W202:no grunt

[ROBB]

Hi All,
A friend of mine has a 2000 C220 CDI Auto (WDB2021332F) which is suffering from poor acceleration, although it revs to 5k there is little boost pressure and kicks down early going uphill .....

Possible MAS??
Is the MAF from a WDB2032062F the same part no. as the MAS on a WDB2021332F ??? (if it is i can change it for mine to try......). Detali will not yeild the part numbers.......

rob

 

[grober]

MAS = MAF for your purposes. Get a proper Bosch one or Pierbug element from ECP dont be tempted to get one of EBAY unless you are certain of the seller. they can be cleaned with the right solvents plenty posts on that

 

[ROBB]

Any ideas people ???

thanks
rob

 

[Dieselman]

Does sound like a MAF fault causing lack of fuelling.
Meter Pin5 with respect to Gnd through the rev range.

Expect approx 2v at idle and 4.2-4.5v at full revs.

 

[IanT]

Does sound like a MAF fault causing lack of fuelling.
Meter Pin5 with respect to Gnd through the rev range.

Expect approx 2v at idle and 4.2-4.5v at full revs.

This same advice diagnosed mine a couple of years back - new MAF element fitted (about £67 from MB) and the car was completely rejuvenated.

Ian.

 

[ROBB]

Thanks folks, I'll try it today

rob

 

[ROBB]

Does sound like a MAF fault causing lack of fuelling.
Meter Pin5 with respect to Gnd through the rev range.

Expect approx 2v at idle and 4.2-4.5v at full revs.

Thanks DieselMan - have a banana :bannana: :bannana:

Pin5 reached all of 15mv @ 4k revs: seems pretty rogered to me!

Now to find one for less than £256 (MB Coventry - theiving b@$tards !!)

Can the element be obtained without the housing??

cheers
rob

 

[BlackC55]

Try Euro car parts.

 

[Dieselman]

15mv seem low even for a duff MAf. Just recehck the readings and off other pins as well. There is Gnd, 12v in, 5v in and variable output(2v-4.5V)

 

[television]

Your cheapest option is to buy from Bosch service centers

Around £145 for the real thing

 

[ROBB]

15mv seem low even for a duff MAf. Just recehck the readings and off other pins as well. There is Gnd, 12v in, 5v in and variable output(2v-4.5V)

I had to use fine SMT wire to connect terminals to meter, so there is a chance it went a little wrong
I will try again tomorrow: this may be a dumb question but will these outputs be measurable from the connector without being connected to the MAS ???

I got no output from P5-Gnd with it disconnected, and v.small o/p using flying leads

ECP do a Bosch one (i gave them the MB part no.) for approx 145+vat

Your thoughts are,as ever, appreciated

rob

 

[ROBB]

Your cheapest option is to buy from Bosch service centers

Around £145 for the real thing

All the parts places i have spoken to tell me that the element is integral to the housing, rather than being seperately available as per W203 types

Is this True?????

cheers
rob

 

[Dieselman]

The voltages from the ECU to the MAF will be available with the connector disconnected, although it's bad practice to test like that as they may go down under load.

The variable 0-5v return from the MAF to ECU will not be there with the connector disconnected as it is a return of the 5v on pin 4.

Does that make sense, if not ask.

 

[Dieselman]

All the parts places i have spoken to tell me that the element is integral to the housing, rather than being separately available as per W203 types

Is this True?????

cheers
rob

Not normally.. The element can be unscrewed.

For info, different engine sizes can use the same MAF element because the housing is a different size so the element sees the same amount of airflow pro-rata.

As long as the connections reveal the same power voltages between the two cars, then your car MAF could be substituted as a test.

 

[ROBB]

It is making more sense the longer it goes on

I didnt check the 5v/12v in ('cause i didn't know they were there ) but i will do tomorrow

Pin 1 has no contact in it, Pin 5 is variable o/p: which is ground??

thanks
rob

 

[ROBB]

Right:
Pin1 = not connected
Pin2 = 12v
Pin3 = Gnd
Pin4 = 5v
Pin5 = variable o/p

:bannana: :bannana: so far so good

There is 5v present, but no 12v: still no o/p from Pin5

There is also a vacuum line break between LH pressure converter & where it connects to the inlet manifold (INLET VALVE MIXER HOUSING): could these issues be connected ???? [EGR vacuum circuit????]

But now there are warning lights: EPC / Coil & a small reservoir???
There was 12v briefly: if this was s/c to 5v ('twas very windy ) would the ECU be damaged??

confused

rob

 

[Dieselman]

I doubt the 12v to 5v short would blow the 12v.

For the MAF to function you need the 12V it's what the amplifier circuit runs on. The 5v is the feed for the variable return to the ECU.

EGR vacuum line disconnection will cause the car to engage limp home mode, usually after a few minutes driving.

It sounds like you may have two problems. The EGR pipe and now shortage of 12V.

You should be able to find the 12v line at the ECU connector by using the meter in continuity mode. Failing that use another 12v feed.

 

[ROBB]

Update:
All is well & good now, turned out that there were 2 problems. Vacuum pipe is now replaced as well as MAS

Thanks for your help folks - Have a banana :bannana: :bannana:

rob