HELP! E90 Acceleration Hesitation with High Aux Fan? (MAF/IAT Codes)

[mmbingo]

Car: 2011 328i xDrive SULEV (N51), Manual Trans (6 speed)

Issue: Last week I noticed when shifting from 4th to 5th and 5th to 6th my car would hesitate before accelerating. Even at WOT, I would receive no power for 2-3 seconds. This was weird but it only happened a couple of times. Then a couple days later (this past weekend), this hesitation happened in between every gear and has continued to happen. Also, when heel/toe'ing to downshift there is no response from the throttle.
Later that day, when I turned on my car the aux fan started running on high (outside temp is 25-35deg F) and would stay on continually while driving, in addition to the hesitation.

Doing some searching, the aux fan condition seems to be a sign of an impending water pump failure. Apparently there should be some codes thrown when this happens, before the check engine light comes on.

So I decided to do the sensible thing and buy a bluetooth scanner - so I bought a "Carista" and used the 1 month of free full features to get BMW-specific codes.

Yesterday: Codes for IAT Circuit High Input (P0113) and MAF Circuit Problem (P0100) appeared, but no water pump codes. So I ordered a new MAF/IAT sensor. Issues continue with hesitation and high aux fan.
Today: (The sensor has not arrived yet) I check for codes again but the IAT and MAF codes do not appear! Issues still continue with hesitation and high aux fan.

A few questions:
1. Is this Carista crap and should I return it and get a more reliable scanner?
2. This sounds like an MAF issue to me - what does the bimmerforum universe think? Would my check engine light appear if my MAF failed (because it has not)?
3. If my MAF/IAT failed, could it lead to my aux fan running on high, or are these separate issues?

Thanks!!

[MIKYZZ4]

Pee codes are NOT BMW specific!

[mmbingo]

I know, but there are other features on Carista that are vehicle-specific features available with the yearly subscription. Sorry, yeah that was wrongly described in the OP.

[shadowpuck]

carista is one of the few i haven't tried yet.

i'm not real familiar with this car, so, i don't want to muddy the waters much. what i will say is when i see circuit codes i think wiring problems and not necessarily components.
how many miles on the car?

[mmbingo]

carista is one of the few i haven't tried yet.

i'm not real familiar with this car, so, i don't want to muddy the waters much. what i will say is when i see circuit codes i think wiring problems and not necessarily components.
how many miles on the car?

The connetor and wiring LOOK alright but I won’t rule that out.
Car has 141k miles. I did try to clean the MAF before this all started and my fear is I got MAF cleaned in a place it doesn’t belong.
On this car, the MAF and IAT are integrated into the same component so I’m hoping the sensor has gone bad and the auxiliary fan on high is simply a failsafe *fingers crossed*

I’ll be getting the new MAF today, but would rather have the root cause confirmed before spending $230.

[shadowpuck]

at 141k if it hasn't had a water pump and t-stat it's probably going to be due; but, given the costs i agree i'd want some evidence before replacing things.

i'd probably take a quick look at some wiring diagrams and figure out where that component gets its signal/power/ground and then see if i could find any problems with the circuit using a meter, etc....
sure, if you have the part already coming in i'd give that a try since it takes minutes, but, i'd be prepared to dig into the circuit....

[Breeze1]

carista is one of the few i haven't tried yet.

i'm not real familiar with this car, so, i don't want to muddy the waters much. what i will say is when i see circuit codes i think wiring problems and not necessarily components.
how many miles on the car?

And add to that the fact that two seemingly unrelated issues + the unresponsive throttle pedal (which IMO is not necessarily related to the MAF sensor) appeared pretty much at the same time, and it makes me think there is a wiring issue that affects all those parts. Maybe a common ground (pun intended)?

[MIKYZZ4]

Check the electrical connections/wires on all mentioned components,
for clean snug connection with no bent pins or corrosion visible.
Afterwards, clear all codes followed by a short drive cycle/test drive.
Post up the results along with any new codes.

[mmbingo]

And add to that the fact that two seemingly unrelated issues + the unresponsive throttle pedal (which IMO is not necessarily related to the MAF sensor) appeared pretty much at the same time, and it makes me think there is a wiring issue that affects all those parts. Maybe a common ground (pun intended)?

Alright - where would be the first place to look for a common ground? Fuse box? I'm terrible with wiring.

[Breeze1]

Alright - where would be the first place to look for a common ground? Fuse box? I'm terrible with wiring.

Based on the E46 but should be the same for E90:

- Main engine ground somewhere behind the front bumper, on the right side
- 1 brown wire and 2 straps attached on cylinders 1(strap), 3(brown wire), 6(strap)
- large ground cable that attaches to the body of the car, in the battery compartiment.

As mentioned, make sure all connectors in the engine bay are snug as well

[mmbingo]

I broke down and took it to the dealer. With school and work I didn’t have time to troubleshoot my daily driver anymore.

The new MAF I put in made no difference.
The dealer pulled codes that said water pump was failing. They replaced the water pump and now the car drives better than it has all 2018. I have no idea what caused the acceleration hesitation in between shifts but it is gone now. Maybe there was a common ground between the water pump and the MAF that just needed to secured? Leads me think maybe the water pump didn’t need to be replaced?
Either way, a new water pump was in the near future (as I’m nearing 150k miles).

Sorry we didn’t DIY tackle this one but thank you to everyone’s input!