I'm planning on converting my TBI car to TPI. Is there any reason that I wouldn't be able to run it with my 8746? I know there will have to be some modifications on fueling but, is it do-able? The reason that I ask is that I can find the 7730 ECMs everywhere but none of them have the V8 memcal.

 

I dont believe it will work due to injector firing is different. I believe the TBI alternates firing of injectors twice per revolutuion and the TPI I belive fires all once per revolution called batch. Maybe someone will confirm. The drivers in puter are therefore different.

 

I knew the injector firing rate was different, but I was told that there is a possibility that the rate could be altered in the 8746. I really don't see why I would not be able to splice in 4 injectors on each side of the TBI harness and have it work as long as I can get it to deliver the right amount of fuel to each cylinder.

 

The issue may be drivers and driver failure. apples and oranges. that thought came up B4 when we attempted to drive 4 TBI injectors(2 x 2 barrell) on a carb manifold. wont allow. Now someone out ther may know what needs to be done as far as a mod of ECU.

Have you tried EBay for V8 memcal? Somewhere I read not available from GM any longer????

 

I've been all over Ebay and all I've found are the MAF memcals. I have one of those already. I bought the whole TPI setup from an 86 IROC with wiring harness, ECM, MAF, etc. Every 7730 that I've found for sale was either from a V6 or it was a V8 that does not include the memcal. That is why I'm trying to see if anyone has done this or has any idea if it can work.

Would I be able to use a V6 memcal with a 350 prom? I doubt the "limp home" mode in the V8 would do me any good since I don't have a stock motor. The memcal is basically just a socket that the prom goes in, right?

If I'm completely wrong then please pardon my ignorance, I'm new to all the ECM stuff. I've been doing alot of reading recently and I'm trying to learn.

 

Not sure if you can run TPI with no memcal. I ran no calpak but that was TBI. I also ran the TBI with a V6 calpack. When in limpmode with V6 calpack car barely ran. I suspect was filthy rich. Others have had issues finding those I recall.

 

Can I run the V8 prom with a V6 memcal? If so then I might go that route. Or maybe the MAF memcal that I have?

 

I dont know. 7730 may rely on memcal to get it right in CL. As soon as you run car on V6 memcal you would find out. What does a V6 memcal cost? Can you purchase just that in salvage yard?

 

Yeah, the junk yards around me are full of the 7730's in the v6 birds & camaros. I can get the complete ECM for $40 with the V6 memcal in it.

 

Ok, I think I have a lead on a V8 memcal. It's for a 305 though and I have a 350. Are all speed density 305 & 350 memcals the same?

 

Here are two of them, but you will need custom tuning.
You would not want an 8746 system if it would work, too old and the proms are too hard to find.

You can't use a v-6 memcal because of the cyl. select, it would throw a code an go into limp mode.

https://www.thirdgen.org/forums/engi...2-memcals.html

 

The '8746 ECM is the same age as the '7730 ECM. No difference in one being older then the other.

RBob.

 

If the 8746 will work then I want it. It would be a much better option than getting raped for a memcal that I'd have to change everything on anyway. I have a local source for the 8746 proms so that is not an issue.

Basically, I'm still trying to find out for sure if the ECM can be modified to fire 8 injectors. If it can then that's pretty much the majority of the battle.

I might end up going the EBL route if the 8746 alone wont work. It would still be around the same price as buying just the 7730 memcal.

 

You can run 8 port style saturated injectors on the '8746, provided that they are above 14 ohms each. This is what the Edelbrock MPFI conversion kits do.

RBob.

 

That's good news. Would that be a basic splicing in of the 8 plugs and just starting the car or is there alot of modifying of the ECM to get it to work?

 

Tuning is an absolute requirement.

Wiring harness changes also include the TPS & IAC. Extending the wires and changing the connectors is typical.

To be honest, and I was hoping you would ask so that I don't feel as though I am spamming (I hate spam). The easiest, quickest method, and bang for the buck is to get an EBL Flash with the Port Mod installed in your ECM (the '8746). Then change the injector connectors, extend the TPS & IAC wires along with installing the proper connectors.

Plug in the EBL ECM, set the injector flow rate (BPC value) in the calibration, flash it in, and turn the key.


Going with a '7730 ECM requires either a lot of re-pinning or a harness swap. You then still need to acquire the equipment to tune the set up.

RBob.

 

I was reading up on the EBL last night and pretty much decided that would be the best route for me to go. I was hooked when I saw the port mod feature. I'll come out better money wise that way then trying to hunt down a 7730 memcal and gathering everything to tune it.

I guess this means that I can put the MAF wiring harness, ECM, and MAF that I got with the intake up for sale now since I wont be needing it at all.

Thanks, I appreciate the help.

 

Hi, I use the EBL with the port mod to tune a RAMJET 350, and I love it. Works great. Lots of support here too. Dean.

 

You may be interested in this option. It'll alow you to keep the harness you already have on hand.

https://www.thirdgen.org/forums/dfi-...ml#post4337155

 

Do you have any tuning hardware now? If not, you will need to get that also, if you choose the 7730 memcal route. With the EBL system theres nothing else to buy, and its super easy to use. No swapping of chips, Make changes in Tunerpro, flash into ECM, and go! But if you reasearched you know this. Its a great system, Dean

 

You can mod a 6 cylinder MEMCAL to be used in 8 cylinder applications. You can find information on this in the DIY PROM forum.

I tried using a '7747 (similar to '8746, if I'm not mistaken), unsucessfully on a custom MPFI intake 409. Tuned on it and tuned on it for over a year, it was driveable, but no where near good enough for the owner or myself. Swapped to a '7730 and within few tuning sessions had it running better than it ever had.

I don't have any experiance with an EBL to compare.