90 C4 Rebuild w/ Edelbrock Pro3 XT EFI
 

Hey guys, I bought a 90 Vette a few years ago that had a blown head gasket and I decided, rather than just replace it, to build a cool customized street car. I took the original block and had it bored 30 over, clearanced, and line bored for a 383. I got the Eagle 383 rotating assembly, high volume Melodon oil pump, extra deep Summit oil pan, Comp roller cam w/ roller lifters, roller rockers, and custom aluminum vortec style heads. Here's where it gets a little tricky. I decided to go with the Edelbrock 3228 Pro3XT EFI setup. The ECM included with it will run all of the engine functions, fans, and idle kick up for AC. However, it will not control the dashboard, AC, or cruise control. The AC system I think I can run with an Arduino to monitor pressure and control compressor on/off. The instruments (oil press, temp, water temp, should run right from the sensors. However, I am not sure about the speedo and tach.. Also, not sure how to run the cruise, maybe an Arduino? What do you guys think?
Thanks for the help!!!

I think you need to call Edelbrock's support team and tell them about your application (going into a 1990 Vette) and give them your concerns. Normally that is done prior to purchase however, so good luck if you have already shelled out for it.

Sometimes you can utilize the new ECM with the OEM; not sure with Edelbrock however. I have the Holley (ECM/wiring harness/EFI system) on an 85. The Holley runs everything (that I required) and I eliminated the one off 85 ECM. But then again, I am utilizing an Auto Meter white face gauge cluster from VetteAid. So I have no avg. mpg and other digital dash functions; never cared for that or utilized it anyway.

However, I think the 90 models have a more sophisticated ECM that might be a challenge for you since you have the updated dash of the later C4's.

Good luck. It's a good system if you can get it to work on the 90 Vette w/o hacking it up.

:cheers:

I appreciate the input. I am just waiting on the 8A supplement book and then I should be fine. I looked over a bunch of it so far and it looks like the CCM runs all of the interior stuff (dash etc..) and the gauges (all except speedo) run off of their own sensors so I don't think it will be a problem to lose the old ECM completely. I bought the EFI system in a hurry because Edelbrock clearanced them for less than half price. I can replicate what the old ECM did, with an Arduino and that will give me complete control over the vehicle electronics. I will keep everyone updated as the project moves on.
THANKS!!!!

I believe I have seen in other threads where they left the oem ecm in place to run th gauges, I believe the AC is controlled by its own coputor except for the iac, I may be wrong.

I am going to guess that you will be utilizing the both ECM's on the 90; the Edelbrock and the OEM; not sure. You might get away with the Edelbrock if you don't mind losing the cruise control.

I am not running cruise control anymore on mine. That was a no brainer for me anyway. I run a ZF6, 3.73 gears and live in beautiful wine country out in Missouri full of rolling hills and gorgeous scenery. Cruise control was an easy give away considering the upsides; now have a car that anyone can tune with a laptop, I can data log, and make any modifications easily as this ECM is ready for most anything; it's self learning. Just plug in the data and drive it for a while. I don't think I ever used the control once since 2001 when I purchased it.

Is the Edelbrock self learning? That was a big deal for me researching EFI sytems; Holley has become a large, EFI company with many products available; they have come a long way since carb manufacturing.

The Edelbrock is self learning and allows me to tune every aspect on the fly. It also has data logging and it comes with a bluetooth wireless tablet to program everything.
I really want to get rid of the OEM ECM to make room and to clean up all the under hood wiring.
I got the schematic book (8A) today so I started going over everything and I have the cruise figured out (it has it's own control module so it only gets 4K PPM signal from the ECM) and I have everything else figured out too (I'll share after it's up and tested). The only problem I see is converting the speed sensor signal to the 4K PPM that the cruise and speedometer need. I am pretty sure, from looking at the schematics, that the speed sensor sends an AC signal. If this is the case, I can use a couple diodes to pull out the high signal. If that signal is 4K PPM then I'm done. If it's something else, I can read the signal through an Arduino input and then output the corresponding 4K. This is theory so if you guys know something I don't, please let me know.
The EFI system will be here Thursday but I am going to pull all of the wiring and redo it so I may not be ready to install it by then. Also, I have to pull the dash because I found the heater core unhooked when I pulled the coolant reservoir so I think it either leaks or is plugged.

I have nothing to contribute on your EFI issue but did want to say that I really like your paint job:cheers:

Thank you. I grew up in a body shop so I wanted to show off a little with this car

OK, so the EFI system is here and the speed converter is in. I have installed the hardware and I am working on the wiring now.

I have a question, if anyone can help. I am attaching a schematic (from the 8a supplement) that shows the ECM role in the transmission lockup control. It appears to me that the ECM does nothing more than connect the two circuits together (446 and 422). I have to ask, couldn't that be accomplished by simply connecting the two wires together at the plug? That's my plan, at this point, unless someone knows something that I'm missing.
Thanks!

..... That throttle body looks pretty tall ... will it fit under the hood ? .....

No, I'm pretty sure it won't. I am planning on modifying the hood a little to accommodate it.

I have seen in other threads where they made it fit but I think there was some machining involved.

Any updates with the Edelbrock 3228 Pro3XT EFI?

For your fourth gear converter lock-up there are a bunch of options.
TCI and monster transmission sell an internal kit for the valve body to lock up the converter. Monster sells an external kit.

I just run a power wire from a lighted 12v switch into the TCC solenoid. If you want fancy run the power wire thru the brake relay switch. That will de-energize the TCC soleniod when your foot is on the brake pedal.

If you want really fancy run two hoobs pressure switches into the 3rd gear and 4th gear passenger side pressure test ports. Use that for the ground circuit.:cheers: