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-   -   Jb4 c43 running rough / throwing engine lights /low boost (https://www.n54tech.com/forums/showthread.php?t=63739)

Looters 11-01-2020 01:03 PM

Jb4 c43 running rough / throwing engine lights /low boost
 
2 Attachment(s)
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?

Terry @ BMS 11-01-2020 04:25 PM

They are o2 sensor/fuel trim sorts of faults. Probably due to the E85 mix. As a test could lower the E85 mix.

At WOT boost looks lower, but temperature is also colder, so you'll have less of a target. If there isn't a boost leak then adding in a BCM would really wake this car up I think.

Looters 11-01-2020 04:32 PM

Thanks for the input. I was running a little more e85 than normal so let it get down to half a tank and topped it off with 93. Seems to have helped some and havent thrown a code yet . Going to order the BCM from your site and give that a try.

Looters 11-07-2020 06:34 PM

2 Attachment(s)
Mind taking a look at these logs? Lowered e85 to roughly 2.5-3 gallons on full tank of 93...I ordered the bcm and installed and first pull after install was easily the quickest the car has ever felt. Few minutes later did a quick 40 to 70 pull and felt super sluggish. Here's both logs. I also replaced both map sensors to rule that out. Any other ideas what to look for or causes?

Quote:

Originally Posted by Terry @ BMS (Post )
They are o2 sensor/fuel trim sorts of faults. Probably due to the E85 mix. As a test could lower the E85 mix.

At WOT boost looks lower, but temperature is also colder, so you'll have less of a target. If there isn't a boost leak then adding in a BCM would really wake this car up I think.


Terry @ BMS 11-07-2020 06:56 PM

Your boost safety is set to 14.1psi, that's way too low. Raise it to 18psi.

Looters 11-11-2020 03:30 PM

1 Attachment(s)
Quote:

Originally Posted by Terry @ BMS (Post )
Your boost safety is set to 14.1psi, that's way too low. Raise it to 18psi.

Ran this tank down to almost empty, filled up with some ethanol free premium and so far no engine lights thrown after 30 miles or so. Going to probably stay away from e85 for a bit. Mind taking one more look at this run with boost control module installed? This was map 2. Everything felt strong.

Terry @ BMS 11-13-2020 04:50 PM

Looks as expected to me!

Looters 02-25-2021 09:37 AM

Just in case its helpful to anyone else with similar issues, I was getting daily codes 2177 and 2179 every time I drove the car. Used one bottle of Chevron Techron fuel system cleaner and haven't had a code since. So obviously the e85 was too much for the stock fuel system on my car over the course of a year. I've been running 93 octane only now.

Looters 11-09-2021 09:10 AM

Old thread but may be of valuable info to some. So had the jb4 off the car for a few weeks and still have been throwing periodic p2179 p2177 codes, haven't ran e85 in a long time. Took it to the dealer who replaced the fuel pump and fuel injectors. Actually said they ended up replacing the whole fuel rail due to lack of parts. Think I'll be sticking to 93 only from here on out.

Quote:

Originally Posted by Terry @ BMS (Post )
They are o2 sensor/fuel trim sorts of faults. Probably due to the E85 mix. As a test could lower the E85 mix.

At WOT boost looks lower, but temperature is also colder, so you'll have less of a target. If there isn't a boost leak then adding in a BCM would really wake this car up I think.



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