Persanity

Im trying to find out if each injector fires at once or individualy or 2 at a time etc on a 3.1 mpfi v6 from a 92 camaro. I started a forum Here about it. Basicly my plan is to take a 2 injector tbi setup and modify it to accept the same injectors as my mpfi setup so i can use all the stock electronics (thats not changing no matter what, ill find away to do it). What id like to focus on (if everybody wants to join me in this conversation) is my therory that since all the injectors fire at once, that using 2 injectors at 3x stock capacity will deliver the same amount of fuel as a stock 6 injector setup, and using 4x injectors should give enough fuel for the supercharger aspect of my project. I hope somebody can help me with the injector firing timing info since it determines what im doing with my custom setup. Also can i get a reprogrammed computer that will fire all 6 injectors at once if its not like that stock? Thank you so much for the hel

Grumpy

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Persanity

what does that mean?

swerve-driver

That may be a reference to the fact that you used a total of 5 periods in your post, but four of them were in the etc.... part.
This was an aggravated offense since during that same post you used a total of ~8 commas!

All the comma's make it tough to read.

But, then again, he may have something else in mind. One never knows.

By the way I am not in a position to help you with your tbi question except to suggest a search.


Best-
S-D

Persanity

every thing i search for gives me spark plug firing order results, not injector firing order results. i know how everybody hates ppl who dont search, ive tried searching on here and on 60degreev6.com with nothing useful found. as to my other post its edited

junkcltr

iTrader: (1)

What ECM is in it? The 1990 V8 730 ECM fires all eight injectors at once. If you have a 730 ECM then it will fire all six at once.

Persanity

The car is a V6 and a 92. I have a stock computer so its whatever the computer is for that car, i dont know what it is. A search on advanceauto.com for a replacement computer gets me a part number of 777730, Is that the 730 ecm your referring to?

junkcltr

iTrader: (1)

Yes, that means you have what they call a 730 ECM around here. That ECM is only capable of firing all of the injectors at the exact same time for all applications (V6 or V8).
You can modify it to fire each bank of cylinders at separate times by adding hardware and code. It is not worth it for what you are trying to do.

Persanity

Awesome. This is exactly what i want/need for my setup. Cause this means i can run 2 injectors off the existing electronics, cap off the wires for the other 4 injectors, and use 60# injectors instead of 15# injectors and have enough fuel. All with very minor modifications. I have a fageol supercharger and i was original going to convert it to work with mpfi. I decided against that incase i ever need to sell it, i want it stock. Anybody here have any thoughts about potential issues?

junkcltr

iTrader: (1)

Make sure the injectors you intend to install are the "high impedance" type. The 730 ECM was not designed for the "low impedance" saturated injectors.
The 730 ECM can be modified to use the "low impedence" injectors by adding extra electronics inside the case on the printed circuit board. A few bright people on this forum have done it. Search for 749 ECM if you find that you want to run the low impedance injectors. Or use a 749 ECM with a few wiring changes.
Using high impedance injectors is a much more simple route. Just plug them in and go.....still have to burn a new PROM for them though.

RBob

iTrader: (1)

Actually, the '730 can drive 1 low impedence TBI injector (1.2 ohm), or 2 low impedence port injectors (2.4 ohm in parallel). The '749 can drive twice that many as it has two drivers. The mod that folks do is to double the number of low impedence injectors the '749 can drive.

This is to use it on an 8 cylinder with 8 low impedence port injectors. The '749 in a turbo Sunbird or GrandAm drives 4 low impedence port injectors, factory stock.

The '730 has been used with a 1bbl TBI setup, factory stock.

RBob.

junkcltr

iTrader: (1)

RBob, I did not know that. I know nothing about the TBI injectors. Will the 730 ECM do the peak-and-hold? I thought it would need the resistor installed to do the peak-and-hold timer.
It has been a while since I looked at the P+H drivers so I am rusty.

RBob

iTrader: (1)

Yep, wouldn't kid ya'. Check the wiring diagrams between the Sy/Ty and the Turbo Sunbird. The Sy/Ty's are saturated and the T-Sunbirds are port PnH's.

The '730 has one injector driver which is the same as each of the '749s drivers.

RBob.

junkcltr

iTrader: (1)

Ahh, now you have me wondering. Last time I had a 730 ECM and 749 ECM next to each other I noticed that one was missing some diodes, caps, and resistors that the other had. There was also the usual chip differences that have been discussed before. I thought that the feedback loop for the P+H control was discon. for the 730 along with a different resistor size.
It is starting to come back now. Yeah, just adding the feedback wire on the 730 ECM would be all you need.
Man, you're good.

Grumpy

Nothing.

You can only edit posts, not delete them, so I just edited out what I'd written.

87tpi7749

RBob, Is it possible to upgrade the driver & resistor hardware in a 730 to work the same as a 749 with 8 P&H injectors?

Reason I ask is I am doing the low Z mod on my 749 and I bought enough hardware to do three more ecms and I have a good 730 here that I'd like to do as a spare.

RBob

iTrader: (1)

Yes & no. To add the second driver requires the addition of a custom SMD chip (44 pin?). U15 IIRC.

To have the 1 driver drive all 8 injectors would require some fancy re-work. A big MOSFET (best would be to parallel 2), and half again the resistance of the senseR, and twice the W rating. Will also need to beef up the traces.

Care would need to be taken when wiring in the senseR. The ohms of that resister is low enough that lead length, board traces, and solder quality are important. A quick mental calc puts senseR at 0.025 ohms.

RBob.