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."

 

TPI is MPFI... I think you are asking about Sequential Fuel Injection vs Batch Fire.

And yes, SFI is better, more precise metering and better fuel economy.

 

Can't add anything to that one.

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If you live in Southeastern US, check us out!
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ASE Master Tech + L1
Savannah, GA

'87 Trans Am
S/D TPI retrofit including functional PassKey,
22# injectors,
JET AFPR,
Ported Plenum,
TB Coolant Bypass,
SSM SFC,
Boxed LCAs,
8mm Accel wires,
Flowmaster Exhaust,
16" GTA rims,
Corvette Servo,
KYB Shocks

'97 Bonneville SSE

 

TPIs are batch fire because they fire 2 injectors at the same time or is it one whole side of the engine (one row at a time)?

 

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.

------------------
If you live in Southeastern US, check us out!
South East Thirdgen


ASE Master Tech + L1
Savannah, GA

'87 Trans Am
S/D TPI retrofit including functional PassKey,
22# injectors,
JET AFPR,
Ported Plenum,
TB Coolant Bypass,
SSM SFC,
Boxed LCAs,
8mm Accel wires,
Flowmaster Exhaust,
16" GTA rims,
Corvette Servo,
KYB Shocks

'97 Bonneville SSE

 

Sequential has better low speed economy. But sequential turns into batch over a certain RPM, like 3000.

 

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.

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88 CAMARO RS
87 IROC-Z DRIVETRAIN
305 TPI, 700R4, 3.73s
ported plenum, performance resource chip,edelbrock TES Headers and cat-back, K&Ns, AFPR, rest is stock.
15.0 @ 92.5 (bald tires)

 

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.




------------------
If you live in Southeastern US, check us out!
South East Thirdgen


ASE Master Tech + L1
Savannah, GA

'87 Trans Am
S/D TPI retrofit including functional PassKey,
22# injectors,
JET AFPR,
Ported Plenum,
TB Coolant Bypass,
SSM SFC,
Boxed LCAs,
8mm Accel wires,
Flowmaster Exhaust,
16" GTA rims,
Corvette Servo,
KYB Shocks

'97 Bonneville SSE

[This message has been edited by GMTech (edited November 21, 2000).]

 

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.

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1991 Camaro Z28
5.7L 5-Speed (originally 305)
13.25 @ 107.18 MPH
Southern California
Member: SoCal 3rd Gen F-Bodies
Webmaster: SoCal F-Bodies
-=ICON Motorsports=-

 

That is a 86+ MAF system wire diagram GMTech posted.
The 1985 is a b***ard year and they were bank fired. Check it out.

http://www.geocities.com/vtcamaro/Pi...rams/pg156.jpg

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86 Camaro Sport
383 Speed-O-Motive Crate Engine, Trick Flow Heads, 58mm Accel TB, 3.73 Auburn Pro, SLP Cold Air Induction and Headers, Dynomax Cat-back, Serpentine belt setup, Dual IROC Fans.

http://www.sethirdgen.org/octride.htm

 

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
[/B][/QUOTE]

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.

Regards,
Gary Anderson

 

Yeah Yeah! Somebody explain please!

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'88 GTA 350
Headers, catback, free mods, Xtreme energy cam, and intake pieces
13.51@104.27, but can run better as it is.

New 2100-2300 RPM converter is in. Hoping for 13.30 or better.

 

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).]