I installed a supercharger on my Jeep 4.0 straight 6 a couple months ago, and have been reading continuously and fiddling with the various tuning options and settings since then.
I'm fairly mechanically inclined, and don't always do stuff the easy way if there's something new I can learn about. This is the first time I've done anything with tuning whatsoever.
It's set up with a piggyback Split Second controller that adds fuel through a 7th injector and retard timing in boost. This has always worked fine and is fully programmable.
However, I was fighting with the PCM not going into open loop at the right time and lean part throttle boost operation. Then after learning about and resetting LTFT the jeep started pulling fuel in the low load low rev range when the piggyback wasn't even doing anything and the supercharger wasn't making boost. And still correcting against the added fuel from the piggyback and staying in closed loop. The Split Second is also supposed to have an enrichment in closed loop provision in the software, but I couldn't get it to do anything.
As a short term solution I raised the Closed Loop ECT temp to max and have been driving in open loop. It's great. Runs a bit too rich in spots but overall really good. Now I'm learning more about speed density tuning and this seems like the way I should progress forward, given it's a MAP. It by far seems to be the simplest and cleanest option.
As of right now I have the rear o2 sensors disabled, along with associated DTCs. The cats are gutted, and I'm reading afr with a wideband x-series AEM gauge.
So my questions:
Do I have all this wrong? Are there downsides to running the Jeep like this full time? I'm not concerned about fuel consumption, just want it to run well and not to break something.
Am I wrong that the upstream o2 sensors aren't doing anything in open loop? I can just disable those as well and simply monitor the wideband o2?
It appears I can do most all of the tuning I want to in the VE tables for fueling, and base and WOT spark tables for timing. Correct?
Are there any external variables that might cause me issues? I live in MN so the yearly temp can range from -30f to 90f. It's my understanding the IAT is still fully functioning in open loop, and the pcm adjusts for barometric pressure on startup?
5YRHmhx.jpg