, you will need to know how to remove the MAF.

I understand how the MAF comes out the car but I dont have pliers big enough to reach to take the clamp off the plastic tube that is behind the airbox. I hope I can get away with just cleaning it. These things are so expensive :X

OK - looks like we have a MAF problem if it's running OK on a default map. Clean it & go from there - might need replacement.

Ok I finally got the MAF sensor taken out and cleaned. what a PITA but the heating element on the inside of it seemed kinda dirty, looked new after cleaning it. I put everything back together and the car starts up on first try. The temperature was in the 30s. Next day I go to start the car it takes some hesitation and I have to step on the gas a bit to get the rpm to shoot up and it will catch and run perfect. Im not so sure its the MAF, I cleared the code and car is running fine once started. I do notice there seems to be like alot of oil/dirt where the cam sensors are. Not clean like in some pics on here. Could leaking cam sensors contribute to this?

Well I deff have leaking cam sensors I just unplugged them to check and there is oil in the connector. Im not sure how far along the harness it has reached but there is no sign of oil at the ecu harness connectors so thats good I guess?

You might have a dirty TB. There have been other 05s on here with that issue. Buy the adapter wires ASAP - if oil has leaked in already you might want to replace the sensors, as well.

I cleaned the throttle body few months ago when I had issues with the 12 dollar hose that broke so I doubt it got dirty again. Could I just clean the current wires with something like maf cleaner, its safe on the maf which is more sensitive than this and install the isolation wires? I still dont think this is causing the hard start. I think its more something fuel related because when i turn my key to prime the fuel pump a few times it starts better (I think0

Oil in the cam sensors can cause all sorts of crap. Especially if it has got down to the O2 sensors. Check this. Clean engine harness & fit pigtales.

When last did your car have a new fuel filter.

Hey Glyn in his first post it says he had new spark plugs and fuel filter about 3-4 months ago.

Sorry - missed that - then he may have a fuel pump getting lazy. I would sort out the oil problem first.

Thanks Glyn, I am leanin towards the fuel pump as well because now I notice that even when the engine is fully warmed up and i turn the car off come back in 10 minutes it will take forever to try. Like it turns over and just dies like its starving for fuel. And right after finally turning over I put it in gear and give it gas it shakes a bit like its going to turn off and then goes on fine. Car seems to have all the power once its running.. IF it is fuel pump which one would I replace on the left or right side under the seat?

Obviously an hpfp. oops wrong car.

I dont understand what you are talking about?

The fuel pump in MOST US cars is mounted in the fuel sender unit under the drivers side rear round cover. I would expect the main fuel delivery problem to be at full throttle but I've known fuel pumps cause starting issues so who knows without checking.

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before replacing the fuel pump, I'd suggest you to check the fuel pressure before starting the ignition and during the ignition start.