Stock 94" TT going 15g, 550cc, flashed 98' VR4 ECU build.

[Drummer]

Have you considered disabling the O2s altogether? Then you can do lean cruise and not have to worry about the rears. Blackstealth said he has done it and it works well.

Also, what emissions stuff do you still have/not have? I will end up deleting it all (since flashable ECUs can't really control EGR) and wondering what all to disable and what the issue your having is.

I still have all the stock stuff intact. When deleted, it wont really matter (purge). The only thing I wonder about is what the ECU is doing when its trying to cycle the purge, like cut some fuel or whatever. Im guessing its negligible and wont matter. I can also disable the 02's and just tune it like Blackstealth has, its just a matter of getting around to it. I still have to put on most of my stuff.

The issues I saw were a super annoying purge solenoid going nuts almost all the time, and my rear fuel trims stop functioning when the downstream 02's are shut off. This caused a lean reading on my back o2, it flatlines when I log it with the o2's shut off. Turn on the o2's, it functions fine, but I get all the codes thrown for the missing o2's. The answer, although not perfect, is the yank all the damn emissons and run without the trims, or add some o2's and stash em.

[HLxDrummer]

That's a bummer, huh? Would be nice to be able to run closed loop with no CELs. Maybe someday. Definitely don't want to have to add more crap to my car to avoid it though (half the reason I went with this setup is to eliminate a bunch of wiring/electronics).

[BlackStealth]

That's a bummer, huh? Would be nice to be able to run closed loop with no CELs. Maybe someday. Definitely don't want to have to add more crap to my car to avoid it though (half the reason I went with this setup is to eliminate a bunch of wiring/electronics).

With a few peripheral bits disabled I drove for days in closed loop without any Check Engine Light coming on, however, it is possible I may have had some stored codes for O2 sensors as the heater circuit are different (96 and newer ECU power up the O2 heater circuit themselves so they can determine whether or not the heater circuit is functioning correctly, where as older ECUs do not power up the heater circuit). This minor issue wasn't serious enough to light up the Check Engine Light, only serious problems light it up.

Currently I'm driving my car open loop because my 18 year old O2 sensor died of old age. To my surprise, the 15-15.5 AFR target I setup during the summer is holding fine during the winter. I would never get the AFR that consistent when I had a piggyback. Because open loop is working so well for me, and also saving some fuel too, I'm never going to replace my worn out o2 sensors. The only O2 sensor I have in my car now is the WBO2 which I monitor from time to time on the lcdboostcontroller.

As for the purge control solenoid, it was perfectly quiet during the summer, and when winter rolled in, it was very noisy. It was an irritating noise, I was considering disconnecting the purge control solenoid altogether, but when I drove the car on a warm day the solenoid was quiet again. I'm going to leave the solenoid alone for now. Also another interesting tidbit, many years ago when my car was only 2.5 years old, my stock purge solenoid made awful noise during the winter, the purge solenoid was replaced under warranty and was quiet for many years until recently.

Overall, the flash ECU runs the car very well compared to the piggybacks I've used in the past without any hiccups.

[Drummer]

With a few peripheral bits disabled I drove for days in closed loop without any Check Engine Light coming on, however, it is possible I may have had some stored codes for O2 sensors as the heater circuit are different (96 and newer ECU power up the O2 heater circuit themselves so they can determine whether or not the heater circuit is functioning correctly, where as older ECUs do not power up the heater circuit). This minor issue wasn't serious enough to light up the Check Engine Light, only serious problems light it up.

Currently I'm driving my car open loop because my 18 year old O2 sensor died of old age. To my surprise, the 15-15.5 AFR target I setup during the summer is holding fine during the winter. I would never get the AFR that consistent when I had a piggyback. Because open loop is working so well for me, and also saving some fuel too, I'm never going to replace my worn out o2 sensors. The only O2 sensor I have in my car now is the WBO2 which I monitor from time to time on the lcdboostcontroller.

As for the purge control solenoid, it was perfectly quiet during the summer, and when winter rolled in, it was very noisy. It was an irritating noise, I was considering disconnecting the purge control solenoid altogether, but when I drove the car on a warm day the solenoid was quiet again. I'm going to leave the solenoid alone for now. Also another interesting tidbit, many years ago when my car was only 2.5 years old, my stock purge solenoid made awful noise during the winter, the purge solenoid was replaced under warranty and was quiet for many years until recently.

Overall, the flash ECU runs the car very well compared to the piggybacks I've used in the past without any hiccups.

This is where I will likely end up going with my build, as we have almost identical setups. Black has been very helpful so far. Im thinking I may just totally eliminate both of my o2's, run all my trims at 100, and use the wbo2 to adjust the fuel tables myself. I dont see why not. Its working for Black.