P0238 and P0106 Codes and resolution

[pondside36]

Well, I haven't been on in a very long time due to car running well and having a growing family..

Full back story:

2002 1.8T
AWE GT28R Turbo Kit, soup to nuts
Okoda Project Coil Packs (40K on them)

Driving home the other day I go the dreaded misfire during acceleration intermittently in 2nd and 3rd gear and finally the CEL came on as I pulled into the driveway.

I hooked up my Vagcom and showed these codes:

5 Faults Found:
16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 008 - - Intermittent
16688 - Cylinder 4
P0304 - 008 - Misfire Detected - Intermittent
17522 - Oxygen (Lambda) Sensor; B1 S2
P1114 - 008 - Internal Resistance too High - Intermittent
16622 - Manifold Pressure / Boost Sensor (G31)
P0238 - 001 - Signal too High - Intermittent - MIL ON
16490 - Manifold / Barometric Pressure Sensor (G71) / (F96)
P0106 - 008 - Implausible Signal - Intermittent - MIL ON
Readiness: 0010 0000
-------------------------------------------------------------------------------

Like a good B6 owner I still had my old 2.0 coils and swapped out the #4 and put a new spark plug in since I was there and was going to do on my next oil change. Cleared the codes, took her for a drive. Noticeably better but still some hiccups during acceleration. My thought was well damn maybe my old but good was not that good. I didn't get the CEL this time though and figured I have a short 15 minute drive into work and can run her through the paces and low and behold minor hicups and CEL triggered.

I hooked up the Vag-com again and got these codes, no misfire this time:

1 Fault Found:
16490 - Manifold / Barometric Pressure Sensor (G71) / (F96)
P0106 - 008 - Implausible Signal - Intermittent
Readiness: 0110 1101

In other area I found these:
Mode 03: Emission related fault codes

Address 10 (Engine): 2 Faults Found:
P0238 - Manifold Pressure / Boost Sensor (G31): Signal too High
P0106 - Manifold / Barometric Pressure Sensor (G71) / (F96): Implausible Signal


So I searched like a good doobie and found several threads but nothing quite matching up, curious as to what the consensus is on how to proceed. From reading cleaning MAF seems like a good start.

Any other pointers would be greatly appreciated.

[old guy]

Since both of your faults are related to boost pressure sensors the first thing I would do would be to check to see how close your G71 MAP sensor and your F96 barometric pressure sensor are correlating. The G71 is usually mounted somewhere on your intercooler or your downstream intercooler piping. The F96 is located in the ECM. The F96 can be monitored in MB 113. The G71 can be monitored in MB 115. If your engine is at idle the ambient barometric pressure as shown by the F96 (MB113) and the requested as well as the measured boost pressure as recorded by the G71 (MB115) should all read approximately the same. If there are any large discrepancies you will need to determine which sensor is out of whack.

[pondside36]

Thanks for the measuring blocks to check, my MAP is installed on the outlet pipe of my FMIC so easy to get to if needed. I also checked PN and I have the original so 133k on it, perhaps it coincidentally failed/partially failed when my misfires occurred. Does anyone know if it (MAP) can just be cleaned?

[pondside36]

Atmospheric, Boost pressure (actual), and Boost Pressure (specified) all read approximately 1000 mbar ... I wonder if it is just a case of having three of the Okoda Plasma could and 1 oem 2.0 coil that is causing the faults in pressures/slight misfires.?

[pondside36]

Ok, so I swapped all the same 2.0 coils in so they are all the same and remeasured at 113 and 115 and now my Boost Pressure (Actual) is 1400 mbar and others are approximatly 1000 mbar. So I guess I'll drive her and see if she is better or not and possibly change MAP sensor?

[old guy]

Are those readings being taken at idle? If so, if you have a problem with your MAP sensor.

[pondside36]

Yes, they were at idle, and that is what I figured from your previous advice. It was just weird that they were all the same the first time. Perhaps as she gets hotter (IAT) sensor starts giving erroneous signals as I can only imagine it is a pressure transducer giving a mili volt reading to ECU.. going to buy a new one tonight. I'll update after it is installed. It was a 20 degrees hotter here today also.

[pondside36]

Also so I understand better, at idle the pressures should all be basically 1 bar or 1atmosphere (14.7 psi). Not until more throttle is applied do actual boost pressure and requested change according to turbo output and all the other sensors inputting into ECU mapping.

[old guy]

Also so I understand better, at idle the pressures should all be basically 1 bar or 1atmosphere (14.7 psi). Not until more throttle is applied do actual boost pressure and requested change according to turbo output and all the other sensors inputting into ECU mapping.

Correct. At idle your barometric pressure sensor (MB113) will give you whatever the ambient atmospheric pressure is at your particular altitude. Since you are at idle the ECM isn't calling for any boost so the requested should match your actual ambient barometric pressure. Your MAP sensor (Manifold Absolute Pressure) is measuring the actual boost pressure in your boost hoses. Typically the MAP sensor will measure ever so slightly less than the ambient pressure (MB113) because of the air movement through the boost hoses.

Typically at idle my MAP sensor reads about 10 mbar less than the actual ambient pressure when comparing MB113 to MB115. For example: F96 = 1013.13, Requested = 1013.13, and G71 = 1003.24

[pondside36]

Replaced the MAP sensor and she is right as rain, no CEL and no hiccups through all gears, boost, and acceleration. Thanks for the help Old Guy as always 😉

[old guy]

Thanks for the update