C250 CDi (2009 W204) Continuous Engine Problems.

[Lee44]

2009 C250 CDi W204 Sport Manual
Does anybody know where my "boost pressure sensor" is situated? It's not the MAP sensor is it, the one in front of the MAF on the air inlet?

Not sure if some of you have read my other threads but my frustrating intermittent lack of boost power and hesitation between 3000 - 4000 rpm on harder acceleration in 3rd gear is still here

So far I've changed MAP sensor.
Had it remapped to try and iron it out but no joy.
Cleaned MAF with correct spray.
Cleaned out plastic inlets to first turbo and seating to turbo (wasn't dirty).
It's had the recall injectors at MB 12months ago.
I've just done a full service including all filters.
WD40 on actuator arm (looks new).

It's been on STAR several times and no faults to suggest symptoms.

I fit the wrong size tyres on rear which some said it would be this messing with speed sensors etc.. However ran vehicle with correct tyres for a week and it is still happening!

I'm changing boost pressure sensor now as I don't fancy spending £200 on MAF if it's not that. (Can a faulty MAF display intermittent faults and cause sooo much loss of boost/power?)

Long post I know, however it gives a big picture and prevents lots of questions

Thanks guys....

 

[Lee44]

I may just of negated the MAF... I've just drove half way to work, pulled over and unplugged it. Drove it and immediately noticed a very poorer performance, like a limp mode etc but no warning lights on.

I plugged it back in and it took off again BUT still the jerking/hesitating between 3000 & 4000rpm.

I've noticed my mpg has dropped dramatically this month as well, in to the low 30's

 

[jj1975]

Hi
When you changed MAF sensor did u get it from MB or aftermarket
I'm asking because aftermarket want work properly
Boost presure sensor and temperature sensor on my w203 are located on pipe from intercooler to inlet manifold b4 EGR valve shouldn't be much deferent on w204 I think
Hope this may help

 

[Lee44]

Hi, thanks for that. I haven't replaced MAF, just cleaned it. The MAP I got original from MB.

 

[Lee44]

Please can someone tell me if this MAP sensor in the picture is also the "boost pressure sensor" or is that a different sensor all together? If its not the same then where is the boost pressure situated?

 

[Lee44]

I feel like Jackanory telling a story on on this thread haha...

Anyway... I unplugged that new MAP sensor and went for a drive.
Hey Presto the difference was ridiculous, instantly came alive, full boost and tonnes of silly torque appeared reflecting the re-mapped power I thought it should have!!? (Admittedly a little jerky in places now and then but the power difference was immense.)

Im wondering if the MAP is detecting too much boost and cutting throttle when plugged in?

I feel my process of elimination is drawing to an end, hopefully see you tomorrow for another chapter:lol:

 

[alexanderfoti]

If the detected pressure (via the MAP) is too high, the car will cut the boost in and out in a very jerky fashion.

You should find a way of monitoring your boost pressure to see if its inside a safe range for your turbos. Im not sure of who mapped your car, but maybe they dont know your car that well and have asked too much pressure of your turbos?

 

[Lee44]

Thanks for that...

Your comment and theory is very interesting. You are not the first to say this. However, I was assured that it was done properly by the company when challenged and got the feeling I was/have peed certain people off by questioning the problem, so I left it alone.

Yes... I had a slight jerk / flat spot specifically at 3250rpm before remap. Had the remap but it was still there. The power and torque didn't feel that different to be honest, especially as I was told it was extra 50bhp, it certainly didn't feel like that! On questioning them they quite rightly stated it was a previous engine fault/sensor to blame.

Acting on this it went to an indie on STAR. It showed the MAP was faulty. I replaced and the flat spot at 3250rpm vanished. However it soon began jerking / hesitating at 3500 to 4000rpm on hard acceleration in 3rd gear. Since the remap the power is certainly intermittent and sometimes does show signs of a remapped engine with tonnes of torque, however the majority of times it feels as if it hasn't been remapped at all. Certainly not consistent.

Starting to make me wonder why numerous emails/messages I've sent to a certain company re further tuning work are now being ignored!

Its getting interesting this....

 

[alexanderfoti]

Hmmmmm

Remember you will generate more boost under load in higher gears, the fact that you say that its worse in 3rd makes me think that its making too much boost. If you dont mind you can PM me the name of the company.

Next step would be to get a bluetooth OBD reader and an app for your phone and log MAP pressure.

 

[Lee44]

That's weird... I've just been discussing the OBD Bluetooth kits to check my boost with my colleagues!! Yeah Il PM you, thanks.

 

[alexanderfoti]

Great minds! (I went through the same thing with my 320 cdi and a bad map)

 

[moj91]

Could you suggest a good OBD reader? I wouldnt mind seeing what mine produces as I am finding a significant lul in power between 2800 and about 3200 rpm, and wondering if this is to do with the map....

 

[Lee44]

Mine will be here this week so Il let you know if it's any good or not first

 

[Merc C250 cdi]

Resolution?

Hi Lee, I have a similar issue with my C250 cdi, did you manage to resolve this issue and if so what was the fix?

any help would be appreciated buddy

 

[DAVID JAMES]

I'd also like to know if this was resolved. Sounds very similar to mine. Same Model, same Year.

 

[Adrian Jones]

Please can someone tell me if this MAP sensor in the picture is also the "boost pressure sensor" or is that a different sensor all together? If its not the same then where is the boost pressure situated?

 

[Adrian Jones]

Hi lee, your finger in the picture is pointing to a map manifold air pressure sensor. The boost pressure sensor is just in front of it a little lower down. They look the same but have different part numbers.

 

[bassam45]

hi guys, have you managed to sort this issue yet? i bought my self a Mercedes C220 CDI Cope 2 months ago and had nothing but engine management light on one after another!

my issue now is the boost pressure sensor is flogging fault according to my cheap chines OBD tester, Error Code is P0236 boost Sensor "A" Circuit Range/Performance!!

however, there are 2 boost sensors on my car, one on the top of the hoes just by the MAP sensor and one on the other end by the manifold!

my question is which one of them two is the Sensor A????? i am pulling my hair here!!

thanks in advance

 

[PChinnery]

Hi
bassam45, did you get to the bottom of which sensor is the "A" and which is the "B". i have a problem with the following code P0241 which relates to the "B" sensor. I have searched the net and can't find a detailed pic of where the two sensors are located.
Regards
Paul

 

[ajlsl600]

i just posted as OM651 i think that tells you where all the sensors are located ,i have only read a bit and looked pictures will read well tomorrow ,i assume yr motor 651 if so take a look.