Code P0170 - E320 Check Engine Light - HELP! - PeachParts Mercedes-Benz Forum

Arthur Dalton · #1 09-19-2006, 03:17 AM

Fuel pressiure regulator can be tested with a fuel pressure test gauge.
However , if gas is evident at vac line , that is a simple verification of ruptured/leaking diaphragm. This fault will make both the pressure at the injectors too high and also allow unmetered gas into the intake through the vac hose. Either will upset the fuel trim , thus the code.

cpiad · #2 09-19-2006, 03:35 AM

Quote:

Originally Posted by Arthur Dalton

Fuel pressiure regulator can be tested with a fuel pressure test gauge.
However , if gas is evident at vac line , that is a simple verification of ruptured/leaking diaphragm. This fault will make both the pressure at the injectors too high and also allow unmetered gas into the intake through the vac hose. Either will upset the fuel trim , thus the code.

Am I right that all I need is a pair of internal retainer ring pliers to remove the vac regulator? Looks like that's all there is to it.

I have a top-notch vac testing appartus ... pulls vacumm and shows reading ... however, I wouldn't know what is a correct reading from a wrong reading. I suppose I could pull a vac and see if the thing holds it ... I am in the process of obtaining a CD shop manual for the car ... apparently the average consumer can't get a paper manual. Having a manual ought to give me a leg up on the thing. I bought the car new in '96 ... and up until now its been Mr. Reliable ... however, even a car with only 57,600 miles that is 10 years old going on 11 will have issues ...

There was a minor hint of fuel smell coming from the vac line, and that's enough for me to assume the diaphram or an internal seal is shot. There's not much to that pressure regulator. Both parts (MAF and pressure reg) came out to about $300.00. I could have spent that much at a dealership and not gotten much beyond getting the code read ... so, I figure throw a few dollars at it and see if the problem goes away. Thanks for staying with me on this ... really appreciate your help and willingness to share your expertise with a neophyte.

Arthur Dalton · #3 09-19-2006, 05:41 AM

< >>

Yeah....... after you release any fuel rail pressure at the service port.

cpiad · #4 09-19-2006, 08:02 AM

Quote:

Originally Posted by Arthur Dalton

< >>

Yeah....... after you release any fuel rail pressure at the service port.

oh, thanks for that one ... could have been a bit messy.

BenzfanNJ · #5 09-19-2006, 09:05 AM

The easiest way to test the pressure regulator is to take the vacuum line off and turn the key to the "on" position. If fuel drips out, there is your problem. If you smell fuel in the vacuum line, it is most likely leaking.
Dave

cpiad · #6 09-19-2006, 10:03 AM

Quote:

Originally Posted by BenzfanNJ

The easiest way to test the pressure regulator is to take the vacuum line off and turn the key to the "on" position. If fuel drips out, there is your problem. If you smell fuel in the vacuum line, it is most likely leaking.
Dave

I've already detected a faint fuel smell ... so I guessed the diaphram was leaking a bit ... also found crud in the MAF .. cleaned it, but light came back on .. so I've ordered both parts ... will install sometime after Sept 25 when UPS drops parts off at the house ... thanks all for the help ... I'll be back with results after I install the parts ... not much more to do in the meantime ...

david s poole · #7 09-19-2006, 11:43 AM

after you install your parts[which i believe shoud fix your problems] you will need to get the adaptions reset.this needs good scanner with mb software.