Your tuner is an idiot. He should have advised you of the modifications to the fuel system that were needed to support your application. Get your truck out of there and never go back. Talk to Troyer Performance or any other competent tuner on this board. They will set you straight. The setup you have at the moment, while Mickey Mouse, will support your blower. You should ASAP get a 255l/hr pump.

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I agree! Get your truck out of there! The FMU and the booster pump are designed to force more fuel through your old 24# injectors to keep the A/F ratio correct while under boost. The 24#ers are not designed to deliver the amount of fuel needed under boost at normal fuel pressure with a stock pump. So, the FMU detects the boost and over rides your fuel pressure regulator to allow the booster pump to blast fuel to those tiny injectors at great pressure to increase the flow.
Now with the 42#ers and the 90mm maf, you don't need to overpower the injectors to get the proper amount of fuel. HOWEVER, the stock pump can't deliver the volume of fuel needed to feed the 42#ers.
Now you can use the booster pump, but that is simply a bad idea AND even then, you want the pressure to be stock as noted in other posts.
Call TROYER! I have a p1sc, 12# pulley, 42#ers, 90mm maf, 255 walbro, and TROYER tuned. 110,00 plus miles.

 

Ok, i get what you guys are saying but HOW do you run stock pressure and 42# injectors, the guy wants me to find out HOW you guys do it so that he can do it to mine. Can you please contact your tuner and ask him please?? Where is Troyer out of cuz i'm in SW Wisconsin and i do not want to travel far. I just want to get this project finished and done right. What are your thoughts about using a L fuel pressure regulator?? because they do raise the fuel press with the boost.
Thanks for all of your help
-Frankie

 

There are two ways to tune around EFI. Through the PCM or around it. An FMU, with stock injectors and stock MAF are designed to run around the computer. However, with the right parameters programmed into your PCM, you don't need the FMU. But you have to have a tuner worth his salt to program the correct values.

Most injectors are designed to run at 39 psi. This pressure is based on two methods, a pump that has a sensor to keep the pressure in the programmed range, or a mechanical device called a fuel pressure regulator. You truck uses a fuel pressure regulator. They should be calibrated to run 39 psi without a vacuum signal. There is no way to change that unless you have an adjustable aftermarket regulator. There's nothing you need to do to attain that pressure, unless your fuel pressure regulator is bad and providing higher or lower signal (absent vacuum).

If your tuner doesn't know how to find the parameters for the injectors, you need to put a lot of distance between you and this tuner. If you have the larger injectors, a means to provide enough fuel to the fuel rail without starving the engine at high load, high rpm, and the correct programming parameters for the MAF transfer function and injector values, the truck should run without the need for the FMU. Now setting a proper timing curve will need to be achieved based on how much boost you're running.

 

Purchase a 255 pump and find a new tuner. You install a better pump. Install 42# injectors. Install 90mm MAF. Then your tuner tunes. WTF is the problem? Either he know what he is doing or he doesn't. Walk away. NO! RUN AWAY......

 

ok well i have an sct eliminator chip, the tuner says that the pcm has a limit on how much air the MAF can read or something like that,i think he said it was like 66#s or something close to that so with that he couldnt make the pcm see as much air as it needed to. i dont know enough about tuning so tell me what u think of this
thanks
-Frankie

 

Are you sure you have a 90mm lightning MAF? That MAF should support 450 hp. If you need more, get the SCT Big Air. Don't overdrive the injectors.

 

The PCM isn't the problem. The PCM interprets data from the MAF to determine the amount of air the engine is digesting. MAFs come in a variety of sizes and calibrations. It's the calibration for the MAF sensor that dictates the amount of air coming through the MAF. The MAF sensor has to have the correct flow data to interpret that air flow.

From what I'm reading, he's telling you the 90mm lightning MAF, if that's what you have, is not large enough for your application. If that is the case, you need a MAF that can handle and interpret higher flow rates. The MAF can only send a voltage signal from say .7 - 5 volts to the PCM and each voltage value indicates an amount of air passing through the meter. Based on how the MAF is calibrated, it may interpret 5 volts as 35 lb./min. or in the case of your Lightning MAF of 62 lb./min. You have to input the correct MAF values in the PCM for the specific MAF calibration, so it can make the correct calculations based on the airflow the sensor is reporting. So, if your Lightning MAF is maxed out, and that seems to be what he is telling you, you need a MAF calibrated for higher flow rates. But if you're maxing out that MAF, you might want to reconsider those injectors while you're at it.

Since you keep bringing up fuel pressure, I have to think you are intending to fool the PCM and the MAF and raise the pressure to pump more fuel into the engine than a properly calibrated PCM would allow given your parts selection. This is not a good idea.

 

I repeat your tuner is an Idiot! I have 42# injectors, 255 pump and P1SC set to produce 12psi. Troyer sent me a 90mm MAF an Xcal 2 with tunes he created for my truck based on what mods I had. Run away from that moron.

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Ditto! Same set-up. Not a big deal for a "quality" tuner.

 

I don't konw what to think at this point cuz he told me that i'm gunnaneed upwards of 50 to 55psi in the fuel rail becaue at the tip of the injector the fuel pressure will be 39 psi at where my fuel is (39-40ish) and when you are boositing there is pressure pushing against the fuel going into the manifold thus i need to raise the fuel rail pressure to compensate for the added backpressure on the injectors. this makes perfect sense to me that's why i keep bringing the fuel press up. having someone send you a tune based on mods doesn't sound like the safest thing in the world, cookie-cutter tuning doesn't really appeal to me because each engine/vehicle is a little different and in different environments act differently so unless he has some kind of gurantee that it will work i dunno if i wanna sink money into this troyer tuning. nothing against anyone but you know i dont want my truck to grenade a motor becuse someone sent me a tune for someone else's truck. but yeah tell me what you think about the statement above about the back pressure on the injectors. Thanks a lot, sorry i don't completly understand but im trying really hard to wrap my mind around this whole concept of tuning. Thank you again for your patients and your help.
-Frankie

 

oh yeah and 1 other thing i already paid a non-refundable $500 for the chip and to have it unlocked, so any way i can use it would be great

 

yes i ordered it directly from ford racing brand new, the label on the box reads; M-1257-L54 90mm LIGHTNING METER so i'm pretty sure that it is a L MAF. How much for the SCT big air and if i need 1 do u know anyone that would like to purchase a brand new L maf??

 

Your not going to make enough power to need anything bigger then the 90mm Lightning MAF.
Didn't you say it was a stock kit at 8 PSI?

Phil

 

Here is a little bit of homework for you. Go to: http://www.fordracingparts.com/download/catalogs.asp Start reading at page 151. It explains injector sizing. If you don't understand something post back your question. If after reading you still feel that you want to remain with your tuner then go for it. I would still recommend a Troyer, on a bad day, tune over your tuner's best day.

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