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Hi, I finally have working UpRev system logging for my car so I took it to a dyno to get a baseline and to compare the sensors readings with the dynos afr sniffer. I have attached a couple of files, the first one is an image of the dyno run and I have roughly drawn my logged sensor reading over the top (in red) of their in the afr section at the bottom. I have also attached a copy of the UpRev log data for this run.
My senors for bank one and two (it is a V configuration engine so two sensors) have quite different readings from each other, and different from the dyno's readings. I am confident the dynos readings are accurate. One bank is reading 0.5 to 1.0 leaner than the dynos, and the other fluctuates a bit. The exhaust has an x-pipe configuration so even though the dyno sniffer was only in one tail pipe I assume the gases are quiet evenly mixed up by the x-pipe.
So my questions,
1) Are my WB sensors in need of replacing?
2) Or is one bank running a lot richer than the other (and the dyno afr being an average of the two)?
3) How much variation between my car sensors and the dynos sensors is acceptable?
The stock sensors are older denso type. They work on a different measurement principle than the Bosch sensors common in aftermarket wideband and OEM in German cars.
It's really hard to balance a normal cross plane V8. This is primarily due to the lengths of the intake and exhaust manifolds. You can compensate for it in the tune but your VK45DE definitely doesn't do that.
Your variation between banks isn't surprising or necessarily a majorly bad thing. If there is a severe imbalance you will throw a code.
Ok, so the overall difference between what the car is logging and the dyno was logging of 5% to 8% is ok?
I can also make a compensating adjustment to the fuel for each individual cylinder, is that worth doing to balance the banks?
You can do it. But keep in mind that it affects fuel trims. In low loads your fuel trims will move more.
thanks again Raymond :)