Please let me begin by saying that I'm too old/lazy/stupid to learn how to "tune". So, save it. Ain't gonna' happen. I go to read the stickies in the PROM section and my eyes glaze over and I start to drool on the keyboard. Plus, I'm tired of sending my local dyno operator on Caribbean vacations. Also, I don't want to carb it. I like my TPI, or derivative, (HSR/mini ram/etc.).

With that being said, I wanna' go with this:

http://www.compperformancegroupstore...Category_Code=

and this:

http://www.summitracing.com/parts/pf...make/chevrolet

Along with the fueling, the EZ EFI does the fans and fuel pump. I can get a kit or wire, (manual switch), my way around T/C lock up. I can tap into the existing harness for power to the dizzy and do the timing by trial and error/ear/spark plugs.

But, I have a few concerns:

A) How do I go about my speedo and, by default, cruise control? Will I need a Dakota Digital? Or, what?

B) Will the factory tach run off my MSD box? Or, will I need to go aftermarket?

C) Oil pressure gauge? I don't have to worry about the whole prime/oil pressure-to-run thing but the gauge is tapped into the ECM, IIRC.

D) The evap canister is also controlled by the ECM. Yes?

E) Is there a ported vacuum source anywhere on a TPI set up? I've never really noticed one way or the other.

I'd like to completely remove the factory ECM and existing harness but due to the above questions, am not sure I can do so without major changes, (i.e. all aftermarket gauges/cruise and hacking up the dash). The evap isn't a great emissions concern but want to make sure the gas tank is properly vented so as to avoid flaming convertible. And, the ported vac source, while not critical, will determine if I use the vacuum advance on the dizzy or not.

Finally, is there anything I've missed? If so, feel free to comment.

Thanks!

 

A) Your speedo and cruise control cannot operate with the raw signal from the VSS input without a buffer (inside the ECM or aftermarket). You can acquire a factory VSS buffer box from '88-89 cars and convert the VSS to the 4,000 PPM signal you need, or go aftermarket, like the Dakota boxes.

B) The factory tach runs off the ignition coil, independent of the ECM. You may encounter problems due to the MSD box which would occur with or without the ECM.

C) Oil pressure gauge is input to the instrument cluster. An oil pressure switch (not the gauge sender) is connected to the ECM for diagnostics, and also paralleled to the fuel pump relay for redundant power.

D) The evap canister is controlled by the ECM, as well as the AIR system port/divert valves, EGR, and TCC lockup.

E) There is a ported vacuum source under the TB intended to supply the EGR solenoid and EVAP. You may be able to use this for a distributor advance unit, but will have to select the diaphragm/springs accordingly.

You can get an early '80s SBC vacuum switch to control the TCC, but will need to wire that through the ignition source, 3-4 gear switch on the trans, and the brake pedal switch. Since the factory wire harness already does that, I'd be very reluctant to just completely rip out the old harness.

Overall, I feel it would be far easier to remove the ECM and adapt the factory harness to your new hardware. The fan relays, FP relay, TCC wiring, instrument wiring, cruise wiring, VSS, HVAC wiring, and a bunch of other circuits are included in the factory harness. Simply adapting that for the 4-5 new/alternate circuits needed should be easier than building a new harness.

One other thing you will need to consider is wiring around the start enable relay from the VATS system. That will need to be done inside the vehicle at the VATS module.

 

Ah, yes! The dreaded VATS. I totally forgot about that.

Thank you very much, sir! Lotsa' good info there.

The kit comes with a new, specific harness. I remain skeptical of my ambition/ability to adapt/merge the two. Besides, part of my rationale was just replacing a 21 y/o, probably decaying harness. Maybe I just ought to bite the bullet and acknowledge I have to re-wire the vehicle. Approach it as if it's a TPI transplant into an older vehicle. I dunno'. I'm conflicted about this.

Still, my first inclination is, I think I'll just leave well enough alone and buy my dyno guy a fresh bottle of sunscreen!

But, deep down, I'd like somebody to convince me otherwise.

Anyone else?

PS I just found the kit for $700 shipped. That's not that much more than one dyno session. Decisions, decisions!

 

BTW, as you've stated, upon closer examination, I probably could adapt the old harness to the new ECM but would still be left with nothing to replace the lost functions of the old ECM. I guess that's my basic question: How to replace some of the old but needed functions of the old ECM along side this new device, in the most efficient manner. My biggest concern would be a need for duplicate circuits, (both will need eng. temp, RPM, vac. signal, etc.).

 

I'm unfamiliar with the FAST system and what it entails. If it is a stand-alone EFI controller it should include all the required sensor inputs, like knock, RPM, MAP/BARO, TPS, CTS, O², and ignition reference. It should also include the required outputs, such as injector pulse, ignition advance/retard, and idle air.

Aside from the aforementioned devices and systems, what additional devices do you want/need? The instruments for coolant temp, oil pressure, tach, fuel gauge, and (if you use the external buffer) the speedo are outside the ECM on their own sensors. There should be no need to replace all that wiring with new wires that just clone the existing system, unless you like building wire harnesses as a recreational activity.

If you want other systems to function, you will need to adapt with either vacuum/temperature controls like the older GM (early '80s) V-8s or stand-alone controls. The vacuum systems can be a tubing/TVS/check valve nightmare - The primary reason most people view "emissions controls" as evil, problematic, power-sucking devils. But they can work if you want/need the controls to pass emissions testing.

For example, EVAP is completely passive, costs NO power, saves you fuel, eliminates water contamination, and just happens to reduce pollutants as a result.

EGR costs NO power, can allow for better mileage, more timing advance, and cooler temperatures, and just happens to help reduce NOx as a result.

TCC helps mileage, keeps the trans cooler, and costs no power. A simple adjustable vacuum switch (OEM style) with the existing vehicle wiring is all that is required.

Your cruise is independent of the ECM, and only needs to share the VSS input as described.

I've done some of these using mostly OEM components and harness, including '57 Bel Air, '72 Chevelle, and '69 Camaro. Those functions which are not supported on the original wiring were supplemented with add-on circuits, like the vacuum TCC and aftermarket VSS in the speedo cable run. I didn't use an aftermarket EFI, but a factory ECM with the external wiring and program modified to the installation such that any factory replacement ECM can be slammed in place to make it run. It shouldn't be that difficult to replace the ECM with the aftermarket EFI and support the rest of the functions.

 

The VATS should still read the key and operate the starter relay, the fuel enable signal to the ECM will be redundant
If you want to remove VATS completely all you need to do is jumper the two thick wires at the starter enable relay
or better still cut and solder them together.One less thing to fail and upset your day
https://www.thirdgen.org/forums/post...460-post3.html

 

If it is the same as other aftermarket systems it supplies all the wiring required ;
all you usually need to the new setup is is permanent 12V power , a switched 12V power supply from Ign switch
and connecting the new fuel pump power to your existing pump wiring.( and fan control if it is part of the pkg )
As stated your existing wiring stays to support the gauges , usually the Ign feed to coil and the starter wiring
You can gut out from the original engine harness anything related to the stock ECM

 

OK This is sounding better.

The EZ EFI in question is a retrofit based on their standalone system. It re-uses the existing sensors. As a matter of fact, it is tailored to a TPI or 5.0 system. It appears to basically be for transplanting a TPI. If used on a 5.0, some GM sensors need to be substituted. My main concern were the gauges and cruise. It appears there are work arounds for those. The EGR is gone as is the AIR. The VATS is a good idea, regardless of anything else. So, a few more nights research to assuage my mechanical ability anxiety and the debit card will probably start to get itchy.

 

I know you are not wanting to learn tuning but you might want to look into dynamicefi ebl p4.
this is a non emission would be easy to install.

http://www.ebay.com/itm/TPI-Speed-De...41f661&vxp=mtr

 

That looks pretty good but this looks even a little better:

http://www.holley.com/554-116.asp

and

http://www.holley.com/558-101.asp

All this leaves is TCC and speedo/cruise. A little spendier than Fast but it has more functions.

 

Nice! Works out to be the same price and uses a knock sensor:

http://www.holley.com/550-601.asp

Plus, I believe it can be set up for TCC with one of the outputs.

Needs a laptop, (or their absurdly priced touch screen) rather than the little hand held thingy. Hope my coal fired Dell works with it. I think I'll give their tech line a call Monday.