s13 mafs hacking
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TopStreet240
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Would using injectors greater than 400cc with a hacked maf cause problems. I was thinking that the maf pipe for big injectors would be very large. I dunno, maybe the air flow would be fairly even and it would have no effect. Oh yeah, im guessing that running a hacked maf in blow thru system is the same as in a pull thru system right?
I think that would be too big, if you want that much horsepower then you should probably go for some form of piggyback fuel computer.
the 370ccs that are generally used with the MAF bring the pipe up to about 3" which is rather large. also this has been proven to about 250rwhp on the ka24de....
for me this is fine, but bigger is always better, Ive recently been considering dsm injectors and a fuel computer, but I think that Im not going to go with that setup, just use the hacked MAF
the 370ccs that are generally used with the MAF bring the pipe up to about 3" which is rather large. also this has been proven to about 250rwhp on the ka24de....
for me this is fine, but bigger is always better, Ive recently been considering dsm injectors and a fuel computer, but I think that Im not going to go with that setup, just use the hacked MAF
with the e-manage you can run injectors as large as you want to. after a certain point in injector upsizing, though, you have to set the car to idle at 1200 or so, because the injectors won't open for a duty cycle *short* enough to give a good fuel/air mixture at 750 or 800 rpm.
I'll be running a dummy MAF setup (exactly cutting the 'real' airflow in half) so that my system will be naturally tuned to 550cc injectors, and then I'll be *downsizing* the settings to work with my 370's. In other words, I'll tell the e-manage that my stock injector size is 550 (actually 540) cc/min, and that my new injector size is 370cc/min.
I'll be running a dummy MAF setup (exactly cutting the 'real' airflow in half) so that my system will be naturally tuned to 550cc injectors, and then I'll be *downsizing* the settings to work with my 370's. In other words, I'll tell the e-manage that my stock injector size is 550 (actually 540) cc/min, and that my new injector size is 370cc/min.
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C-Kwik
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andrave wrote:dude, I was thinking, if E manage can only control like 150% of stock injectors, say you used a hacked mafs and e manage...what then? technically couldn't you then use much larger injectors?I've been thinking this over, I'm pretty dumb when it comes to this though...
The limitation has to do with the stock ECU. Hacking a MAF is about as effective as using a piggy-back to alter the airflow signal. Whether you go with a stand-alone by itself, double it up with a hacked MAF, or even a bigger MAF, the ECU still needs to see the same airflow signal to provide the injector signal you want.
For example: If say you wanted to see a pulse width of 10 milliseconds, then you would need x voltage going to the ECU. So say with a stand-alone by itself, it would convert y MAF signal voltage to x to the ECU. If you used a hacked MAF, the MAF voltage may be z to the stand-alone, but then the stand alone would then need to convert it to x before it goes to the ECU.
The actual limitation tends to be limited to injector size and the ECU's ability to maintain idle. Injectors have a minimum opening time and if the injector is too large, the injector will spit out too much fuel at idle and run rich. Could cause anything from a rough idle to stalling completely to fouling plugs regularly.
however, the problem is not in the injector size itself, but the minimum pulsewidth that the injector can function at. this is at point X, specified in cc/min. If you are idling at 800, the lowest the flow can go is X cc/min.
If you are running rich, you can bump the idle to 1000 or higher, and set your fuel correction to not kick in till you're off idle. That way, you're getting the minimum pulsewidth, so the same amount of fuel, but more air is coming in so the mixture is headed more towards lean. X cc/min of fuel + more air = closer to stoich.
and of course you'd have to have a properly tuned map off idle.
again, the *only* limitation of the e-manage that I can see is in minimum and maximum pulsewidths and MAF voltages in your setup. If you start maxing either your MAF input or output, or start hitting minimum or maximum pulsewidth, you've hit a wall. Otherwise, the sky's the limit.
If you are running rich, you can bump the idle to 1000 or higher, and set your fuel correction to not kick in till you're off idle. That way, you're getting the minimum pulsewidth, so the same amount of fuel, but more air is coming in so the mixture is headed more towards lean. X cc/min of fuel + more air = closer to stoich.
and of course you'd have to have a properly tuned map off idle.
again, the *only* limitation of the e-manage that I can see is in minimum and maximum pulsewidths and MAF voltages in your setup. If you start maxing either your MAF input or output, or start hitting minimum or maximum pulsewidth, you've hit a wall. Otherwise, the sky's the limit.
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C-Kwik
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That is correct. But to explain further, basically, the more air goes through the MAF, the more air goes across the hotwire. As air passes around the hotwire, it carries away some heat from the wire. In order for the MAF to keep the wire the same temp, it has to increase the voltage to the wire. If more air passes around the hotwire, the more voltage it needs to maintain that temperature.
how does the ecu monitor the temp of the MAF's 'hotwire'? If the temperature that the MAF tried to keep the wire at could be lowered by an amount, that could allow the MAF to count more air, i think. or maybe adding voltage to the MAF. You know what would be another option, putting the MAF into one of the intake runners and quadroopling ur injectors. hmmm it would decrease the airflow to one cylinder...
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C-Kwik
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Jonny 290 wrote:The Apexi SAFC series do NOT adjust any injector signals. The only thing they adjust is MAF voltage.
E-Manage is an example of a system that *can* modify injector signals, although it's not required.
The only modification to the injector signal the E-manage can make is to lengthen it by adding it's own injector ground. It can only shorten pulswidths by modifying the airflow signal the same way the SAFC does.
safc only modifies airflow? **** I swear I thought they were puttin it in that weird *** suzuki aero SX turbo that some magazine had and they had the instructors on intercepting the injector wires, they said it could log duty cycle and stuff...apexi safc2... ckwik are you talking about basic emanage or emanage with injector maps using the support tool and a PC?
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C-Kwik
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I've never heard of any additional signal ability out of the SAFC.
As far as E-Manage I'm talking about tuning with a PC and having the injector harness installed.
To understand part of this, you have to understand how the E-Manage installs to the ECU. It does NOT intercept the injector wires. Injectors always have power from the battery. To power the injectors, the ECU provides the ground. Since the E-Manage only splices into the ground wires for the injectors, the E-Manage can not shorten the duration by manipulating the ground. The ECU ground will always be open based on the airflow signal. However, the E-Manage can provide a ground for the injectors when the ECU disconnects the ground signal. This allows the E-Manage to add injector pulsewidth, but it can not take it away other than to manipluate the airflow signal to fool the ECU into thinking the motor is getting less air.
If there is a SAFC version that can provide a function like this, it would likely work in a similar or the same fashion. If any piggy-back system were to intercept and add it's own injector signal directly, then it would no onger be a piggy-back, but rather it would become a stand-alone as it would no longer rely on the ECU to provide the fuel maps.
As far as E-Manage I'm talking about tuning with a PC and having the injector harness installed.
To understand part of this, you have to understand how the E-Manage installs to the ECU. It does NOT intercept the injector wires. Injectors always have power from the battery. To power the injectors, the ECU provides the ground. Since the E-Manage only splices into the ground wires for the injectors, the E-Manage can not shorten the duration by manipulating the ground. The ECU ground will always be open based on the airflow signal. However, the E-Manage can provide a ground for the injectors when the ECU disconnects the ground signal. This allows the E-Manage to add injector pulsewidth, but it can not take it away other than to manipluate the airflow signal to fool the ECU into thinking the motor is getting less air.
If there is a SAFC version that can provide a function like this, it would likely work in a similar or the same fashion. If any piggy-back system were to intercept and add it's own injector signal directly, then it would no onger be a piggy-back, but rather it would become a stand-alone as it would no longer rely on the ECU to provide the fuel maps.
wait a sec. so can i get a safc-2 and forget about modding the maf? This doesnt seem to make sense as the MAF only has so much voltage. The safc2 modifies the afr but i dont see how it could increase the amount of air the maf can read. it only modifies the signal coming to the ecu so that u can lean/richen ur mixture a bit.. right?