2G 420a Turbo Fuel Question

xtremeoracing · Sep 18, 2014

Hi all, new member here. I own a high performance shop in Miami and have worked with LT and LS GM based cars basically all my life, so with that said... I am a noob when it comes to Mitsubishi.

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I bought a 1998 Eclipse RS as a daily driver, and after promising myself to leave the car alone since its my street car... I decided to turbo it. It obviously comes with the infamous ( as I've learned ) 420A. So I knew I wasn't going to get much power out of it.

This is what I've done so far, and in a bit ill get to what my problem is.

Turbonetics T3/T4
Turbonetics Wastegate set at 7psi
GReddy BOV
Synapse Missing Link
Air to Air Intercooler

I installed everything and was obviously running lean when in boost. Yes the Missing Link got rid of the fuel cut, but the car obviously can't keep up fuel wise. So I went ahead and installed a Blox 12:1 FMU. I thought this would do the trick, but although a tiny bit richer, I am still leaning out when going into boost.

Now my question is, Would my problem be that the stock fuel pump can't maintain the pressure levels the FMU is forcing? or will I also need bigger injectors? and if I do, how the heck do I prevent the car from running rich at idle and when not in boost? Would an Apexi S-AFC help with this?

Thanks in advance for the help, I know this topic has probably been beaten to death and I sympathize, as a forum moderator myself I know sometimes people don't search and just ask questions, but telling me to search for the answer probably takes as much time as just actually answering my question.

Sjd6795 · Sep 18, 2014

Yea safc-2 would be a good choice to go it's what I use on my car. Your injectors should be fine but you might want to pick up a wideband 02 and some sort of tuning device before going any further. Depending on what your goals are you could pick up a set of used 450cc injectors that the 4g63 turbo cars use. I'm not sure if the fuel pump and injectors work in the 420a but it would be a good thing to get to just be up to par.

xtremeoracing · Sep 18, 2014

Sjd6795 said:
Yea safc-2 would be a good choice to go it's what I use on my car. Your injectors should be fine but you might want to pick up a wideband 02 and some sort of tuning device before going any further. Depending on what your goals are you could pick up a set of used 450cc injectors that the 4g63 turbo cars use. I'm not sure if the fuel pump and injectors work in the 420a but it would be a good thing to get to just be up to par.

Thanks for the quick response. My goals are to be close to 200hp. I plan on rebuilding the engine in about a year and perhaps then I will go with a stand alone and a little bit more boost. But that is far far away... So with that said. You recommend I get a Walbro 255, 450cc injectors along with a SAFC-2?

PS. I already have a wideband and have a fuel pressure sender/gauge on the way as well.

Sjd6795 · Sep 18, 2014

You wouldn't even need the walbro 255 for those goals if you went with a 255 you'd need to buy a adjustable fuel pressure regulator. You could go with a walbro 190 and be fine for 300+ HP.

xtremeoracing · Sep 18, 2014

Sjd6795 said:
You wouldn't even need the walbro 255 for those goals if you went with a 255 you'd need to buy a adjustable fuel pressure regulator. You could go with a walbro 190 and be fine for 300+ HP.

With an adjustable FPR I could kick the Blox 12:1 Fmu to the curve correct?

Sjd6795 · Sep 18, 2014

That's correct then you wouldn't have a set amount and you can adjust it as you need.

xtremeoracing · Sep 20, 2014

Sjd6795 said:
That's correct then you wouldn't have a set amount and you can adjust it as you need.

Any tips for setting up and configuring the SAFC2?[DOUBLEPOST=1411262357][/DOUBLEPOST]Also would a SAFC work as well? You mentioned SAFC2...

Sjd6795 · Sep 20, 2014

The safc2 is just the newer version and they can be bought for close to the same price. I believe it has more options and can tune a little better. And as for tips on tuning each car will be different I used a base tune for a 4g63 to start out with then I adjusted from there. You can probably do the same even having all the rpm points set at 0% would work just to get an idea of where you are at.

You'll mainly be focusing on the lower rpm throttle points until you are ready to start doing mid and WOT pulls. It's fairly easy once you get the hang of it, I'll try to dig up some threads that I used when starting out and edit this post with them.[DOUBLEPOST=1411274674][/DOUBLEPOST]I can't find any of the links but it just make sure all your rpm points are setup then do -12% on each of the rpm points. You could probably do -6% on 4k and up, you will do this for both low throttle and high throttle. Your idle rpm should be set for 800 and when you get it to idle around 14.5-15 you can take it out for a easy cruise and see how the a/f ratio is. Also once you are in the ball park with the a/f ratio adjust it by -1% or -3% at a time. Then go out for a drive and repeat if necessary. Once you are to the point of tuning just send me a PM and I can help you a lot more. Until I know what the a/f ratio is I can't really go in depth on tuning. As for guides on installing they can be found all over the place just do a simple google search.

xtremeoracing · Sep 21, 2014

Sounds good, I will go ahead and send you a PM once I am ready! Thanks again for the help.

bryanwheat · Sep 21, 2014

I would definitely upgrade the pump to a 190 lph before anything if you haven't already.

xtremeoracing · Sep 21, 2014

bryanwheat said:
I would definitely upgrade the pump to a 190 lph before anything if you haven't already.

That is my next mod, I also bought a .4 bar spring. It feels like even after I get the fuel problem resolved this engine is going to blow up with the current .5bar spring. I can rebuild it rather quickly but I don't want to have to deal with that right now.

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