Possible fuel problem, suggestions?

[Hondahunter_666]

My roomate has a 1998 Eclipse GSX and he is falling on his face soon as he hits full boost. We think it's simply a fuel problem, but I'll list his mods here and if anyone else has an idea, feel free to let me know!

18G Greddy turbo upgrade kit,
Greddy FMIC,
Walbro 255lph fuel pump,
TurboXS MBC,
HKS Hi-Power 3" catback exhaust.

He is still using the stock injectors (for now) and also has the boost set at 16psi. If he brings the boost down you think he'd be alright?

btw: he does have injectors and a FPR on the way so we know about that one ...

 

[kgtalon95]

my guess would be fuel-cut.....but thats just my guess

 

[Hondahunter_666]

but why would it be cutting fuel way before redline? would the stock MAF not be able to handle the amount of air or is it something else?

 

[Thomas91169]

^^^that is exacly why he is hitting fuel cut

the MAF is reading way more air than stock, and tells the ECU that it needs to stop or it will blow up.

a Piggyback style fuel controller will help push back the fuel cut, but those only work so well.

id look into dsmlink or such if your buddy has the money and a laptop.

also maybe bring the boost down a bit, and make yourself a boost leak tester(www.vfaq.com). if there are leaks, the turbo is sucking in more air than it should to create the given 16psi. if you had leaks and fix them, you could see 20psi without touching a boost controller cause of now getting the full amount of air in the intake and not leaking it.

 

[Hondahunter_666]

I'm assuming like an S-AFCII is what you're suggesting correct?

(sorry still slightly new to the DSM world, but learning all I can.)

If that's not what he should get then what would you recommend?

 

[95gstnotwalkin]

yes an afc woud work a little but your only real way to get rid of fuel cut permantely is to go dsmlink or have your ecu chipped. As soon as you get injectors, i would personally get a GM 3" maf and translator and set that to your fuel injector size and fine tune with an AFC. i like the idea of fuel cut as a safegaurd , you just need to tune and adjust things properly so you dont get it. If you do everything right, you can have 500 hp on a 3" gm and not have cut at all.

 

[sweet97]

Check www.ffwdconnection.com for a socketed EPROM ECU. I could be wrong but I think for a 2G they are around $230. which is a good buy. Then order a stage 3 chip from www.dsmchips.com I simply use the MAFT. no afc and do fine. I recommend 650/680cc injectors as they are the most versatile working with 16G's and even my 60-1. Mark

 

[Diplomat]

I'd like a bit more detail of the issue he's having. We're assuming what he's experiencing is fuel cut given your description and list of mods provided. What I'm looking for is some clarification on what you mean when you say he's "falling on his face". For instance, when he accelerates, does it seem like he's got decent pull before boost (vacuum to 0 p.s.i.) and then feel like it gets weaker immediately after that as boost builds? That would likely be an air/boost leak. You can thank Mitsubishi for putting the MAF at the beginning of 50 yards of air intake tubing, creating many opportunities for boost leaks to develop and ruin your fun.

Or is the problem more like everything is fine as he accelerates until he hits full boost (or close to it) and suddenly there's no power for a moment? Some describe it as hitting a wall. To me it's almost as if someone turned the ignition off and on quickly. That's fuel cut (a.k.a. MAF overrun). You can thank Mitsubishi for using a Karmaan vortex MAF.

If the problem is a boost leak than he needs to simply make a boost leak detector like Thomas suggested, and go from there. More than likely he'll find at least a couple boost leaks. Even if he finds and fixes a leak, he really should still invest in some sort of fuel control. That's a step that usually precedes turbo upgrades. He really should have something for that already, and he'll certainly need something once his injectors arrive.

If it turns out he's got the ol' fuel cut, then he needs to back off on the boost or, again, get something for fuel management. Some of the more popular choices include, but are not limited to Apexi's SAFC, ECMTuning's DSMlink, or AEM's EMS. The SAFC is the less expensive alternative and is a piggy back style fuel tuning device. It's wired in between the ECU and it's sensors to fool it into giving you more or less fuel when you need it. DSMlink has quite a few more features beyond just fuel control making it a bit more difficult for the novice to use but is a more well rounded tuning device. The AEM EMS is the more expensive route. However, since it replaces your ECU, its tuning potential is limitless, assuming your skill and understanding of how to program it are also limitless. For the most part, DSMlink is considered to be more user friendly than the EMS as well as less expensive, but you have to figure in the cost of a socketed EPROM ECU if you don't already have one laying around.

If you want more information on fuel tuning devices, I'd suggest your friend do at least a couple hours of searching and reading on the subject before making any decisions.

As mentioned above, your roommate might want to make a GM MAF in a blow through set up part of his wish list. More and more DSMtuners are going this route since leaks before the sensor are less detrimental and the GM MAF doesn't impede airflow as much as the OE MAF.

By the way, is that a complete list of his mods above? I'm sure you're friend hasn't done all of this work to his car without so much as a Pocketlogger... has he? Does he have a membership with DSMtuners.com yet? It's free, ya know? We're here to help each other avoid common pitfalls and occasionally yell at the new guy for not using the damn search button.

 

[kgtalon95]

^^^^^^^ Dido

If he can't afford the afc or dsmlink try backing down the boost a bit. If the problem goes away then I think it would be safe to say that fuel cut was your culprit. And tell your buddy a full list of mods would be helpful too.

Did he do a real boost leak test after the fmic install??

 

[Hondahunter_666]

No actually he didn't do a boost leak test after the FMIC install. We checked everything and it seemed to look good, but no leak test. Also, the problem is more like when he hits boost, he loses that power that he seemed to have before the boost. It doesn't stutter or anything, just doesn't accelerate like you think it should. My Super 16G boosted FWD Talon eats him alive through a quarter mile. He can take me only through his first gear, soon as he hits about 4,000 rpm in second I'm passing him and FAST. If that seems to be a boost leak, then I'll suggest that to him. I hope he's willing to listen to this like I told him to listen about venting his BOV!