Originally Posted by velociabstract
I can agree with a lot of what your saying. In my case I data log on the street but can't (won't) go WOT in 3rd to redline anywhere but the track or dyno. I do some WOT pulls in 2nd. Then I hit the dyno to confirm and see what's happening in 3rd. My AFR's are perfect in first and second gear. The recent problem is only at the top of third. Perhaps at the top of 4th as well but I rarely pass 140.
I agree that before getting a tune you should have a wideband. I did! I'm a dyno tune guy from experience. After having a few canned tunes that IMO were way off I got a dyno tune that I think was perfect. So, from the graph do you think I'm out of fuel pressure or near the duty cycle limits or something else?
Les
les i dont think its a fuel pressure or a idc issue. the 178 doesnt have a history of going static at wot. if the pulls that the tune was built for were 2nd gear pulls theres part of the problem. the biggest engine load is during 3rd gear and of course 4th gear. the workhorse is 3rd and sees high rpm for extended periods. so the tune has to take that into consideration. if it were me and take this with a grain of salt. i would do a pull from 30mph in 3rd gear to redline or until the afr goes lean. send that to your tuner and have him tune for the lean issue. once tuned lather rinse repeat! each time the lean issue should move farther up the rpm band until its gone. until i had a proper afr for the range i race the car in i wouldnt abuse it. may cost you the season but will save your engine.