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ODS
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Discussion Starter #1 (Edited)
500cc injectors with the Lex MAF?

Some say the stock 450cc injectors work fine, others say its a ticking time bomb and 550's should be used... But once 550's are used most agree that you run rich and it needs tuning... So why not run 500cc injectors?

I tryed to find a similar thread already and was not able to...

One more thing, I heard the HKS Fuel Cut Defenser can cause your car to run lean because it tricks your car into thinking your pushing less air then you actually are, therefore your motor injects less fuel... At what boost pressure off the stock (or a 60-1) turbo would this actually start to be a problem at? I only plan on pushing 15psi at max, but crusing around 10-12... So I dont want the ignition cut kicking in...

(Yes, I have changed the head gasket to a titan 1.4, with ARP head bolts and all that good stuff, I plan on putting a new Walbro 255lph fuel pump fairly soon)

SMo'
 

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A Happy Dad
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2,321 Posts
If you do the Lex and 550's you'll never hit fuel cut at that boost and if you set it up right you won't run too awful rich either, you do need the fuel pump upgrade for safety and make sure to drill out or remove the j-tube or you will run pig rich
 

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I don't want an MK4!
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Sounds like a decent idea. I would be interested to see what your A/F's look like at WOT in 3rd and 4th.

Dan
 

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ODS
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Discussion Starter #4
Purpose of removing/drilling out the J-tube? Or should I say, what is the purpose of the J-tube?

Anyone else have any comments on this topic? I really appreciate all the help!

SMo'
 

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The J-tube is typical Toyota over-engineering.

If your FPR were to fail, the J-tube would allow you to maintain halfway decent fuel pressure until you could get to a shop.
 

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1JZ BLING!
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You shouldn't hit fuel cut 15 psi on the upgraded CT.

15 psi is just getting started for a 60-1 wheel.

Most injectors are labelled as 550 and that is where the figure comes from. 500 is fine too if that is what the injectors are spec'd at.

The restriction of the J Tube will cause a higher fuel pressure when used with a high flow pump @ high boost. Drilling it out prevents that problem. Just find a drill bit the same size as the top hole and use that bit to drill out the bottom hole to match. Make sure you get any metal bits out and do it off the car.
 

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RoastBeefCurtain Commando
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I run the LEx AFM on stock fuel and run 14-15psi without any fuel cuts or any lean spots. Matter of fact I still run a little rich.
11.7-11.8:1 under full boost.

Yes it is smart to upgrade the old parts, but not needed in all cases
 

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ODS
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Discussion Starter #8
I think what I will do is use an electronic boost controller to keep things a little safer while tuning the boost pressure and see if I can get it to 12psi without hitting fuel cut... If I can hit 15psi without fuel cut then thats just a plus...

If I do hit fuel cut, I think I will put the Lex MAF and slap the car on a wideband to see how lean it is (of course putting the MAF on while the car is sitting on the dyno, not driving it to the dyno)... If it runs a little lean then put some 500's... If it is extremely lean then 550's... Either way I will be upgrading the fuel pump in a matter of months just because I dont want to do it after it breaks... I already have a new (factory) FPR...

Thanks for the advice and help on the topic...

SMo'
 

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The purpose for the Lex/550's is because the Lexus allows 25% more air in and the 550's are approx 25% bigger than stock. This makes for very easy and simple tuning as the ECU isn't freaking out because you have too much or too little air or fuel. The stock setup runs very rich, as does the Lex 550 setup. When tuned it's a very very good thing though. My car, IMO worked the absolute best when it was tuned on 550's and the Lexus.
 

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lex and 550's

how much will the car run rich, without tuning, if it's all 25% larger then it should run kinda like stock right, i'm all stock air/fuel right now and i think i'm running rich as shit anyway, i get lots of black smoke out the exhaust, i've only got a k&n drop-in, full 3inch from turbo back, and apexi bov for engine type mods, and i'm spiking boost to 13psi going into second and sometimes in the middle of higher gears causing the car to hit fuel cut and costing me precious time i don't want to lose at a track. i'm trying to get rid of that without using the hks fcd i have, but i also don't want to hurt my car
 

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88turbocharged said:
how much will the car run rich, without tuning, if it's all 25% larger then it should run kinda like stock right, i'm all stock air/fuel right now and i think i'm running rich as shit anyway, i get lots of black smoke out the exhaust, i've only got a k&n drop-in, full 3inch from turbo back, and apexi bov for engine type mods, and i'm spiking boost to 13psi going into second and sometimes in the middle of higher gears causing the car to hit fuel cut and costing me precious time i don't want to lose at a track. i'm trying to get rid of that without using the hks fcd i have, but i also don't want to hurt my car
Without tuning it's going to run VERY rich. The car with 440's runs plenty rich as it is. When you put 25% more air and 25% more fuel in there, you still are going to have a very rich condition. The 25% difference is just a balance. Since you have the same amount more air and fuel, the ECU doesn't freak out and try to mess with timing or fuel because you have added equal amounts of air and fuel. With your mods and the 550's and Lex, VERY VERY rich. BUT, you can back that screw out on the Lexus as far out as you want to bump up that fuel cut a bit.
 

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how bad is it that i run 16-17 psi on stock fuel system other than the lex/550's? I have a 3" full exhaust and K&N intake, but i'm otherwise stock. i don't get any pinging or detonation as far as i can tell.
 

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Nocheez said:
how bad is it that i run 16-17 psi on stock fuel system other than the lex/550's? I have a 3" full exhaust and K&N intake, but i'm otherwise stock. i don't get any pinging or detonation as far as i can tell.
On a stock CT, you are just blowin hot air. Anything above about 13 or 14 is just wasted on that thing. You will more than likely make better power on 13 or 14 than 17. I'd do 550's and Lexus and ditch the FCD though. Ticking time bomb.
 

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great thread going here.........finallly some info!

I've got the lex/550 upgrade as well and I'm pretty rich. Grey puffs b/t gears when it's on the mat, but mostly you can smell it!
How do you lean it out a bit?
 

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I don't want an MK4!
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magnus_heydoc said:
I've got the lex/550 upgrade as well and I'm pretty rich. Grey puffs b/t gears when it's on the mat, but mostly you can smell it!
How do you lean it out a bit?
WB and SAFC.

Awesome tuning tools for the MK3, but you can't have one without the other in my opinion.
 

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call me stupid...............

(Try not to chew me out too bad here for this response--I'm just not a tunner by trade!)
I know a WB is a wideband.
What's a SAFC and how are these used together to lean my mixture out some?
I can get my guy who builds race cars to straighten things out. He's a corvette guy, can fab anything, is super smart but just doesn't have alot of experience with turbo applications.
 

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to keep in good range

would it be possible to just get the lexus afm and replace the fuel pump to up the fuel cut but not run to rich, from the sounds of it and from some things i've read the 440's are actually plenty big to supply fuel for a stock ct (which i have), i'm only looking to run about 14psi for now and am wondering if it is safe and the car will run well with just the lexus afm and a 255lph fuel pump for fuel mods for now? then when i upgarde the turbo i can get the 550's and an safc.
 

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the bomb

I understand using 440s with the Lex is a ticking time bomb. It can be done but you need to have the right gear to be sure. It's better to error on the rich side than it is on the lean side. I've been advised to run 550s with the Lex. What the hell do I know, I'm running rich now.
 

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Madd Tyte JDM yo ®
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no one runs 500cc injectors because its a waste of money and time. why spend all that money for injectors that there is no demand for and you will probably have to upgrade from later on anyways?

you can make your 440's flow the same as a 500cc by just bumping up your fuel pressure. but youll need an SAFC to tune out the rest of the fuel curve.

stock afm/440cc cars run super rich under boost as it is. with just a filter and exhaust, ive seen them touch 10:1 AFR's. Idealsupra's car hit 10:1 w/ no real mods besides a BIC ddp, exhaust and apex-i intake. i would have to pull 12-15% fuel out to get it into the 12:1 area. so its entirely possible to add the lexus, bump the fuel pressure and still run on stock injectors.. if you absolutely had to. you should just do the 550's regardless of whether or not its "Safe" to run 440's. we all know that we want more HP and boost later, so you may as well just bite the bullet and get the injectors too.
 
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