EFIDynoTuning Forum

Regarding the damper spacing, I am also doing an EDIS setup, and also ran in to issues with the explorer harmonic balancer (mine was several inches out due to how the serpentine belt rides in the trucks). I contacted DamperDudes and they told me they wished they could help, but they don't have the correct parts to make the custom damper. What I ended up doing was getting an old explorer damper (which you have already) for the trigger wheel/dimensions, a new balancer to be modified, and had a local machine shop make it all fit. I haven't installed it yet (getting parts together still), but it's looking good so far.

For my setup, the machine shop turned down a step on the rough cast portion of the balancer, near where the seal rides. Then the machine shop made a bushing to fill the space between that new step and the trigger wheel. It was then press fit together to the depth and timing of the explorer balancer trigger wheel. It was press fit so if I find I need to adjust the positioning of the trigger wheel for some reason, I can heat it and move it out slightly. Others have done similar, so I have *some* confidence this will prove to be a reliable setup. The balancer was a cheapo OEM style from Summit racing (~$90), the metal was from a scrap yard (~$5), and the machine work was about $75. This ultimately came in around the same or cheaper than DamperDudes I think.

I've been working to improve the fuel modeling in my tune, and I've been making use of the various history tables to do so (thanks to decipha for making them available), but having issues. I've mostly been using the N_IMAF_IEGOs (Fuel Error 1+2 Filtered, but I have no wideband so this is just based on KAM/LAMBSE) history table, and noticed that my fuel error across any IMAF ad count is very inconstant as RPMs change. Generally, at low RPM/higher ad counts fuel error suggests I need to enrich (error greater than 1), and at higher RPM/lower ad counts I need to lean out (error less than 1). My error is fairly large, with fuel errors being +/- 8% across some individual add counts.

The injectors are Accel 24# injectors (rated at 43.5psi). My fuel pressure regulator is a newish replacement, and the rail is the factory fuel rail. Fuel pressure with no vacuum is approximately 39-40psi, the FPR drops it to about 34psi at idle/high vacuum conditions. The MAF is a 76mm BBK "Calibrated 24#". I started my injector slope tweaks from the Accel datasheet values/injector reference, and the MAF transfer comes from the "Calibrated 24#" reference.

To try to fix this error, I have been decreasing my high slope value and increasing my low slope value. After changing these values, then resetting the other SP* values as needed to get the proper scaling, I usually take a 20 minute drive with some highway and backroads to mature the KAMs. However, my two slope values are now over 25% different from each other, and I still have not been able dial out this error across any specific ad count. I've only seen minor change, which makes my think I'm missing something. My goal ultimately is to get each ad count to have a consistent fuel error (within +/- 3%), and then have confidence that I can use that fuel error to dial in my MAF transfers.

I'm wondering if my test procedure is including too many transient conditions, making my numbers confusing, or if maybe my injectors just have terrible flow characteristics. Any thoughts would be appreciated. Thanks!

Awesome, thank you! I really appreciate it, and the write ups too.

Thanks for the response! I've taken a look, but can't seem to find a patch that modifies the input. Since I don't need the 2 step rev limiter at this time, I can remove the patch (Z_XTWO_STEP), but wouldn't the inverted input cause me to look at incorrect values in some other parameters?

I'm familiarizing myself with the tools (Quaterhorse and TunerPro RT) before I start making meaningful modifications to my engine. Right now I have a 1989 F-250 351 Windsor with a S5-42 manual transmission, A9L converted with SEFI, MAF, 2 HEGOs, 3" exhaust w/ shorty headers w/ EGR, 24lb/hr accel injectors, BBK calibrated MAF, no cats, and otherwise stock.

I applied the A9L2 base tune, have the GUFX_210129 definition file, and the Decipha_210225 ADX file. I then modified the base tune based upon the write ups to reflect my injector information, MAF curve, etc. I did my first hard pull in 2nd gear, and ran in to the rev limiter at around 4800rpm. Did some digging, it appears to be the same RPM as the the two step rev limiter value. I was moving and at WOT during this event, and I'm not sure why this kicked in.

Doing some more digging, I found that the NDS flag was reading as neutral. Watching the whole log, it appears that the NDS responds in reverse of what it should. Electrically everything appears in order (neutral=0vdc on pin 30, gear=greater than 4.5vdc on pin 30), so I am wondering if there is a corruption somewhere, or if I goofed something?