Jb4 c43 running rough / throwing engine lights /low boost
Thread Starter
Junior Member
Joined: Feb 2019
Posts: 38
Likes: 6
From: Buffalo, NY
2016 c300 4matic
Jb4 c43 running rough / throwing engine lights /low boost
I have a 2018 c43 with jb4 only. Run 4-5 gallons of e85 with a tank of 93. For the past week I've been seeing engine lights daily for 2177 and 2179 codes. Also the car is running sluggish on any map. It will often hesitate/ jerk after startup and driving until everything is warmed up (logs attached). One morning it nearly stalled out and rpms jumped around a ton. Logs show boost levels not where they were on previous runs on map 2 and 3. What could be causing this?
Member
Joined: Aug 2020
Posts: 96
Likes: 82
'17 C43 AMG [Stage 1+]
I'm gonna go on a limb and say that your issues are stemming from your use of ethanol. our cars really aren't built for ethanol unless you do proper fuel system upgrades for it
Other than that I would for sure double check your wirings
Other than that I would for sure double check your wirings
Senior Member
Joined: Mar 2018
Posts: 323
Likes: 103
From: Central Florida
'15 C400 and '15 ML350
OP, im guessing you have a faulty wire connection on the JB4, and from the codes I would start with the green fuel pressure plug.
Also, what firmware version are you running?
Member
Joined: Apr 2017
Posts: 120
Likes: 19
From: Toronto
C43 AMG Sedan
Does JB4 alter AFR? I'd run just 93 octane and run stock map and see how the car handles it. This is one of the reasons why proper ecu remap/flash are better as they are able to control AFR.
Thread Starter
Junior Member
Joined: Feb 2019
Posts: 38
Likes: 6
From: Buffalo, NY
2016 c300 4matic
Appreciate everyone's input. I'm going to disconnect the green wire and see if that helps. I never had any issues prior to it being connected about 2 months ago. I topped off the tank with 93 so there is very little e85 in there and the car idles terribly on cold starts and will pull very strong on some pulls and fall flat on its face on others. I was running firmware 7, just updated to beta 8 and will see if anything changes.
Stock spark plugs are iridium and made by NGK. There isnt an "upgraded" spark plug available for out motors unless you want to take some chances with silver core plugs being slightly colder.
OP, im guessing you have a faulty wire connection on the JB4, and from the codes I would start with the green fuel pressure plug.
Also, what firmware version are you running?
OP, im guessing you have a faulty wire connection on the JB4, and from the codes I would start with the green fuel pressure plug.
Also, what firmware version are you running?
Member
Joined: Dec 2019
Posts: 111
Likes: 32
From: West
C43
Both codes are generic codes for lean conditions (I’m guessing generic, unless merc is specific, but your logs and symptoms match up).
My guess is it’s being caused by low fuel pressure. Your logs show leaner afr, lower fuel pressure, and higher trims than you want. It could be because of your e85 mix. You’re running a very high mix. Having said that I ran similar mix as you and had some issues, but not the ones you are.
THE OTHER THING is your Fuel OL value is 60 where as mine was 50 and you tmap value is different than mine too. I honestly forget what tmap was for but fuel ol controls the extra amount of fuel requested. For instance setting it to 0 would disable the green wires effect.
long story short im fairly certain you have a fuel problem. Decrease e85 mix (make sure timing stays ok). I’m almost certain you’ll be fine octane wise and probably get improved performance with with a lighter mix. Check with BMS if you should reduce fuel ol to 50 (I forget if this value auto adjust overtime).
if you unplug green wire I’d be really careful about running that thick a mix of e85. Also if you just throwin in 6 gal of e85 and topping up, how much fuel was left from the previous fill? Cause you could still have a couple gallons of e85 left over, now your at 8 gallons in the tank, which is far far far too much.
orher possibilities are inrake leaks, exhaust leaks, bad maf sensors, bad injectors
Edit: (additionally I’d stop doing pulls until it’s sorted. It’s probably “very strong” on some cause you make more power when lean but things get very hot, possibly destructively hot)
My guess is it’s being caused by low fuel pressure. Your logs show leaner afr, lower fuel pressure, and higher trims than you want. It could be because of your e85 mix. You’re running a very high mix. Having said that I ran similar mix as you and had some issues, but not the ones you are.
THE OTHER THING is your Fuel OL value is 60 where as mine was 50 and you tmap value is different than mine too. I honestly forget what tmap was for but fuel ol controls the extra amount of fuel requested. For instance setting it to 0 would disable the green wires effect.
long story short im fairly certain you have a fuel problem. Decrease e85 mix (make sure timing stays ok). I’m almost certain you’ll be fine octane wise and probably get improved performance with with a lighter mix. Check with BMS if you should reduce fuel ol to 50 (I forget if this value auto adjust overtime).
if you unplug green wire I’d be really careful about running that thick a mix of e85. Also if you just throwin in 6 gal of e85 and topping up, how much fuel was left from the previous fill? Cause you could still have a couple gallons of e85 left over, now your at 8 gallons in the tank, which is far far far too much.
orher possibilities are inrake leaks, exhaust leaks, bad maf sensors, bad injectors
Edit: (additionally I’d stop doing pulls until it’s sorted. It’s probably “very strong” on some cause you make more power when lean but things get very hot, possibly destructively hot)
Last edited by Trekt43; Nov 5, 2020 at 03:47 AM.
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Thread Starter
Junior Member
Joined: Feb 2019
Posts: 38
Likes: 6
From: Buffalo, NY
2016 c300 4matic
Thanks for the input. To clarify I let it get down to half tank and topped off with 93 (so should be 2.5-3 gallons of e85 still in there on a full tank). I'm going to run this tank down and just fill up with 93. I'm wondering if maybe I messed up the drivers side map sensor on the intake when connecting the green wire I had some difficulty disconnecting it. They are cheap so it's worth a try. Appreciate the help. Im going to stop doing pulls but here's two back to back last night attached, one where the car was falling flat on its face and the other where it pulled hard (1/8 mile in 7.65 sec)
Both codes are generic codes for lean conditions (I’m guessing generic, unless merc is specific, but your logs and symptoms match up).
My guess is it’s being caused by low fuel pressure. Your logs show leaner afr, lower fuel pressure, and higher trims than you want. It could be because of your e85 mix. You’re running a very high mix. Having said that I ran similar mix as you and had some issues, but not the ones you are.
THE OTHER THING is your Fuel OL value is 60 where as mine was 50 and you tmap value is different than mine too. I honestly forget what tmap was for but fuel ol controls the extra amount of fuel requested. For instance setting it to 0 would disable the green wires effect.
long story short im fairly certain you have a fuel problem. Decrease e85 mix (make sure timing stays ok). I’m almost certain you’ll be fine octane wise and probably get improved performance with with a lighter mix. Check with BMS if you should reduce fuel ol to 50 (I forget if this value auto adjust overtime).
if you unplug green wire I’d be really careful about running that thick a mix of e85. Also if you just throwin in 6 gal of e85 and topping up, how much fuel was left from the previous fill? Cause you could still have a couple gallons of e85 left over, now your at 8 gallons in the tank, which is far far far too much.
orher possibilities are inrake leaks, exhaust leaks, bad maf sensors, bad injectors
Edit: (additionally I’d stop doing pulls until it’s sorted. It’s probably “very strong” on some cause you make more power when lean but things get very hot, possibly destructively hot)
My guess is it’s being caused by low fuel pressure. Your logs show leaner afr, lower fuel pressure, and higher trims than you want. It could be because of your e85 mix. You’re running a very high mix. Having said that I ran similar mix as you and had some issues, but not the ones you are.
THE OTHER THING is your Fuel OL value is 60 where as mine was 50 and you tmap value is different than mine too. I honestly forget what tmap was for but fuel ol controls the extra amount of fuel requested. For instance setting it to 0 would disable the green wires effect.
long story short im fairly certain you have a fuel problem. Decrease e85 mix (make sure timing stays ok). I’m almost certain you’ll be fine octane wise and probably get improved performance with with a lighter mix. Check with BMS if you should reduce fuel ol to 50 (I forget if this value auto adjust overtime).
if you unplug green wire I’d be really careful about running that thick a mix of e85. Also if you just throwin in 6 gal of e85 and topping up, how much fuel was left from the previous fill? Cause you could still have a couple gallons of e85 left over, now your at 8 gallons in the tank, which is far far far too much.
orher possibilities are inrake leaks, exhaust leaks, bad maf sensors, bad injectors
Edit: (additionally I’d stop doing pulls until it’s sorted. It’s probably “very strong” on some cause you make more power when lean but things get very hot, possibly destructively hot)
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Thread Starter
Junior Member
Joined: Feb 2019
Posts: 38
Likes: 6
From: Buffalo, NY
2016 c300 4matic
let the tank get to empty and filled up with some ethanol free premium. So far so good and haven't had any cel codes pop up. BCM seems to help keep power between shifts better than before 👍
Thread Starter
Junior Member
Joined: Feb 2019
Posts: 38
Likes: 6
From: Buffalo, NY
2016 c300 4matic
Last edited by JL1000; Jan 14, 2021 at 08:29 PM.
Thread Starter
Junior Member
Joined: Feb 2019
Posts: 38
Likes: 6
From: Buffalo, NY
2016 c300 4matic
Not that anyone has been wondering but I used a bottle of Chevron Techron fuel system cleaner and the car has been code free the last 6 weeks after throwing daily codes.
Newbie
Joined: Apr 2021
Posts: 2
Likes: 2
2018 GLC43 AMG
The amount of ethanol in "E85" changes throughout the year in a range of 51% - 83%, depending on climate. As stations change over, I've found that I have issues as my computer tries to adjust to the new concentration levels, particularly at startup.
Thread Starter
Junior Member
Joined: Feb 2019
Posts: 38
Likes: 6
From: Buffalo, NY
2016 c300 4matic
As an update I had driven a thousand miles with the jb4 off and have not ran any e85 for about 10k miles. Was still getting occasional lean codes. Even with the jb4 off. Took it to dealer who ended up replacing the fuel pump and injectors. Think I'll stick to 93 from here on out
