limp mode with 3 bar map - 16490

eddie_1

Veteran Member
Joined
Dec 27, 2004
Location
Hannover, Germany formerly Toronto & NY
TDI
Jetta Wagon 2003 TDI tuned to 170HP, A6 Wagon 2008 TDI 2.7L tuned to 340HP
I just installed the 3 bar map and got CEL with DTC 16490 Manifold / Barometric Sensor (G71) / (F96) : Implausible Signal P0106 35 00. I had recently upgraded to 1722 turbo and pp764 everything was fine. Today as soon as I put in the 3bar map I lost all boost. The ECU is specifying different boost when I drive around, I logged some data group 10, 11 but the actual is always at atmos pressure. 999.6 mbar. Is this is a rc3 tune for 2.5bar sensor issue? i.e. is the voltage from the 3bar sensor much lower than the 2.5bar sensor and it is confused? Some folks were saying it would boost more with 3bar map, in my case it is the opposite. Unless it is connected properly, but i made sure it was ok and the wire is not damaged by the pulley or anything.
 

vwmikel

Vendor , w/Business number
Joined
May 5, 2005
Location
Las Vegas, NV
TDI
'94 Golf Sport TDI
eddie_1 said:
I just installed the 3 bar map and got CEL with DTC 16490 Manifold / Barometric Sensor (G71) / (F96) : Implausible Signal P0106 35 00. I had recently upgraded to 1722 turbo and pp764 everything was fine. Today as soon as I put in the 3bar map I lost all boost. The ECU is specifying different boost when I drive around, I logged some data group 10, 11 but the actual is always at atmos pressure. 999.6 mbar. Is this is a rc3 tune for 2.5bar sensor issue? i.e. is the voltage from the 3bar sensor much lower than the 2.5bar sensor and it is confused? Some folks were saying it would boost more with 3bar map, in my case it is the opposite. Unless it is connected properly, but i made sure it was ok and the wire is not damaged by the pulley or anything.
When the key is turned on the ECU checks the correlation between the MAP sensor and the atmospheric pressure sensor in the ECU. If they are not saying the same thing then the ECU doesn't know what to believe and goes into limp mode as you're experiencing. For this not to happen the ECU needs to be reprogrammed with the correct linearization for the new MAP sensor.
 

eddie_1

Veteran Member
Joined
Dec 27, 2004
Location
Hannover, Germany formerly Toronto & NY
TDI
Jetta Wagon 2003 TDI tuned to 170HP, A6 Wagon 2008 TDI 2.7L tuned to 340HP
I had measured the MAP voltage from before with the 2.5bar stock map so I could compare with current 3 bar MAP.

Stock 2.5 bar MAP:
With Ignition on, Engine Off : 1.94V
With Ignition on, Engine Idle: 1.98V

3 bar MAP:
With Ignition on, Engine Off : 1.62V
With Ignition on, Engine Idle: 1.65V

It appears the ECU does not like the difference at engine turn on as you said.
 

Jugghack2

Well-known member
Joined
Oct 29, 2007
Location
Spanish On, Canada
TDI
00 Jetta TDI Stick
could a person put a pull up resistor in the circuit to raise the voltage a little and sacrifice a little boost in the process maby control it as a temp fix till a chip is installed?

Brian
 

eddie_1

Veteran Member
Joined
Dec 27, 2004
Location
Hannover, Germany formerly Toronto & NY
TDI
Jetta Wagon 2003 TDI tuned to 170HP, A6 Wagon 2008 TDI 2.7L tuned to 340HP
I think it is doable for sure. Since the MAP is just a variable resistor changing according to pressure difference. One could put a resistor on the ground side like a pull down which will bring the start voltage up to the 1.94V. One could measure the resistance across the map and size the pull down accordingly or use a pot and tweak it. Essentially it will end up looking similar to the 2.5bar map if I'm not mistaken. I guess it is the hassle of doing that vs putting the old map back in. Either way I have to remove the bumper again.
 

eddie_1

Veteran Member
Joined
Dec 27, 2004
Location
Hannover, Germany formerly Toronto & NY
TDI
Jetta Wagon 2003 TDI tuned to 170HP, A6 Wagon 2008 TDI 2.7L tuned to 340HP
First time around the screws broke off prob because washer fluid ate them....had to drill em out. But you just gave me a good idea try to use bolts to replace them next time. Easier to get at with angled extensions and ratchet.
 

TDIJetta99

Top Post Dawg
Joined
May 17, 2005
Location
Port Jervis, New York, USA
TDI
03... Faster than yours =]
Usually I can get the MAP off without even taking the bottle out, but with it removed, you can get your whole arm in there to mess with the MAP sensor...
 
Top