Fuel cut with MAF-T?

[PorterzSupra]

Well basically I turned boost up a little to 15 PSI (yes its nuts) with my T66 from 9.5 while on race gas. I have the MAF-T with the AUX set to C to disable fule cut. In 4th and 5th I am getting fule cut!! :nono: I know there is no boost leaks because it is short hard metal piped. Whats goin on here guys???

- Eric

 

[IJ.]

Not running out of fuel from the pump?

 

[PorterzSupra]

I have a Walbro 255 pump with 550's and fuel pressure at 55 PSI. The ign lights light up and the car suddenly jerks off like classic FC

 

[PorterzSupra]

when I set the AUX to C the car was on, maybe there is somethin special u have to do to set it idk? but while I was clicking thru the dials the car would die down and stumble a little but it came back when I got to C

 

[IJ.]

Does fuel cut cause a code normally?

 

[PorterzSupra]

I dont think so but you would know more then me, it dont keep check engine light on. The car leaps forward under boost then jams the engine off for 1-2 seconds

 

[IJ.]

LOL not as far as the stock ECU/GTE combination goes Porter!
(never owned either I went NA>Standalone)

 

[hottscennessey]

Okay, all you need is to tune. I had the same problem, trust me, you can buy piggybacks to cover up the problem (which eventually caused more problems.. FCD) but all i did was up the Fuel pressure a little bit, and cut back on the WOT, and I was golden. I've run over 21 PSI and I havn't hit fuel cut yet, tuning only with MAF-T.

 

[PorterzSupra]

yea but with a T66 there is more airflow and thats what the FC is dependant on not boost, the PSI is not the factor, my turbo can put out the same flow at 7 PSI as a CT26 at 25. The MAF-T says it will take out FC all together my changing the aiflow signal. What do u mean u cut back WOT? Did u richen it at WOT?

 

[hottscennessey]

Yea, I understand airflow. Up the fuel pressure and Lean out your WOT Maf-t base setting. The added fuel pressure will richen the A/F ratio, and when you lean the WOT it cuts back on the signal, or the ammount of "airflow" your ECU sees. What the Maf-T does it alter the signal from the MAF, when you lean it, you are cutting back on that signal, so the ECU in turn puts in less fuel. If you cut back on the signal you are lowing the ammount of airflow the ECU "sees". Since the ECU is not "seeing" as much signal, that means its not seeing as much airflow, thus not triggering FC. But since you are raising the fuel pressure, you're making sure not to run lean. And as I said before, use a wideband to assist you.

It took me about 30 minutes and 5 pulls to elemnate fuel cut, if you do a little at a time you can see fuel cut occouring higher and higher in the RPM's until it doesn't happen.

In short /\ the FP
and \/ the WOT

 

[PorterzSupra]

okay thx hot!

 

[IJ.]

See the beauty of SM is someone usually has an idea !
(learn something new here daily)

 

[1TuffSupra]

sorry to distract from the thread but are any of you guys using the maft pro to control timing? I havent done a search or anything, but I went to their website and found that it can control timing as well on limited applications. Kind of considering going this route rather than eventually changing out my NA electronics for the turbo one since it can control a/f ratios and timing and works on any MAF equipped car.

 

[rakkasan]

sorry to distract from the thread but are any of you guys using the maft pro to control timing? I havent done a search or anything, but I went to their website and found that it can control timing as well on limited applications. Kind of considering going this route rather than eventually changing out my NA electronics for the turbo one since it can control a/f ratios and timing and works on any MAF equipped car.

to date, Maft Pro only monitors timing, not control. FTS is working on a control feature for MKIII's, but it hasn't came to fruition yet.

 

[1TuffSupra]

ah, thanks man. This is why I love this forum, I got a great, educated answer in less than 5 min, lol.

 

[Boss302]

Yea, I understand airflow. Up the fuel pressure and Lean out your WOT Maf-t base setting. The added fuel pressure will richen the A/F ratio, and when you lean the WOT it cuts back on the signal, or the ammount of "airflow" your ECU sees. What the Maf-T does it alter the signal from the MAF, when you lean it, you are cutting back on that signal, so the ECU in turn puts in less fuel. If you cut back on the signal you are lowing the ammount of airflow the ECU "sees". Since the ECU is not "seeing" as much signal, that means its not seeing as much airflow, thus not triggering FC. But since you are raising the fuel pressure, you're making sure not to run lean. And as I said before, use a wideband to assist you.

It took me about 30 minutes and 5 pulls to elemnate fuel cut, if you do a little at a time you can see fuel cut occouring higher and higher in the RPM's until it doesn't happen.

In short /\ the FP
and \/ the WOT

but if you lean it out the computer is not seeing the actual amount of air going through so how can it send the signal to the injector for the right pulse and duration to appropriatley burn the mixture? by only uping the pressure this will cure the problem how?

 

[hottscennessey]

I dont really understand the question, but I'll try my best here. The ECU still thinks porterz is running 440's, you cant tell the ECU, oh wait, i have 550's now, so you have to sneak it by it another way. Its signal scaling, if the ECU were to put out as much fuel as it needed for this amount of airflow, then porterz would have hit fuel cut back at 6 psi. MAF-T uses signal scaling, by putting in the injector size, MAF-T puts you in the ballpark of how much the signal must be scaled to keep the mixture right. By tuning, You make sure the Signal is scaled so the VF's are happy, and under WOT you make sure the AFR is straight. If your signal is not scaled down enough, or if you have too high a signal going to the ECU it will trigger FC, so by upping the FP you make sure not to run lean, and then by leaning the signal and cutting fuel you are still under fuel cut. If your signals too high you hit fuel cut, if you drop the signal and dont up the fuel pressure you run lean. So NO, solving the problem does not rest in upping the fuel pressure, solving the problem rests in cutting signal. The FP just keeps it Rich mechanically, rather than richening it electronically with pulse/duration, putting you in FC land.

 

[PorterzSupra]

Just for the record I leaned back the base and turned up FP, no more FC, HOT was correct =) THANKS!!

 

[SPD TRP]

Been following this post and want to to make sure you guys are working with maf translator, and not the PRO, right?

Thanks---just want to be clear.

Wayne

 

[hottscennessey]

Porterz, glad to hear it worked!

3rdtime, Yea this is just the MAF-T, but the same basic principles would apply with the MAFT PRO.