The stock crap computer cant keep up and feed the auto x ray quickly enough to keep up to the 1 second interval data grabs.
How lean is .75x - .78x on a narrowband sensor?
Am I risking engine damage driving like this?
Why is it that I have had my Accel Gen 7 Dfi for almost a year and brought it to 3 shops that said that they could install and tune it and it is still sitting in the box?
Yes the .7xx range on a NB is too lean. NB sensors vary, but .7xx is too lean. Get that thing on a wide band and/or get TunerPro RT or Datamaster so you can do some real logging. Your combo sounds pretty serious, but your factory ecm will do the job with the right tune. What injectors are you running? You might be able to increase the fuel pressure to get you closer until you get a better chip burned. Even better, get an Ostrich or an Autoprom and tune on the fly.
This brings up an interesting question. How do your 02 readings look in the higher gears?
My narrow band 02 readings tend to run leaner in the lower gears, and tend to richen up as the gears go up. Each gear tends to read a little richer than the previous, starting with something like 750 mv in first gear and finishing with something like 900 mv in 4th gear with a 13:1 Target AFR.
I haven't found a good way to compensate the tune for each gear, short of super rich A/F ratios on the order of 8-9:1. This seems to fatten up the lower gears somewhat and still run around 900-950 mv in 4th. I suspect the fuel pump is the limiting factor, but I don't really understand the gear dependency.
I wonder if the car is actually running leaner in the lower gears, or if the O2 readings are skewed due to scavenging or some other effect under rapid engine acceleration. If the lower gears really do need more fuel, then I would think ecm would require a means to provide extra enrichment.
27 lb injectors and 48 lb pressure at idle (low vacuum) drops to 42 at 2000-2500 rpm cruise and goes up to about 52 at wot.
I noticed that the engine builds vacuum when the comes up near the cams operating range. I think the vacuum causes the fuel pressure to drop and then rise when in the no vacuum wot range. I dont know how this effects the fuel precisely.
Would I be better off disconnecting the vaccum line after tuning the car when the DFI goes on? Speed Density system seems less lossy with my setup, the 700 cfm MAF sensor is a big restriction right now
You need a WB to do this. NB tells you nothing. If you get a ZT_2 or Innovate, they include the software so you won't need to depnd on the ECM for the scan. ZT-2 gives me 35frames/sec.
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Still nowhere near tuned, check out my chart from scan and comment
