MAP Sensor questions (combined with p0106 backstory)
 

Couple of questions for the forum:

On the MAP sensor there are two lines coming out of the top port (red arrows), running to what appear to be diaphragms or actuators (blue circle) . What are those "diaphragms"?
Also, there is a lower port coming out of the MAP with a line that disappears under the passenger side intake plenum. (green arrow). Where does that go?

https://cimg2.ibsrv.net/gimg/www.mbw...f6fcb05e4f.jpg


Backstory:
Yeah so I just got my EC tune and the first drive I threw a P0106. I reset it and it came back a second time. Just reset it once more for diligence.
Two times I've noticed a very short rough idle when I come to a stop. I've read about this "hiccup" issue, but the symptoms are not conclusive and I have not logged AFR

Wow... zero replies? I guess I’ll just keep trying to bump this thread

I guess this forum is pretty much dead....:mercy:

Thats not a MAP sensor, thats the secondary air injection switch over valve. The line on the bottom is the vacuum supply thats plugged in the back of the intake/supercharger. The two lines up front go one to each diverter valve, thats what opens to allow air from the air injection pump into the exhaust via ports in the head.

Your MAP sensor is on the back of supercharger near the bottom

Haha... thanks. I actually did figure that part out after posting this up. Too bad it's not the MAP. I thought it was because I had watched a video where the E class had it in that same location. I thought "well that's easy to get to". But then after more homework.... WRONG. it's under the throttle body.

Did you ever replace your MAP sensor? I just got a P0106 code yesterday. It has gone away, but I’ve been having very rough idle where it almost wants to stall sometimes. Other times it wants to unsuspectingly surge, where if I wasn’t paying attention, could’ve cause me to ram something. I’m guessing I have a bad MAP sensor. Was it easy to replace?

thanks,

matt

Do you also have a sl55 with EC tune?

i had the same problem with my sl55 immediately after the ec Tune and pulley - no other changes. P0106 hiccup issue with 75mph cruise, just like e55s with throttle body swaps plus tune.
I replaced the MAP sensor (pita) with no change, cel would come up under same conditions and if I played around with throttle position some while cruising the cel would stay off but rough idle and surge at idle immediately following after restart.

put the stock tune back on, no issue, no p0106 or idle stumble after high speed cruise. Flashed back to the ec tune, came back.
I contacted EC about it, reluctantly they made another tune but no improvement. I didn’t hound them further about it but seems I wasn’t alone with the weird p0106 quirk.

I have a 2003 SL55 with an EC tune. I was having the surge and performance issues prior to the time though. The P0106 code came and went and hasn’t returned. The car still runs rough, however.

Hey man... no I have not done it yet. I'm just finishing up a build on one of my other cars that has taken about 9 months.. I can't have multiple cars apart at the same time... too much. My wife would complain. LOL.

From what I see online, it's under the throttle body. So it's a little bit of work.

BW

Dang man... I told them about it too and they said it wasn't the tune. The bad part for me is that I had to send my ECU out because it wouldn't flash. I tried 3 laptops and multiple reinstallations. But I'm upset to hear that you're having the same problem.... they need to support us.

BW

That sounds like a huge hassle! Fortunately I had no flashing issues.
There are a lot of possible causes for this p0106 code, in my case it was definitely the tune bringing it out which was confirmed with the back to back testing once I pinned down exactly how to replicate the problem. I actually diagnosed and went through all the other check points for this code before contacting EC, I know many people will just immediately point towards the tuner (hence why I replaced the MAP, TB, did vac leak/smoke tests, etc first)

I think this could possible be limited to ECs tune on certain 03 only sl55s, perhaps within a certain build date/ecu calibration. Like I said EC/Jerry did provide a revised tune after pestering for a few weeks. Jerry said he never had to tweak a tune for this problem before (and has done thousands of MB tunes), and said to stick with stock tune or use another tuner if I have more issues - that was that. The revised tune had tweaked MAP voltages and seemed better but unfortunately it just didn’t completely solve the problem. I changed my driving style to avoid 75mph cruise, especially up long hills, and it almost never popped back up.
Perhaps my car still had an underlying issue that only the tune would make apparent as it is pushing everything beyond stock limits, but we just couldn’t track it down.

You could reach out and request the revised tune they made for me and see if it helps in your case, feel free to pm me for more info.

Vnova if you had this issue BEFORE the tune was even installed there is no way the tune can be blamed, although it could be exacerbating the issue as with any tune it is going beyond the stock parameters for more performance and having the car in proper condition is even more critical. Faults and weaknesses are exposed more readily. I would start with the proper diagnosis for this code though, check for vac leaks especially any rubber hoses connected to the intake tract. Do a smoke test. inspect and clean TB, Check throttle angles. Then try the MAP.

Having trouble locating the MAP sensor. Is it accessible from the top of the engine, or do you need to get under the car? I have my air intake apart and don’t see anything under the throttle body. See pic below.

https://cimg0.ibsrv.net/gimg/www.mbw...be5d2ac2a.jpeg

Anyone replaced their MAP sensor? Now that it’s getting warmer again, it’s time to revisit this and get it fixed. See my question and photo above regarding where I can access this sensor. Any help would be appreciated. Matt

04 with EC tune I can’t recall if I had the surge before or after the tune but I had one of the p codes appear once on a cruise, went away after a restart. I’m willing to bet it’s all the same issue we are having.

perhaps bad gas from time to time?

My car was doing it well before I ever did the tune. I want to get the sensor replaced and then go from there. Problem is... I can’t locate the damn thing.

Same problems after Tune installed
 

Installed fixed 77mm pulley drove it with my stock tune for a few weeks and no codes or problems. I Installed RaceIQ tune from Anthony and the car ran like crap and kept throwing P0106 code with rough idle, surging. I put stock tune back on and won't be using anyone's tune..