Nistune Forums

First off: This is Brian on Russ's name just making one thread.

Has anyone experienced the A/F to start jumping all over the place at high RPMs....such as 5500-6000+? It doesn't feel or sound like it's misfiring or anything. The A/F is smooth up to the 5500-6000 mark and then it just goes crazy. I've attempted to change the ignition and the fuel tables to see if I could get any positive change at all, but no luck. I also had Russ (sorry to put you through that Russ ) pull the spark plugs and I regapped them from .039 to .033. I had this sort of issue with my boosted Integra....it was from the boost blowing out the spark due to too large of a gap. I figured it couldn't hurt to see if that would help, but that did nothing either.

I've attached the fuel map, so you can see if there are any problems that stick out to you. I haven't touched partial throttle yet so the table still has some cleaning up coming toward it. Also, can you explain a little as to why the values go from 192 in the 4800rpm row to like 7 in the 5200rpm row?

I contacted Russ, and hopefully he'll send me the dyno chart so you guys can see what I am talking about and have a little more information to work with. Basically if you've had this problem and figured anything out it would be greatly appreciated if you can share that info. Thanks again!

The extremely high numbers (192) indicate the cell is tagged to use closed loop operation. In other words it uses the O2 sensor to verify and correct the AFR while the engine is operating in those cells of the fuel map. When in closed loop the ecu will richen and lean the mixture continuously in an effort to keep the average near the target AFR. The target afr in closed loop mode must be near 14.7:1 because thats where the narrowband o2 sensor is accurate. If you were to take a log of your AFR while cruising in closed loop you would notice a saw tooth pattern.

Can you post a pic of the stock map? My guess is that the closed loop cells dont normally reach as high in the rpm and load range as your current map is going. Maybe theres a lag in the ecu and it's still in closed loop when you are reaching those higher rpms?

clicking 'flags' will make the closed loop areas a different colour

then using 'filtered' mode rather than raw mode will make adjustments to the numbers so they dont include the flag bit value in the display numbers

Got back on the dyno this afternoon. After we finished we burned the bin file onto a chip and did one more pull. All the crazyness disappeared. Seems that something couldn't keep up with all the information at the high RPM's

Wish me luck we are going autoX on sunday with 20+ HP and 30+ ftlbs of torque more than we had last year.