Nope it's the coding of the pcm itself. A leak prior to the wastegate solenoid will give a false reading if the boost created by the turbos, which then tells the turbos to make more boost, then the TIP Senser sees something other than it is expecting to see which then throws off the O2 sensors leading to additional trimming.
Now you really lost me. I would be thinking there should be an over boost code if there was a large enough boost/vacuum leak before the was tegate solenoid and this should be shutting him down with power, but on the flip side the PCM is still looking at the MAP sensor. The MAP will determine how much fuel is added not the TCBP sensor? That's the question I was asking about.
The combination of the MAP, intake air temp, and fuel rail pressure is what controls fueling is what I'm aware of. If that's not the case, please explain the job of the two pressure sensors.
With the turbo's wastegate pressure activated and normally closed, with a leak of boost to the wastegate solenoid your going to over boost. Im on this page. The pcm will see this and should do something to prevent damage. The throttle body i guess could be used to limit the boost or the recirculation valves, if it's small enough maybe just a lower duty cycle the TCBP. But whatever is in the intake, the pcm should fuel based on the MAP not the TCBP.
The O2s are a check sum is how I look at it. The PCM already knows if the sensors are perfect, how much fuel to add. But if there is a biased sensor, or a mechanical concern the pcm can add or subtract fuel. ( a map sensor off by maybe a psi, or a set of fuel injectors that dont inject as much fuel as the should)
He could have a bum O2 that's not reporting.properly to the PCM. Too
With map there is really no unmetered air leak possibilities unless you remove the throttle body. I would think there would have to be a huge vacuum leak for the system to not compensate.
Another thought. All else ok. If there was a vacuum leak, under boost it may turn into a boost leak. So the fuel trims should get closer to 0 and wastegate duty cycle increase to compensate for the leak (MAYBE) depends what is causing the leak.
Carbs are easier, but at the same time, there is a lot more that could go wrong quickly. The pcm (electronics) will usually tell you there is a problem before things go south. It takes a lot of learning to understand what a car is telling you via listening, and looking.
