OM642 fault

[bembo449]

this isn't my 300c , its a fellow memebers car , hes had code P0299 on his OM642 for over a year , he's tried all sorts ,. MAF etc but nothing fixes it , he's currently running with the MAF unplugged , so the cars running perfect , I hoped as its an MB unit , one of you may have a suggestion that he / they haven't thought of yet , its running a DPF / EGR delete , swirls removed and resistor mod although he's only using 1 4.7OHM one in there , the fault has appeared since a garage repaired his oil cooler seals , so its not a coincidence , the car bucks and jerks with maf connected but not when its uplugged , any ideas , fire away folks

 

[Doug1234]

I would expect a leak on the boost side somewhere, there is a sensor on the rear of the throttle body that can come loose and bleed pressure off.
Its tricky because although its a Merc engine the ecu software is quite different ... for instance he has the egr delete and this cannot be done on the Mercedes software (resistor mod can be used on egr on these ) and neither on the 642 in my 06 Jeep even though its Chrysler.
It will be either an air leak or the egr /dpf mapping deletes conflicting with the maf over air flow rates, has he replaced the resistor on swirl at all just to rule it out ?.

I use this sprinter forum for a lot of info, and this thread from it may be of use
https://sprinter-source.com/forums/index.php?threads/12972/

 

[Doug1234]

Apart from the egr and dpf delete has the ecu been mapped for more power ?, what if the turbo has sticky vanes and cannot build boost as quick as mapping wants it to ?
Does it only throw the codes when engines pushed hard ?

 

[mattkh]

this isn't my 300c , its a fellow memebers car , hes had code P0299 on his OM642 for over a year ......any ideas , fire away folks

The P0299 code indicates that the Turbo or Supercharger "A" has excessively low output. The ECU looks for a specific range of boost and when the low boost is detected by the ECU, it sets a P0299 code. This code will illuminate a Check Engine Light on the dashboard and may put the vehicle in limp mode

Is the EML coming ON..?

 

[bembo449]

understood , yes the EML is on , it goes off when the MAF is reconnected but then the car bucks and jerks on part throttle

 

[mattkh]

Have any temperature sensors been checked for correctness of reading..?

 

[Wighty]

Is the MAF a genuine one or a “monkey “ one ? (Or a faulty MAF ? )

 

[bembo449]

Is the MAF a genuine one or a “monkey “ one ? (Or a faulty MAF ? )

gen bosch item was used pal

Have any temperature sensors been checked for correctness of reading..?

will pass that on . let you know what he comes back with

 

[Larkone]

Turbo actuator playing up?

 

[mioba]

I had this on my W251 a few months back, was a split pipe. Not saying by any means its the problem but needs diagnosing by a competent garage,

Just going by the "diganisis" on this thread would be very costly.

 

[Larkone]

Just re-read the original - did the garage dislodge or remove the resistor mod when they did the oil cooler seals or did they re-connect the swirl flap motor? By the way it should be a 4.7k ohm resistor. Also check the garage put all of the seals properly for the pipework leading up to the turbo - nothing lipped or twisted over, has been seen before on here.

 

[Larkone]

I had this on my W251 a few months back, was a split pipe. Not saying by any means its the problem but needs diagnosing by a competent garage,

Just going by the "diganisis" on this thread would be very costly.

No one has suggested anything that would cost money beyond the time to do some basic common sense checking - money only comes into play once you start replacing components and then would agree - get it on a diag machine.