Replaced intake manifold - cylinders 1 and 4 not firing
Senior Member
Joined: Dec 2018
Posts: 285
Likes: 60
From: New York
2010 E350 4Matic sedan
Did you ever solve this?
I have gotten a couple of misfires over the last 4 months on cylinders 1 (twice) and 4 (once). Codes were the misfire codes (p0301) and I also got P050B (cold start ignition timing) at the same time. On all 3 scenarios I replaced the spark plug and the problem went away. Since cylinder 1 came back a second time I just ordered a new coil pack to replace the old one. Unlike you, I have NOT replaced my manifold yet as I have not seen a reason. I have a 2010 e350 with 138k miles. Runs great. Only other thing I see is that my LTFT are running lean about +25 to +35%. So not sure if that is connected to the misfires.
Last edited by pb39374; Mar 1, 2026 at 08:35 AM.
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Joined: Apr 2019
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From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
LEAN MISFIRE FAULTS
I have gotten a couple of misfires over the last 4 months on cylinders 1 (twice) and 4 (once). Codes were the misfire codes (p0301) and I also got P050B (cold start ignition timing) at the same time. On all 3 scenarios I replaced the spark plug and the problem went away. Since cylinder 1 came back a second time I just ordered a new coil pack to replace the old one. Unlike you, I have NOT replaced my manifold yet as I have not seen a reason. I have a 2010 e350 with 138k miles. Runs great. Only other thing I see is that my LTFT are running lean about +25 to +35%. So not sure if that is connected to the misfires.
Your ignition is fine but fuel is not
Next you'll want to read the fuel rail pressure and tank pump pressure. Low pressure forces lean supply.
At 138kMi... you can have a plugged up dirty fuel filter and if GDI in addition also a worned out HPFP.
Last edited by CaliBenzDriver; Mar 1, 2026 at 01:59 PM.
Senior Member
Joined: Dec 2018
Posts: 285
Likes: 60
From: New York
2010 E350 4Matic sedan
Thanks - I actually put in a new fuel filter about 3 weeks ago for 2 reasons: 1) it was 15 years old which is the recommended replacement by MB (non-GDI) 2) with the hopes of fixing the LTFT problem. I also replaced my fuel pump about a year ago. I am started to think vacuum leak somewhere
Last edited by pb39374; Mar 1, 2026 at 02:25 PM.
Out Of Control!!
Joined: Apr 2019
Posts: 11,958
Likes: 6,802
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
Thanks - I actually put in a new fuel filter about 3 weeks ago for 2 reasons:
1) it was 15 years old which is the recommended replacement by MB (non-GDI)
2) with the hopes of fixing the LTFT problem.
I also replaced my fuel pump about a year ago.
I am started to think vacuum leak somewhere
1) it was 15 years old which is the recommended replacement by MB (non-GDI)
2) with the hopes of fixing the LTFT problem.
I also replaced my fuel pump about a year ago.
I am started to think vacuum leak somewhere
You are dealing with non-GDI, new tank filter and new pump with an +30 rich trim on a lean engine.
the parts you've replaced were overdue
The only question is what's going on then ?
Read the ECU fuel rail sensor with a scanner**.
The next possible big leaker at 138kMi is the PCV at the rear of bank1. "A lot of air calling for a lot of gas"
** MB Fuel sensors do go bad.
Last edited by CaliBenzDriver; Mar 1, 2026 at 02:58 PM.
Senior Member
Joined: Dec 2018
Posts: 285
Likes: 60
From: New York
2010 E350 4Matic sedan
I got reminded recently that our MAP engines don't care about vacuum leaks the way MAF do.
You are dealing with non-GDI, new tank filter and new pump with an +30 rich trim on a lean engine.
the parts you've replaced were overdue
The only question is what's going on then ?
Read the ECU fuel rail sensor with a scanner**.
The next possible big leaker at 138kMi is the PCV at the rear of bank1. "A lot of air calling for a lot of gas"
** MB Fuel sensors do go bad.
You are dealing with non-GDI, new tank filter and new pump with an +30 rich trim on a lean engine.
the parts you've replaced were overdue
The only question is what's going on then ?
Read the ECU fuel rail sensor with a scanner**.
The next possible big leaker at 138kMi is the PCV at the rear of bank1. "A lot of air calling for a lot of gas"
** MB Fuel sensors do go bad.
Out Of Control!!
Joined: Apr 2019
Posts: 11,958
Likes: 6,802
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
Non GDI in-tank pump: 60Psi
(GDI secondary pump: 2800Psi)
These values are available in the ECU module live data.
If you see pressure is significantly low or collapses... that's bad.
Last edited by CaliBenzDriver; Mar 1, 2026 at 10:08 PM.
Senior Member
Joined: Dec 2018
Posts: 285
Likes: 60
From: New York
2010 E350 4Matic sedan
The fuel rail sensor pressure readout needs to hold nearly steady pressure under load.
Non GDI in-tank pump: 60Psi
(GDI secondary pump: 2800Psi)
These values are available in the ECU module live data.
If you see pressure is significantly low or collapses... that's bad.
Non GDI in-tank pump: 60Psi
(GDI secondary pump: 2800Psi)
These values are available in the ECU module live data.
If you see pressure is significantly low or collapses... that's bad.
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Out Of Control!!
Joined: Apr 2019
Posts: 11,958
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From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
Injector pulse circuit
Based on all the prior roll up... this is aiming towards an injector issue which may be a bad ECU output MOSFET. Any chance you can listen to your injectors?
We're not talking new injectors until we're sure they are getting pulses with low spray output.
You can't really measure high-frequency pulses to get a significant number but for our purpose here: you can rule out good/bad ECU output using AC (limited to near 60Hz range).
There may be a bad +12V power source fuse (ECU switches the Gnd side circuit)
Last edited by CaliBenzDriver; Mar 10, 2026 at 09:37 AM.
Senior Member
Joined: Dec 2018
Posts: 285
Likes: 60
From: New York
2010 E350 4Matic sedan
that proves perfect fuel rail pressure.
Based on all the prior roll up... this is aiming towards an injector issue which may be a bad ECU output MOSFET. Any chance you can listen to your injectors?
We're not talking new injectors until we're sure they are getting pulses with low spray output.
You can't really measure high-frequency pulses to get a significant number but for our purpose here: you can rule out good/bad ECU output using AC (limited to near 60Hz range).
There may be a bad +12V power source fuse (ECU switches the Gnd side circuit)
Based on all the prior roll up... this is aiming towards an injector issue which may be a bad ECU output MOSFET. Any chance you can listen to your injectors?
We're not talking new injectors until we're sure they are getting pulses with low spray output.
You can't really measure high-frequency pulses to get a significant number but for our purpose here: you can rule out good/bad ECU output using AC (limited to near 60Hz range).
There may be a bad +12V power source fuse (ECU switches the Gnd side circuit)
Out Of Control!!
Joined: Apr 2019
Posts: 11,958
Likes: 6,802
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
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From: Fleriduh
W212 E63S Wagon - GSL580 - E63 - E350 - C300
This thread freaked me out - last weekend in about two hours, maybe two and a half I put a new top end on one of my cars. Other than having to reset the throttle, and forgetting the cable to the MAS....smooth as can be (not to rub salt in a wound). I think that something more was going on before the new air intake system was put on.
