Whipple Charged

Mike, no question, they are mucho importante, you really shouldn't tune without, but I was stating that it's much more difficult for a wide variety of applications, you can surely make them work, but you also have to know when your getting false signals. Typically speaking, many tuners use the Bosch 5 wire sensors with their Motec systems, which are far cheaper than the Horibas, but the Horibas are very, very accurated when calibrated properly. As for the 6 wire sensors, they have an extra heating circuit, UEGO sensors is what there called. Because of this extra heating circuit, you get much more accurate air fuels when your in the peak power range such as 12.5:1 and below. The extra heating circuit helps burn the excess gas off the sensor for a more accurate reading. Other than that, there very similar in design. This is what the Horiba uses.

Another problem you have is the life of the sensor and with some air fuel systems, it does a self calibrated offset. We have to test our sensors in a special chamber to check its accuracy for the automotive side because of emissions, it's so critical. Boats, its more about just making power and making it live, so no matter what meter you have, if you've proven that combo to work whether it says 13:1 @ WOT, your making peak power, it's not detonating

As for velocity, I did mean exhaust air velocity. So when I said that air flow could cause a problem, with our data logging system in 8 cylinders, you can actually see when the cylinder was fired because the scope is that fine. But when the exhaust is trying to scavenge at slow speeds, there is tremendous turbulence in the marine exhaust and I can guarantee with many, many data files that show how imporant sensor location is at slow air speeds in the exhaust. But when you get to the collector and take the average, it's typically no where near the same air fuel. If you don't run 8, then your assumming that all 8 are within a certain % of distribution, you could have one 14:1 and one 10:1, your average would be skewed. Most of the problems come from cold start, as the motor will misfire a bit if air fuels are not dead on, if it misfires from bad ignition, improper spark, overly rich, etc. then you can get the cylinder to flame out and pump air, this will give the user a reading that typically would not make sense. Its also possible to be so rich, your lean. This happens when the fuel simply cannot be fired and runs right out the exhaust, but what was combusted could be near what the proper air fuel is. So you add more fuel, you can just make it worse, it gets leaner (combusted). These are just some of the things I've run into so thats why I worry some about the "stand-alone" systems, theres just so many things that can vary.

To my knowledge, PFM uses a 4 wire sensor.

FAST and Accel both can use a 5 wire sensor which are much more accurate than the 4 wire. It's certainly better than nothing and typically everything works out, so didn't mean to be negative, just wanted to let people know it's not always that simple.

Thanks,
Dustin

MikeW

Dustin
AAHH.... 6 wires for multiple heater circuits. That is interesting. Bosch pioneered the "Planar" type sensor. We then incorporated this technology into the our Broad Band. I am not sure anyone else uses this technology. First a planar is built in layer and the sensor element is only 1.5mm thick. So keeping it heated to the 1292° - 1472° F it needs to work in is not a problem. Also it's operating range is: ë = 0.7 to 2.2 (atmosphere) (10.29:1 to 32.34:1). The Broad band Planar uses a "Pump Circuit" to draw negative Oxygen Ions into the sensor so movement in the Exhaust is not that critical for this sensor to operate- And your right, dose not mean be accurate. I understand better what you where referring to and I do agree that sensor placement is important.
MikeW

MikeW

Oh... as for the bosch being cheaper..lol . Let me just say there was a little pricing problem. If you know anyone who use them and can still get them for the lower price. better stock up now. We kinda drop the ball on that one.
MikeW

Tyeegs

I have Holley hp on the LS7 in my Lund 1950 IO. I tuned it closed loop. Run it open loop and check occasionally. Never looked at spark plugs while tuning. Ran great for two seasons. Pulled the engine to switch the cam from stock to 114 deg lsa 120 duration both lobes. Discovered major carbon buildup on pistons and cylinder heads. Wet IMCO exhaust with O2 sensor in spacer between lower and upper manifold. Has anyone else experienced misleading lean reading by O2 sensor in these marine applications thereby tuning unwittingly rich? BTW I have two sensors that I swap out. They read the same way.