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

My stock 94 TT is getting 15g's, 550cc RC injectors, walbro 341 pump, BlackStealth EBC/logger, tanabe turbo back, Innovate WB02, Greddy S BOV, MSD wires, NGK 7 coppers, 3SX fuel pressure guage, full vac reduction w/all deletes, open air filter, 98 VR4 ECU, ACT clutch (installed already), and perhaps a thing or 2 more. All of the parts above I have. May go with an FMIC at the end. I will be doing it in stages, to make sure that each step works before proceeding. Im sure I will run into some kind of trouble, any help appreciated!!

PS This will be a street car, on 94 octane pump gas. I will be keeping the stock MAF, as I dont plan on going over 450hp.

STAGE 1 : PLUGS, INJECTORS, FUEL GUAGE AND 98 ECU w/ADAPTER HARNESS

Did this today and the car fired up on first crank. I got a CEL about 30 seconds later, dont have the reader ready yet. The purge solonoid went nuts clicking. Car ran fine as far as I can tell. A few pulls, all good. Fuel pressure at idle was about 35-38psi. Engine mounted guage so I cant see it while driving (yet). Dont know why the purge solonoid went nuts, Im assuming that the 98 ECU sees things a little strangely on my 94 engine. The flash on my ECU is set up for 550cc's, but maybe not correctly for my 02 sensors, dunno.

You need a MAP for the 98 ECU as it's looking for it. Swap your Plenum with a 98 plenum and put the stock MAP sensor on the plenum and wire it in.

I will simply disable the MAP in my flash file and reflash, if I can. I also have to find out the differences o2 sensors, if there are more on the 99 (its a 99 flash) then I need to disable ones that are not on my car. Would the missing MAP sensor make my purge solonoid go nuts on and off? It seems to cycle, and speed up with RPM. I unplugged it and drove with no ill effect that I noticed. I also need to root out anything in the 99 flash that does not pertain to my car. I will get this sorted out in short order, as there are a few members that are miles ahead of me like greg and aaron. Im not sure how far along these guys are, its been a while since ive been around. Im going to pull the CEL tonight with blackstealths logger and post here. I am also working to tweak the flash, already bumped the RPM to 800 at idle, and scaled the injectors to 550cc. I will be disabling all to do with the vacuum reduction (EGR etc.) Want to get rid of all the useless stuff in the engine bay.

great stuff man...keep us posted on the results...is blackstealth making harnesses? I'm also on the lookout for a 98-99 VR4 ecu...keep me posted if you find one for sale please. Thanks :)

Blackstealth is not making them as far as I know (you can message him to ask), as these are being made by others as a package, and the market is rightly theirs for their work on the 3000gt file for ECUflash. Im not sure if they have the 98-99 VR4 ECU, but they have other ECU's modded to work. I wanted a 98 VR4 ECU so I got one. VERY VERY hard to find. 500$ mininum usually. If I see one I will let you know. Set up your ebay auto searches to find key words, like vr4 ECU, part numbers etc. One pops up here and there.

For those who are wondering what you need to do this, you need a 98-99 VR4 ECU or a modded ecu from other cars, a wire harness adapter to plug the new ECU to your cars harness, a tactrix 2.0 flash cable with mitsu adapter, ECUflash software (free at tactrix.com), the 3000gt rommeta file for ECUflash to be able to read a 3000gt file (this is where the real brainy work is being done, getting this file updated), and of course a stock 99 VR4 file that you will be modding to suit your car. Im not sure, but Greg E and the boys may have kits for sale, they were on their way, but I havent spoken with them for a while. They were working on a sweet kit, maybe its ready? Again, Im not sure where that went....

Anyway, the flashed ECU way of tuning is great, clean, and with a good EBC/logger, can get you running smooth.

Read the CEL codes with the blackstealth logger. My car (Canada, FED emissions) Has only 2 heated O2 sensors, and the 99 flash looks for 4. Also, my EVAP system purge solonoid is goin nuts on/off when it never did before, so I unplugged it and im getting CEL for that too. I need to get the newest 3000gt file for ECUflash, as mine is old and I think the brainy boys have more things figured out and named in ECUflash. Im also getting strange trims... the logger reads a low/mid/high, and my low trims are at 50 at idle and coasting, at 120 on acceleration. Not sure what that means, but my o2's are coding like crazy, when there were no codes at stock. Here are the codes I have read so far :

P0155 - o2 heater circuit malfunction Bank 2 sensor 1 (need to disable, not on my 94)
P0156 - o2 circuit malfunction Bank 2 sensor 2 (need to disable, not on my 94)
P0161 - o2 heater circuit malfunction Bank 2 sensor 2 (need to disable, not on my 94)
P0135 - o2 heater circuit malfunction Bank 1 sensor 1 (did not throw a code using stock ECU)
P0136 - o2 circuit malfunction Bank 1 sensor 2 (did not throw a code using stock ECU)
P0141 - o2 heater circuit malfunction Bank 1 sensor 2 (did not throw a code using stock ECU)
P0443 - EVAP purge control valve circuit (unplugged, solonoid was going nuts on/off, didnt do that with my stock ECU)
P0446 - EVAP vent control circuit malfunction (related to unplugging the solonoid also?)
P1104 - Turbo wastegate solonoid - this is removed from the car, I am using an EBS. Need to turn off in the flash if I can.

There are a few things I have yet to learn about the differences between the 99 flash file I am using and the 94 car Im using it in. Any insight would be greatly appreciated! To be continued...

Cleared the codes, pulled the neg battery terminal and plugged in the purge solonoid back in. No CEL, a couple codes gone for the purge, but rest are still there.

What does the purge solonoid do?

Its part of the EVAC system that recirculates gas fumes from the tank to the intake.

is it also responsible for reducing the vacuum in the fuel tank? I noticed that when I remove the fuel cap it makes the usual pssshht noise which I htink is vacuum not pressure build up. Also when I turn my car off I can here a solonoid/relay clicking a few times. Perhaps mine has issues.

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Originally Posted by GTOJOE

is it also responsible for reducing the vacuum in the fuel tank? I noticed that when I remove the fuel cap it makes the usual pssshht noise which I htink is vacuum not pressure build up. Also when I turn my car off I can here a solonoid/relay clicking a few times. Perhaps mine has issues.

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They tend to get louder with age. When it clicks, its toggling open/close.

STAGE 2 : VAC REDUCTION AND FIRST BASIC ECU SETTINGS

Today I got all setup for flashing myself, and pulled the current flash from my ECU. It was an almost stock 99 flash, with scaled injectors and a couple other things. Since I will be moving to the Chromed ECU flash files, Im going to start by doing the complete vac reduction (struggly) and setting up all the preriphery values in the flash to turn off the EGR, EVAP, FPS, downstream 02's that my car does not have, MAP and maybe something else. The 99 flash file looks for many things that im deleting, and some things my 94 does not have. Im currently getting a ton of codes because my periphery settings are not set for my build. This is the most basic part of setting up my flash. Still have to learn to tune later, in final stage of this build.


Many thanks so far to Greg, gate, aaron, green lantern and others for getting me rolling.

I'm not moving forward with mods until I take a little closer look at the cars condition to make sure everything is running well. I have a slight idle issue, and am getting some 02 readings that I would like to get right before moving on.

What is your idle issue?

My idle is a little uneven, when logging it can jump +-20 ish, but not that bad. Ive never rebuilt the throttle body or checked for intake leaks or anything like that. All the parts are original. 65K on the car. It has 60k service done, new plugs wires and my compression is perfect. The 02 sensors seem to be working OK and Im reseting my trims and going for a ride just to take a peak. My purge solenoid is going off steady once I pass 160 deg. coolant temp, and its loud and annoying. I was told this should not happen, and Ive read that it may happen on newer than 95 (ECU is 99). Im supposed to be able to disable it in the flash, but thats not working either. Might not be a big deal if I just remove it all. Just little things to check before moving on. Im liking my HHH logger better than EVOscan, but with Chrome ECU you can only use EVO. Im just using the first flash (99 vr4 stock) and plugging numbers into that for now (Im new to logging, like to use the HHH for a bit).

You may have the conversion harness wiring wrong.

Yea, I thought it might... it was build by a guy who knows his stuff, and I did check the pinouts for the purge and a couple other things and they were ok. The datalogging all logs correctly also. There are many factors that the ECU reads in order to tell the purge system to cycle, and there are differences in how the purge system works on a 98 compared to a 94. It may be of no consequence if I do the full vac reduction. Seems to be doing no harm. There is the problem of the current flash-based tuning - when you disable the donwstream 02's you lose the rear bank trims, and I tend to run rich (I think) and my 02 sensor flatlines. I believe this little kink may be worked out soon though. Flash tuning is still evolving for the 3s, and getting better as it moves along.

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Originally Posted by Drummer

There is the problem of the current flash-based tuning - when you disable the donwstream 02's you lose the rear bank trims, and I tend to run rich (I think) and my 02 sensor flatlines. I believe this little kink may be worked out soon though. Flash tuning is still evolving for the 3s, and getting better as it moves along.

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Interesting enough. That periph is switched in the DIamante ECU program. Well the Diamante ECU has only two O2. A precat and a postcat one. So I have a theory that periph when switched goes from dual bank trim with four O2s, to single trim with dual O2s. I have tested this theory and I haven't disproven it. More testing needed.

That sounds like it could be true. In order to get good logs of all my trims and both my 02`s, I need to leave that periph on. The problem is that I get codes for the 2 02`s i dont have. If I disable the periph bit for the 2 donwstream 02`s I dont have, I get 100 trims and reads a flat line, which I was told is rich. Not sure what Im going to do about it just yet.

With the full vac reduction and emission stuff yanked, and all my mods installed, I should be able to get a good solid flash tune regardless of what the ECU is trying to do with the emission stuff. BUT, I do hope it evolves to the point that makes it more elegant, perfect tuning solution with the bugs worked out.

fix this?

No, Im just a tester. I dont know if the boys working on this figured it out yet.

Just put in some Lc1s and be done with it. YOu can sim the post cat O2s off the Lc1s. Or flp th periph and install one post cat O2 sim.

Yea... i just really wish I could plug in the 98 VR4 ECU and simply disable the post cat 02's and have the upstream 02's work along with both of the banks trims. Im lazy :P I do have a MTX-L Innovate kit sitting at home. I was going to install it after the exhaust joins for tuning later.

Jay, yes turning off the downstream o2 sensors is a problem. Solution, don't turn them off. I have not manipulated any of the periphery on my car. Everything is factory in that regard.

Classic O2 sims do not work on the 98/99 ecu due to the way the ecu looks for o2 levels (more on this later), but there are two solutions:

1. Move the o2 sensors out of the exhaust stream with spacers.

2. I have a custom o2 sim modification that I developed that works 100%. Been passing obdii emissions with no problem for three years. I could have used method 1 because I still have to leave my o2 sensors in the car to pass "visual" inspection and the sim does not bypass the heater and heater warm up checks, just the output.

Back to the o2 sim issue. It seems the engineers at mitsubishi decided to check downstream o2 by comparing it to the upstream o2. At any given check point the downstream must read lower than the upstream. Classic o2 sims which just send a random signal to the ecu can and sometimes (read : often) do fail this check.

As far as I know this only pertains to the newer 98/99 ecu.

Care to share that o2 sim mod? :P I dont plan on installing 2 more o2's, so Id rather just fool the computer into seeing them.

Check your pm for detailed info on why you need to still have the o2 sensors hidden somewhere.... I am to sick to repost the info on my cell phone...

Some differences between the 94TT and the 99TT :

-The '94 EGT sensor is not used on the 99
-the 99 MAP is not on the 94
-the gas tank pressure sensor andthe EVAP vent solenoid on not installed on a '94
-The 99 manual says how the evap system works and how it uses the fuel tank pressure sensor and MAP (This is probably why my evap purge solenoid is going nuts)
-The O2 heaters are done off the MFI relay on a '94 instead of the ecu like a 99
-There are two precat O2 sensors and no post cat sensors on a '94


The ECU is expecting to see EVAP stuff that is not there, not to mention the MAP, o2's etc. Its doing strange things with the purge solenoid on my 94 because of this. Im wondering if the ECU will mess with F/A and timing when its trying to cycle the purge. Im told its probably nothing to worry about. I can either try to install the missing sensors or remove all the emmissions completely, set the periphery and forget it. Aaron has a working model of this currently. Some things can be shut off in the periphery bits, some things arent that simple (like shutting off downstream o2's causing rear trims to be lost). I may have to add the downstream o2's to get around this and just stow them.

For now the build is on hold until I get a lot of other stuff done :)

Thanks Blackstealth, Aaron, Jester, Greg, Jeff, Charger, Brett for the input so far.

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.

Your names are too similar.

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Originally Posted by HLxDrummer

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.

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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.

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).

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Originally Posted by 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).

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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.

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Originally Posted by BlackStealth

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.

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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.