mercedes driver

So have a 2005 e320 cdi with a no start problem and need help to suss out the issue.

Ok, so long story short. Decided to do some preventative maintenance by changing out injector seal on #1 cylinder. Have done it before on this engine on other cylinders and all went fine. Buttoned everything back up and car ran rough. Something like the cylinder wasn't firing. ODB scan says open circuit on that cylinder(#1). Pulled rail-injector fuel lines from rail to chase wiring on top of motor for short/arc. Nothing out of ordinary so buttoned everything back up. Motor turned over but would not fire off....like air in the lines. Tried turning over a few more times(car/starter turning motor over to clear lines of air) then car would no longer pump over. Not froze...just no longer would turn over electronically. Thought battery may be a bit drained from all the trying, so pulled battery and charged to make sure ok and possibly(hoping) to reset comp. Car will now fire up for about 1-2 seconds then shuts down. Seems like an electrical shut down.

I am wondering if there is some parameter the comp. is looking for, yet not seeing (or something outside set parameters) and then shutting down the engine? Already spent lots of money to have the car towed and diag. at indy shop only for them to tell me everything i already knew. They want to go further but think its mechanical. My gut feeling is they didn't dig deep enough with software to figure out shut down which i believe to be electrical. So lets have some fun and net diag a car!

LexBrett2

Does your code reader only show an open circuit in cylinder 1? Are there any other codes present? Is it possible there is a fuse blown for engine electronics that is producing the code? I know it sounds silly, but something similar happened to me one time.

With the no start issue, could the crankshaft position sensor be malfunctioning as a coincidence.
Good luck with this, it is so frustrating when you go to fix your car and then you break it!

mercedes driver

Yes. Only have a cheap obd code reader. Other codes are for #5 glow pug and glow plug module. Those are from some time ago and its in a warm weather climate so never an issue. Might be a fuse/relay for engine electronics that is the cause but i don't know what that would be. Hence why i am hoping the collective can help zero in on the issue(s).

CPS shouldn't allow car to start/run if bad, no? No signal from the sensor no lighting up the injectors for fuel injection. The indy that scanned the car says all sensors check out as fine. I don't know if an intermittently working CPS sensor would show up on the scan as troubled. Would think it at least throw a code.

LexBrett2

CPS problems could cause a variety of bad things: no start at all, intermittent start, and stalling while driving with no warning, totally sucks. I learned the hard way, and it appears to be a very common problem with mercedes.

Russell Ormerod

Does it run with that cyl injector unplugged? On a diesel if one injector fails the ecu will shut all off

mercedes driver

Yes the car ran plugged and unplugged. Wouldn't be surprised if car could run with 2 cylinders down. Not sure where that information about ecu shut off regarding injector fail but don't think that is true.

mercedes driver

So the question remains......can a CPS fail without throwing a code? Whether it be specifically a code for the cps or an ancillary code that would reference back to the cps through trouble shooting daig.

Or in my case, can one work every time at start up for 1-2 seconds then fail and not throw a code?

Russell Ormerod

Throw your cheap tester in the bin, look at actual values on DAS and you will have your answer in 2 min.

mercedes driver

Not sure where anyone got the idea that i was trying to diagnose the car with a cheap odb scanner, but that is not the case. I only used that to pull basic codes stored. It was sent to an independent mercedes service shop to be full diagnosed. Unfortunately they have not been able to tell me anything more than i already knew. Would think that if the cps was acting up they would be able to read that on their "professional" software/reader/interface tool(s). Now whether they know enough to dig deeper with the software to suss out the issue i don't know. Don't know how far they went to try to solve the issue. The fact that they can't tell me anything i didn't already know makes me suspect there wasn't much more done that pulling codes.

However, this seems to be veering a bit of course. If someone feels it could be the CPS then a trouble shoot of that fault would be helpful. I again, point to my queries in my previous post.

Russell Ormerod

Find out what diagnostic tools they using, it doesn't sound like they know what they doing, there is a specific menu on DAS for your issue. Crank the engine and read..
RPM
Cam/crank sync
Rail pressure
Quantity control value

What fault codes do they get?
Do they clear? Do they come back?

LexBrett2

IMHO:
The interesting thing about the auto mechanic industry is that is almost entirely unregulated.
You do not need a license and anyone can open a shop.
So, if you don't want to figure out the problem yourself, an "Indy" may or may not actually be able to help.
Even if they are ASE certified, that has no bearing on whether they understand Mercedes cars.
I'm in no way suggesting to go to the stealership.
I personally figure things out on my own and almost always figure it out.
I'd sell a car before going to the stealership.

Strigoi

A lot of this.

Had a buddy bring an SL500 by my house last night so my housemate could scan it and see why it wasn't shifting. Almost certain it needs a new shifter. This guy is a competent custom bike builder and even knows newer Harley fuel injection/computer stuff. He could not figure out what was wrong with that car. He said that Mercedes and all of their systems just don't make sense to him.

kajtek1

Most of MB software programs don't make sense to me neither.
For example I had Airmatic sitting on very freezing night just fine.
I start driving early in the morning and what I concluded later - some water in the system froze compressor.
But again, the car was well leveled when I start driving, yet 3 minutes later the computer open the valves and let the the air from bags to go out, starting all the red lights on the cluster.
Have whole list with stuff like that.

Russell Ormerod

Lexbret2 i agree with you auto industry is not regulated here in South Africa either. So any idiot can open a workshop and call themselves a specialist. You just pay a fee and you RMI certified. It's a joke.. the guys that really know there stuff are few and far between. And you right the agents are no better. I guess this problem occurs all over the world. Maybe I am wrong!

mercedes driver

Ok, so have some updates. Not much new to report but its what i have at the moment.


Got the car back from the indy shop. The only thing i know now that i didn't before is the fuel pressure. Well, i'm having to take this guy's word for it. This is the same person who said they can work on diesels, uses the star/das diag. although he never showed it to me, then at the end admits he doesn't have the proper tools to get into it further.
So anyway, i had asked him to print out, if possible, but taking note would be fine, the 4 things you folks asked about....rpm, cam/crank sync, rail pressure, quantity control value. Turns out all he could "recall" was the rail pressure at 'somewhere around 430ish psi, then drops to around 100psi when cranking. Asked if he was sure the pressure sensor was good to which he said no code was thrown for that so he thinks its ok. However, he didn't actually test it...if there is a way.

He seems to think it is the hp pump. I think he's deduced this because he says when he cracked an injector fuel line there was very little leakage from the connection joint. It might be, but i have no way of knowing as i have relayed to you what he has to me. Only thing i can say about this is that there are zero leaks from the pump. The car has never given any indication of possible building failure...I.E. very a hard start, nor a stall, or a sputter, or anything else. Just cranked right up the first time every time with never a hiccup.



So to say the least i'm disappointed with how things have turned out thus far. Ready to hear so feedback and suggestions.



Caveat: I know the best way for you folks to be able to help someone diag an issue is to be able to have access to the das system readouts. I'm sure the procedures and trouble shoot routes are well documented. However, maybe we can try to think under the assumption of no electronic diag assistance? Lets figure we are out in the middle of nowhere with nothing but a tools set and no other way to get home. These motors aren't all 'that' complicated so sussing out an issue the old fashion way(lots of diesel knowledge able to deduce trouble shoot routes based on process of elimination) should be within our abilities. Ready to try some good old outback engineering?

rapidoxidation

You're sure there's no air in the lines, or in the HP pump? Pretty sure rail pressure for a cdi is on the order of 20,000 psi... but if there's no liquid to pressurize you're not going to get far. How does one guarantee the lines are primed and free of air? If you pull a return line from an injector, are you getting fuel from it? I'd be inclined to pull the glow plugs to relieve cylinder pressure then spin the engine using the starter until you're 100% sure the lines are filled with fuel.

Russell Ormerod

100 psi under cranking.... forget about it ever starting!
You need around 3700 psi before it will start.
Fuel filter blocked?
MB sell a high pressure kit so you can overhaul the pump.
Good luck