2006 e320 CDI has me bamboozled... full Starscan read outs in post
05-10-2018, 12:38 PM
#1
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W211 CDI
2006 e320 CDI has me bamboozled... full Starscan read outs in post
Sorry for such a technical first post, but I've been a long time lurker here, and this issue has me finally posting for help.
Here's the scenario... My 2006 e230 cdi (250k) started shuttering and smoking really badly after being driven for about 3 miles/8-12 minutes. Once it warms up, it detonates (pops, knocks) and smokes really badly due to running rich, and shutters at idle... while bellowing rich diesel smoke.
I used my cheap OBD scanner and showed an 02 sensor failure on Bank 1, so I replaced the 02 sensor in the pic below. The old one was caked up big time.
Go back out for a drive, and it didn't fix the issue, but no other pending or current codes show up. I assumed it was the EGR, so we tested it, and then I removed it but everything functions properly, so I've no ruled out EGR and O2 sensor.
I take the car to a friends home with the MB scanning software and here's where it gets interesting.
The car doesn't show any codes in our initial diagnostic run, but I suspected a possible injector failure, so we ran the injector test. I show one injector near the margin of being "bad" on the report (a variation of 5 is bad), but I'm not convinced that the #1 cylinder injector is bad enough to cause the car to run this poorly. Here's the report.
We then run the high pressure rail test, it revvs up the car, causes massive clouds of diesel smoke, and the car detonates badly and eventually dies out from running out of fuel. Once that happened we get the error below... "Low Rail Pressure"
Here's where I'm stumped. How in the heck can low rail pressure result in a car running rich? I can't make sense of the low rail pressure causing the car to smoke badly, and roll coal while driving down the road.
What am I missing? What would you do next?
Here's the scenario... My 2006 e230 cdi (250k) started shuttering and smoking really badly after being driven for about 3 miles/8-12 minutes. Once it warms up, it detonates (pops, knocks) and smokes really badly due to running rich, and shutters at idle... while bellowing rich diesel smoke.
I used my cheap OBD scanner and showed an 02 sensor failure on Bank 1, so I replaced the 02 sensor in the pic below. The old one was caked up big time.
Go back out for a drive, and it didn't fix the issue, but no other pending or current codes show up. I assumed it was the EGR, so we tested it, and then I removed it but everything functions properly, so I've no ruled out EGR and O2 sensor.
I take the car to a friends home with the MB scanning software and here's where it gets interesting.
The car doesn't show any codes in our initial diagnostic run, but I suspected a possible injector failure, so we ran the injector test. I show one injector near the margin of being "bad" on the report (a variation of 5 is bad), but I'm not convinced that the #1 cylinder injector is bad enough to cause the car to run this poorly. Here's the report.
We then run the high pressure rail test, it revvs up the car, causes massive clouds of diesel smoke, and the car detonates badly and eventually dies out from running out of fuel. Once that happened we get the error below... "Low Rail Pressure"
Here's where I'm stumped. How in the heck can low rail pressure result in a car running rich? I can't make sense of the low rail pressure causing the car to smoke badly, and roll coal while driving down the road.
What am I missing? What would you do next?
05-14-2018, 10:11 PM
#3
MBWorld Fanatic!
More likely a faulty rail pressure sensor, reading "low" but it's not, so the car commands more fuel pressure to make it "right", but in actuality, that's too rich. More testing needed to be sure but that's my guess.
