187

So just a small update. Unplugging the VPC and using the TT MAF seems to make the 1500rpm hold issue go away. I plan on doing a MAF cold start + rev comparison with my log files to see whats going on.

Ali SC3

iTrader: (10)

sounds like the vpc tune needs some adjustment. unfortunately the vpc is also tuned to run a gte motor.

SC3002JZ-T

Hey Ali thanks for these informative posts. I have been wanting to do this mod and finally got around to it today. Car fires up, idles, and drives great off boost but when it sees about 5 psi in 2nd gear wideband goes 10 and it just sputters. I have read all the posts and some people run 550's like me and dont have any problems. I also replaced the MAP sensor but it did not help. Double checked base timing and tps adjusted. Do you have any advice? When i got the aristo ecu it had some leaky capacitors and i replaced them so do you think it could be a bad ecu?? Any info would be appreciated..

Ali SC3

iTrader: (10)

Yeah the thing about 550's it they always work in regular driving, but not always in boost. They will drive fine but very rich, so you did the mod perfect.
That is why I changed the first page to 550's needing a piggyback, cause unless you flow a lot of air down low in boost the extra fuel will wash out the spark. did you do it with the stock ignition or with coilpacks, if you did it with the stock ignition then you need to gap down you plugs to like .026 at least and try again. it still probably won't work until you get a piggyback like a safc or map ecu to pull fuel with. On mine it would boost fine but it would read a solid 10 on the wideband which means it was much richer than that and it was dumping fuel, this is with vvti coilpacks at .032 gap. It smelled so bad and would backfire but did boost to 15 psi or whatever it was at at the time, but yeah I got the map ecu on there and setup and it runs perfect now with 550's.

The people who are saying it works are not describing how bad it actually is. you will wash out your plugs then your cylinder walls and possibly wear out your engine much faster.
I like my air fuel ratios and timing to be on point all the time, every time. That is the whole reason why I did this modification and ditched the GE ecu.

SC3002JZ-T

I am using vvti coils and gapped at .030 bkr7. Some people said it ran fine and ecu learned with 550's but not mine. I already ordered a SAFC so we'll see how it runs then. Thanks for the reply.

Ali SC3

iTrader: (10)

yeah no problem, it does run fine for the most part it just doesn't boost right unless you have a very efficient turbo even then its still too much fuel. a safc or map ecu will correct it, I like the map ecu personally.

lexex

I've gone in huge circles. I have a 97 sc300. My plans originally was to do the jdm obd1 since at the time I didn't need emissions, now I live in Atlanta and I do. So I was looking at any possible nonheadachy piggy back options but doesn't look like that's possible. Feel like I might get yelled at to just do it right and go big but I don't want a drag car and this is my daily. I really, at least at first, only want about 100hp more, so feel like I might be able to get away with less. I have a few options to get around emissions so I'm thinking of going aristo obdi still, which correct me if I'm wrong but it should plug right in and just follow the obd1 directions and no extra harness work right? Would I be able to get by with my stock 330s if I'm running >10lbs boost? I can get 440s if it's a must just trying to go light with this auto trans. Also just wanting to confirm if the rc sl4-440 injectors are the correct part number and we'll work for my runners? I'm not planning on upgrading coils, just what's necessary like maf to map, iat and igniter. Am I right to believe that I should be good getting by with this before I get bored and start upgrading everything else to get more higher numbers? Or would the ecu hate the 330 and run lean even with dialing back the turbo? Sorry for such noob questions, just getting into boost cars and I get so much conflicting info on these obd2 cars

SCereal

iTrader: (4)

lexex, maybe just doing a usdm GTE swap would be the better way to go? I don't know the rules on if you have to have the same engine for emissions in GA but might be a better way to go for you. Probably more spendy but you'd be well ahead for future mods and to keep johnny law happy.

That said, if you go Aristo ecu, I wouldn't run 330s and I'm hoping you used the wrong greater than/less than symbol because more than 10lbs of boost definitely isn't going to cut it. That's 25% off from what the ECU will be expecting so better to just give it what it wants and go from there. It does just plug right up with the exception of what's already noted. Aswilley's build thread on here has some great details on the wiring for the 97's. Mine does too but not as well documented or as coherent. We both have 97's and we both went JDM aristo ECU and we both had great success without alot of the issues other people reported.

lexex

Ok, ya I better go with the 440s, not that more on cost anyway. Lol and yes my greater than symbol is facing wrong direction. I probably will go jdm ecu since I have a buddy with one that will sell me for $100. The emissions part, I have a few options, which are mostly legal, my parents live outside of the emission zone so could put that as my address if I needed to. Thanks for the advise, I'll start collecting parts for the build after a little more research

lexex

Also thanks for the aswilleys suggestion, looks perfect for what I'm looking for. This thread is great, but nice to have one specifically for our car. Especially since 2k+ posts would take a while to read through

Ali SC3

iTrader: (10)

never try and use the 330's they will go lean everywhere and its very dangerous to be lean in boost. they don't even drive the car right really and running lean is not good for your motor especially in cold start situations.

generally speaking you can only use a piggyback to compensate for larger inejctors than the ecu calls for, not smaller. 440cc is the bare minimum and reccomended for the least hassle with the JDM ecu.
on the part numbers I am not positive on that part number, they are sort of cryptic to deal with so double check injectors will fit for your application.

also because you have a 97, you have the newer lower runner, which takes the wierd style injectors. this is covered in aswilley's thread as well.
you have to either change the lower runner to obd1 style, or you can try and make the injectors work or use different style injectors.
I think you obd2 guys can handle researching your own injectors you need that for practically any kind of turbo setup.
I always reccomend swapping to an obd1 lower runner, or if keeping obd2 runner then try and find the right style injector to fit your obd2 runner.
I am not a fan of sticking obd1 injectors on the obd2 runners, but at the end of the day anyone can do whatever they want to their car whether I think its a good idea or not, so they will have to decide.

install the 440's and you will enjoy it. if you can register somewhere without emissions then what are you waiting for no question about it do it and use the JDM ecu and you car will run great. if you have to use the US ecu to keep emissions you will likely have issues like everyone else unless you can figure out the misfire issue.

lexex

Ya just got done reading the thread, wish he would report back but looks awesome build. I'm looking into lower runners now, I'm cheap, but not stupid. Fairly confident there is a junk early sc300 somewhere near me to rob off of.

ashtray

iTrader: (12)

I've got the lower runners if you need them.

joe diego

iTrader: (3)

Is the pre-96 Cali spec lower runner the same as the federal pre-96 lower runner?

Ali SC3

iTrader: (10)

yeah swapping to obd1 lower runner and obd1 throttle body is the best way to go for the longrun.

not sure what cali had for obd1. I know cali spec obd1 has heated o2 sensors and that blue vsv on the fuel pressure regulator, but not sure if they have the obd2 style runner or not.
but I can tell you guys how to spot one very easily

this is a picture of a obd2 runner. how you can tell is that black hose on the top left coming from that metal pipe. the metal pipe comes straight out of where the injectors look like they are sitting. this is the obd2 emisisons hose thing and any runner that has this hose coming off of it, uses obd2 style injectors.
Also note that obd2 style injectors have the blue plastic tops, the obd1 uses brown plastic tops so another easy way to spot your injector style.


in this picture you can see that hose going from the lower runner to the throttle body, as the obd2 throttle body has an extra port off the IACV just for this hose.


so if you see that hose you have the obd2 style injectors. to delete it properly you need obd1 lower runners and an obd1 throttle body, or you can just cap off the port on your obd2 throttle body or repurpose it, your choice. you might even be able to just swap the older IACV on the newer throttle body but I am not sure if the shapes are the same, don't have a 96 motor laying around anymore.

easiest would still be to find the right style obd2 inejctors as its a pain to remove the lower runner in the car, but I haven't heard of anyone actually doing that yet.