Hey all, I had a question about why the fuel injectors on an 86 harness are wired like they are; with all of the grounds grouped together and all of the power wires grouped together for each bank. This to me seems like it would spray fuel 4 times more per cylinder than needed. Am i missing something or is it really like this and why?

 

All 8 injectors are connected in parallel and all 8 fire at the same time. That means that some of them are firing at the backs of closed intake valves. That's just the way it works.

 

Do you know why they designed it like this tho? It just seems like a waste of gas and wouldn't be that good for performance either.

 

WHY - I'd say it don't damn matter - it's how it was/is - if you're going to own one you need to understand HOW IT'S DONE

A read for you that I'm surprised Cliff didn't link.

https://www.corvetteforum.com/forums...-debunked.html

 

Thank you for your valuable input. I don't own an 86 actually, I have an 84 that I'm converting to a pro flo. And that is why I asked, because I am trying to understand better as to why it was designed like this. To say it doesn't matter bc that's the way it was done is ignorant. Just bc things were done one way doesn't mean that its the best way. Who knows maybe it is the best way, but to me it seems like the fuel spraying on the back of a closed valve would cause fuel to pool and that wouldn't be the best for atomization.

 

Well after looking over the link you attached, this is what I was looking for. And like I said, not most efficient but still good.


"I've been saying the same thing for years.....ONE inj circuit split in two thats divided into 4 each side.

Makes NO sense...ZERO, NONE for there to be an alternate bank fire when the ign firing order flops back & forth alternating which side gets a spark..
The TRUE theory behind the TPI injection bank ()batch fire is more accurate) is to have them ALL fire so there was a fuel charge WAITING in the port as the intake valve opened.
Some proof of this comes from the minute hp increase from sequencial multiport fuel injection...a much much faster inj driver set, with 8 seperate channels that allowed each inj to fire as needed, not as a batch. This was very cool and a big atta-boy for the tech geeks at GM, but it yielded less than 20 hp for all that it did. True that big power comes from small steps and SMP EFI (multiport) did help, but it also proves that batch fire was 90% as efficient and a bunch less complicated. Remember, as the hp numbers went UP the MPG stayed where it was as these inovations appeared and gave balance to the new system.
The big advantage with multiport EFI is that now there was some lattitude in the cam timing and ign timing with the fuel timing now able to be customized to the cylinders so when cams or ign changed so could the fuel program...more small gains that eventually added up to big hp. Before, there was fuel being sprayed whenever...some cyl got wet fuel while others got mist...it found some balance in rpm at some point obviously, it worked, but it was not something that could be dialed in for precision.

Single circuit, split in 2 then by four. 2 fuses to cut the load on each side on the first split. Less likely to short with only 4 inj to protect. So, 2 fuses.They cut the odds in half that way.
This is also why our L98s suffered and were so sensitive to crappy injectors...not being efficient in the first place, anything less than 100% was going to cause a problem pretty quickly. Besides, batch fire was behind many a catastrophic failure....I'd MUCH rather have a single inj short out and run on 7 cyl than for the whole bank to flood...due to one shorted inj. (as me how I know)."

 

I have a 1988 Coupe with an automatic transmission and it gets thirty miles per gallon on the highway. With the cruise control on I enjoy decent mileage and all the comforts of a performance car.

For a car built in its era I am impressed. The electronics are simple by todays standards, but they work reliably if maintained well. The system is a sound design and has Millions of miles of proven reliability.

At 100,000 miles the compression in my L98 was still very tight. It doesn't burn oil like a Ford.

For the fun factor the L98 engine and fuel system work just fine! I may enjoy the power of my C3's 427 a bit more but I can jump into my Coupe and drive it anywhere I want in comfort with the AC blowing and a great stereo playing. I love my C4 even if it does "batch fire" the injectors!

Have a great day with your Corvette!!

 

Wow that is pretty good MPG! My 84 got 25.5 over a 2,400 mile road trip 2 years ago. Kinda curious what it will get now.

Yeah the engines and electrical systems are pretty good when maintained. While doing work to my car I realized that the 85+ systems used batch fire but was confused bc I did not know this style of injection system existed. Thought it was all sequential.