BigTurboC4

Just installed JB4 in my ‘17 C43. Green fuel wire is plugged in. Running 93oct and map2. CEL P0087 will not go away. I also haven’t driven it yet and there was no cel before JB4. I looked around and saw changing the fuel open loop to a lower number could help. Tried 0 and 30 to no avail. Any thoughts other than taking it apart, hoping the cel stays and having the fuel pump replaced under warranty?

MaverickC43

When u turn car off the code pops back up upon startup?
The light on the dash pops up ?
or when u read the codes in the jb4 it’s there
When u clear the code with the jb4 the code still is there ?
go record a log and see what it looks like and send it to bms.
I’m sure you've seen a lot of posts about this.
I’ve had it

MaverickC43

I’ve had my loop at a few numbers before things got right
I’ve gotten some great runs with the jb4, but there are times where it feels jerky and shifts are off.
it’s not a full tune, so I guess it’s what we get

BigTurboC4

Well I went out and did a 3rd and 4th log. The light stayed on. I drove it to get beer. Shut it off. When I started it up two minutes later the cel was off. Log attached. Definitely felt like fuel cut or whatever you wanna call the fuel pulling near redline. Car loses power, tries to slow quickly.

MaverickC43

Yep
I’ve had it
first time I thought it was bc I had low fuel and was going uphill.
Turning off the car has always cleared it.
I haven’t always been logging when I’ve gotten it
Been a handful of times on 2 C43s and it always been when I was pushing the car hard

allanyeung99

I have this code pop up but no idea what caused it, could be because the fuel pumps are going out but I also had a shop diagnose it. They ran a bunch of test on the fuel system and they said everything was fine, then I took it to me tuner and they said it could be a 'hiccup' with the tune and that its just the car getting used to the tune. I got the code cleared for about two years now and recently it came up again, this time I'm thinking its the fuel pumps, but I deleted the code and still haven't came up, and the car is still running fine, just waiting for my Mercedes Tech guy for another diagnose. If its the fuel pumps, I'm planning on just upgrading to Spool performance fuel pumps.

BigTurboC4

I would hate for the fuel pumps to be going bad, while it is still under warranty, the car only has 39k miles on it. The code has since gone away so fingers crossed it was just a learning issue with the software.