HiPSI

iTrader: (2)

That doesn't sound healthy at all, something is holding the engine back. Have you thought about trying to eliminate the MAF setup and converting it to a map sensor? Mine runs super smooth, no issues! I popped a IC pipe rolling into a 3rd gear WOT pull and just cruised it home, didn't affect drive ability at all. No stumbling, stalling hesitation just drove home like a non boosted sc300 till I got to the garage and put the pipe back on.

My 2g MAS based DSM would leave me stranded on the side of the road undriveable all the time. The MAF was also really funny about which pipe I used and how the intake was setup, any variance in airflow or reading would cause weird issues.

myLEXsc400

Yeah, so the car runs fine when i keep it under 4k rpm. HiPSI, your car is OBDI and on a JDM ECU. I'm OBDII and usdm 97 supra ECU bc I need to pass emissions.

The problems start right at 4k when the car hits a wall. After doing a bunch of pulls (i know i should not have been since it might efff something up more) the ecu lets it rev a little better, but its still incredibly slow and the car barely pulls at all. A stock SC300 would be quicker, because like you said, something is holding the car back. Oh, and it smells terrible. I got a headache after driving it 45 minutes home from the shop. And my sister who was following me in my SC400 said she smelled the fumes a lot too (hard to describe what it smells like, but a weird, very strong stench of hot half-burned fuel i would say). On a couple occasions the car backfired hard enough to shoot small flames/sparks out the exhaust I have been told.

Here are two more videos (excuse my whining about how nothing happens/car does not pull):

Ali SC3

iTrader: (10)

I think it sounds great except its going abnormally rich in boost so you aren't making any power and it washes out the spark. the turbo sounds like its spooling just fine it just hits a wall when the wideband reads 10:1.
Normally it doesn't hit 10:1 that fast or at all, like mine is in the 11 range when I hammer it and you want to be in the 11-11.5 range... not 10.
at 10:1 when its not changing you are likely much richer than that even 9:1 because the aem wideband stops reading at 10... so my guess is that its getting too much fuel. \
at 9:1 the boost is going to basically cut off immediately.
I am guessing the injectors you have are flowing a little more than the stock "550's" that come on a US supra and its enough to wash out the spark. If you grab an safc you might be able to fix that issue the easiest vs changing injectors. Im just thinking maybe the stock tt ones arent exactly 550, someimtes when tested they flow a little less like 530 etc...

this explains why in lower rev ranges the o2 sensor can compensate just fine, cause its 14 when driving around, but as soon as you hit it and it goes in open loop its a solid 10:1 on the gauge. when you see a solid 10:1 on an AEM gauge, likely its much richer than that 8 or 9:1 and the engine wont run like that. its very simple.

Every time that happens you should be getting some kind of backfire out of the exhaust cause there is so much gas it washes out the spark and then ignites in the exhaust causing a backfire (and sometimes cool flames).

IF you used your stock maf you would get even more fuel, so keep the tt maf and use a safc and try pulling like 5-10% fuel I think you will pull all the way to redline after that it looks like the mod is done correctly is the good news. no matter what ecu you are on when you are richer than 10:1 you are not going to get good ignition at all. Ideally you should see it fluctuating in the 10-11 or 11 range then at least you know its not richer than 10.

Some other types of widebands will read really rich values so you know exactly how much richer, but with the aem if you see a solid 10:1 you are way too rich.

Kris9884

iTrader: (7)

This would be an awesome outcome actually, running rich is a simple fix.. Fingers crossed man

HiPSI

iTrader: (2)

Now that I think about it, when I had my AEM UEGO wideband installed, it would peg 10:1 A/F and I figured it was better rich "safe" then sorry. After switching over to the Innovative unit that I have now which allowed me to datalog the pulls I realized how rich it really was. Granted I'm on 550cc injectors, and the JDM ecu wants 440's, but I had like -15% taken out across the board, and it would peg 9:5.1 A/F at WOT. You could hear it cutting out and miss firing during the pulls and it felt like it was bogging / holding back. Pulled fuel to appx -25% across the board in the upper band and what a difference it made! Night and day and completely solved the hesitation / misfire feeling / hesitation it was doing prior. Back to back pull after pulling more fuel the car is noticeably faster and keeps pulling to redline.

A tune or someway to simply pull fuel, and possibly a dyno wideband that reads into the 9's will probably go a long way with your setup.

Edit: This is exact what Ali said above ^^ lol. But I actually experienced this as well when I first starting making boost.

Double Edit: This also means your mechanic (that we've been talking ill of) might of been correct in his vaque assumption / diagnosis of "It just needs a tune".

myLEXsc400

so this is as simple as just getting an SAFC and pulling fuel? Which one should I get? Is it something I can do myself?

Ali SC3

iTrader: (10)

Yeah the description of the problem threw us off I thought there was something wrong with how it was running but it sounds perfect it just cuts out as soon as the turbo spools. any type of safc can do this, safc1, safc2, safc neo. you are just going to pull whatever percent it needs all across the rpm range, so the safc2 of neo which has much more tuning points you will not really use. the newer ones look nicer though and have more breakpoints but any of them will get the job done.

you can also go something more sophisticated like a map ecu, and delete the maf at the same time and can fine tune a little bit. greddy emanage can do similar stuff and also the aem fic.

myLEXsc400

Thank you for all the help, guys! I just want the cheapest option, so I think I will be going with the SAFC. I'll order it and report back on the results. I'm praying to God thats all it needs.

99SC42

iTrader: (44)

Ive been asking or a video for a long time..

Ali SC3

iTrader: (10)

Also the story with the smell and backfiring really says it all, usually a result of running rich and washing out the spark.

Hope it works out let us know if you need help wiring it up follow the usdm stuff online for the maf cars.
Also a good turbo tip is before doing any pulls set your vents to recirculate and you won't get the open waste gate smell coming into the car every time.
it makes a huge difference. one of my pet peeves in fact cause when you restart a sc300/400 it goes back to taking in air from outside so I have to hit that stupid button everytime I get in the car..

myLEXsc400

Ok great, thanks for the air recirculation tip!
My SAFC came in today, and I will be trying to get it tuned early next week. I get it wired up like you would wire up a gte supra, i imagine?


Also, what things should I double check to make sure everything is good? Just for clarification, what should my timing on the distributor be set to? Or will it not matter anymore. I'm on stock HG

HiPSI

iTrader: (2)

From Ali's recommendation in the past.

GTE HG - 8-10 deg base timing
Stock HG - 6-8 deg base timing

Definitely make sure it's not set to high with the stock compression on pump gas. I would have it tuned conservatively maybe 12psi tops? I'm not sure what is considered to much on the stock head gasket but I would leave it around 10-12psi until you can get the GTE HG in there.

It might not be a bad idea to put some fresh plugs in depending on how long you've been driving so rich on the current ones.

Ali SC3

iTrader: (10)

Yes like a usdm supra. the wire you will be cutting in half and using for the safc will be the maf wire, not the map sensor wire. so the diagrams that say to use pin B66 are the right on.
basically this one is for the US and how you should wire it.

You are still on the stock headgaset? very brave sir very brave.
I would try 6-7 and listen for any signs of pining during initial acceleration from a stop especially low rpm's second gear. Its not so much the boost I am worried about its that the vacuum part of the tune is more aggressive on a gte. It should hold up though give it a try. keep boost under 10 psi at first.



follow the rest of the instructions here for setting it up, except when you get to entering values on the low/high part, you will actually be setting both low and high to the same amount all across the entire rev range.
start with a negative number like -5 or -10 and see how that helps. remember to make the change for all rpm's and for both high and low, you don't want it doing different things in different rev ranges.
I like to put the setting in the safc (like -10 across whole range for example), then reset the main ecu, then start it up and let it warm up and learn on its own.
If I find it wasn't enough or too much, I turn it off, make the adjustment, reset the ecu and let it learn again. making changes while its running is just going to get confusing since the o2 sensor is in play but some do it that way also.
it will make more sense when you try it, its not that hard, its like playing with a gameboy.
http://mkiv.com/techarticles/afc/index.html

Yeah thats about right, I haven't actually run this with the stock headgasket, but I have run an aem on the stock headgasket on pump at 11 psi for like a year so it can definitely be done.

If you are using the regular copper plugs, its not a bad idea to change them out when you run really rich for a while, they can foul out.

if you used the recommended Iridiums like the Bkr6eix or Bkr7eix with the Ix on the end then those generally wont foul out just keep running them they will clean themselves out more or less. I have run mine in all sorts of horrible conditions too much fuel, too little fuel, too much timing (thanks aem for letting you do whatever you want), all sorts of weird fueling and never fouled out a set. still running them at .032 gap which is more than what some others have been running. They are so hardy you can tune on them and then run them for a long time.

myLEXsc400

Thank you for all the info Ali! It's a big help! I will be attempting to get this car sorted sometime next week.

HiPSI

iTrader: (2)

Is it the original HG? I would be setting money aside for a GTE HG, and ARP headstuds. Maybe pick up a spare head and have it cleaned, lightly resurfaced and ready to drop on to make the whole process and less down time. The original 17-20 year old headgasket is not going to take well to NA-T once you get it tuned right and it starts making some good power. Just a heads up... Mine slowly went bad shortly after going NA-T.