Extremely sluggish BlueTEC - PeachParts Mercedes-Benz Forum

muleears · #1 06-05-2017, 04:24 PM

After a 150 mile trip, by 07 E320 Bluetec became extremely sluggish and threw a P0101 (Mass air flow) code. I bought two new Mercedes MAF's and installed them (another story entirely). Car still runs the same. Erased codes, changed fuel filter (just in case). The car when first driven after being started runs fine, accelerates well, just like it should. But as soon as you slow down it loses all power. Doesn't misfire or stall at all just very very sluggish. You have to feather the go pedal to accelerate at all, if you push it too far it just slows down. Hills are virtually impossible. Does the computer have to be reprogrammed when new MAF sensors are installed (that's stuck in my head that may be the case). Any input is appreciated, I'm stranded at home...

engatwork · #2 06-05-2017, 04:32 PM

Did the code clear?

muleears · #3 06-05-2017, 04:53 PM

I can clear the code but comes back after being driven. Once it didn't come back until the subsequent restart. But yes, it does come back after being cleared by the reader.

engatwork · #4 06-05-2017, 05:12 PM

My first thought is a boost/pressurized part problem. How many miles are on it? No code reset after air flow meter change BUT you have to fix what is making code come on.

muleears · #5 06-05-2017, 05:20 PM

130K miles. Runs perfectly and has normal boost when first started, runs great until you slow down, then no power. May even be going into LHM, I'm not sure never had a car in limp mode before. In a nutshell when started it runs fine until you have to slow down for a curve or light, then the sluggishness begins. I am baffled... Thanks for the help btw.

muleears · #6 06-05-2017, 08:03 PM

Have sent it to my Indy, will know more tomorrow.

engatwork · #7 06-05-2017, 08:06 PM

With the fault code it will be in LHM.

muleears · #8 06-06-2017, 09:17 AM

I believe you are right, that is why it is so slow, its in third or fourth gear. Whatever gear LHM chooses with the 7 speed tranny. Spoke to my indy he mentioned that some of the early 7 sp. trans had a problem with the valve body and sticking in gear.... Hope that's not the case here. Like you said, I think its just going into limp mode for some reason. Would the MAF's be sufficient reason for LHM though?

engatwork · #9 06-06-2017, 09:21 AM

Yes but I have seen MAF sensor fault codes be caused by stuff other than the MAF.

muleears · #10 06-06-2017, 11:01 AM

Quote:

Originally Posted by engatwork

Yes but I have seen MAF sensor fault codes be caused by stuff other than the MAF.

Yes, that must be whats happening. Thanks for the information.

crazy4diesel · #11 06-06-2017, 02:28 PM

It is for sure in LHM. When a code comes back after being reset, it's a hard code, in other words it can't be reset without replacing the sensor that's not happy.

muleears · #12 06-06-2017, 04:18 PM

Quote:

Originally Posted by crazy4diesel

It is for sure in LHM. When a code comes back after being reset, it's a hard code, in other words it can't be reset without replacing the sensor that's not happy.

I replaced both MAF sensors, that's what the code was for anyway, unless something else is causing the code like engatwork said. It was the P0101 code.

crazy4diesel · #13 06-06-2017, 04:48 PM

P0101 is a very generic code. Basically it says there is "something" wrong with the air flow. The MAF often gets blamed, because it's the one tripping the code. But, what it means is that among all the air flow related sensors, the MAF is getting a different reading. So, it could be the MAF, but it could also be one of the other sensors. The dealer's code reader probably has more detailed codes for the CEL which might pinpoint the problem. One reason why they charge so much.

This thread might help, at least it will show you it could be a lot of odd things you don't even consider. Persistent P0101/CEL on 2007 Bluetec - Mercedes-Benz Forum

engatwork · #14 06-06-2017, 05:16 PM

I've got one customer that has one of these (09 E320 bluetec) and in ~135k miles the only issue it has had similar to this was the intake manifold flap actuator failure because of the oil on it. I did not find it that big of a deal to change out but the lady at the MB parts counter told me to make sure I did not break any of the plastic bits or I could possible be looking at a new intake manifold. I am of the opinion that that and having two maf sensors built into the ducting is a BS design but what do I know?.

jay_bob · #15 06-06-2017, 10:05 PM

OK I will bite on this one

We had the swirl flapper motor fail on the 08 ML320. I was in the car while my wife was driving. She looks over at me and goes 'wth, I can't make 45 mph up this hill!'

CEL was on, we limped it the rest of the way home. Got the code reader out and it was the code for the swirl flapper.

Temporarily unplug the little bugger. The connection is about dead center in the valley of the V right behind the fuel filter and in front of the turbo. This is one of those gray tab connectors. You have to carefully move the tab towards the wire end of the connector about a 1/4 inch, it will click. Then you take your thumb and pinch the gray tab toward the center of the connector while pulling the connector out of the socket.

Find a 4.7 k ohm resistor and bend the leads to look like an ohm symbol. You want to put the leads into the two center holes of the connector you just unplugged. Put some tape around it so that nothing shorts out. Then try to clear your codes again.

This is a *temporary* fix until you can get the swirl flapper motor replaced. The swirl flaps are very important to the engine performance. It actually works off the pressure waves created by the opening and closing intake valves and the rushing air to enhance the charge in the cylinder. Your performance and MPG will suffer and the intake will get even more gunked up than normal if you leave it like this.

Go to F C P E U R O parts and order the 642 oil cooler kit and do the oil cooler job. Might as well do the oil cooler, you are 90% there for the swirl flapper.

As for the intake, there is an adaptation required for new MAFs, or even new air filters, with Xentry.