W211 2005 E320 CDI oxygen sensor replacement...
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Junior Member
Joined: Sep 2014
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From: Vero Beach, Florida
2005 E320 CDI 150K miles and counting
W211 2005 E320 CDI oxygen sensor replacement...
Fellas,
I have been suffering from lowering fuel economy for the last couple years. I am wondering if maybe changing my O2 sensor would help. It appears that I only have one sensor right? I have 164K miles on my car, and power/fuel economy seems to be low compared to other examples. Any help would be appreciated!
I have been suffering from lowering fuel economy for the last couple years. I am wondering if maybe changing my O2 sensor would help. It appears that I only have one sensor right? I have 164K miles on my car, and power/fuel economy seems to be low compared to other examples. Any help would be appreciated!
Thread Starter
Junior Member
Joined: Sep 2014
Posts: 16
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From: Vero Beach, Florida
2005 E320 CDI 150K miles and counting
Don't waste your time or money! I suspect that if you really charted your driving habits you will find that nothing has changed.
However if you feel that strong about the issue, I would go to a good diesel guy and request an injector leak test----what are the results??
PS: If you don't remember what a leak test provides--google diesel leak test
However if you feel that strong about the issue, I would go to a good diesel guy and request an injector leak test----what are the results??
PS: If you don't remember what a leak test provides--google diesel leak test
Thanks for the information! I'm certain things have changed unfortunately. I chart fuel economy in Fuelly and I see a trend. I've done quite a few things to sort the issue out. I've done the injector leak off test, and the results seem to be fine. Ran 3 tests which were virtually identical. It took 6 minutes and 10 seconds to get the first bottle to 10 ml at idle. It has been 12000 miles since I last tested them and had the same results as before. Values are as follows:
Injector:
#1 9.5ml
#2 8.5ml
#3 10ml
#4 7.75ml
#5 8.75ml
#6 8.75ml
Here is what they sound like with a coil pickup:
And what they look like on a scope:
From what I read the leak off values are within tolerance unless anyone else has better knowledge/information? I have also checked and verified the fuel pressure to the inlet of the new fuel filter is 68 psi at idle, and never dipped below 65 psi while getting on it. I haven't checked the fuel pressure post fuel filter but suspect it is just fine. I'm still gathering parts to install the post fuel filter pressure test tee. I know that MAF sensors and 02 sensors have a finite life and at 164K miles perhaps a couple new ones would be beneficial?
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Junior Member
Joined: Sep 2014
Posts: 16
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From: Vero Beach, Florida
2005 E320 CDI 150K miles and counting
Great question. Fuel filter, PS fluid, coolant fluid/reservoir changeout, brake fluid, rear differential fluid, transmission fluid(14 Qt flush/pan drop), EGR valve cleaned(and verified that it actuates when driving), MAF sensor cleaned with CRC cleaner, air filter, brakes/rotors(greased caliper pins at that time), verified turbo VNT arm moves freely, and some other items I am missing I am sure. I am fairly confident everything is up to date. Unfortunately none of those service items took care of the lowering fuel economy.
I installed the EGR delete circuit some time ago as a test and noticed funky shifting, too much boost(verified with a mechanical calibrated boost pressure gauge), and I believe a CEL from the MAF IIRC.
Last edited by josh8loop; May 17, 2016 at 01:05 PM.
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Joined: Mar 2008
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From: 1 hours drive north of Sydney Australia
2007 W204 220CDI Classic Sedan
Looking outside the square , what about the brakes binding slightly?., different less efficient tyres?,boot full of golf buggies ?,roof racks ?
Thread Starter
Junior Member
Joined: Sep 2014
Posts: 16
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From: Vero Beach, Florida
2005 E320 CDI 150K miles and counting
I like the way you think! However I don't think this one will be that easy to troubleshoot
No roof rack, and usually travel with nothing in the boot. When I did the brakes(akebono) and rotors I made sure to properly grease the caliper slide pins. Everything is silky smooth there, and no excessive heatup after a drive from the rotors. I have low RR tires on it, however I have had some poor tire wear of the inside of the rears that I have been slowly been working through. I recently installed a rear camber kit to allow adjustment so hopefully my tires wear more evenly. I plan on replacing the front wheel bearings(no noise yet, just a bit sloppy) and having a proper Hunter alignment performed to get things in shape. Maybe after an alignment and the wheel bearing replacement things will get better fuel economy wise, but usually I'm not so lucky.
