I just finished putting my engine and tranny back in about 2 weeks ago and I had a quick question. Does it matter which wires go to which fuel injector as long as you get the set of two right? Basically is TPI a batch firing or true MPFI? And if batch would it matter if I got the two wires mixed up as long as they are still going to the same set. Engine seems to be running great, but wanted to make sure.

 

Yep, you got it.
Basically you cant mix them up, because it doesnt matter. They do batch fire so even if somehow you connected one to the opposite side of the engine, it would never know the difference.

batch... meaning yes its right bank left bank. Still doesnt matter if the right is on the left, nothing in the car will ever know the difference.

[This message has been edited by madmax (edited September 11, 2000).]

 

Are you sure about that? Doesn't just one bank fire at a time? I have heard both.

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Mike Metzler (Desert86Roc)
Mike@SpeedworldMotorplex.com
[*] Webmaster: SpeedWorldMotorplex.com[*] Click Here For My Racing Page[*]86 IROC 305 TPI (406 build in progress)
ET's @ 1250 ft[*] 14.28 @ 95.461 mph (uncorrected, NOS, no headers)[*] 15.365 @ 86.785 mph (uncorrected, Headers, no NOS)

[This message has been edited by Desert86Roc (edited September 11, 2000).]

 

Its pretty hard to get em swapped up. They are routed and cut to length where you pretty much have to stretch it too far to get the wrong wire on the injector.

As far as that goes, each side is color coded. one side is green, the other is blue with a pink/black also for each.

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-86 IROC
Vortech stuffed EFI 406 in progress

 

I agree with Guido about mixing them up because of length, but as far as I know they fire in banks. As long as you have all the original ones on each side it doesn't matter which injector it is on.

 

thanks for the clarification guys

 

I had my #2 & #4 injector wires crossed, and it ran slightly rough with a detectable loss of power.

Fredzep 90 GTA 350 5spd

 

Its both. A TPI is batch fire, but is still consider MPFI because there is one injector per intake port. 8 cyl + 8 intake ports + 8 injectors = MPFI I think you were thinking of SFI (sequential fuel injection) which is still MPFI, but each injector is fired individually based on pistion position. These systems use a Crank and Cam position sensor (someting our cars don't have).

Not true. Even though they are batch fire, they do differentiate from side to side. If the #1 cylinder needs fuel, injectors 3,5,and 7 will also fire, but #1 will get its fuel. If you switch them all on the same side, 1,3,5 and 7 still get fired, regardless. If you switch them side to side, when #1 needs its fuel, 2,4,6 and 8 will get it and #1 will get nothing untill #8 goes to fire, so it will be out of sequence and run like crap (if it even starts).

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"I used to have a handle on life, but then I used it as a plunger and broke it" -The Wave

ASE Master Tech + L1
Savannah, GA
'87 Trans Am-K&N,Cold air induction, SSM SFC, Boxed LCAs, 8mm Accel wires, Flowmaster, 16" GTA rims.
'97 Bonneville SSE
South East Thirdgen

[This message has been edited by GMTech (edited September 17, 2000).]

 

GMTECH,

I am curious about the re-wiring of the TPI fuel injector setup. They are a bank to bank system. Since there is no crank sensor, it is not sequential injection, rather just a port injection version of a TBI.

Does the pulse width for the right and left banks differ, or are they the same? IE. Logically if the ignition was comming on cylinder 5,7 firing, it should pulse the driver's side more than the passenger side.

So then, would it make sense to re-wire the left and right banks so they fire every second cylinder in the firing order rather than physical banks.
IE. if the firing order is 18436572 (If I got it wrong, just ignore it, i don't recall and I am too lazy to go and check).

Would it not make more sense to wring the left and right banks to be

1,4,6,7 and 8,3,5,2 ?

Instead of

1,3,5,7 and 2,4,6,8

Would that provide a *better* fuel distribution? It would be interesting to add a crank trigger sensor the the TPI setups and then see if you could alter the programming to use it. Probably easier to buy a DFI that uses SPFI.

Your thoughts?

Mark.

 

You are thinking way to technical. Since TPI's have one O2 sensor, it cannot vary the pulse width for each bank. When your injectors are firing at 2.34ms, they are all firing at 2.34ms. Each bank, right and left, fire at a seperate time. I don't think the ECM used for TPI will not support a sequential setup, since instead of two injector drivers in the ECM, you will need eight.

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"I used to have a handle on life, but then I used it as a plunger and broke it" -The Wave

ASE Master Tech + L1
Savannah, GA
'87 Trans Am-K&N,Cold air induction, SSM SFC, Boxed LCAs, 8mm Accel wires, Flowmaster, 16" GTA rims.
'97 Bonneville SSE

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

 

How does it know which bank to fire? When I put my distributor back in I did the old way of finding the comp. stroke on one and then wiring the dis. from there. It runs fine except(before and after I did that) it will not pull past 3700-4000 RPM. Could this play into that?



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dgreene
'87 Firebird Formula 350 TPI, Ported Plenum, Adj. Fuel reg, gutted cat, catback exhaust, air foil, K&N air filter, chip,170 thermostat,Borg Warner Posi 9 Bolt w/ 3.23 gears....

 

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dgreene
'87 Firebird Formula 350 TPI, Ported Plenum, Adj. Fuel reg, gutted cat, catback exhaust, air foil, K&N air filter, chip,170 thermostat,Borg Warner Posi 9 Bolt w/ 3.23 gears....