I have a 1999 c280 with a m112 v6 engine. The car has been sitting for 3 years and im trying to get it road worthy again. First let me start with the symptoms i am having. I insert the key and there is about a 3-5 second delay before the engine actually starts to crank. It is cranking over pretty healthy but still does not start. Also if i let go of the key right after it begins to crank it continues to crank on its own for about another 5 seconds and then cuts off by itself. So the long list of everything i have tried. I changed the crankshaft position sensor twice, changed the camshaft position sensor, changed the coil packs, and spark plugs, changed the fuel filter and hoses, swapped the k40 relay for one that i know works, and i even testeda different crankshaft sensor wire, still no luck. Checked for fuel pressure, which was good. Checked for Spark found the spark plugs where not getting spark. I should mention when I removed the wire for the camshaft sensor the 5 second delay before cranking went away for a while and then came back. Also when i unplug the crankshaft sensor wire the engine still cranks over the same. Is the engine supposed to crank at all without the crankshaft sensor plugged in? when i pulled the spark plugs, they had a oil residue on the plugs and on the coil wire ONLY on the passenger side of the engine, the drivers side plugs were clean.. not sure what that could be. maybe from flooding the engine from trying to start it 50+ times?? Also i should mention that i have a complete running part car with same exact motor and specs that i have been using parts off of to help solve this issue. I am led to believe it is a electrical issue but not sure where else to look. any input would help, thank you

 

adge202,
Have you scanned for any saved codes?
You've thrown alot of parts at this.

 

Battery replacement was not listed in the original post. Have you replaced the main battery, and auxiliary battery if one exists?

Crank and no start is either a fuel, spark or electronic (sensor) problem. Start with the origin of the electrical system - the battery.

 

unfortunately im not getting any codes. check engine light is not on

 

the battery is out of the equation. that was replaced as well with a brand new one. i know it has to be a electric problem but cant find it, ready to give up

 

Does this vehicle have an auxiliary battery? With the the large number of parts you have replaced, it could be you have overlooked something that you have touched already.

Start from the beginning and provide more diagnostic info. What does it do, and when. What doesn't it do, and when.

Stick with the path of why the plugs weren't getting spark. Change spark plug and coil position sequentially to see if a pattern emerges.

 

no im pretty sure the w202 chasis does not have a aux battery. well its 100% confirmed thats its not starting because of the no spark, but if its not the Crankshaft or camshaft sensor or the wiring for those sensors. where else should i check?

 

Something is not adding up.

You are getting crank and no spark, is that correct? And no codes?

Look through the ignition system again. I think you need to start from scratch again and confirm function on each system.

Do you have a code reader or a real time data display? You need data to check what is going on.

 

correct.crank no start, no spark, no codes, all i have is a cheap OBD code reader

 

just uploaded this so you can see what its doing

 

Do you smell fuel:
- after prolonged cranking?
- after prolonged cranking when removing a spark plug? Smell the spark plug also.

How do you know you have no spark?

Time to pony up and buy a better code reader or take it to an indy mechanic to have it scanned. You need more data.

 

yes i smell fuel after prolonged cranking. i used a spark plug tester to determine the no spark. im trying to avoid having the car towed, if i cant figured it out soon that what ill have to do

 

Crank and fuel but no spark.

Ignition system is the priority in my view.

How do you know the coil packs are good?

 

i swapped the coil packs from my running parts car over to this one that wont start. before i swapped, the other car started right up and drove good, just had transmission problems, which is why its the parts car

 

after many.. many hours of researching I made a checklist off all the possible reasons why it would not be getting a spark. Here is what i came up with. If i missed anything that you might know of please feel free to add it to the list

 

update: i bought i OBD reader that was on the more expensive side. ($200 launch Creader III). It was able to scan for codes that the cheap reader could not. And it is a brand specific scanner that offers mercedes and a bunch others, but w202 chassis is not available, the earliest model i could scan would be a w203. this seems to be a problem with a lot of scanners not able to read the w202 chassis. Anyway i could not scann the computer for errors, only the CEL codes that was triggered. here is what i got

 

 

p1747 has to do with shift solenoid. maybe CEL was triggered when i was servicing the 722.6 transmission. I only drove the car around the block one time since then.
p1580 has to do with the throttle body. possible stuck throttle body actuater or Throttle position sensor.

so guess what, i swapped the throttle body and TPS, while also cleaning it, from the other c280 i have. and that still did not solve the crank no start. i cleared the codes and now the scanner is not picking up anything. so not sure why i got a for throttle body actuater or TPS

 

Crank but no start? Pull a sparkplug connector and see if it's getting spark. If not check the crankshaft position sensor and then check the wiring that runs from the sensor connector to the ECU for continuity.