bad MAF? JHM supercharged S5

A5/S5/RS5
#1

2008 JHM stage 1 supercharged S5

I’ve got some codes that I’m trying to troubleshoot:

004200 - Intake Air Switch-Over Valve (N335)
P1068 - 004 - Open Circuit
Freeze Frame:
Fault Status: 01100100
Fault Priority: 2
Fault Frequency: 2
Reset counter: 255
Mileage: 169520 km
Time Indication: 0

Freeze Frame:
RPM: 396 /min
Load: 100.0 %
Speed: 0.0 km/h
Temperature: 41.0°C
Temperature: 26.0°C
Absolute Pres.: 980.0 mbar
Voltage: 10.287 V

008569 - Bank 2; System Too Lean off Idle
P2179 - 001 - - MIL ON
Freeze Frame:
Fault Status: 11100001
Fault Priority: 2
Fault Frequency: 17
Reset counter: 255
Mileage: 169527 km
Time Indication: 0
Date: 2007.07.29
Time: 17:51:33

Freeze Frame:
RPM: 2026 /min
Load: 7.1 %
Speed: 81.0 km/h
Temperature: 90.0°C
Temperature: 23.0°C
Absolute Pres.: 980.0 mbar
Voltage: 13.970 V

008567 - Bank 1; System Too Lean off Idle
P2177 - 001 - - MIL ON
Freeze Frame:
Fault Status: 11100001
Fault Priority: 2
Fault Frequency: 15
Reset counter: 255
Mileage: 169527 km
Time Indication: 0
Date: 2007.07.29
Time: 17:51:36

Freeze Frame:
RPM: 1991 /min
Load: 9.0 %
Speed: 79.0 km/h
Temperature: 90.0°C
Temperature: 23.0°C
Absolute Pres.: 980.0 mbar
Voltage: 13.335 V

000257 - Mass Air Flow Sensor (G70)
P0101 - 004 - Implausible Signal - Intermittent
Freeze Frame:
Fault Status: 00100100
Fault Priority: 2
Fault Frequency: 2
Reset counter: 255
Mileage: 169793 km
Time Indication: 0
Date: 2018.12.25
Time: 23:58:10

Freeze Frame:
RPM: 2239 /min
Load: 7.8 %
Speed: 61.0 km/h
Temperature: 91.0°C
Temperature: 3.0°C
Absolute Pres.: 1000.0 mbar
Voltage: 14.097 V

I’m thinking the MAF is the culprit for the lean bank conditions as the idle LTFT is normal and the off idle trim LTFT has been pegged at 20+%. I cleared the codes to reset the fuel trims to see if it happens again. LTFT at idle is -1.7 in bank 1, -1.9 in bank 2, LTFT off idle is 16.8 in bank 1, 19.1 in bank 2. So I logged air mass in 2nd gear, full throttle. The max value is 360+ g/s.

Can anyone with a JHM stage 1 supercharger kit let me know what you see for mass air flow?

Is the Intake Air Switch-Over Valve known to go out in these cars?

Thanks,
Cass

#2

cass I have the JHM kit now on my B6 S4. I love it. Great kit and your on the right site. TONS of the JHM supercharged guys are here and all help eachother share info on our kits. I know a few JHM guys are on here as well as us customers.

So I would look at the MAF code for sure get to the bottom of that. That is going to almost always be the issue. Its hard to pin down what exactly is the cause of the lean off idle but MAF would be the first place to look if your getting a code.

Also generally when you see a lean off idle it means your getting unmeatered air in the motor. So check for any leaks post MAF I actually got one on my SC S4 due to a small leak.

Intake air valve. I think its going to be a small valve connected to your air box door flap. That should be an easy one. Just plug that back in and zip tie it out of the way.

#3

I looked for vacuum leaks the best I could and made sure all the hose clamps were tight. I figure if there’s a vacuum leak somewhere, the LTFTs at idle would be off due to the post-MAF unmetered air getting in. If I’m thinking correctly, this would make the AFR, detected by the primary o2 sensors, lean. This would cause the LTFT at idle to increase and compensate for the unmetered air.

I’d like to be able to compare the mass air flow numbers that other JHM stg1 supercharged S5 cars are getting with what I’m getting. If others are reading much higher g/s, then I either have MAF going bad or the supercharger is not boosting as it should. But I would not expect the car to be lean off idle nor have high off-idle LTFTs if the latter is the case.

I was under the impression that the intake air switch-over valve is the actuator linked below. It’s located at the front of the intake manifold. Am I wrong? Not sure how to test it with VCDS or if it’s possible at all.

https://www.eeuroparts.com/Search/67340/140883/Air-Intake-Manifold-Actuator/Audi/S5/2009-2009/?gclid=Cj0KCQiAmuHhBRD0ARIsAFWyPwhR4ozCRfk-ZtgeeSgwgBVwaG0Gi4auoUxwx1B6isQyBKqpdfBTc-YaAoBGEALw_wcB

#4

So, the JHM kit gets rid of the airbox, and a resistor is provided for the intake air switch-over valve. I unplugged the resistor and it appears to be ok. Anyone know what kind of resistance it should see so I can test it with a multimeter?

#5

Just to be clear, you have a 2008 S5 with a production date before 12/2008 right? So you have the metal intake manifold like the Q7s? I like to be sure because the 2009 and newer V8 S5s have the three piece plastic intake manifolds (one big upper and two smaller lowers). Pretty sure that if you had the later style plastic intake manifolds that you would be seeing fault codes for the intake manifold flaps stuck closed like the white 2010 S5 that I regularly work on.

Have you checked that the intake switchover valve electrical connector is plugged in or the resistor is wired in correctly? With an open circuit code I am wondering if it is plugged in fully or if the wiring is damaged.

The intake manifold lower flapper motor/valve did fail quite often on the other cars that share that style intake manifold like the FSI V8 Q7/A6/A8 and the FSI V10 S6/S8 but we need to check the simple stuff first. The V10s have bigger issues with their intake manifolds that you can read about in the S6 section but I digress. Audi had a TSB describing the problem and correction of replacing the valve with an updated part to solve the problem. Let me know if that link below works for you because it is the PDF of the TSB.

https://www.google.com/url?sa=t&source=web&rct=j&url=http://www.revbase.com/BBBMotor/TSb/DownloadPdf%3Fid%3D172571&ved=2ahUKEwiL6KeTzejfAhUEJt8KHaPaD3gQFjABegQIARAB&usg=AOvVaw1N6plbj7MLbMzN9cCkBJOE

Those side intake manifold flaps should move at a low rpm to open up the intake port of the cylinder head to allow more air in. The software determining when the flaps move might be changed for the tune. Usually on these older Bosch ECUs I will go one measuring value block at a time until I find the values that I want to see. Please don’t quote me on it but for some reason I seem to remember the side flaps being in the 110-120 range.

The state 1 SC JHM cars are usually between 330-370 g/s MAF readings depending on the car and conditions so you are doing well in my opinion. I remember seeing 340 g/s while still stage 1 on my B6 S4.

#6

Yes, I have the metal intake manifold. Looking at the TSB, none of the codes listed have been triggered and stored in the ECU. So, I’m assuming it is working appropriately. The TSB does say there’s an intake manifold runner flap adaptation in Guided Functions. Not sure how to get to it, though.

I tested for continuity in the JHM resistor for the intake air switch-over valve and no beep, so I likely need a new one. Would this affect fuel trims at all?

It sounds like my MAF is operating as it should if the air mass is comparable to other JHM s/c vehicles. Since clearing the fault codes, the implausible MAF signal has not been triggered. I do have stage 2 sitting on my floor (since Nov 2017, sad faces), which comes with the upgraded HPFP internals. It may be time to put those in and see what happens. Or maybe there is a vacuum leak, but again the idle LTFT do not suggest so and visual inspection hasn’t revealed any. Otherwise, I don’t know why I would be throwing the lean codes.

#7

So, I thought I would update this thread in the event someone in the future could learn something from this issue.

I got a replacement resistor from JHM for the intake air switch over valve. This of course got rid of the associated code.

However, the lean off idle codes returned after some driving. I went ahead and bought a new MAF. This seems to have been the issue. Still no codes after 2.5 tanks of driving around. Something else I learned from my research, I had been getting random parking brake malfunction and ESC warnings pop intermittently while cruising. Didn’t think much of it, but a post a found on Audizine from JayBQuick on Audizine that said these warning occur with failing MAFs. I didn’t find this post until I installed the new MAF in the wrong direction (and yes, I knew better than that and still installed it in the wrong direction lol) and kept getting the warnings. So, there was my issue. Hopefully, this helps someone in the future.

#8

Great update. This will be a great big help to those looking for this in the future.

Also good to know about the ABS. That would make sense

#9

Thanks for following up with the fix. I seen plenty of people turn to forums when they have problems and don’t follow up with the fix to help another in a similar situation.

1 Like
#10

Yes, I’m another with a JHM Stage 2 supercharger plus extra tweaks and add-ons.

#11

It’s it helpful. I always appreciate when people follow up.

Welcome.

1 Like