merc c class- wont start when cold

[andybaz]

Hi all, never done anything with merc's, this is a out of hours project, merc 2002 c class 2.7 auto, you can crank it an she wont start, keep cranking and eventually we get a code, screen shot attached here, once she has been started and run, the owner tells me it will run all day, but obvioulsy now it does not want to start, given it about 5 pre heats and then cranked and no joy.
Thinking may walk away from this, know nothing about the merc motors, off to do a little bit of googling to see if i can find anything,or if any one knows of any good merc sites for info, may be pay as you go for diagnostics etc, i know if i ring merc from work tomorrow, saying we have a car in workshop they will say they need to see it. Working in 2 degrees evenings is a bit cold .

If any one wants to comment, feel free, the definition against the code means nothing to me, the screen shot is 'cranking'.

[andybaz]

The attached screen shot is the cold start data option on the pro 10.4

[markt]

hi andy...have a look at the fuel pressure again whist cranking,it shows it to be at 180 bar on the live data?..if this is so then it is too low..i take it the system is common rail? then the pressure needs to be at least 220 - 240 bar approx but someone out there will have an exact figure of what it should be i bet .
a bit crude but give it a quick sniff of easy start to se if it does fire.

[andybaz]

I was also thinking may be a fuel filter, dont know how long the current one has been on, need to get some more info on the code before start changing any parts , cheers

[andybaz]

Update folks, seen as im currently no longer mobile, sent my side kick round to have a look at the throttle pedal switch and possibly spray some easy start into her, bare in mind it is not cold today, throttle pedal switch unpluged, viewed, nice an clean, sprayed some cleaner into the plug (loom) to make sure no muck or fluff etc an d refitted and she started 1st time, but my side kick should have tried to see if started with out disconnecting the pedal as it is not a cold day, so the owner is going to monitor this problem.

I will be going back to get some live data from cold start so i have good base values of starting on normal, hot an cold days, to add to my libary of data/ screen shots.

I have found the P1222 code on the web, same description as on the s'pro:

P1222 IFI Accelerator Pedal Position Sensor (R25/2)

If this problem pops up again and i managed to fix, will update accordingly cheers for your views mark, much appreaited, and i havent forgotten about contacting for a X machine .

[andybaz]

Updates folks, as the car now starts,weather has warmed up, very annoying, the owner is taking the motor to merc, so when i find out what the outcome is, as this is very intermittent, will post here

[markt]

will probably turn out to be something silly like dodgy connector or ecu fault
seeing as its off to the dealers.always summit i tend to overlook,haha.
keep us posted.

[andybaz]

will probably turn out to be something silly like dodgy connector or ecu fault
seeing as its off to the dealers.always summit i tend to overlook,haha.
keep us posted.

Will do, an i just found a web site here where they mention something about a fuse under the bonnet, i'll kick myself it thats all it is !! Cant be that simple ! ... better not be

[andybaz]

Update folks, still doesnt start, well me client had driven the merc to the merc dealership, left it with them to sort...... (a number of days) they returned 'NO FAULT FOUND', currently my client has not been charged the plug in read fee ,thank you merc, so he collected the car, it is currently at his relations location, who also own a merc, relations merc started ok - temp 3degree's, this car still wont start.

Client armed with my code read screenshot and will be talking to them tomorrow to get them to go out to the car and see exactly whats happening. The problem is, if the temp rise a little then the car will start, it wouldnt start yesterday in the freezin rain and it wont start today, light 2" covering snow on it, by 2pm, snow thawed, car clear, still wont start, unfortunatly to far for me to go an plug in, about 1.5hr away, BUT right on merc door step

Seeminlgy there is a problem like vauxhalls with split vac pipes - common problem on merc but not for non starting.

If you want to know merc plug in fee, just ask, but make sure you sitting down

[markt]

i used to have a sensor simulator to mimmick the coolant sensor range until i ran it over.lol...used to help quite a lot with faults relating to faulty sensors,wiring or even ecu faults as when you set the range to a certain temp and if it still didnt start then you could rule out things like wiring,water ingress in certain components/modules etc etc
next time you have a motor in with a similar problem try removing the sensor and either cool it or heat it ( depending on the fault youre having ) and see what influence it has on it.
i have a couple of manufacturers sensors in my toolbox drawer for such an occasion,its better than having the coolant spiling all over until i decide to buy another simulator .

i wouldnt be surprised if they take little notice of the printout as they like to have the fault replicated on thier machine and sometimes regard aftermarket tools as being mis-leading.lol,that said, a few i know of both in the past and recently have only a few people who know how to detect pesky faults via the diagnostic tool...they were too quick to plug in and see no codes and then take thier conclusion from that.
i will add this though that not all dealership techs follow that plan as i know a few who are dedicated to the task in hand, but what i have seen in the past doesnt leave much to the imagination and especially last week when we sent a motor to the dealers and had to ask a mate outside the dealership to look at it whilst there with them and he was surprised at the lack of diagnostic knowlege by them towards their own tool,hehe.

[rem3th]

Air on the fuel pipes, one of the seals is letting air in the system. had that problem with a few M class and A class, when is cold the seal gets hard and let some air in, then it comes difficult to start, check bubbles in the pipes from the filter to the pump and from the pump to the rail. changing the 2 pipes sort out the problem

[delt266]

Mercedes C Class

Air on the fuel pipes, one of the seals is letting air in the system. had that problem with a few M class and A class, when is cold the seal gets hard and let some air in, then it comes difficult to start, check bubbles in the pipes from the filter to the pump and from the pump to the rail. changing the 2 pipes sort out the problem

What 2 pipes are you referring to and what is their location on the car?

Thanks!