Yeahhh. I was kinda banging my head trying to figure out what else was wrong. So we were right the first time and they just got you a bum part.
Audizine has taken a different turn. The good thing is more and more guys are getting sent here for help.
I agree, im much more comfortable over here. AZ is usually just bickering.
What a great thread. I’ve had this MAF issue for a long time since beginning of 2014. I haven’t really driven my car much because of it. Probably a little more than a 1000 miles in the past year. I did replace the MAF sensor in 2014, like you maybe I received a bad MAF as well.
I’ll get a new MAF again.
Have you ran any logs?
I have ran logs. The lambda control percentage would jump from 0 to 25 instantly. Every time it jumped the car would stutter. I’ve checked the resistance from the sensor harness to the ecu and it was .5 ohms. Resistance is good. I replaced the sensor and cleaned the filter. The old sensor screen was black. I cleared the codes and drove it, so far so good. Runs a lot smoother. Even with the codes erased and the old sensor the car ran funky. Let’s just hope it stays that way. Have another code for the light sensor g399.
I spoke too soon. Although the car does run smoother, it started to act funny again.
PBULLARD, can you show us some logs on measuring blocks 1, 32, 33 on both banks?
Here are the codes and logs. I have 03-31-01. 032 by itself. 32-31-01
https://docs.google.com/document/d/1MW6WWoqfWCRxVs2qjOTiLw9So8IEuJTISHp_VqBpF9E/edit
They are set as private
https://docs.google.com/spreadsheets/d/1gd7xoZog555xPlpJacsr8OAReokCbpEgpIcufRtsdiA/edit?usp=sharing
https://docs.google.com/spreadsheets/d/1chSHakPk9DhEBpxw1HbtTn08sokWsjSh32izc9bwcf4/edit?usp=sharing
https://docs.google.com/spreadsheets/d/1NykRiclm3OC37qYyo6X5RXdylG42WGGFhkqn6NxvJU4/edit?usp=sharing
Hope you can view them.
Your long term fuel trims from block 32 indicate a lean condition at idle and load. The LTFT at idle is actually in spec, but the LTFT at load is pretty bad. This indicates a lean fueling issue - the motor is not getting enough fuel or is getting too much air. The fuel trim numbers don’t indicate a vacuum leak to me since the short term is way negative at idle and WOT. Are you getting any lean codes?
The O2 lambda actual/specified in block 31 seem okay to me. Can anyone else comment on these numbers?
I would start with the following:
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Confirm that your O2 sensors are connected to the proper connectors. Cross connected O2 sensors can do crazy things to the fuel trims like we’re seeing in these logs. Have you changed your O2 sensors recently?
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With the car running check fuel pressure at the fuel rail with VCDS measuring block 106. I’m not sure what spec is for the S4, but it should increase with engine load. Can someone provide the spec for this number?
Also take it easy on the high rpm pulls until we know why it’s running lean.
Clarification on fuel pressure data from ross-tech wiki:
Group 103
Field 1: Fuel Pressure (Low), Specification: 2800…7200 mbar
Field 2: Fuel Pump Adaptation, Specification: -1000…+1000 %
Group 106
Field 2: Fuel Rail,Pressure (actual): 55% or below is normal at idle
55% to 60% is a gray area, it may be okay, but may indicate a problem
Above 60% implies there is a failure or restriction
-Causes of low pressure can include kinks or restrictions in fuel lines
-Fuel filter issues including restricted/clogged or incorrect part number
-Failing lift pump in fuel tank.
Group 140
Field 3: Fuel Rail Pressure (High), Specification: 25.0…110.0 bar
Increase the Engine Speed while checking this value, the Pressure has to rise with the Engine Speed.
Note These data specifications are specifically mentioned in reference to the 2.0 TFSI, but the same groups can be used for analysis.
Okay when I get a chance I will log the fuel pressure. It will be later today.
Good, and can you please describe your symptoms once more and provide any codes the car is showing?
https://docs.google.com/document/d/1MW6WWoqfWCRxVs2qjOTiLw9So8IEuJTISHp_VqBpF9E/edit
These are the codes. While I’m cruising on the freeway about 70-75 the car will through the MAF code and it will sputter, then try to get away from me, and sputter again, then drive normal.
The P0101 code threw me for a second in regard to the fuel trim analysis, but there’s a technical bulletin for your car saying low fuel pressure can cause MAF codes.
https://i.imgur.com/xj7VOUj.png
I’m still sticking with a fueling issue as the primary, but check the things on that list too. I can post the procedure for checking the MAF sensor if you need.
I just put a new one in. Doubt it’s the MAF. That means I got 2 bad new ones. I’ll try the fuel pressure measuring blocks
There could be electrical problems causing the MAF to malfunction. Does it read between 2 and 5 g/sec at idle? Did you check voltage on the harness connector?