Evo 5 , running lean

Hi guys , I'm new to this and not too sure if I'm out of my depth .

I've got a Mitsubishi evo 5 and it's got a hks f con v piggy back ecu , but at cruise and on full throttle pulls it's running lean ,. Advice would be great if anyone has a evo and has done the sd conversion to the stock ecu, and can advise me on tuning it or just advice from someone who can help would be great .

Thanks Ross .

Can't help, personally, but the more information you can provide the better for those with experience with these engines.

For example, any logs, injectors, charge cooler, intake and/or exhaust changes, fuel regulator, etc?

First thing I'd be looking at would be the fuel regulator and the pressure reference hose for cracks or leaks.

Hi Gord , Thanks for the reply , I think you are right that it is fuel / pressure issue possibly , I will try and explain what has gone on , and what I know .

So I got the car 2 years ago nearly , and when I got the car it was a fresh import from japan already modified , so what i know it has got -

Stock bottom end . upgraded tomei arms 7960 turbo , tomei 260 cams , has a tubular manifold and a 3 inch turbo dump pipe and exhaust with sports cat, khs mushroom filter and hks hard pipe intake kit (no maf) , upgraded intercooler / piping ( not known) , it has the fuel pump hard wired and was a different pump to stock , it's on stock injectors , and it is on speed density but is on the hks f con 5 piggyback ecu ? ( not sure on that tho).

So when I got the car, a few days after owning it it started misfiring . Put new spark plugs in and new coil packs and leads fitted ( that wasnt the issue 🤦‍♂️),.. Found the fuel pressure low so I fitted a adjustable fuel pressure regulator ( recommended to me by a tuner ) , so I got that set and had it dyno'd and that was the result , now I know when I took it to the tuner he removed a little inline filter / one way valve from a vacuume/ pressure line ( i dont know if that was or would make a difference to the line going to the stock fuel pressure reg originally or have a affect on fuel pressure ?) ...

So from there it then had a new exhaust manifold fitted due to the tubular was cracked (would this have much difference on the car tune wise ?) Ran ok tho .

I then tried a brand new original stock fuel pressure regulator that when fitted the car would misfire/ only rev to 4k , then I was advised by another tuner to change the fuel pump (walbro 255) had no affect except pressure was too high tho at 50 odd psi - 3.6 ish bar , but then I hooked it back up to the adjustable fpr and set that to about 3 bar and it would rev great.

I have no logs or anything on the car as I am waiting for tactrix 2.0 cable for evo scan , I have been told by all the tuners that it should have gone bang by now , but I have checked the cylinders and cant see any signs of dett / knock .I'm told the injectors are maxed out so to speak .

The other issue I get is slight bucking/ hesitation on light throttle , but I'm mainly concerned about killing the engine ..

So any advice would be amazing , thanks guys .

Ross.

If fuel pressure is correct the next thing i would look at is fuel map. 4g63 doesn't like lean mixture at all. How lean is your fuel under boost?

Hey , thanks for the advice , I'm hoping when I get the adapter I can hook it up and check the maps ( I just dont know how the piggyback ecu will be affecting the stock ecu ) , ive tried uploading a video of the afr's while the car is being driven but it wont let me attatch the video , in my first post there is a attached pic of the dyno run tho if that helps

What afr reading do you see on the gauge under the boost?

I have some software for hks piggy backs that i can share with you but you will need to buy special cable to be able to connect it to your laptop...

The afr on the guage is around 13 when on boost , if you would share the hks software Shota that would be Amazing , and what is the special cable needed ? Could you send the software in a email?

rossie69@live.co.uk ..if you can .

Thanks again

13 afr on boost is way too lean for 4g63... It should be at least around 11.5-12.2 up to 1 bar of boost and up to 10.9 above 1 bar boost.

In order for me to send you software i need to know what type of hks piggy back ecu you've got. There are a few different ones so is software...

The cable picture is attached.

So I am lucky it hasn't damaged it then ,.. I have attatched pics of the hks I hope that's what you need , and I will try have a look for that cable now !😁👍

It is hks f-con v pro 3.1

It is not just a piggy back but can be used as a stand alone unit.

I will send you software but without cable you will not be able to change it...

Ok so I dont need any pass key or it wont be locked at all ? , and if I get the cable I can definitely tune this ecu then ? , as the car still has a sock ecu aswell

You don't need any keys to unlock it. Stock ECU handles idle stepper motor and that's pretty much it - the rest is handled by fcon

Amazing sounds promising ,.. so I have had a look at the cable and there was 2 options I'm guessing the picture of the one you sent over is best for my f-con (pic attatched of the other PC adapter lead , and one I've found that I hope is the same as yours), is the hks easy enough to map as I have never tuned a car before , I realy apretiate your advice and help by the way !😉🙏

Software sent

The cables you posted seem to be the right ones.

F-con software is very user friendly. It takes just an hour to figure it out...

Thank you soo much ,.. I am well excited now , I just want to be able to drive the car without having to worry about melting it ! Cant wait 😁👍

Top man !!!...I'll check the software now 😉,

I will still need advice from you tho , I hope that's ok ?

Fell free to write me anytime. My personal email address is georg1970@bk.ru

By the way - here is very helpful sitehttps://1jzmerc.com/hks-faq/hardware/f-con-v-pro-gold

Thats brilliant , I realy cannot thank you enough at this time ! 😉🙏 . I will get this onto the computer and get the cable and I will be in touch ! .. super exited ,thanks again !