mko

94 Galant ES 4g64

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Ok, i dont have 420A, but Im too curious how this works. I read a couple of threads about turboing 420A and it didnt look anything like turboing 4g63 or
4g64 engines. Im particularly curious about the fueling the engine under boost. I read that the stock injectors are being used with some 10:1 fuel regulator or something - how this affecs the ECU. Do you use the stock maf, or use MAFT or some else if it works. And why not use bigger injectors like the Mitsu engines? All that fueling with stock injectors is little blurry to me. Can this be done to 4g63 engine? What horsepower do you put down with this setup? Any other tricks that are worthy to know?

Thanks in advance!

thabassman87

1996 Eclipse GSX "GSeX" (6 Bolt Swappin')

1995 Eclipse RS-T "Claire" (Sold)

1989 Dodge Dakota 3.9L V6 2WD

420a engines don't use a MAF. You use the FPR to raise the fuel pressure hince the 10:1 ratio. 10 psi of fuel for every 1 psi of boost. Instead of increasing volume, you increase pressure. You don't use a FPR with the 4g63. Mainly used for NA engines that get boosted.

mko

94 Galant ES 4g64

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Thanks its more clear now. I didnt make it clear enough - what i meant was that fpr is used when you boost 4g63 n/a. How do your engine determine the A/F ratio when theres no MAF


So, if I boost 4g63 and use 10:1 fpr with stock injectors should make no difference than using 450cc injectors. then what is the effect of the higher fuel pressure on A/F ratio, if theres any?

One more thing, whats the duty cycle of the injectors when you use 10:1 fpr, and how do you controll the A/F?

thanks

thabassman87

1996 Eclipse GSX "GSeX" (6 Bolt Swappin')

1995 Eclipse RS-T "Claire" (Sold)

1989 Dodge Dakota 3.9L V6 2WD

It's a mix between the o2 sensors/map sensor/tps/computer. You can run 15 psi on 450cc injectors whereas you can only run 8 psi on a 10:1 fpr so no a fpr isn't as good as stock dsm injectors. It does put more stress on the injectors. You can't control the A/F unless you have some sort of tuning device. You can monitor with a wideband tho.

Flipboi89

96 Eclipse 420a-T

isnt this thread about a 420a? lol. Yes under boost such as 7 psi we use a fmu 12:1. After more boost the ratio changes evenually to a 1:1

jack_of_trades

~'03 Mitsu. Evo VIII

~95 Talon ESI(turbo'd) sleeper (for sale)

That was completely wrong. Sorry, not bashing. The stock ECU runs the same duty cycle whether you run WOT (wide open throttle)with the car N/A or with a turbo strapped on. Its running off of a fuel map in open loop with a predetermined fuel curve. This is not adjustable at ALL and the only way to adjust it is to trick the ECU by telling it that the map sensor signal is less than it really is. This makes the ECU run in a different section of the pre-determined open loop fuel map, which would be lowering the duty cycle to the injectors.

What we do with the rising rate fuel pressure regulator is to supply TOO MUCH fuel to the engine so we can use a piggyback controller like the Apexi S-AFC to REMOVE fuel to a desired fuel curve (preferably 11.0-11.5:1 AFR while boosting 1+psi). A piggyback fuel controller cant ADD fuel because the map sensor is already maxed out so we are at the ECU's maximum injector duty cycle that it will use in the fuel map. The issue is the timing map. Its set in stone too. The ECU assumes you're running the engine at 0psi (WOT with an N/A engine) so the ignition timing is quite aggressive when you add 8psi of boost on top of that. Also, if you're running a piggyback fuel controller like the S-AFC and you trick the ECU into thinking its running at less than WOT, the timing curve can actually be MORE aggressive! Thats because ignition timing usually retards as the engine load increases. Since you're tricking the ECU into thinking the engine load is less than it really is...it advances the igntion timing even more than it was before!!! The one thing that saves us is the fact that this igntion timing curve was designed for 87 octane so when running 93 octane, we're able to withstand this aggressive timing curve a bit more. Like I said, this timing curve isn't adjustable when running a rising rate FPR and a piggyback fuel controller. If you step up to the AEM fuel/igntion controller, you now can adjust your fuel curve using larger fuel injectors with lower fuel pressure (still need a 1:1 rising rate FPR though) and you can also RETARD the ignition timing to a safer level! Thats why I've preached the worthiness of this product since it came out. The reason turbo'd 2GNT's blow up isn't because of the fuel, its the aggressive igntion timing that causes detoniation (aka: engine knock) which can kill our weak engine internals at the blink of an eye.

Also, I've been preaching the importance of the PROPER sized FMU ratio forever but some fools still tell everyone to use the 12:1 FMU. Stop it!!!! The idea is to use whichever ratio gets you as close as humanly possible to a 11.5-11.0:1 AFR while at WOT. That way you don't have to remove that much fuel with a piggyback fuel controller. Like I just mentioned, the more you need to adjust that piggyback to lean out the fuel mix, the higher you're making the ignition timing!!!!! I don't suggest lening out a S-AFC more than 5%. If you need it leaner, get an adjustable FPR and lower the fuel pressure a little more.

We need someone to datalog a WOT 3rd gear pull and show a graph of the fuel and timing. Anyone tested out the Evoscan v2.5 software on a 2GNT yet?