Nistune Forums

Spent some time getting a 300zx road tune correct using logging etc. Set it to a nice flat 11.5 WOT.
Then put it on the dyno tonight and the dyno's AFR was reading 12.8 and my LC1 which was in the other tailpipe was reading a nice steady 11.5
So i swapped the sensor from the left to right an visa versa but still had the same result.
So i ended up tuning the car to read 11.5 AFR using the dyno's wideband which resulted in my LC1 reading 10.5 ish.

This is really dissapointing and i would like some input or idea's as to why.

Things to note. Last nights road tuning was with an older sensor. But on the dyno i used a brand new sensor that just arrived. On the dyno my new sensor was reading exactly how i had roadtuned it.

Could the mainline dyno sensor be incorrect?

Have you tried recalibrating both of the sensors?

LC-1 requires both heater calibration (without wideband plugged in) and then O2 open air calibration to function properly. It requires re-calibration often if used frequently (see LC-1 documentation regarding this)

If doubting Nistune try logworks but the software just reports what LC-1 gives us, there is no lookup tables for these units

Yes that is correct. I performed a full calibration with the new sensor before dyno tuning. I normally do a free air calibration before each road tune too.

Its weird though, cruise and idle AFR are identical between my sensor and the dyno sensor but WOT is different. Im using an innovate tailpipe sensor holder. Maybe that isnt in the exhaust far enough and i should make up a longer pipe to go deeper into the tailpipe.

Design of the bung used can have a massive impact. We have seen this here also

Ok. What type of holder/bung do u use?
I thought the innovate holder i use should be perfect as it desgned just for this. Where the dyno holder looks to be a bit of pipe with the sensor in it.

I would like to be able to weld a bung in every ones exhaust but its just not practicable for me most of the time

PL made his own bung up and we used that at one time, but to avoid police attention etc with my cars I have it installed in the exhaust of both cars now

I had similar issues. I had a Tech-edge and the dyno I normally use has (I think) an Autronic. Could never get them to match. I then bought an LM-1 and it's pretty close to the dyno wideband.

Tailpipe adaptor can make a big difference. The dyno place uses a long piece of pipe with a relatively small dia pipe that goes right up inside the exhaust system. And hangs out a bit too. I made up an adaptor very similar to the Innovate unit. It has two shortish pipes welded together with a small hole between the two - resulting in a low velocity exhaust gas stream flowing across the sensor. Unsurprisingly this was found to work best. Maybe Innovate do know something...

I'm now urging owners to fit permanent install widebands to their cars (particularly track cars) and these readings are close to what I tune. They run the sensor closer to the engine rather than in tailpipe of course. This seems to result in slightly richer readings. So my sensor in the tailpipe reads slightly lean. Which at least makes for a nice safe tune.

PL

Cheers PL.
How long was the pipe u used and what diameter?
I might copy my innovate one and just enlarge it so it sticks further in.
Im using an LC1 but i might try my dyno shops LM2 to see if they match. Its alittke scary to be out tuning at 11.5 AFR then on the dyno it reads 12.8AFR. Hard to know which one to trust.

My pipe is ony about 10 inches long. Longer would be better. Not sure on dia - it's not big. Tried to make it as close to the Innovate one while still using local materials...

Yes, not trusting AFR measurements is a bad place to be. I was in this personal hell for quite awhile before I could trust the numbers.

Got caught awhile back and started to worry again when doing some tuning on my brother's bike (Suzuki SV650 track bike). Damn things have an air injection system on them! So the wideband was trying to tell me that it was running 18:1 at full throttle. It was running fine and the heaters certainly weren't glowing, so I knew something was wrong!!

PL