Originally Posted by DonnieD

I have front cat delete. I deleted with star.

I think we are hitting load v/s throttle threasholds that are not in the tune. Think about this. If the throttle is supposed to be 18% at a given load range and we are achieving that load at 12 % throttle- the ecu may not have that duty cycle built into the map and available to tell the injectors to open enough.

Originally Posted by DonnieD

I am writing this article as a continuation of the thread about the EC tune and 550 injectors coupled with an 82 mm throttle-body causing erratic idol and running conditions.

The engine runs perfectly most of the time however it does run erratically after a long run at extremely light throttle and then trying to re-accelerate. When this occurs the engine runs extremely Lean to the point it will backfire buck and pop. At times when pulling up to a red light at idle it will do the same thing.

At first I thought this was a result of the 550 injectors causing a rich overall mixture and the computer compensating for it. So i reinstalled the stock injectors and has Jerry from eurocharged send me a new tune. It displayed the exact same drivability issues.

I then contacted other industry pros to help out. One led me down the path of the throttle body and gave me a good argument. Since NO 112-113 engine ever came with an 82mm TB, the calibration just isn't there. I think this is very well the case.

I took apart a stock TB and an 82 to measure a few things. Here is what i found!

The gear set and stepper motors are identical in every way. The sweepers are slightly different in the resistance value. I am going to try a set of resistors to get an identical setup to stock to see if that is the problem. Ill let u guys know.

Originally Posted by bstudey01

I spoke too soon. Just took the car out to find some hills and bamm!! Actually was only doing about 65 going up the hill and felt the slight hiccup stft's maxed. I knew it was too good to be true. Question for others that are having this exact issue, do you guys also get a hiccup once and a while at lower speeds upon light throttle application. I do notice it sometimes around town at about 30 when I press lightly on the gas. No, it is not the s/c engaging and it feels almost identical to the one on the highway but it doesn't cause the stfts to go out of whack or throw the code. Just thinking out loud. Anybody swap the cap from a 74 to theirs yet? I may try this, seems like it shouldn't be too difficult

Originally Posted by SLOWCAR930

I have hiccup, going on dyno and tune next week gonna try and get rid of it. Mine was there when car was factory. Now with mods seems a little worse

Originally Posted by E55Greasemonkey

Berti have you made any highway trips with yours yet, in the 70mph cruising range that the others are reporting? Going to install mine in a few weeks and getting nervous.

Originally Posted by SavMan

82mm TB was the first mod I had fitted in my car, it was then driven to another tuner to fit a crank pulley, decat and tune. The tuner called me that on the way to his workshop he got a CEL and the same B28 pressure sensor error, it happened ever since.
I have had new map sensor, new wiring to map sensor the TB & bypass TB, 3 TB's, 2 different intakes & pretty much every "fix" that people have suggested.
I have had a couple of times when it has happened at low speeds (less than 40) but 90% of the time it is around 80mph cruising and then slight uphill.
If I gun it or accelerate now problem, I have taken the car to 180's several times at full WOT and no issue and can drive for hundreds of miles at less than 70 without issue.

Originally Posted by MindBend

180's!! (is that MPH or KPH?)

Originally Posted by bstudey01

Sounds like you have tried almost all options. Which tuners have you tried, not to start a controversy, would just like to know. Also have you tried swapping the caps from a 74 to the 82?

Originally Posted by PACougar

Swapping parts isn't going to fix this problem, it's a tuning problem and I suspect it has everything to do with throttle percentage and map pressure triggering a conflict in the ECU under closed loop operation. That's why once you go beyond a certain size TB it seems to cause the problem. The bigger a TB the lower the throttle percentage at a given load. Of course knowing how finicky MB's ECU's can be car to car and year by year, I think that's why some people have it happen and others don't.

Originally Posted by SavMan

I looked at that some time ago as I had the same thought, logged a ton of data and not once did it happen during transition. It is always when in closed loop.

Originally Posted by adianaty

Out of curiosity how did you determine if it was in open or closed loop?

Originally Posted by SavMan

Log fuel system status, the AEM one I have calls it Fuel OL

Originally Posted by adianaty

Thanks Savman, logged it and in my car I can confirm its happening closed loop as well and not in the transitions.

Originally Posted by adianaty

Very well could be. I think Savman has it right that the parameters coming in from the sensors don't exist on the map and the car goes into this unrecoverable mode that only gets "reset" with a key cycle. It wouldn't surprise me that these are not readily available as a damos and are hex coded to keep the processing duty cycle down. Trouble shooting and finding that would take some serious work. I'll try and do some more research on the Bosch ME to see if there is a place to look since my guess is that if this was an easy fix, the tuners would have accommodated it already...Time to talk to tuners outside of the Benz world that are familiar with the Bosch ME strategy to get more insight.

Anyone know of another forced induction speed density car that uses the Bosch ME? Everyone I can think of uses a MAF system.