Tylercheo

Hello all. I need all the help I can get. I have a 2001 W210 (M112 Gasoline Engine) that cranks...and cranks...and cranks again...but it won't start. I was driving down the highway one night and I suddenly lost all response from the accelerator pedal. I pulled over to the side of the road and shut off the engine, and it hasn't started since. It threw one code that night, crankshaft position sensor (P0335). Following advice from a mechanic friend and the internet, I replaced both the camshaft and crankshaft position sensors to no avail. The car also has a new mass airflow sensor, new plugs and wires, a new fuel and air filter, and has had a recent oil change. Before that night my car was running better than it ever had before. This has left me very confused.

To try and diagnose the problem, I checked all the basics. I am getting spark, the fuel pump is working, the compression seems right, and the battery is good. The engine will run on starter fluid for as long as it is sprayed into the air intake, but dies immediately without it. When running on the ether, depressing the gas pedal results in a loss of power or the engine cutting completely.

I am beginning to think the issue is a computer or an electrical issue. The engine doesn't seem to be getting any fuel. If so, this is starting to seem like I am in over my head as a DYIer.

In my search of the issue, I found that the crankshaft sensor doesn't seem to be getting any power (when tested with a multimeter) both with the ignition on and when the engine is cranking. I tried replacing the wire to the crank sensor with one I took out of an identical wiring harness. Still no power. I tested the leads for that same wire where they come out of the ECU. No power there either. Could this be a sign that my ECU is bad?

I purchased a MB SD C4 multiplexer and a laptop loaded with XENTRY, DAS, AND HTTWIN along with it, but I'm not sure how to use it yet other than to check fault codes and perform some actuations. Nothing I saw there has helped me out yet. In case the issue is in fact with my ECU, I pulled two identical ECUs from a junkyard to replace mine with. I'm thinking that if I can virginize them with the SD C4 and install them in my car, I can figure out if my ECU is the issue. Does anyone have any experience with doing this? I really don't know my way around the DAS yet or understand anything about immobilizers.

If I can clarify anything or answer any questions about what I've tried so far, please let me know. Everyone has been telling me I should junk the car and buy something else, but my stubborn 22 year old self wants to prove them wrong. I love my car too much to do that. If anyone can steer me in the right direction I'd really appreciate it. I've gone three weeks now without a car!

NRR

Hi Tylercheo,
If you have error codes : crank shaft sensor error or tooth position not read then
It would be worth trying this : (1) remove the crankshaft sensor, (2) spray rustoff cleaner onto the flywheel through the sensor mounting hole (while a second person rotates the crankshaft manually and car is in neutral gear) (3) after full rotation spraying and cleaning of flywheel, refit your crankshaft sensor (4) try to start engine normally.

Since you have brand new sensors the defect is not in the sensor but maybe there is some coating on the flywheel which is preventing the sensor from getting a reading therefore it cannot tell the engine in what position the various moving components are and when to fire and start. Once cleaned the flywheel would then allow the crank shaft sensor to identify the marking and send a firing signal to the ECU which would then order the starter, coil and plugs to ignite.

Regarding the ECU - it is individually calibrated for the vehicle so a spare picked up without calibration may not help. There are specific ECU expert shops who can reset your ECU if defective - however why not clean your flywheel first and see if you get the start - good luck.

Plutoe

Hey Bro, there is more to the starting system than the CPS---don't start throwing parts at the car until you use your new system that will aid in defining the correct problem----additionally, the DAS Xentry system is not capable of virginizing any ECU or TCU---therefore be careful of your expectations, especially when screwing around with your car!!

kajtek1

Looks like Plutoe is repeating the knowledge he just picked up from member with 11 replies.
Before jumping big guns, why not try basic stuff?
Since diagnosis is already lack of fuel, the $19 fuel pressure gauge can tell if that is mechanical or electronic problem in just seconds.

Tylercheo

Hi kajtek1, there is definitely fuel in the rail and I can hear the pump running every time I turn on the ignition. I had borrowed a fuel pressure gauge, but I didn't get a reading on it. I had assumed that it was because the engine wasn't actually starting, only cranking. Should I have had fuel pressure the entire time I was cranking?

Tylercheo

Hi NRR, that was a great suggestion. I'm going to try cleaning the flywheel today. Hopefully it does the trick. If it does not, how can the ECU be reset? Is there a way to verify that it is working 100%? Is that something a regular mechanic could do for me? Is it something I can do on my own? Or would I have to ship it to someone to have it be done.

Sorry for all the questions. I'm a complete noob when it comes to engine wiring and control units!

kajtek1

The fuel pump comes on for few seconds with ignition turned on and then stays on all the time when engine is turning.
I remember about 60 psi running pressure and the rail should have about 15 psi residual pressure, favorable overnight.
If you recorded no pressure -looks like you have your answer.

Tylercheo

I'm not getting any fuel pressure reading at all when cranking. I'm going to put the gauge in after the fuel filter tomorrow after work to make sure that the pump is actually pumping fuel. The pump relay is fine and the fuel pump is whirring like a champ, but I haven't actually verified if the fuel is reaching the rail. That might be my issue.

All relays and fuses are intact, so the only other thing I'm thinking it could be is either the K40 relay module or the ECU, or both, are not completely functional and so they are not getting a reading from the crankshaft position sensor.

NRR

There is a useful U Tube link about the ECU - this may help. Do share an update on how you resolved the problem.

Tylercheo

The problem was actually in the fuel filter, which had been replaced not even a month prior to the issue. I had checked all ignition components, fuses, pumps, and relays. Everything was in working order. The only issue was the absence of fuel pressure. I finally checked the fuel line. That brand new filter was defective and had a clog in it. I replaced it with the original filter (16 years old, OEM, 160,000 miles) and the car started right up. All that time I had trusted that the new filter was in working order. That was a lesson for me. OEM parts only. They're worth the money.