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+--- Thread: w202 no boost preassure (/showthread.php?tid=6609)
w202 no boost preassure - Repetitio - 07-02-2015
hey, just bought my c250 turbodiesel yesterday. We recognized that there is a lot of power missing and went to a garage. They looked at the failure memory and told us the car doesn´t build any boost preassure...Do you have any idea what this could be? Engine sounds very well, no smoke, runs good, starts good, only thing is it has like no power
are there any weak parts of the turbo that i could check myself? BTW the car has run 188000 km. Thanks
RE: w202 no boost preassure - fega72 - 07-02-2015
Hi! Possible air leak between the turbo and the cylinder head. If your car has got the plastic intake manifold my bet is the manifold gaskets (O rings).
RE: w202 no boost preassure - Repetitio - 07-02-2015
If there would be a leak, i would here that or not? car is build in 1996... I will check that later. But if there would be a leak, i would here that or not?
RE: w202 no boost preassure - barrote - 07-02-2015
check wg actuator hose , and EGR solenoid valves for proper operation, usually in those cars EGR messes up with the WG actuator .
look for vacum hoses loose . u´ll find your problema.
RE: w202 no boost preassure - Repetitio - 07-02-2015
well i pulle dof the egr hose and checked the wg actuator that goes in on the top. all of them are ok...what i recognized is, that the power gets worse the warmer the engine gets. Any ideas what this could mean?
RE: w202 no boost preassure - barrote - 07-02-2015
that makes sence with what i was directing u . in those cars the wg is open when engine is stoped. once the engine is solicited to produce power from idle it will close the wg to get u some boost! sometimes the wg does not close and boost cant build , therefore makes the engine a lot less powerfull.
the thing is that the EGR system usually is closed when big power is solicited, so the ingestion of exaust stop, the wg operates to fully closed and boost will build up.
if for any reason the EGR main valve is open, boost wont build cause it escapes to the exaust and the engine is running on hot air and exaust fumes.
if i was u , first i checked for lose hoses or leaking hoses in this system, EGR and WG actuator,
2- checked leaks in the turbo piping
3- check waste gate actuator operation u can even close it mechanically for trial, anyhow when u throtle the car unloaded (park and hood open) u should feel the turbo hoses getting harder with the pressure.
4- EGR valves
5- assuming the MAF is operating well and the engine is not going limp mode, u may have a turbo problema.
if u follow this u´ll son find the cause , i bet vac lines.
RE: w202 no boost preassure - Repetitio - 07-03-2015
Found the issue, i think it was the air filter. As soon as i took the piping away from the filter, the turbo was running happily. I drove a round and the power was great. I got a new filter and everything is fine. I also put away the egr hose, maybe this solved the issue?
RE: w202 no boost preassure - Repetitio - 07-12-2015
DAMN! Same problem came up again, i drove the car for 1 week without problems! I dont know what to do, checked all pipes and everything, can´t find the problem. Anybody got an idea what it could be? maybe something electronically?
RE: w202 no boost preassure - barrote - 07-12-2015
follow post #6 , sure it wasn´t the air filter...
something is outside is place ....
RE: w202 no boost preassure - Volker407 - 07-15-2015
Yes, check air filter again.
Under the air intake behind the fuel filter there is a "fuel pre-warming switching device"
That sometimes gets stuck and the many plastic connectors around it like to become leaky.
When they do you suck air into your fuel system. The clear tubes should be free of air bubbles.
Gruß
Volker
RE: w202 no boost preassure - Repetitio - 07-15-2015
I think its not a problem with fuel if it doesn´t build any boost preassure? I checked all pipings again, and found a little leak in the vakuum line (you´ve been right). I fixed it for trying with some tape, but it wasn´t the issue, car has still the same problem. When i close the wastegate manually, it builds up boost preassure...It´s really starting to piss me off. If try to "suck" at the vakuum lines with my mouth, do they have to be completely closed? Or is it normal that i can suck a little air through them? Sorry for so much sucking but since i´m from germany i dont know another word
i hope you guys know what i mean
RE: w202 no boost preassure - Booster - 07-15-2015
(07-15-2015, 11:48 AM)Repetitio I think its not a problem with fuel if it doesn´t build any boost preassure? I checked all pipings again, and found a little leak in the vakuum line (you´ve been right). I fixed it for trying with some tape, but it wasn´t the issue, car has still the same problem. When i close the wastegate manually, it builds up boost preassure...It´s really starting to piss me off. If try to "suck" at the vakuum lines with my mouth, do they have to be completely closed? Or is it normal that i can suck a little air through them? Sorry for so much sucking but since i´m from germany i dont know another word
It needs fuel to make boost.....
No fuel - no boost.
(Not saying this is your issue I'm just saying)
RE: w202 no boost preassure - barrote - 07-15-2015
u got to check the vac lines , actuators and electrical lines. in the vac lines there are restrictors, u can´t make it with out a diagram.
find someone that can help u with "autodata" usually u find both vac and electric diagrams.
ussually is something in the EGR system, that is preventing the turbo to kick in. or u can just plug a vac line to turbo actuator a F&%$# everithing else, as long as the vac is at the actuator the car will rock.
sorry i dont have diagrams for that car, only next week i may find some , for that i need VIN number of your car, the wdb202XXXXXXXXX nr.
regards
RE: w202 no boost preassure - Repetitio - 07-15-2015
With evry mod it smokes, anyway no boost...what dies this valve normally do? Can i just take it off and put the VAC line at the WG?
RE: w202 no boost preassure - barrote - 07-16-2015
yes u can, but be sure the vac is not leaking somewhere,
like that u´ll have turbo blowing all the time and boost protection will be by exaust pressure compensation same way as before with some exceptions, wich have to do with emissions, not power.
anyway u still want the schematics?
RE: w202 no boost preassure - Repetitio - 07-16-2015
Great, works with Direct plug on
dies that mean the valve is broken?
RE: w202 no boost preassure - barrote - 07-16-2015
no , u´re making a huje judment mystake!!!
your car has a turbocharged engine, fitted with a waste gated turbo charger, wich in order to build pressure the waste gate need to be closed.
so the engine has a EGR system wich along with the catalitic converter enable it to be euro3 compliant.
To avoid that engine to produce some visible smoke(low emission), and be powerfull and economic they fit a MAF sensor and a computer to run an electric pump based on a map. and cause MAF numbers are dependente on the boost pressure a MAP for the turbo to kick in was added. when EGR system need to be active the boost must be low or nil, so another map was added to control EGR system.
So MB decided to use electro/vacum actuators to run the system, your problem can lie in many places in that car, it can be the wastegate actuator electro/vacum switch damaged or a line leak, as it can be the MAP in the computer, or the main EGR valve actuator.
basically this to say that probably u have more than one thing going bad.
if u have the schematics both electric and vacum , u can check the system in its all. or u can just forguet that a ride with the WG actuator pluged to the vac unit.
that depend on what u what the car to be.
RE: w202 no boost preassure - Repetitio - 07-17-2015
Car goes in limp mode with Direct plug...didnt happen the first time. You have an idea why? What to do? I would just plug it in Direct uf it would work xD
RE: w202 no boost preassure - Repetitio - 07-17-2015
Ah and thanks a lot for this detailled helpful answer
RE: w202 no boost preassure - Repetitio - 07-18-2015
Well ok, now the car is building boost...with evry mod boost rises above 1,5 bar. Can the little turbo hande this for longer times?
RE: w202 no boost preassure - barrote - 07-18-2015
yep dont worry with it, as long as it does not choque the exaust is ok. but if it does EGT rises and can melt your engine..... 3rd gear up a Hill at 5k will do that hehe
RE: w202 no boost preassure - Repetitio - 07-19-2015
well i wanted the car for drifting...so very hard stress for engine and so on, i think this will cause problems any time :/ I will pm you my VIN number, then i may find the issue