Hey guys, this forum is great. I've recently been on mitsubishi-forums.... lets just say theyre terrible and i shouldve never started there in the first place. Well over the past year I've been building my RS a/t. Here is my mod list:

52 trim ebay turbo
12:1 fmu
fmic
255 walbro
2.5 inch straight exhaust
missing link
oil/boost pressure gauges
and thats basically the important stuff

Now on to my problem. ever since i first drove thsi, i had a problem where i would give it maybe more than 20% throttle and the car would
stutter and buck if i gave it more gas. if i let off the gas while doing this, i would end up accelerating. Ive been dealing with this for about 6 months now. I have no clue on what to do. Any suggestion would be nice. It could be fuel cut? possibly a boost leak, yet i check everywhere. and i might be... well only god knows really. or you guys. Its embarassing pulling up to a light next to a civic with a coffee can on the back, and i cant do anything about it... Could it be that im pig rich???? let me know guys, thanks

First impression to me is way too much fuel. If its bucking under throttle and when you let up it wants to accelerate, that to me means when you let off the gas the air:fuel is actually going towards something it can use instead of just raw fuel. Have someone drive behind you when you go WOT and see if its backfiring/blowing black smoke out.

Also, did this problem just arise or has it been like this since it was turbocharged?

Originally posted by 740 turbo brick
First impression to me is way too much fuel. If its bucking under throttle and when you let up it wants to accelerate, that to me means when you let off the gas the air:fuel is actually going towards something it can use instead of just raw fuel. Have someone drive behind you when you go WOT and see if its backfiring/blowing black smoke out. Also, did this problem just arise or has it been like this since it was turbocharged?

This has happened since the first drive of my build. would it be wise to drop in the stock fuel pump and disconnect the fmu and give it a try?

Originally posted by bigray1111

Originally posted by 740 turbo brick First impression to me is way too much fuel. If its bucking under throttle and when you let up it wants to accelerate, that to me means when you let off the gas the air:fuel is actually going towards something it can use instead of just raw fuel. Have someone drive behind you when you go WOT and see if its backfiring/blowing black smoke out. Also, did this problem just arise or has it been like this since it was turbocharged?

This has happened since the first drive of my build. would it be wise to drop in the stock fuel pump and disconnect the fmu and give it a try?

No.

What injector sizes do you have?
Fuel pressures?
Wideband readings?
If you have no way to tune that should be your next purchase.

Without anything to tune or give you feedback you are shooting in the dark.

I have the stock injectors, no way to monitor a/f and no way to tune... im only in highschool and ive put every dollar i have into this car haha. pretty bad on cash...

I understand. Just keep in mind that turbocharging the stock 420a in your situation (without proper monitoring/feedback) will likely end up in some form of internal damage from poor fuel or detonation control.

Investing a small amount now may prolong a costly rebuild in the future. Hypothetically, what would happen if you blew a piston ringland and needed a rebuild? All the money you have dumped into it is useless.

youre very right. i would just like a little more "insurance" and knowing that it would work before i go ahead and spend more money. know what im saying??

Hey guys i was looking around, i hate to be cheap... i really do. but sometimes i have to. the car isnt my daily so its not that much of a problem not running but anyway, i found this http://cgi.ebay.com/ebaymotors/VTEC-CONTROLLER-AIR-FUEL-RPM-TORQUE-DIGITAL-GAUGE-/390291695085?pt=Motors_Car_Truck_Parts_Accessories&hash=item5adf32a5ed#ht_1799wt_1162it says its a vtec controller but i noticed the air fuel control part. lmk if this could work for me. if it does, id be able to buy a wideband as well.

It is garbage.

would it help tune my fuel ratio? im stuck in the water. if you guys can figure out a way i can do this for 200$ id be VERY happy.

You want to tune or monitor you A/F ratio? Your FMU can give you basic control by setting pressure and changing the disc out.

i want to be able to tune and monitor my wideband, like you said. thanks for the quick replys.

IMO, i'd start saving up for an safc (which can normally be found used for around $100-$150), and definitly a wideband (which can be found for around the same price). With no way for you motor to communicate with you, you dont have to much information on which direction to go with correcting the issue.

does this 'bucking' occur when you transition into boost? I see you have a missing link, but am curious anyway

Its when i hit boost even .5 psi. I bought a fcd first, thought i twasnt working, got the missing link, nothing changed. I did just order every single sensor for the IM manifold, got a steal for 15 bucks, couldnt pass it up. even if theyre all still good i can resell the sensors. hopefully get some money to go towards the safc. i got a a/f gauge from a friend, just not wideband. im gonna hook that up asap.

what version of safc can i use? the blue with silver generation one is the cheapest ive seen, other than the dial ones, but im not that cheap...

do me a favor and try these 2 scenarios:

1. remove one of the charge pipes and give the car more throttle and see if it'll buck as it did before. This'll distinguish whether it's a boost issue or not.

2. remove the missing link (ML) and blow through the bottom o-ring'd part on the ML. if you can blow through it, it has a bad check valve, hence, your issue is a bad ML. pic shown for reference (bottom is the o-ring'd part i'm speaking of)



you can try #2 first, easier to test

Originally posted by bigray1111
Its when i hit boost even .5 psi.

I'd be willing to be it's your missing link. Your ECU has no idea what to do when it sees positive manifold pressure, other than to pull fuel and retard timing, as I recall. Check to see if the valve on your ML is hosed. And spend the $10 on a decent FCD. Again, cheap insurance.

More than anything else you need a wideband right now.

Originally posted by Fallen4ng31

Originally posted by bigray1111 Its when i hit boost even .5 psi.

I'd be willing to be it's your missing link. Your ECU has no idea what to do when it sees positive manifold pressure, other than to pull fuel and retard timing, as I recall. Check to see if the valve on your ML is hosed. And spend the $10 on a decent FCD. Again, cheap insurance. More than anything else you need a wideband right now.

I remember this true as well. ECU sees the MAP go just barely past 0kPa, and its like WtFuxors is THIS??1?! and has a tantrum.

It could also be the MAP sensor. You said you installed an FCD first, can you verify the MAP wiring was reconnected properly and you're actually seeing a MAP signal at the ECU?

Look for the yellow wire / black stripe in the ECU harness. Start the car, let it idle, and test with a voltmeter that you're seeing ~4.0V+ on this wire.

Originally posted by DarkOne
It could also be the MAP sensor. You said you installed an FCD first, can you verify the MAP wiring was reconnected properly and you're actually seeing a MAP signal at the ECU? Look for the yellow wire / black stripe in the ECU harness. Start the car, let it idle, and test with a voltmeter that you're seeing ~4.0V+ on this wire.

try that ^^^ too

Well i got my new sensors, didnt help a bit. which means im gonna make a few bucks hopefully off my old sensors. But i got my 95 fuel rail as well. I saw a whole bunch of hoses and junk in the rear near the fuel tank. im guessing that supplies certain pressures atm? Can somebody find me or draw me up a diagram of where i install the fuel rail, the stock fpr that the 95 rail has, and fmu. Thanks.

i also forgot to mention, after checking my gauges, i reach 4psi and then the car does its fuel cut symptom thing. If i give it half throttle the car has tiny pops out the exhaust, anything past that, louder pops. Im about to gap my plugs to like .15 and see what happens.

Originally posted by bigray1111
Well i got my new sensors, didnt help a bit. which means im gonna make a few bucks hopefully off my old sensors. But i got my 95 fuel rail as well. I saw a whole bunch of hoses and junk in the rear near the fuel tank. im guessing that supplies certain pressures atm? Can somebody find me or draw me up a diagram of where i install the fuel rail, the stock fpr that the 95 rail has, and fmu. Thanks.

so im basically retarded. I installed my FMU right before the fuel rail. I guess this was causing an extreme lean state? would make sense imo... now for me to convert this to the 95-96 fuel system, all i need to do is hook up the fuel rail, and for the return line just run a line back to the tank off the rail? or do i need to take some shit out.

Guess what guys, the car is currently running like it should, ive never been more happy. I took out the FMU and moved it to the rear, car is running great. ive got some adjustments that need to be done, but other than that it runs amazing. Pulls hard, cant wait to drive it more. but im working now.. THANKS GUYS. if i can buy a 2gnt.com sticker from somewhere ill buy it, couldnt have asked for more from u guys.

Originally posted by bigray1111
Guess what guys, the car is currently running like it should, ive never been more happy. I took out the FMU and moved it to the rear, car is running great. ive got some adjustments that need to be done, but other than that it runs amazing. Pulls hard, cant wait to drive it more. but im working now.. THANKS GUYS. if i can buy a 2gnt.com sticker from somewhere ill buy it, couldnt have asked for more from u guys.

Glad we could help. We don;t have any stickers currently, but we're working on it. You can always "like" us on Facebook, though!

D

feels good to get things running properly from the 2gnt knowledge base doesn't it. bookmark it!

well my first gear pulls are great, spools a little slow though. But on a certain closed off area around here (heh) i was able to hit 105 before the turbo, with 2 people in the car. now with the turbo, i hit 90... in second gear its very slow acceleration. idk what to check now. i made a boost leak tester a while ago, its been a while since ive used it. should i check that?