EFI System Upgrade or Full Car Re-wire First?

Looking for input/advice here.

I am planning my two major winter projects and trying to decide on install order...
Project car: 1940 Ford Tudor with Chevy Ramjet 350/Mefi 3 system all done in 2004. Wiring is a mess - PO used all red wire with no labels, 1980's Chrysler fuse box, VW windshield wipers, VDO gauge cluster, Vintage Air, and so on... Car is running/driving, (running as well as an early Ramjet 350 will run).

Any advice on order of installation?

1. Re-wire the entire car with my AAW Highway 22 Plus Universal wiring kit
2. Remove the Mefi3 EFI and replace with my Holley Terminator X kit
3. Do both at once?

I expect this may be personal preference, but looking for input anyone might have from previous experience. I am comfortable doing both projects myself.

 

I'd rewire the whole car, make sure everything is good, then dive into the EFI end of things. While you are wiring be mindful of what you can add and will be able to remove with the EFI conversion so you aren't going back and adding wires later.

 

I’ll bite

My personal preference would be to gut all the wiring out of the car and to start with the main wire harness. I think I’d wire the entire car first leaving the engine as the last system to wire or the last system to terminate and finish and integrate the FI harness with the rest of the engine harness so it looks like one. You can easily semi separate the FI wires but still run them together with the other stuff

 

I'd tackle the rewire first to see if you still have a running/driving car. Once fully satisfied with the wiring job, move to next project.

I subscribe to doing ONE project at a time. Thoroughly test, then move on to the next project. I try to keep the car running and driving, or nearly so, all the time. Too many projects spend 30 years in the back corner of the garage because it became overwhelming to get all the jobs back together.

 

Uhhhhhh...........

I think I would take the car to one of the local tuning experts and see what they can do about making the car run even better with what you have in place. The reason I say that is because you know it works already and they may be able to make it work really well......or tell you to switch if its not a good set up. One reason I say that is the OEM set ups often have MAF sensors in the air intake that monitor air flowing into the engine.......a direct reading. SOME of the earlier OEM set ups did rely on a MAP (Manifold Absolute Pressure) sensor.(No MAF)..........and the computer used that to calcuate air flow (instead of measuring it) and fuel needs.
A Holley set up will use a MAP sensor and not have the MAF.

If you get the current set up working well/better, thats a known good thing you have when you start rewiring the whole car.........so one less probability that something is wrong. Ask the guy who tunes the system for you if he can tag the wires that you will need to cut and attach to the new harness. There should only be a few that need cutting and reattaching. He can simply look at his diagram for the ECM (Computer) thats in your vehicle and tell you which wires they are.
Once you have the new harness in place and its all working well, then when its proven..........decide if you still want to convert to the Holley system. Nothing wrong with the Holley, and you can even tune it yourself.......but I would do it in the two stages I suggested rather than fight both problems at once.

 

I'm one of those guys that would rewire car first. Then I would do fuel injection separate.

I wire all my vehicles with stock type components and once done then I do "add-ons" separately. Add-ons are things like electric fans, fuel injection, line lock etc.

I like the ability to be able to remove add-ons and still have a running driving car or if I decide to sell it and I want to keep the line lock or the fuel injection and replace with a carb then I have the harness that I can just swap over to another car too.....


...

 

Thanks all. I'm leaning towards the rewire first - keep engine bay work for next project. I won't continue on any EFI topics here (didn't realize).

 

Rewire 1st would be my take but unless you are having a failure with the ramjet, I'd keep it. Oem components have a history of longer lasting components. If the ecu dies on a terminator, you call a tow truck and send the ecu back in. Do some research to see how the time frame is on that. All efi systems require clean voltage. If the efi connections on your car are compromised, it could create numerous problems. One other item I will add is the addition of a high amp alternator. When you add up ac, efi, halogen lights, elect. fan, good stereo, the numbers are surprising. Good luck with your work.

 

The basic Ramjet itself is fine, but the MEFI3 ECU is not tunable without sending out ($) and they can only do a few things. It's an open loop system - no O2 sensor - and pretty crude. It was designed as a marine engine and later sold as a crate motor, but your points are taken.

Great call-out on the generator. The PO that did the current build did a pretty good job overall with quality components (for 2004). I have a 10SI-style alternator with no markings - just chrome. One hint so far is what looks like a 14 gauge wire from Alt to Bat (starter) which would be a little light if over 100 amps. Will dig more on this.

In the pic below, you can see some early 2000's pieces... I need to do something with that upper radiator hose (not sure how I'd burp it if I needed to).

 

Can’t you just upgrade the puter with an aftermarket and add any o2 or other sensors as necessary to keep the factory injectors and plenum?

 

Yes - exactly what I have planned using the Holley Terminator kit. Lots of talk with them. No major changes - even plugs in to the current injectors, TPS, IAC, MAP. I need to add an O2 sensor, wire one adaptor, and give it clean power. They even have an adapter harness for the distributor to provide position sensor data (the Ramjet does not have a crank or cam sensor). This will be batch fire as original, but if I want to upgrade to sequential fire in the future, there's a kit for this ($). No other changes needed for my current plan. Excited about this!

 

I would probably start with the rewire of the entire car, but you need to know which wires will need to be changed for the EFI to operate. I would plan for those wires needed for the EFI so you can include them as you install the body wire harness.

 

Gut it and start over. Curious what do you plan to use to control ignition? Cam sync distributor with remote coils?

 

A new distributor may be part of phase two (sequential fire, coil per plug, etc). But I've been told by Holley is that all I need is their HEI GM Small Cap Ignition Harness (558-304) to run with what I have currently.

From Holley: "You won't have any "cam" sensor with your existing distributor (GM Small Cap HEI), so you would just follow the diagram for that system with the 558-304 harness. Your existing distributor is your "crank" sensor, in this configuration."

 

Ok - nearing ready to start re-wire. This won't be a clean rip with existing wiring in tact.. but have all my circuits mostly identified and do***ented. Chomping at the bit to hear my side-cutters at work.

A partial shot under the dash...

 

Can't blame you for wanting to get rid of that. It would be really hard to follow where that one red wire ran (for what ever was not working), having it bundled with a few other red wires, and the troubleshooting becomes a nightmare quickly.

 

Any progress on the rewire project?

 

In full swing. Using the AAW Highway 22 kit and it's so nice to have different colors and labels for everything! About 80% there. Spent a bunch of time on good grounding (engine, frame, body, firewall) and new 1/0 battery cables (Pos and Neg) from the trunk located battery. Pos to the starter and then to the AAW Megafuse block, and Neg to the engine. Then a large ground strap from same point on the engine to the frame, and smaller straps to the body in 3 locations, and so on. Progress!

All this while planning for the Holley Terminator kit, and a Dakota Digital RTX Dash, interfaces, etc...

I'll take some pictures when I get things a little more ****oned up.

 

I second the "rewire first" approach. That wiring mess would require more time to diagnose and identify the circuits than it would to rip out and redo properly.

About the only thing you're going to need to run to the new EFI ECU is a 12V+ IGN wire to turn on the computer. Sometimes I'll use the big pink IGN wire in the AAW harness. Everything else will be separate from the main wiring harness (BATT =/-, fuel pump, fans, ignition, etc.). I prefer to power the fuel pump via the ECU rather than through the fuse panel. The ECU only provides power to the fuel pump if it sees engine RPM and/or oil pressure, depending upon brand. Wiring the pump through the fuse panel, the pump gets power at key on constantly. Not only is this annoying when you're trying to diagnose an electrical issue or just need to have the ignition on for any reason (fuel pump runs and draws voltage), but the pump will continue to run in the event of an accident until the key is shut off.

You mentioned Dakota Digital gauges, check out their Expansion Modules that allow the gauges to tap into the various ECUs for most gauge inputs. They make a Holley-specific one that provides most, if not all, signals for your basic gauges, and then some. This simplifies the install and saves the need for installing a bunch of additional sensors for the gauges alone.

If you're running A/C, it can be tricky to trigger the fans to run when the A/C is on through a trinary switch using the ECU's fan wire since it uses the coolant temp sensor to trigger the fans. A savvy person could wire the ground trigger of the trinary switch inline with the same ground trigger wire on the coolant temp sensor however...

One more thing, do yourself a favor and don't bury the relay and fuses that are hard wired into the EFI harness as you might have to get to them periodically to check. Its especially a nightmare if someone else built the car and hid the ECU in a hard to reach spot. Ask me how I know...

Good luck!

 

You might consider buying a spare dashboard and making connections on a work bench. Then resell the dash when done.

 

Great info - thanks.

I hadn't decided on fuel pump wiring, but powering by the ECU makes good sense. I ran new 14 gauge positive and ground from the pump and have it dangling up front. The only thing I've seen in PO's receipt pile is a purchase of a G series pump and tank from Yogi's in 2004 - but will probably test for current draw.

I am going to use the RTX-40F-X dash and the BIM-01-2-HLLY interface for the terminator. Working out my diagram now... With the BIM interface above, I can apparently read RPM, Engine temp, Intake/manifold temp, MAP, A/F ratio, Oil pressure, and Fuel pressure from the Holley CAN bus...

For the fans, I'd also planned to leverage the terminator along with the programming for AC kick, etc. My AC is an older Vintage Air and a binary safety switch. While it was working fine, it's a bit of a mess (door vacuum lines unplugged, etc). Still researching this...

 

Good thought.

 

I would replace the binary switch with a trinary so the fans come on with the A/C.

 

After having done Ol' Furd with a complete new harness, plus the Holley Terminator, I would suggest going all in and do both at the same time. It's much cleaner to integrate both together. The AAW kit will provide a solid ignition wire to power the Terminator system. Your fuel pump would be wired in conjuction with the Terminators relay, and will prime the system on start up. It'll turn the pump off after a few seconds, which is handy when you do any tuning work with the Terminator. All you would need is a wire from the pump to the relay. Easy.
Plus you will want to mount the Terminator inside the car, as it is not waterproof. Another good reason for wiring it all together. Then put the relays and such in easy to reach places.
Far less work overall to do both and be done with it, rather than pull some of the wiring apart to install the Terminator later. Plus the terminator was to easy set up and get 'er fired up the first time.
One thing to note on the Terminator. The universal kit most likely has a bunch of connectors for systems you may not need, as it was in my case. My son pared the harness down and included only those wires and connectors I would need for my own application, eliminating a bunch of unnecessary clutter.
But, it's up to you.

 

Thanks - exactly what I decided to do. Re-wire is 80% done, Terminator is next with planning in parallel) like the fuel pump and Dakota dash.