Safc with 255pump but stock injectors?

[AlekTSI]

Ok guys my set up isnt anything special.. I have a small 16g with a 255 pump but only stock injectors. I just recently got my BOV properly recirculated into a new dejon tool intake pipe with a brand new K&N filter. I also have an narrowband(i know widebands are more accurate)Autometer AFR gauge and a palm IIC datalogger with MIIC on it that haven't been installed yet. I was thinking I could buy a safc and take my car to a shop to get all these things installed and working to get a decent tune. Is this a bad idea? will the safc even really do anything without a real upgraded fuel system? thanks for any help

 

[gbradley]

Sure. You can tune with the safc right now to lean the wot afr for more power.

 

[stroked_AWD]

Take it to a shop have them install the safc and tune it. Your only running a small 16g so its not going to hurt using stock injectors.

 

[ArticNemesis]

You aren't going to be doing any tuning on the AirFuel gauge you have. If the shop supplies the wideband to do the initial tuning, then it's possible, although you won't have any warning if something goes wrong.

 

[snowborder714]

You should get an AFPR for the 255lph pump.

Also, you'll max out the stock injectors pretty quickly once you start tuning. And as Brad said, the only proper way to tune at this point is to rent a wideband from the shop for tuning.

 

[PIMking]

Take it to a shop have them install the safc and tune it. Your only running a small 16g so its not going to hurt using stock injectors.

Do us all a favor and try not to post stuff that is incorect.

Your going to need a logger at least to log for knock.
Loggers can be had for around $100. I personally never used one but I have DSMlink that is a great tuning tool.
Plus the logger will tell you your injector duty cycle to see how close you are to running out of injectors.

Your also going to need an Adjustable fuel pressure regulator. (afpr) That 255lph is going to over run the stock FPR.

Also That 16g is going to flow more air at 15 psi than a 14b at 15 psi and that 14 b will flow more air at 15 psi than a t25 will at 15psi.

So even though your putting stock boost 12psi on the 16g your flowing more air than the 14b at the same boost. So

 

[AlekTSI]

I have a cheap datalogger that i picked up from ebay.. I can just rent a wideband at a shop to tune on?

 

[Dsmj89]

Why don't you just buy a wideband and call it a day ? You'll eventually need to have one anyways to properly monitor your a/f readings at all times. Save the money and get one.

 

[snowborder714]

^I agree.

While it is possible to rent wideband usage, I believe it can be around $75/hour or so to rent it. For a little over $100 more, you can buy your own unit (some even come with a gauge). This way you can tune yourself if you'd like and constantly monitor your wideband readings.

A tune is not a "set it and forget it" type of thing. While it is to some extent, there are many factors that can alter your tune. By having your own wideband, you can make those changes when necessary.

 

[AlekTSI]

I was running up to 16psi before i hit a fuel cut before the winter hit.. I know i should have gotten a wideband but i picked up the autometer one for like 20 bucks.. thanks sfor the help

 

[dsm-onster]

Get an AFPR. You will need one for the 255 pump anyway to prevent fuel pressure regulator overrun.

This is what I did. I ran the base fuel pressure (fuel pressure with the vacuum line disconnected) at 60psi. The walbro 255 can still flw enough to maxout 750s-850s at 22psi and 60psi base fuel pressure. Your 450s will flow about 530cc. This will be plenty of flow for decent results with a small 16g (300-330whp).

You will now have enough fuel and turbo to overrun your stock 1g maf. You will also need a means to tune the 530cc fuel injector flow. An safc will do this, but you will need a maf upgrade for anything over 300whp. There's maf translator or safc with a 2g maf as the most affordable options. I suggest the second option.

I also suggest an intercooler upgrade for anything over 250whp.

 

[AlekTSI]

I don't have $ to upgrade to a 2g maf. I just got a dejon pipe and recirculated my BOV into and it idles much better than it did. will the Safc still be effective with the restrictive 1g maf?

 

[dsm-onster]

You can about max out your stock injectors at stock fuel pressure at the safe limit of your 1g maf be for overrun. Overrun has nothing to do with choking airflow. It is when there is more airflow than the maf can consistantly meter. It "drops" counts and the ecu sees much less airflow than actual. This causes the ecu to dial back injector pulsewidth and sudden leanness occurs. Often taking out headgaskets or much worse.

You will likely reach fuel cut before that however. So the safc will push back fuel cut if you can run higher fuel pressure with your stock injectors, since the maf will be reporting lower airflow than actual to compensate for the higher fuel injector flow. Fuel cut occurs at a certain gram/rev airflow. So you will gain by being able to see more power before fuel cut.

Another way to get more out of your setup is the hack (remove the lower honey comb) the 1g maf. If you have an safc you can correct for the hacked maf and have zero drivability issues. When hacked, it will report about 5% less airflow. This gives you about 5% more airflow potential before the 1g maf overruns. This is good for about 20more hp before overrun.

Stock fuel maps run you down to 9.4ish:1 a/f ratio. You will definately gain by tuning.

You don't need a wideband. You have a 1g. Tune for zero knock. You will see knock long before you see a lean enough a/f ratio to lose power with pumpgas and stock intercooler. A maf car does not change tune at different times of the year or different atmospheric conditions, because the airflow is actually metered there are no variables unaccounted.

A wideband is neccesary for tuning a speed density setup (no maf), or tuning with a fuel and setup that will allow you to go lean past best power without detonation Like running e85. Or running gasoline and water/meth injection. I'm not negating the value of a wideband. I have an lm-1 for which I paid $500. But I also run water injection and a decent front mount intercooler.

Personally I would save the money that would be used for a dyno session so I could get a 2g maf; and take the car to the track to tune it yourself. Just simply shoot for the best 1320 trapspeed with no knock. Drive it around for a few days to dial in your fuel trims (you can't dial in your normal driving ecu controlled fuel metering with a dyno anyway). Once your closed loop (fuel trims) is dialed in, go to the track. You only have 2 variables to tune: boost and the safc fuel correction. Your 2g maf will not overrun, you will have enough fuel at 60psi base fuel pressure for up to abotu 350whp and you have enough turbo to do that, as well. You will need an intercooler upgrade to actually see that power safely, but that will be all you need to get a healthy setup running strong.

 

[->PrOjEcTGS<-]

Fuel cut at 16psi? Do a BLT I bet you will find a leak somewhere. You shouldn't be getting fuel cut that early I don't think.

 

[dsm-onster]

I did. I hacked my maf and was able to push it off to a later boost.

 

[->PrOjEcTGS<-]

ok. I've had fuel cut disabled in my chip for so long I forgot what it was.

 

[dsm-onster]

It's not at a specific boost. It is at a specific gram/rev. Most stockish setups seam to hit fuel cut at 16psi typically. But I've had it happen at 13-14psi because the temp was cold enough. I've also moved from a higher elevation to sea level and the fuel cut comes on sooner. Higher airpressure and lower temperature each raise that gram/rev number.

 

[->PrOjEcTGS<-]

I always saw it at about 18psi... That was way before the 2g MAS and the SAFC I had way back then.

 

[AlekTSI]

OK.. well would my car be ok to drive without the AFPR for a while while i get some $ around if i lower my boost level a little bit? ANd i shouldn't hack my maf untill i get a safc to compensate for the extra airflow right? I really appreciate all your help

 

[->PrOjEcTGS<-]

I wouldn't hack your maf period. Makes tuning difficult later down the road when you swap to something other than a SAFC. You want the most accurrate airflow measurement possible to make sure you're hitting the right spot in your fuel and timing maps.

 

[dsm-onster]

Well, there's no tuning method that doesn't easily make a hacked 1g maf work like factory. Even if you use tunerpro and an eprom emmulator, you can plug in the hex values for a GVR4 maf and it will run like stock since the gvr4 maf is a 1g maf with the lower honeycomb removed at the factory. Anything better than safc has what's called *maf compensation* incorporated; OR is as easy as and tunes the same as the safc (nearly the same percentages will be plugged in). If you're looking at a system that doesn't output an accurate reading when you need an accurate reading after compesation, then you should look for a more powerful tuning system. With dsmlink, tunerpro, etc, you will still get an accurate airflow reading. Calibrating the maf is common knowledge (plenty of sources to step you through it) and easy to do.

It is as easy to do as dialing in a 2g maf for what ever tuning solution you use. You have to compensate for difference hertz numbers with either maf you choose: 1g hacked, 2g, evo/3g. So that's no reason not to do it to me.

I wouldn't do it because the 2g maf can be had for $50. If you're going to have to calibrate a maf, you might as well spend the $50 and get a good used 2g maf that will meter 60-70% more air before overrunning.

 

[AlekTSI]

Alright.. well do you think it will be ok to run it the way it is at lower boost without the AFPR?

 

[dsm-onster]

You will likely have fuel pressure overrun with that fuel pump and the stock fuel pressure regulator. You will have bad gas mileage and likely poor closed loop performance.

 

[AlekTSI]

closed loop? whats that? I'm a newb i know

 

[->PrOjEcTGS<-]

Closed Loop refers to when the ECU is taking information from the O2 sensor, sensing whether it is lean or rich and adjusting it accordingly. Therefore the "loop" is closed or O2 circuit is complete and being used. Closed loop is used during idle and cruise situations. You will see your O2 voltage swing high and low during closed loop. This is the ECU leaning the car out and then richening it back up.

Open loop is used for WOT. Basically the ECU does not reference the O2 sensor. It just looks at how much airflow in g/rev is coming into the engine. This determines the load that the engine is under. It then looks up the RPM to find out what Timing and Fuel to give it. There are a bunch of other variables the come into play but that is the basics of it.