MAP sensor code, running lean (CSL Management)

[Zach_E46M]

Hey guys, glad to finally have a forum back. You may remember me formally known as "." but this forum won't allow that name. I'm supposed to be on the road right now on my way up to tail of the dragon but unfortunately circumstances with my car have kept me from doing that. Long story short, I dropped my car off to have the subframe reinforced a couple weeks ago and planned to take it up to an event at the dragon this weekend. With everything going on the job took a little longer than planned but I picked the car up today with the main things done but some finishing touches left to do with the intentions of dropping the car back off when I got back. When I drove the car home, everything seemed great, car drove well. After I packed up, last thing I did was upload a minor tune tweak just to try something and cleared the adaptations and went to leave but suddenly the car wasn't driving nearly as well. Suddenly it was idling very lean and it stalled 3 times just trying to get out of my driveway. Decided to try some driving and noticed at WOT it's lean as well hitting stoic at WOT rather than high 12's low 13's as it should. Put back the tune that was on it before to rule that out and still the same. Then pulled the codes even though a CEL is not present and find:



Cleared it and after a few minutes it comes right back. Next step I took was to replace the MAP sensor with one I had laying around. I had recently replaced this when I was chasing down a different idle issue that was solved with an EGT sensor so I don't believe it was ever bad in the first place so I tried the previous one. No luck still throwing the code and running rough. Then I proceeded to check all the wiring from the plug to the DME. Everything looked good, I cleaned all the connections and no luck. Next I used a volt meter to check everything was getting power and signal and appeared good. Here's a video of the volt meter monitoring signal at the dme but I don't know enough whether this is normal readings or not, looks like the MAP sensor is working fine to me and you can see how lean it is running at idle:

https://youtu.be/8JMXSL3b218

Really stumped, don't know what else to try or what else it could be. Any help is appreciated, thank in advance.

Background info: Running Karb CSL airbox w/ Kassel MAP sensor kit and DME. DME is an original HP DME not a HP conversion.

[Slideways]

Do you have an installation of INPA? It might be worth resetting adaptations again and checking the MAP sensor reading using the software.

Edit: Just to add, the lean running condition could mean a vacuum leak somewhere.

[Martyn]

What's the reading with the ignition on and engine not running? The values at idle / revving look fine by the way.

As Slideways says it's deffo worth resetting your adaptations as you'll probably find it clears the short term fuel trims and sorts the idle out.

[ac427]

Just to make sure the MAP sensor is ok try this;

https://www.ecuworx.co.uk/2016/03/15...g-a-csl-clone/

Just noticed the previous post

[Arith2]

You need to figure out if the DME is recieving the right signal. You should have some vacuum in the intake manifold at idle. I would contact Karbonius about normal values from the MAP. Do a resistance check on wires for source voltage, signal, and ground to rule that out and then check the sensor itself. 1-2V at idle is around what you'd want in reference to your voltage test. 4.5V is basically 1bar and each decreased volt is basically 5in/Hg. You could smoke test the car. For AFRs to be that bad, there either has to be something disconnected, a huge hole somewhere, or the MAP circuit has a point of failure.

I wish you had a scan tool that showed live data because that would be so invaluable. Right now we are just kind of throwing darts at the board.

[Zach_E46M]

Pulled the airbox off to check for any obvious vacuum leaks and have not found any. I checked the voltage of the signal wire with the key in position 2 but not running and one sensor read 4.14V and the other read 4.10V which according to the link provided for checking you MAP sensor is working properly is off as it should be between 4.9-5V but seems really coincidental that they’re both reading basically the same and that both would have gone bad. I do not currently have a working version of INPA as I haven’t gotten it work on my computer (maybe I’m just an idiot) but I have cleared adaptations with both the foxwell tool and with bmwlogger and neither fixed it. I do agree with AFR’s where they’re at it definitely sounds more like an air leak but I have yet to find it and seems weird that it drive fine on the way home then as soon as I wanted to leave it suddenly is where it’s at.

[Slideways]

Pulled the airbox off to check for any obvious vacuum leaks and have not found any. I checked the voltage of the signal wire with the key in position 2 but not running and one sensor read 4.14V and the other read 4.10V which according to the link provided for checking you MAP sensor is working properly is off as it should be between 4.9-5V but seems really coincidental that they’re both reading basically the same and that both would have gone bad. I do not currently have a working version of INPA as I haven’t gotten it work on my computer (maybe I’m just an idiot) but I have cleared adaptations with both the foxwell tool and with bmwlogger and neither fixed it. I do agree with AFR’s where they’re at it definitely sounds more like an air leak but I have yet to find it and seems weird that it drive fine on the way home then as soon as I wanted to leave it suddenly is where it’s at.

Here is a good tutorial to getting INPA working on a Win10 installation -

Maybe there is a leak at the MAP sensor or one of the o-rings on the air rail?

[Arith2]

I'm starting to think of rarer causes but they are possible issues nonetheless.
Coolant Temp sensor in the block reading cold(you haven't mentioned it so probably not)
EGR happening too much.
Bent valves
Exhaust Leak
Clogged PCV

Do the sensors share any circuits? They might have a common power or ground. Wires are stupid sometimes and this is a custom set up. Maybe a connection corroded or has a loose solder point. You got a diagram of the set up? Maybe the instructions

[SliM3]

MAP sensor is probably not scaled correctly. Whenever I do a non-OEM designated MAP for this car I have to plug it up to my Arduino to insure the scaling matches the linear curve. I run a 2-bar, soon to be 3.5 bar for FI, but you can see the process I go through to get the scaling correct. I can populate the correct scaling for your MAP if you want to send it to me.

[terra]

What map sensor are you using?

[Philom5]

Hi guys, I know this is an old thread but was the lean issue ever resolved ? I'm also having a lean idle issue with my S54 swapped E28 M5. The MAP reading using TestO shows 3.5v at key on-engine off, and 800 mbar. At idle it shows .6v-.9v and 150-230 mbar. For reference, my current location, Long beach, CA, is showing 1010 mbar. I still need to verify voltage at the sensor but it's weird how for months the idle AFR was rock solid and then one day it started climbing at idle. Under load the AFR is fine and in the 14.8s This lean idle thing is bizarre.