Ed In TN

I have a 1998 ML320. Every now and then we will be driving and the car will completely shut down. It restarts again in a minute or so. I have tested for spark and everything seems to be ok with the plugs. The check engine light is on, but the code for that is a bad EGR valve. I have talked to a few techs and they said this would not make the car shut down. I am not sure if this is a fuel problem, bad relay or possibly a loose connection at the fuel pump (ground or something). Has anyone had a similar problem? Any advice would be greatly appreciated.

Thanks,
Eddie Rodgers

teky

what code was it?? the problem could be related to the emmisions system not just the egr valve like the cannister purge valve which is also part of the system

Ed In TN

The codes were 173-fuel trim malfunction and 400 EGR flow malfunction.

teky

i thought as much they are both linked P0173 fuel trim bank 2 malfunction, cause = intake leak/air system/fuel pressure/fuel pump/injectors/EVAP canistor purge valve and HO2S heated o2 sensor, any of these will give the egr valve a code because the emmisions is suffering so i dont think its the egr valve, im going for a leak in the intake gasket/vacuum line off or split or lastly a faulty cannistor purge valve wiring connector... code P0400 is the egr valve flow malfunction probably a hole in the pipe feeding it or gasket

Ed In TN

Thank you very much that gives me some things to look at tonight. I really appreciate your help with my situation. Thanks again.

saturnstyl

I almost guarantee you, its the crankshaft position sensor. When it fails, it will not set any fault codes, the computer can't see the flywheel trigger points, and does not know when to fire spark plugs or injectors. The whole motor just shuts down. This typically only occurs when vehicle is hot, and the vehicle will restart after is cools and run just fine. EGR won't keep the engine from running unless the valve is stuck wide open, then it would likely set misfire codes instead. I think you have a restricted egr tube or bad solenoid. The usual fix is to replace the egr valve/solenoid combo along with the egr tube.

mercedestech1

I am currently a tech with MB,as long as the vehicle doesn't "sputter" or "bog" before it dies,the crankshaft position sensor is most likely the problem. Be sure to check the wiring on the back side of the crank sensor (cut loom apart) for corrosion-this has also been a problem for these vehicles. Water runs down the harness and corrodes the back side of the connector-you will not be able to see any corrosion on the sensor side.

Good luck.

pointman

whoa! two techs say crank... how about the fuel pump gentlemen?

teky

i mentioned the fuel pump in my diagnostics i have only been doing cars for 40 yrs "time served" and would never garantee a fault unless i was 100% sure, so im still going to guess its an air leak but if i were there i would garantee i would find the fault very quickly

saturnstyl

I wouldn't think the fuel pump as much as the crank sensor. The fuel pumps usually only create a No-Start condition. They rarely cause a start then randomly shut off situation.

azinn

Where is the crank sensor located and how much do they cost?

mercedestech1

If the fuel pump stopped working you would still have residual pressure in the fuel rail,appx. 3.9 BAR(about 60 psi). This pressure will slowly bleed down every time an injector opens. The engine will slowly start misfiring and lacking power then die. If the crank sensor intermitantly fails the engine will stall immediately! Yes,there are other things that could cause these symptoms,but the crank sensor is the most common,the easiest and the most inexpensive of them all.

mercedestech1

The crank sensor is located on the the back side of the engine block,on the drivers side,(where the transmission meets the engine),it's price will differ from dealer to dealer but generally it will cost around $100-200.

saturnstyl

Its buried at the back of the engine. Its located on top, where it reads the flywheel position. Might be best to have someone change it for you, its tricky sometimes, and usually quite hot. Just one of those things.... Sometimes they come right out, other times they fight you all the way. I believe its an E8 torx bit, a long 1/4" extension and universal, and ratchet. Pull off engine cover, climb on top of motor, reach down on the drivers side at the back of the motor. Unplug, replace.

teky

not totaly happy with this crank sensor theory it seems too much like mb tech guess work $100/200 well that would be nice for them but an upevil for a loose/corroded pipe for pennies

teky

mercedestech1 meet saturn becuse i dont think either of you know what your talking about apart from you must have shares in crank sensors, learn to diagnose problems

saturnstyl

Sounds like a troll hiding behind a computer fellas. Ignore him and he just might go away!

teky

could be but i know what im talking about son

mercedestech1

Your right,I dont know what I'm talking about,after all I only graduated with high honers at technical school specifically for the diagnosis and repair of automobiles.Oh and I forgot to mention that I finished 1st in my class at the Mercedes-Benz graduate training program.I would like to hear your argument why you think it's not a crank sensor!!!

teky

yes i know all about that toilet paper i was there you know and i have many degrees HNC/HND, the difference was hands on as opposed the paper/classroom i learned more when i was working than in school/uny, i went to university to learn and met guys/gals who knew more than me because they had hands on and they beat me hands down so i went to trouble shooting which is my 4t and with the later cars its paid off but i know many who dont have this toilet paper and do extreamly well

teky

as i said the crank sensor can easly be tested

saturnstyl

Wow this forum makes it easy! Click on his name, then view his profile. Add him to your "ignore" list, and his worthless "contributions" go away. I like this place!!!

Mr Simonazzi

How do you test the crank angle sensor, I have this same problem.
If its intermittant will the test still work?

saturnstyl

The crankshaft sensor can be tested with an ohm meter, the problem is it usually only fails when its hot. It will test fine until it fails, then it will read open circuit. Trying to heat one with a torch is pretty futile also, its best to pull it out right when the engine dies, and the opportunity is rare. It might have cooled down enough by the time you have removed it and will test ok.

Mr Simonazzi

Mine quits when the car is driven only 1/2 - 3/4 mile. Would it still be the crank angle sensor.