hi everyone
i have a 2000' mercedes s430 (w220), i recently been having a starting problem,
when i turn the key the car sound like its going to start but it just keeps trying and it wont start

the problems only happens sometimes, and usually when it happens i have to wait about 10 minute and try to start the car again then it will start.
i noticed that the problem dosent happen when the engine is cool, (like in the morning when im about to drive to work), i think most of the times it happened i had driven the car somewhere and parked for less then 2 hours and tried to start it again.
i took it to a friend who works at the dealership and he ran it through the diagnostic system but the computer dosent show anything.
i know its NOT the Battery (changed it already) and its NOT the fuel pump (there is fuel pressure) and its not the fuel pump relay.

i tried looking all over the internet for answer's but i could'nt find anything except on one forum someone said that something like this might be caused by a bad relay but they didnt say what relay to check.
any help would be greatly appreciated

 

does it click couple times instead of starting??or it actually turns the starter but doesn't start?

 

it dosent click, the starter keep turning but it dosent start

 

i had same problem with mine, if your computer doesn't throw any codes, then you should check all your ground points for SAM's. The problem in mine was a bad ground wire for the rear SAM. Check into that and let me know what happens

 

Replace the crank sensor. most likely will be the fix.

 

Hi,
Unfortunate that no codes showing to assist you.

Problems like this are notoriously difficult to locate without an extensive investigation IF codes are not showing. Something obviously doesn't like being warm under start conditions....but doesn't mind these conditiond once going since no other symptoms are showing.

Did you change the battery AFTER or BEFORE the problem manifested itself. If the engine is cranking NORMALLY then it is VERY unlikely that the battery was at fault!

Plugs, leads, coil packs, fuel pressure, injector harness insulation, MAF, engine sensors, EIS, extraneous CAN issues (wouldn't have thought a SAM module would affect the engine high speed CAN since this is different to the Body CAN), ECU, poor connections inc ground etc etc.........could all be at fault.

Shooting from the hip I also would have the CPS Crank Position Sensor high on my list of suspects...However although this is easy to fit (on the gearbox bell housing) this costs money and maynot be the issue. These sensors are however known to give similar symptoms circa this vintage of vehicle. Your call!
I'm NOT SURE but I believe somebody stated recently that the CPS doesn't store a code when it goes partially defective.

IF the symptoms are readily repeatable you need to confirm whether the "spark" and / or "fuel pressure" are present during the NO START. (Pull HT lead and connect to spare plug during start procedure....take usual precautions to prevent electric shock from the HT!) This may help reduce the list of possibilities.

I believe your vehicle has the auto sequence start function whereby once you have turned the key you can let go and the system does (you hope) the rest. If so it is possible that the EIS Electronic Ignition Switch (which controls this sequence with a series of non replaceable internal relays) is faulty but would determine whether a spark is present during a no start first so as not to waste your money unnecessarily.

Good luck.

Stuart

 

Good write up, checking engine sensors would be a good call!

 

thanks everyone for the answer, im going to replace the crank sensor and see if that fix the problem.
ill post an update after i replace it in case someone have similar problems.
thanks again.

 

DID YOU MANAGE TO SORT THE PROBLEM OUT???

I HAVE EXACTLY THE Same problem!!! Only thing is the car cuts out while I'm driving NOW!!! Any ideas???

 

I HAVE THE SAME PROBLEM! DID YOU MANAGE TO LOCATE THE PROBLEM?