Help! E350 engine misfire nightmare.
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Help! E350 engine misfire nightmare.
I bought a used 2013 E350 4Matic with the 3.5L V6 back in December w/ 115K miles. Drove it for four months without issue (about 3K miles) and it threw a CEL and started stuttering. Codes read were random engine misfire and misfire on #3. Took it to a Mercedes dealership, they put in a gasoline additive, new plugs and coils on all cylinders ($1800). Ten miles after leaving the dealership, CEL came back on and engine started misfiring again. Misfire on #3. Took it back and they found a bad injector on #3 stuck open ($1200). Got it back, drove it about 30 miles and once again, started stuttering, CEL came back on and now codes read are random misfire, or misfire on #4, #5, or #6, with #6 being the most frequent. Additional tidbit, I've been using E85 from the only station within 200 miles, and there's not a huge base of Flexfuel vehicles in the area.
Any thoughts? I love the car...it's my first Mercedes...but I'm about to give up.
Any thoughts? I love the car...it's my first Mercedes...but I'm about to give up.
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From: Phoenix, AZ
2016 E350 Sport 2WD
[QUOTE=smatda;9145288I've been using E85 from the only station within 200 miles.[/QUOTE]
It's hard to be 200 miles from a fuel station. And it makes filling up the tank pretty expensive just driving to and from/
I don't think I've seen this posted in a Mercedes website but many American cars can reset the alcohol level of the fuel in the computer with a scan tool. Perhaps Mercedes, too.
It's hard to be 200 miles from a fuel station. And it makes filling up the tank pretty expensive just driving to and from/
I don't think I've seen this posted in a Mercedes website but many American cars can reset the alcohol level of the fuel in the computer with a scan tool. Perhaps Mercedes, too.
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Thread Starter
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Joined: Apr 2025
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It's hard to be 200 miles from a fuel station. And it makes filling up the tank pretty expensive just driving to and from/
I don't think I've seen this posted in a Mercedes website but many American cars can reset the alcohol level of the fuel in the computer with a scan tool. Perhaps Mercedes, too.
I don't think I've seen this posted in a Mercedes website but many American cars can reset the alcohol level of the fuel in the computer with a scan tool. Perhaps Mercedes, too.
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From: Jakarta-Indonesia
2014 - W212.065 - E400 ( M276.820, 3 liter Turbo) RWD not Hybrid
If I were you I would replace all the 4 oxygen sensors and flex fuel sensor, if indeed ur car has such sensor....I am sure Flex fuel cars must have the fuel quality sensor.
https://mbworld.org/forums/e-class-w...flex-fuel.html
.
I read E85 is more harsh on oxygen sensors.
By age and mileage, those oxygen sensors is good enough to replace anyway and so would be the flex fuel quality sensor.
I have no experience with E85 fuel, but when reading the AFR of E85, its kinda complicated.
For E85 fuel, the stoichiometric (ideal) air-fuel ratio (AFR) is approximately 9.8:1. This is different from gasoline, which has a stoichiometric AFR of 14.7:1.
https://www.advancedfueldynamics.com...an%20condition.
.
https://cecas.clemson.edu/cvel/auto/...e%20cylinder.\.
https://mbworld.org/forums/e-class-w...flex-fuel.html
.
I read E85 is more harsh on oxygen sensors.
By age and mileage, those oxygen sensors is good enough to replace anyway and so would be the flex fuel quality sensor.
I have no experience with E85 fuel, but when reading the AFR of E85, its kinda complicated.
For E85 fuel, the stoichiometric (ideal) air-fuel ratio (AFR) is approximately 9.8:1. This is different from gasoline, which has a stoichiometric AFR of 14.7:1.
https://www.advancedfueldynamics.com...an%20condition.
.
https://cecas.clemson.edu/cvel/auto/...e%20cylinder.\.
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From: Pepper Pike Ohio
24 GLS580 '23 E450 4matic 12 E350 4Matic
Hopefully your dealer put in the correct plugs.injectors and coils, the E-85 cars have much different ignition parameters and the parts are all different. I believe the E-85 cars use the Euro firing sequence as opposed to the US spec cars also. I have only run E-85 twice in my Sport in 12 years of ownership, the loss in mileage and performance was not worth the effort or cost savings to me personally, but the car ran fine
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From: San Francisco
2011 E350 4MATIC Estate Wagon
E engine misfitre
Could the Direct Injection somehow be involved?
MB began DI on the 212 2012 models, & I flirted with buying a pre-owned E Wagon which had
blown a cylinder @ 20,000 miles. During my test drive @ Fletcher Jones / Fremont, the engine had a 3 second lag in acceleration, & the Mgr. would not approve shop tech work to correct, so I walked.
The dealership wholesaled that Wagon to a used car lot down the street 3 days later.
i subsequently bought a 2011 EWagon from MB
Santa Rosa which was the last Port Injection motor.
MB began DI on the 212 2012 models, & I flirted with buying a pre-owned E Wagon which had
blown a cylinder @ 20,000 miles. During my test drive @ Fletcher Jones / Fremont, the engine had a 3 second lag in acceleration, & the Mgr. would not approve shop tech work to correct, so I walked.
The dealership wholesaled that Wagon to a used car lot down the street 3 days later.
i subsequently bought a 2011 EWagon from MB
Santa Rosa which was the last Port Injection motor.
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From: Southern US
2010 E550, 273 Engine: 2012 S550, 278 Engine
Hopefully your dealer put in the correct plugs.injectors and coils, the E-85 cars have much different ignition parameters and the parts are all different. I believe the E-85 cars use the Euro firing sequence as opposed to the US spec cars also. I have only run E-85 twice in my Sport in 12 years of ownership, the loss in mileage and performance was not worth the effort or cost savings to me personally, but the car ran fine
It should run just fine with normal 91 oct fuel. The fuel sensor in the car tells the car systems what fuel is in use for adjustments in the engine parameters.
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From: Pepper Pike Ohio
24 GLS580 '23 E450 4matic 12 E350 4Matic
I assume since they have a wider range of fuels to use at different Octanes, I have a flex fuel car and a non-flex fuel car and the coils,spark plugs and injectors are different part numbers.
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From: Pepper Pike Ohio
24 GLS580 '23 E450 4matic 12 E350 4Matic
MBWorld Fanatic!
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From: Pepper Pike Ohio
24 GLS580 '23 E450 4matic 12 E350 4Matic
MBWorld Fanatic!
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From: Southern US
2010 E550, 273 Engine: 2012 S550, 278 Engine
Yes, the parts can be different but if the car was built to be "Flex Fuel" then the parts should work with any fuel you put in the tank up to that E85, would you think? So different fuels in Flex Fuel car should not cause any misfire issues...?
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From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
misfire is not simply caused by "bad spark"
Lean mixture misfire just as well.
When the gasoline is switched, the fuel maps are tweaked accordingly but remain the same ie. not wiped clean. (try simply clearing ECU faults to force a relearn).
A pair of clean new Bosch Lambda a good idea to restore performance on stock engines that burn vaporized API-SN oils.
Lean mixture misfire just as well.
When the gasoline is switched, the fuel maps are tweaked accordingly but remain the same ie. not wiped clean. (try simply clearing ECU faults to force a relearn).
A pair of clean new Bosch Lambda a good idea to restore performance on stock engines that burn vaporized API-SN oils.
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From: Pepper Pike Ohio
24 GLS580 '23 E450 4matic 12 E350 4Matic
Obviously they couldn't get enough fuel or the correct spark or stoichiometry with the stock injectors, plugs and coils, yes the car runs fine on 91 octane, that was not the question, it was running both E-85 and 91 octane premium through the same parts, Maybe the standard injectors couldn't flow enough fuel, maybe the standard plugs weren't hot enough or could maintain a good spark kernel, maybe the stock coils could not recharge fast enough to fire again? maybe the standard program was too narraow in it's parameters to accommodate E-85? I would also imagine the fuel delivery system has different O-rings and gaskets as well.
Last edited by pierrejoliat; Apr 22, 2025 at 09:15 AM.
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From: Jakarta-Indonesia
2014 - W212.065 - E400 ( M276.820, 3 liter Turbo) RWD not Hybrid
While E85 is typically cheaper per gallon than gasoline it might be more expensive per mile. Since ethanol contains less energy per volume than gasoline, FFVs will generally get 15%-27% fewer miles per gallon when fueled with E85, depending on the car and the driver’s driving habits.
Source : https://www.energy.gov/energysaver/a...iving%20habits.
So if throttle happy dude like me, can my injector handle 20%+ more fueling than normal ? Tough request I think.
Source : https://www.energy.gov/energysaver/a...iving%20habits.
So if throttle happy dude like me, can my injector handle 20%+ more fueling than normal ? Tough request I think.
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2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
Joined: Nov 2016
Posts: 7,847
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From: Maryland
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
Flex-Fuel (and E85) was a response to gasoline shortages or to help farmers with corn prices or both. Regardless, I don't see it as anything other than a red-headed step-child (or worse). The thing is that in the US at least, E85 does not mean 85% ethanol content, but rather a maximum of 85%. The ethanol content can be anywhere from (typically) 10% to 85%.
Interestingly, when I had water intrusion problems with my 2014 C350 Flex-Fuel car, it was the connector for the Flex-Fuel (Fuel Quality) Sensor that got soaked and caused all sorts of problems. I did get a CEL (DTC P0718) but no misfires. The thread is here: 2014 C350 Fuel Quality Sensor (Flex Fuel Sensor) P0178 - Solved
That said, I would check under the carpet in the front and rear for wetness or corrosion. In my case, the drain channels for the sunroof had become clogged causing water to back up and spill into the passenger compartment. I suspect this is a common problem with our cars. Once I drained the water by removing a floorboard plug and blew out any water from the connector with compressed air, my problems disappeared. The Flex-Fuel fuel quality module sits in-line of the fuel line to the engine and is located under the car in the vicinity of rear of the driver's door.
Interestingly, when I had water intrusion problems with my 2014 C350 Flex-Fuel car, it was the connector for the Flex-Fuel (Fuel Quality) Sensor that got soaked and caused all sorts of problems. I did get a CEL (DTC P0718) but no misfires. The thread is here: 2014 C350 Fuel Quality Sensor (Flex Fuel Sensor) P0178 - Solved
That said, I would check under the carpet in the front and rear for wetness or corrosion. In my case, the drain channels for the sunroof had become clogged causing water to back up and spill into the passenger compartment. I suspect this is a common problem with our cars. Once I drained the water by removing a floorboard plug and blew out any water from the connector with compressed air, my problems disappeared. The Flex-Fuel fuel quality module sits in-line of the fuel line to the engine and is located under the car in the vicinity of rear of the driver's door.
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From: Pepper Pike Ohio
24 GLS580 '23 E450 4matic 12 E350 4Matic
It appears those are the non-flex fuel plugs,injectors and coils, If your car does have option 929, OOPS!
Last edited by pierrejoliat; Apr 25, 2025 at 08:49 AM.
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From: Pepper Pike Ohio
24 GLS580 '23 E450 4matic 12 E350 4Matic
I'm wondering if the dealer put in the wrong parts, those part numbers are all for non-flex-fuel cars, I would assume the stock injectors cannot get enough fuel into the cylinder using E-85, I might clear codes and fill with premium to see, it could run fine on premium with those coils, plugs and injectors. But if in fact he has option 929, all of those part numbers listed are incorrect for that car. 
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W212 MY'14 M276-3.5NA @75kMi
it's a lot easier to get the wrong parts than the correct ones 
It's not hard to deliver rich mixtures with 3,000.Psi fuel pressure.
That's a vicious cycle:
poor combustions > leaner mixture > more misfires!
Lean misfire makes any good engine weak. It not easy to run cylinders evenly. Thank God for oil viscosity to seals piston rings.
It's not hard to deliver rich mixtures with 3,000.Psi fuel pressure.
That's a vicious cycle:
poor combustions > leaner mixture > more misfires!
Lean misfire makes any good engine weak. It not easy to run cylinders evenly. Thank God for oil viscosity to seals piston rings.
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Update: Something's changed, for the better....
The story so far...filled up from empty with E85, misfire developed on 3. New coils and plugs, misfire on 3 again. Drove it down to half a tank, filled it back up with premium, still misfire on 3. Took it back to dealer, new injector on 3. Drove it 20 or so miles...misfire on 6. Drove it down another half tank, refilled with Ethanol free, cleared codes....
Drove it for 30 or so miles, It stumbled once (and it wasn't really a stumble more of a bump) that the threw the CEL...misfire on 6 and catalytic eff low (that's a new code). Otherwise the car is running fine today?? I've cleared that code...let's see what happens tomorrow.
The story so far...filled up from empty with E85, misfire developed on 3. New coils and plugs, misfire on 3 again. Drove it down to half a tank, filled it back up with premium, still misfire on 3. Took it back to dealer, new injector on 3. Drove it 20 or so miles...misfire on 6. Drove it down another half tank, refilled with Ethanol free, cleared codes....
Drove it for 30 or so miles, It stumbled once (and it wasn't really a stumble more of a bump) that the threw the CEL...misfire on 6 and catalytic eff low (that's a new code). Otherwise the car is running fine today?? I've cleared that code...let's see what happens tomorrow.
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Joined: May 2012
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From: Pepper Pike Ohio
24 GLS580 '23 E450 4matic 12 E350 4Matic
Update: Something's changed, for the better....
The story so far...filled up from empty with E85, misfire developed on 3. New coils and plugs, misfire on 3 again. Drove it down to half a tank, filled it back up with premium, still misfire on 3. Took it back to dealer, new injector on 3. Drove it 20 or so miles...misfire on 6. Drove it down another half tank, refilled with Ethanol free, cleared codes....
Drove it for 30 or so miles, It stumbled once (and it wasn't really a stumble more of a bump) that the threw the CEL...misfire on 6 and catalytic eff low (that's a new code). Otherwise the car is running fine today?? I've cleared that code...let's see what happens tomorrow.
The story so far...filled up from empty with E85, misfire developed on 3. New coils and plugs, misfire on 3 again. Drove it down to half a tank, filled it back up with premium, still misfire on 3. Took it back to dealer, new injector on 3. Drove it 20 or so miles...misfire on 6. Drove it down another half tank, refilled with Ethanol free, cleared codes....
Drove it for 30 or so miles, It stumbled once (and it wasn't really a stumble more of a bump) that the threw the CEL...misfire on 6 and catalytic eff low (that's a new code). Otherwise the car is running fine today?? I've cleared that code...let's see what happens tomorrow.
Last edited by pierrejoliat; Apr 27, 2025 at 08:34 AM.
