... some background info. The car is a 2000 A4 1.8TQM with a GIAC chipped ECU and a stock ECU. The GIAC version is P09 and the ECUs are P boxes. Also, I have the 710N bpv (the updated one from the TT).

I was getting rich codes with both ECUs. Dealer diagnosed problem to be MAF. They replace the MAF and I haven't had any rich codes since. I suspected the heated O2 sensor but they said it looked fine. They also checked for vacuum leaks and exhaust leaks... none.

I'm now getting overboost codes with the GIAC chipped ECU. (I haven't tired running the stock ECU since this code).
17963 - Charge Pressure: Maximum Limit Exceeded
35-00 - -

Either I get the code and it cuts engine power or I just get the intermittent code and no loss of engine power. I got the code once, cleared the code, then got the code again so I cleared the code and did the throttle body alignment and set the readiness code. Went for a drive and logged blocks 114 and 115. Everything looked ok but I really don't know what I'm looking at.

I did a lot of reading on where this problem might be, BPV, N75, wastegate... but I want to make sure I know where to look next. Before the new MAF, I never had an overboost problem.

I went for another drive today and logged 114, 115 and 120. and tried some long hard pulls from 2000rpm up to 6000rpm. On one of the pulls, the car threw the 17963 code again... while I was logging. I looked back at the data and I see that I got a boost spike of 1.5bar.

Anyone have any ideas of where I should look next. I have the data file if anyone can help me figure this out, I can email you the file.

Thanks,
Kirk

 

You might also want to check the vac line going from the N75 to the wastegate to make sure there are no leaks, 1.5 bar is a bit high for the P09 chip which should only be running 1.1-1.2 bar. If you wish to talk more about it you can catch me on aim at SCAC CMH, btw I ran a chip on my 2000 1.8t at 1.65 bar(24psi) on the street.

 

verify the overboost valve,and the vacum lines wich comand the valve.