1990 ECU Delete?

Hammer97321 · Feb 18, 2021

I have a 1990 GT that I pulled a 1968 date coded 302 motor with factory fuel injection on. Yea confused me as well. My plan is to build as 331 Stroker on recommendation of the builder so I am not looking an discussion of Pros an cons on that subject. Instead of factory fuel injection I plan to install TB EFI and MSD ready to run distributed and both of those should not need the stock ECU. I was looking at engine electrical and short of dealing with fuel pump going through the ECU there does not appear to be anything vital that I need the stock ECU for. 1 non-vital thing is WOT to AC. Has anyone deleted the factory ECU and what needs to done for fuel pump or do those circuits just need to be grounded.

Mustang5L5 · Feb 18, 2021

You'll have to get yourself a 1990 EVTM and start with that to determine what wires to pull out. The ECU harness on the pass side contains most of the wiring and can be mostly eliminated but you'll need to go through that wire by wire. The driver's side harness is mostly power distribution. There is a main harness that crosses the firewall and this I believe carries the headlight harness wiring which you will need to sort out.

You'll likely want to convert to a non-ECU controlled fuel pump setup anyway like a 1985 Mustang, with a mechanical pump.

Hammer97321 · Feb 18, 2021

Mustang5L5 said:
You'll have to get yourself a 1990 EVTM and start with that to determine what wires to pull out. The ECU harness on the pass side contains most of the wiring and can be mostly eliminated but you'll need to go through that wire by wire. The driver's side harness is mostly power distribution. There is a main harness that crosses the firewall and this I believe carries the headlight harness wiring which you will need to sort out.

You'll likely want to convert to a non-ECU controlled fuel pump setup anyway like a 1985 Mustang, with a mechanical pump.

I am not sure a mechanical will make it as the Holley sniper I am looking at requires 60 PSI and I already have the upgraded in tank fuel system pump/lines for the motor. Checking wires is easy now since they are all pulled into the cab for restoration.

Mustang5L5 · Feb 18, 2021

Hammer97321 said:
I am not sure a mechanical will make it as the Holley sniper I am looking at requires 60 PSI and I already have the upgraded in tank fuel system pump/lines for the motor. Checking wires is easy now since they are all pulled into the cab for restoration.

your right...I breezed over that part. Disregard that.

I would imagine you would just run a relay and used the Holley to activate the relay. In that case you can run the pump circuit independent of the main harness

Hammer97321 · Feb 18, 2021

Good thought. I checked and they do provide a out to relay for fuel pump. While digging around found it can also cut out ac, run electric fans and other things. Now it is just going thru the electricals that I have and see how accurate they are and start playing with wires.

Mustang5L5 · Feb 18, 2021

Honestly, I’d make your own standalone harness and just leave the main body harness. You can even hide all those drivers side wires in the fender and even delete the starter relay if you go with a 92+ mini starter.

of course this all depends on your electrical skills

Hammer97321 · Feb 18, 2021

Mustang5L5 said:
Honestly, I’d make your own standalone harness and just leave the main body harness. You can even hide all those drivers side wires in the fender and even delete the starter relay if you go with a 92+ mini starter.

of course this all depends on your electrical skills

revhead347 · Feb 18, 2021

There are no advantages to putting a throttle body fuel injection system in over the factory fuel injection. I'm not sure what your goals are here. Throttle body injection systems are designed to be an upgrade for carb cars. It's going to be a serious downgrade for a 1990 foxbody; higher costs, worse driveability, worse low end torque, worse overall power band, less reliable, etc. What is the driving factor in swapping out the injection system?

Kurt

Hammer97321 · Feb 18, 2021

My electrical skills are pretty good. Retired Navy trained in electronics. I did plan on getting rid of most of the wiring and only using what made sense like the wires back to run the fuel pump and some other small pieces that make sense to reuse. I have not worked much on Mustangs in the past so I did not know about using the 92+ mini starter so I will have to look at how that wires. thanks for that.

Hammer97321 · Feb 18, 2021

revhead347 said:
There are no advantages to putting a throttle body fuel injection system in over the factory fuel injection. I'm not sure what your goals are here. Throttle body injection systems are designed to be an upgrade for carb cars. It's going to be a serious downgrade for a 1990 foxbody; higher costs, worse driveability, worse low end torque, worse overall power band, less reliable, etc. What is the driving factor in swapping out the injection system?

Kurt

Hammer97321 · Feb 18, 2021

My engine builder does not agree the horsepower is better with the stock EFI compared to a TB EFI with a single plane high rise manifold. Money spent on good EFI lower and upper intake, new injectors, throttle body and ECU reprogramming to match everything to the 331 and new airflow is not that different to Sniper EFI and manifold. I already have upgraded fuel system to handle up to 600hp so that is the same for both. Nothing is set in stone yet so I am open to a spirited discussion.

jrichker · Feb 18, 2021

Hammer97321 said:
I have a 1990 GT that I pulled a 1968 date coded 302 motor with factory fuel injection on. Yea confused me as well. My plan is to build as 331 Stroker on recommendation of the builder so I am not looking an discussion of Pros an cons on that subject. Instead of factory fuel injection I plan to install TB EFI and MSD ready to run distributed and both of those should not need the stock ECU. I was looking at engine electrical and short of dealing with fuel pump going through the ECU there does not appear to be anything vital that I need the stock ECU for. 1 non-vital thing is WOT to AC. Has anyone deleted the factory ECU and what needs to done for fuel pump or do those circuits just need to be grounded.

some diagrams to help you. with the fuel pump wiring...It says carb'd cars but the principle is the same

6. You will need to run some new fuel feed lines or braided hose. The 3/8" aluminum tubing works well, but you will need a flaring tool and bending springs to fabricate the lines. Braided hose is easy to run and route, but is much more expensive. It is about $3.50-$4.00 a foot plus the end fittings, which are $3-$4 each. Fabricating hose assembles can be difficult, but anyplace that makes hydraulic hoses can do it for you for an extra charge. See http://www.amazonhose.com for more information.

7. For some help fabricating your own stainless steel hose assemblies, see
8. http://www.turbinefun.com/Stainless_Braided_Hose_Assembly.asp

9. For stainless steel braided hose and fittings for automotive use:

10. See http://www.summitracing.com/search/?keyword=stainless steel hose&dds=1
11. http://www.summitracing.com/search/?keyword=stainless steel hose&dds=1

12. http://www.jegs.com/webapp/wcs/stor...hall&searchTerm=stainless+steel+hose&x=18&y=4

See http://www.eaton.com/Eaton/Product...rformanceProducts/FittingsProducts/index.htm for more information on High performance automotive hose products

AN fittings require a 37 degree flaring tool. A standard automotive or household plumbing tool is 45 degrees and cannot be used with AN flare fittings. If you do, the flare is subjected to too much stress when the fitting is tightened, and is likely to fail or leak.

See http://www.mscdirect.com/ , http://www.mcmaster.com/ or for the flaring tool you will need . Prices start at $85 and go up

http://www1.mscdirect.com/CGI/N2DRVSH?PACACHE=000000013509163

http://www.mcmaster.com/#flaring-tools/=b4fxc3

Last time I was in Summit racing, they had a 37 degree flaring tool for less than $40. It may or may not be a catalog item.

Hammer97321 · Feb 18, 2021

jrichker said:
some diagrams to help you. with the fuel pump wiring...It says carb'd cars but the principle is the same

6. You will need to run some new fuel feed lines or braided hose. The 3/8" aluminum tubing works well, but you will need a flaring tool and bending springs to fabricate the lines. Braided hose is easy to run and route, but is much more expensive. It is about $3.50-$4.00 a foot plus the end fittings, which are $3-$4 each. Fabricating hose assembles can be difficult, but anyplace that makes hydraulic hoses can do it for you for an extra charge. See http://www.amazonhose.com for more information.

7. For some help fabricating your own stainless steel hose assemblies, see
8. http://www.turbinefun.com/Stainless_Braided_Hose_Assembly.asp

9. For stainless steel braided hose and fittings for automotive use:

10. See http://www.summitracing.com/search/?keyword=stainless steel hose&dds=1
11. http://www.summitracing.com/search/?keyword=stainless steel hose&dds=1

12. http://www.jegs.com/webapp/wcs/stores/servlet/KeywordSearchCmd?storeId=10001&catalogId=10002&langId=-1&N=0&Ntt=stainless+steel+hose&Ntk=all&Nty=1&D=stainless+steel+hose&Ntx=mode+matchall&Dx=mode+matchall&searchTerm=stainless+steel+hose&x=18&y=4

See http://www.eaton.com/Eaton/ProductsServices/ProductsbyName/Aeroquip/AeroquipPerformanceProducts/FittingsProducts/index.htm for more information on High performance automotive hose products

AN fittings require a 37 degree flaring tool. A standard automotive or household plumbing tool is 45 degrees and cannot be used with AN flare fittings. If you do, the flare is subjected to too much stress when the fitting is tightened, and is likely to fail or leak.

See http://www.mscdirect.com/ , http://www.mcmaster.com/ or for the flaring tool you will need . Prices start at $85 and go up

http://www1.mscdirect.com/CGI/N2DRVSH?PACACHE=000000013509163

http://www.mcmaster.com/#flaring-tools/=b4fxc3

Last time I was in Summit racing, they had a 37 degree flaring tool for less than $40. It may or may not be a catalog item.

The diagram helps. I planned to use the existing fuel pump wiring with inertia switch and I have already put in fuel system upgrade with new pump and metal line rated for up to 600hp

TOOLOW91 · Feb 18, 2021

Do a port fuel injection setup . Rather then the throttle body setup get a Holley terminator x . Remove the engine harness and ecu completely . Install the new unit and harnesses and just wire the fuel pump into the stock harness . You can intergrade the ac and stuff as well .

CarMichael Angelo · Feb 19, 2021

Hammer97321 said:
My engine builder does not agree the horsepower is better with the stock EFI compared to a TB EFI with a single plane high rise manifold. Money spent on good EFI lower and upper intake, new injectors, throttle body and ECU reprogramming to match everything to the 331 and new airflow is not that different to Sniper EFI and manifold. I already have upgraded fuel system to handle up to 600hp so that is the same for both. Nothing is set in stone yet so I am open to a spirited discussion.

I‘d tell your engine builder to stick with machine work rather than advising against conventional wisdom.

Your engine builder should also tell you that a TB injection system will share the same fuel distribution issues the same way a carb does on any small block ford engine. The outside four corners always have the potential to run lean due to the distance the fuel/air must travel when compared to the inner four cylinders. When starting from scratch, and converting over to an aftermarket F/I system, it only makes sense that you’d want to take steps to ensure that every cylinder gets the benefit of the equal fueling that you’ll get from an injector pointed at each intake port.

Now, if it’s your intention to stay N/A with this combo, and be done with it, then you’ll probably be fine, as fuel distribution issues only become relevant when a power adder enters the picture, but...if you have any aspirations of adding one in the future, whether that be a SC, Turbocharger, or a plate nitrous system...you’ll regret the decision to put a TB fuel injector on the engine.

Dont go backwards.

revhead347 · Feb 20, 2021

Hammer97321 said:
My engine builder does not agree the horsepower is better with the stock EFI compared to a TB EFI with a single plane high rise manifold. Money spent on good EFI lower and upper intake, new injectors, throttle body and ECU reprogramming to match everything to the 331 and new airflow is not that different to Sniper EFI and manifold. I already have upgraded fuel system to handle up to 600hp so that is the same for both. Nothing is set in stone yet so I am open to a spirited discussion.

Sometimes they get more peak hp, but the average hp is always lower with a TB injection. Bottom line, cars generally run faster with the conventional port injection. As also mentioned, cylinders 1 and 5 tend to run lean.

Kurt

Hammer97321 · Feb 20, 2021

Ok I hear you on the pros of staying with current style injection. So instead of ripping out ECU what is the process of tuning ECU to support new setup because I do not expect the stock tune is going to be suitable. I have used flash programmers on newer GMs but I know nothing about how to tune the current ECU.

TOOLOW91 · Feb 21, 2021

Hammer97321 said:
Ok I hear you on the pros of staying with current style injection. So instead of ripping out ECU what is the process of tuning ECU to support new setup because I do not expect the stock tune is going to be suitable. I have used flash programmers on newer GMs but I know nothing about how to tune the current ECU.

See post 14 . Remove the stock harness and put a Holley efi setup in it using the port injection . Or keep the stock hanress and put a fully tunable mega squirt in it .

1990 ECU Delete?

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