After starting this to evaluate the effect of putting turbo blankets over BorgWarner K03 turbochargers I decided to keep the effort going by adding logs that I have of my car with K04 turbos, and some other K04 equipped cars, and then my F4H data logs. F21 data hasn’t been as easy to come by but I have a couple data points.
I’m a bit surprised to find that the short lived FrankenTurbo F4H spools as well as the K04.
Next I’ll be adding TiAL 605 v1 data to the chart.
To recap: I began by doing some pulls to check out a new software tune and verify the calibration on some pressure sensors was correct. During a third gear pull something went wrong and the wastegate duty cycle dropped to zero and the tone of the vehicle changed.
I found a wideband O2 sensor plug had come out of the downpipe changing the tone but I still couldn’t figure out why the boost had dropped so suddenly:
I was able to determine that the sensors were generally within 1 psi of the vehicle map sensor – shown above.
I disconnected the compressor signal lines from the N75, separated the individual lines from the tee, and attached a sensor to each line to monitor the pressure in the housings independently. Those results were not good, one K03 was boosting to almost 25 psi and the other not at all.
I started the disassembly process to try and find the source of the problem. After looking in the charge pipe and exhaust pipe I moved onto taking the motor out to inspect the turbocharger. After taking it off I cannot find anything wrong with it.
I’m thinking of having it rebuilt just for the sake of it, ‘while I’m in there’, and if I do will send this ones partner along with it for the service as well.
After pulling off the passenger side intercooler the charge pipe coming off the compressor housing looks fine:
And looking at the catalytic converter for the passenger side it’s looking fine as well:
Next up is the motor coming out so that I can visually inspect the passenger side turbocharger.