Why cant i tune past 16psi with my setup

[a1320eclipse]

ok, setup is: 90 tsi awd. Mods: 3" catback, k&n, ground wire kit, walbro 255, turboxs hpmbc, safcII, logger on mmcd, hacked maf, but have a stock one.

So it was on 15 running fine, got my safcII, got it all set and tuned, but when i go past 16 i hit fuel cut. ive seen guys running 18 on about my same setup with no probs, am i doin something wrong, or is that all im really capable of? weather depending, i can get 17, but its unrelaible. should i just tune 16 and be happy for now. getting my downpipe next week, and next paycheck either 550s or fmic, what would be best to go with?

 

[CanadianTSi]

Are you adding Fuel with the S-AFC?

 

[a1320eclipse]

yes i am, and at 17psi tryin to eliminate knock i get to +25% or so at 4k with a knock count of like 12 and then it cuts, but i can tune 16 with a knock count of like 3-5. and only goin +17% at 3k to +20% at 7k with no probs

 

[delta448]

I've never used the logger, but maybe you should check your injector duty cycle if you can with it and if you're still on the stock injectors. The stock 450cc's at stock fuel pressure won't flow enough to handle much over 16psi.

With the 255lph, you could be overrunning your stock FPR, you probably should have an aftermarket adjustable FPR with the 255. Then you could also turn fuel pressure up a bit and adjust a little with the SAFC. It shortens injector life a little though.

If I were you I'd get the 550's next instead of the FMIC.

Just my 2 cents though.

 

[Module Unknown]

Sounds to me like you are inducing fuel cut with your safc. You do know how both the safc work and how fuel cut occurs right? The short short version...

The safc alters the airflow signal that the ECU sees.

Fuel cut occurs when the corrected airflow exceeds a preset limit.

Normally, most people that have an safc also have larger injectors and have to intially pull out fuel to get fuel trims in the right place. This of course starts you off tuning with an airflow signal that is further away from the preset limit that will trigger fuel cut. With your stock injectors and you just adding fuel (increasing the airflow signal), you're telling the ECU that it's seeing much more air than it actually is, it freaks out because it's been told that your stock fuel system can't handle that much airflow, and in an attempt to save your engine it cuts fuel and spark.

If you have any way of increasing your fuel pressure, you could always try that for now which would allow you to subtract fuel with the safc... but I'd just wait.

That's just my guess though. I could be totally wrong and you could have some other problem present.

 

[Talesin]

1) Boost leak test. Can't stress this one enough, and think that DSMers should boost leak test once a month, honestly. It's about $7 to Home Depot a leak tester together, and solves a ton of problems.

2) Getting a FMIC would only make the fuel cut worse. You'd be flowing more air then, as colder charge = more compact air = higher flow. You'd get more power, but run on less boost. Which CAN be a good thing... less lag, cooler charge (the further you get toward exceeding a turbo's efficiency map, the hotter the charge output is) and the looks factor that seems to be the primary reason most people get an FMIC. :b

3) Larger injectors are what you need. That and an AFPR... if you're running that 255 with the stock FPR, you'll overrun it at the low end, and over-lean at the top end. An AFPR will give you a constant fuel pressure, and make tuning the car MUCH easier.


Personally, if you don't have an AFPR, I'd go with a $200 Import Evolution aeromotive kit, and the 550s (or 650s if you intend to run more than 18 psi, and don't mind a slightly chunky idle). Save the FMIC for later on. Also, I'd swap to the un-hacked MAS once you get the larger injectors on. It'll give you a FAR more accurate airflow reading than the hacked unit, and again, allow you to dial in a more precise tune, with a much smaller randomization margin.

 

[JamiesTSI]

With the next pay-check you should buy a wide-band. Check your knock sensor, make sure it is not ozzing goo everywhere.

1. Are you sure its not just phantom knock? For lack of a better term the 1st gen. knock sensors are wothless, any little engine noise will trigger them. I run a second gen. knock sensor on my set up.

2. By adding fuel with the AFC it sounds to me like you may be at the point of over running your MAF. Are you seeing any black smoke out the back from an overly rich condition?

3. You need to know what your air fuel ratio is.

 

[daren_p]

Didn't read all the replies, but you said your running stock injectors & adding fuel. SAFC is a piggy back and your adding to the MAF signal. Your telling the ecu there is more airflow then there really is, so it hits fuel cut earlier. If you want to boost higher you need to install larger injectors so your removing fuel with the SAFC. This tricks your ecu into thinking there is less airflow and will take more airflow to hit fuel cut. On a side note, you should be getting an aftermarket fpr for the 255 pump.