chevyboy07 91

Well, this is a TPI specific factoid, but I'm sure anyone on here could appreciate this regardless.

So, I'm reading AUG 2003 Hot Rod...in the pit stop section is a TPI Q/A thing going on. I BET that someone from TGO wrote the editior with his question.

ANYWAY.....

We all know that TPI is batch fire...left bank/right bank..got it.

But DID YOU KNOW that the RamJet (also batch fire) systems use a different cylinder combination to their batch fire? It is as follows 1467, 2358. As you can tell....there is a similarity here to the firing order /ignition sequence.

SO WHY IS IT LIKE THAT??????

Apparently the RamJet's ECM was designed by DELCO MARINE....to incorporate a unique, fail-safe capability. If an over-temp condition occurs, one of computer's 2 drivers will shut down (each fires half the injectors) ...so if it ever happened, it would **SMOOTHLY** disable every other cylinder.....virtually creating a 4 cyl engine and hence "limp-home" mode. 4 cylinders pump air to cool the engine , 4 provide the power.

IS THAT COOL OR WHAT?????

(I hope nobody tells me "welcome to last year" or "repost") or something like that

afremont

Makes complete sense, I wonder why the rest of the TPI setups weren't done that way. It's just wiring.

mxcrazed

Well I guess you could move your injector wires around to make it do that, shouldn't be difficult at all, you would just have to switch the wires from 4 and 6 to 3 and 5 and vise versa this is probably a good idea if you have a tpi. I bet you would get some power out of it too because the injector would be firing at a more appropriate time.

1989GTATransAm

iTrader: (3)

Hmmmm. Looking at the wiring diagram all the injectors fire at once on TPI. It looks to me that the two output ports that fire the injectors are hooked together. So if that is true all 8 injectors fire together.

ljnowell

A lot of other car manufacturers are doing this. I didnt know the ramjet did it though, thats kinda cool.

RBob

iTrader: (1)

I have my doubts that this is true. The reason is that 'batch fire' fires all injectors at the same time. The '86 - '89 (1227165) and '90 - '92 (1227730) TPI ECMs only have 1 injector driver. So all 8 injectors fire at the same time.

The '85 TPI ECM (1226870) has 2 injectors drivers. However, both drivers are enabled from the same signal. So again all injectors fire at the same time.

This makes ALL 3rd gen TPI setups batch fire. Which is having all injectors fire at the same time.

RBob.

mxcrazed

Sorry the origional poster said If he were correct that would have worked oh well...