Anybody actualy check there air/fuel ratio before leaning out or modding?

[rcr1978]

I have a 07 m8 and put a wideband on it to check it before I started modding. Well the sled is bone stock except a RKT secondary, fuel regulator set to 44psi and the 08 updated ecu reflash. My sled may be a isolated case but you guys leaning out these sleds might want to rethink things I found on mine under almost all throttle conditions especialy wot it was around 13.9-14-8 When you move the throttle in fast the factory ecu appears to have a accelerator pump feature it's way rich like 10 and below for a second. Either my o2 sensor is in a bad spot or this thing is damn lean, I put the sensor on the inside radius in front of the temp sensor. I ordered a dynojet box but have not recieved it yet but when it shows up I will see if it will run better with tuning just for the hell of it before I by the SLP single if it gets worse maybe I will move the sensor to the neck of the can.

 

[ditch1000]

You should have the sensor mounted in the end of the expansion chamber. Right before the narrow part at the end of the pipe. If you like I can post a pic later.
You can set the ACEL on the Boondocker box to get rid of the fat spot when it is accelerating. It works quite well.

 

[rcr1978]

I did alot of reading before I picked a spot for the 02 sensor. Is it really going to change my readings? Koso, SLP, and numerous others all say the expansion chamber. Then there is a few for some reason say just before the can in the neck of the pipe, the only reason I could find for the different locations was heat problems ruining the sensor. I bought the adapter/heat sink to try and prevent the heat problems.

 

[DaveW2]

Are you guys really confident is the results you are getting with air/fuel gauges on 2-strokes? I am considering getting one, but after reading the manual for the NGK AFX I would have serious reservations, since it says:

"Due to scavenging of 2-stroke engines, the true AFR reading becomes distorted. The nature of 2-strokes is inherently one that is not compatible with exhaust gas sensors."

 

[JMCX]

As part of tuned pipe operation some of your fresh intake charge goes out into the pipe and then gets crammed back into the cylinder by the return pulse from the back of the expansion chamber every cycle. On a two stroke you need to get your O2 sensor as far away from the piston as possible but where it will still run hot and not become a unwanted restriction to exhaust flow.

Move your sensor and let us know the results.

 

[snowmanx]

Not sure what you mean by leaning out? If you are running 13.9-14.8, at wide open throttle, that seems pretty darn lean to mean. Seems to me that people are riching them up, to run at 12.5 at WOT. You are then richening it up.

I want to run my 1000 at 12-12.5 at WOT, if I ran it at your numbers it would burn down. That is on a turbo, so I don't know if that makes a difference, but I don't think it should.

Please clarify, if those weren't stock numbers at WOT, I'd be telling ya to add fuel.

You didn't say where you are seeing those numbers, at idle, I'd lean it maybe a touch, midrange it looks pretty good, and likeI said, WOT you're too lean.

Now, if they are not accurate, that's a whole new ball game, but I know several guys just running the A/F gauge, myself iincluded, and no EGTs, and it's been fine.