Not Your Typical P0301 Code - Misfire Cyl 1
09-03-2021, 07:37 PM
#1
Newbie
Thread Starter
Join Date: Jul 2013
Location: Glendale, AZ
Posts: 2
Received 0 Likes
on
0 Posts
2010 E350 Coupe, 2013 C250 Sedan
Not Your Typical P0301 Code - Misfire Cyl 1
Discussion Starter · #1 · a moment ago
I've done the obvious. New MB coil packs. New Plugs. Here's the story.
2013 C250. 97K miles.
The engine had been getting noisy over the years when started. I found out about the extended warranty on cam adjusters and the dealer repaired it under the warranty a few weeks ago. When I picked it up, they mentioned I might have bad plugs or a coil pack causing the intermitent misfire. Misfire? The vehicle has never had a misfire. I scan it often up to the point of dropping it for that repair. There hasn't been a single misfire in the 75K miles I've owned it.
To avoid the MB tax, I buy real MB coil packs and and the recommended NGK 93911-4PK LKR7AIX Iridium IX Spark Plugs. Still get a misfire on Cyl 1. I move plugs and coil packs around. No change. The original 100K mile plugs looked ok albeit they could be regapped.
P0301. The car runs ok. No rough idle. I clear the code and it immediately returns. The pending never clears because it's immediate. Drove it about 100 miles and it never got better.
In the interim, the high pressure pump was replaced with a real MB high pressure pump. There have been intermitant codes. They went away. Car ran better at higher RPM. Still has the P0301 misfire.
So back to the dealer. Told them all of the above multiple times.
Direct from MB today: On 26072680 Ran short test. Had codes P030100 which turned the light on-misfire cyliner 1, 2nd code P008A23 low fuel pressure and voltage, did not turn the light on Vehicle passes SDS compression. Has over 4 bar low fuel pressure to 5.5 consistently. Passing on low side, Leak down is 4% on all 4 cylinders. The new coils are factory. The plugs are aftermarket. Not sure about the high pressure pump. The fuel issue would require more diagnostic time, I recommend starting with factory plugs and a 100 mile road test with the new plugs.
P008A23? That's a new one. I assume it is a result of the test.
The diagnosis. They tell me they have to replace the plugs with real MB parts for $300+. I told them ok but I'm really going to be pissed if I'm out that money and it doesn't fix the problem. The parts are the recommended ones minus the MB logo. Got to play the game. We will see.
Ideas? Could the cams be out of time when they did the warranty repair? Would being off a tooth allow it to run and not generate a cam or crank code?
The car is scheduled to be replaced in two weeks and it can't be with a check engine light.
To summarize in the order done:
Noisy cam - Dealer replace adjusters under warranty
Returned to me with a new symptom - Misfire on Cyl 1 consistently.
Replaced coils and plugs.
Still misfire.
Replaced high pressure pump (different problem)
Still misfire.
Back to dealer.
Compression test good. Ran some diags on injector.
They say the "aftermarket" plugs will have to be replaced.
Thanks in advance.
I've done the obvious. New MB coil packs. New Plugs. Here's the story.
2013 C250. 97K miles.
The engine had been getting noisy over the years when started. I found out about the extended warranty on cam adjusters and the dealer repaired it under the warranty a few weeks ago. When I picked it up, they mentioned I might have bad plugs or a coil pack causing the intermitent misfire. Misfire? The vehicle has never had a misfire. I scan it often up to the point of dropping it for that repair. There hasn't been a single misfire in the 75K miles I've owned it.
To avoid the MB tax, I buy real MB coil packs and and the recommended NGK 93911-4PK LKR7AIX Iridium IX Spark Plugs. Still get a misfire on Cyl 1. I move plugs and coil packs around. No change. The original 100K mile plugs looked ok albeit they could be regapped.
P0301. The car runs ok. No rough idle. I clear the code and it immediately returns. The pending never clears because it's immediate. Drove it about 100 miles and it never got better.
In the interim, the high pressure pump was replaced with a real MB high pressure pump. There have been intermitant codes. They went away. Car ran better at higher RPM. Still has the P0301 misfire.
So back to the dealer. Told them all of the above multiple times.
Direct from MB today: On 26072680 Ran short test. Had codes P030100 which turned the light on-misfire cyliner 1, 2nd code P008A23 low fuel pressure and voltage, did not turn the light on Vehicle passes SDS compression. Has over 4 bar low fuel pressure to 5.5 consistently. Passing on low side, Leak down is 4% on all 4 cylinders. The new coils are factory. The plugs are aftermarket. Not sure about the high pressure pump. The fuel issue would require more diagnostic time, I recommend starting with factory plugs and a 100 mile road test with the new plugs.
P008A23? That's a new one. I assume it is a result of the test.
The diagnosis. They tell me they have to replace the plugs with real MB parts for $300+. I told them ok but I'm really going to be pissed if I'm out that money and it doesn't fix the problem. The parts are the recommended ones minus the MB logo. Got to play the game. We will see.
Ideas? Could the cams be out of time when they did the warranty repair? Would being off a tooth allow it to run and not generate a cam or crank code?
The car is scheduled to be replaced in two weeks and it can't be with a check engine light.
To summarize in the order done:
Noisy cam - Dealer replace adjusters under warranty
Returned to me with a new symptom - Misfire on Cyl 1 consistently.
Replaced coils and plugs.
Still misfire.
Replaced high pressure pump (different problem)
Still misfire.
Back to dealer.
Compression test good. Ran some diags on injector.
They say the "aftermarket" plugs will have to be replaced.
Thanks in advance.
