TPITuned Port Injection discussion and questions. LB9 and L98 tech, porting, tuning, and bolt-on aftermarket products.
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Which is better TPI or MPFI? From what I've heard, TPI is a burst of fuel into all the cylinders at the same time and MPFI is a more precise shooting method, where less fuel seems to be wasted. Wouldn't MPFI be better since the cylinders do not all fire at the same time? or do they? Someone tell me please.
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-El Douche
"Like a midget in a urinal I was gonna have to stay on my toes."
If you will notice that that the right side and left side have different color grounds, and go into different pins in the ECM which would make one assume that each bank fires seperatly, but if you look at a diagram of the ECM, it shows that they are connected in the ECM so I think all 8 fire at once.
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I THINK THE COMPUTER FIRES 4 CYLINDERS AT A TIME. I'M NOT SURE IF THEY ARE ALL ON THE SAME SIDE THOUGH, THAT IS ALSO CALLED BANK-FIRE INJECTION (SOME FORDS HAVE IT).
IT WOULD SEEM MORE EFFICIENT TO FIRE WICH-EVER 4 CYLINDERS NEED THE FUEL THE MOST, MOST LIKELY NOT ON THE SAME SIDE.
NOTE-THE FUSE BLOCK HAS 2 FUSES FOR INJECTORS, INJECTOR 1 AND INJECTOR 2. IF ALL THE INJECTORS FIRED AT ONCE, WHY WOULD THERE BE 2 FUSES? IF YOU PULL ONE OUT THE ENGINE RUNS ROUGH, SO I BET IT SHUTS OFF 4 CYLINDERS.
BUT I'M NOT SURE ABOUT ALL THAT.
Originally posted by '87FAKE-IROC-Z:
IT WOULD SEEM MORE EFFICIENT TO FIRE WICH-EVER 4 CYLINDERS NEED THE FUEL THE MOST, MOST LIKELY NOT ON THE SAME SIDE.
NOTE-THE FUSE BLOCK HAS 2 FUSES FOR INJECTORS, INJECTOR 1 AND INJECTOR 2. IF ALL THE INJECTORS FIRED AT ONCE, WHY WOULD THERE BE 2 FUSES? IF YOU PULL ONE OUT THE ENGINE RUNS ROUGH, SO I BET IT SHUTS OFF 4 CYLINDERS.
BUT I'M NOT SURE ABOUT ALL THAT.
Yes it would seem that way, but we didn't desing these cars, so it doesn't matter what we say. But the banks are side to side.
Yes, there are two fuses, good observation, but like I said earlier, the ECM grounds both banks at the same time, making it a "true" batch fire. If you still think I am making this crap up, see for yourself.
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That would explain why I only have one injector pulse width variable on my Diacom, while an LT1 has two. Which year is that diagram from? I have one for a speed density car at home, I will check it out and report back.
Originally posted by El_Douche_86: Which is better TPI or MPFI? From what I've heard, TPI is a burst of fuel into all the cylinders at the same time and MPFI is a more precise shooting method, where less fuel seems to be wasted. Wouldn't MPFI be better since the cylinders do not all fire at the same time? or do they? Someone tell me please.
The wiring is for redundancy.
Use an ohm meter and you'll see all the 165s and 730s have a single injector driver inside. SEFI only matters at idle, Unlike people *think* happens, the fuel is sprayed at the back of a hot valve while it's closed so that the fuel is better vaporized.
You need the SEFI if your running like 50#/hr injectors. Othter then intown mileage when you're idling ALOT there is no difference (other then emissions)
FWIW there are 3 firing strategies, batch, bank to bank, and SEFI
FWIW there are 3 firing strategies, batch, bank to bank, and SEFI
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Grumpy,
I'm really quite green with this. Could you please explain the three strategies in some detail and give some examples of each?
And is the Edelbrock system truely sequential, or is that some type of marketing slight of hand? How would one go about figuring something like that out? Thanks, and be patient, I'm trying to learn.
Think about it guys... Just going by their names alone, wouldnt batch-fired mean all 8 at once, bank-to-bank would be 4 at once, and SEFI is 1 at a time.
Oh, and yes, according to my 1992 Helms manual, the speed density computer has the injectors connected internally just like the picture above shows. It fires all 8 at once. I learned something new.
[This message has been edited by Kevin91Z (edited November 29, 2000).]
