5.0 efi wiring question
#1
08-28-2008
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5.0 efi wiring question
I am swapping a 89 5.0 efi motor from a Cougar into my 84 Bronco II and have a few questions on what parts I need to use.
The 89 5.0 is a non-H.O. spec motor I am assuming.
I have a complete wiring harness from a 87 5.0 T-bird with its ecm. I also have a 87 Mustang GT speed density ecm.
I will be using the harness and the t-bird ecm but what to use a Mustang HO upper intake and stock throttle body since they are much bigger than the non-HO stuff. See any problem with that? Or can I slide a HO cam in it also and use the Mustang GT ecm with a HO firing order? Will the injectors still be wired correct or are the injector harnesses different for the HO motors cuz of the firing order?
The 89 5.0 is a non-H.O. spec motor I am assuming.
I have a complete wiring harness from a 87 5.0 T-bird with its ecm. I also have a 87 Mustang GT speed density ecm.
I will be using the harness and the t-bird ecm but what to use a Mustang HO upper intake and stock throttle body since they are much bigger than the non-HO stuff. See any problem with that? Or can I slide a HO cam in it also and use the Mustang GT ecm with a HO firing order? Will the injectors still be wired correct or are the injector harnesses different for the HO motors cuz of the firing order?
#2
08-28-2008
Speed density PCM's are not mod friendly.
Mass air systems actually measure the airflow so the PCM can match it with the correct amount of fuel. By contrast, each speed density system uses a set of tables calibrated for what the airflow should be using the original combination of middle-of-spec factory parts. Anything that changes airflow (intake flow, exhaust restriction, cam specs, etc.) can throw the mixture off.
Mixing parts from two different speed density systems may create a system that does not perform well.
For the best chance at a good running, fuel efficient engine, it would be better to go with a mass air system using the original combination of PCM, MAF, injectors and fuel pressure for that calibration.
Mass air systems actually measure the airflow so the PCM can match it with the correct amount of fuel. By contrast, each speed density system uses a set of tables calibrated for what the airflow should be using the original combination of middle-of-spec factory parts. Anything that changes airflow (intake flow, exhaust restriction, cam specs, etc.) can throw the mixture off.
Mixing parts from two different speed density systems may create a system that does not perform well.
For the best chance at a good running, fuel efficient engine, it would be better to go with a mass air system using the original combination of PCM, MAF, injectors and fuel pressure for that calibration.
#3
08-28-2008
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I chose to run speed density cuz I dont plan on modding motor other than the HO intake and T.B. I will run stock manifolds too.
I am goin to be runnin thru a snorkel and a MAF will just complicate things/plumbing. If I have to I guess I can just run all the non-HO spec motor parts,ecm then...even at just under 200hp and 250ft/lb it will still be a fun little ride.
I am goin to be runnin thru a snorkel and a MAF will just complicate things/plumbing. If I have to I guess I can just run all the non-HO spec motor parts,ecm then...even at just under 200hp and 250ft/lb it will still be a fun little ride.
#4
09-02-2008
#5
09-03-2008
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#6
09-03-2008
#7
09-03-2008
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I'm going to post the ' I told you so ' message now before you even go to turn the key.
Speed density is a set of charts that the engine will read from. Certain RPM measurements will amount to certain amounts of fuel being added to the mixture. When you change elevation and air densities, the ECM cannot ( rather wont want to ) calibrate for the changes in the fuel map/curve. Sure, its said it does and everyone will point to the reference charts programmed into the PCM.. but go ahead and listen to everyone and find out for yourself
Your BEST bet in saving the headaches of the future is just to setup a Mass-air system from the start. Speed density is junk and will give you many headaches.
I understand your not looking for huge power, but your going to have to put on a fabbed exhaust ( non-stock ) fot the swap . That equates to a different flow from factory. Add in the manifold you plan on using and more air from a slightly larger TB then what came with that Speed-Density PCM.. you might be out of tolerances before a cam, let alone adding ANYTHING to it.
ECC4 is what you want with a MAF from a 92-95 302. 19lb injectors and a standard order distributor/cam. Life will be so much better.
Speed density is a set of charts that the engine will read from. Certain RPM measurements will amount to certain amounts of fuel being added to the mixture. When you change elevation and air densities, the ECM cannot ( rather wont want to ) calibrate for the changes in the fuel map/curve. Sure, its said it does and everyone will point to the reference charts programmed into the PCM.. but go ahead and listen to everyone and find out for yourself
Your BEST bet in saving the headaches of the future is just to setup a Mass-air system from the start. Speed density is junk and will give you many headaches.
I understand your not looking for huge power, but your going to have to put on a fabbed exhaust ( non-stock ) fot the swap . That equates to a different flow from factory. Add in the manifold you plan on using and more air from a slightly larger TB then what came with that Speed-Density PCM.. you might be out of tolerances before a cam, let alone adding ANYTHING to it.
ECC4 is what you want with a MAF from a 92-95 302. 19lb injectors and a standard order distributor/cam. Life will be so much better.
#8
09-04-2008
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Just to be clear... I am a 37 year old guy who has been messing with 5.0 Mustangs since the late 80's so I know all about them what it take to make em work. I helped a buddy get his 86GT to run mid 13's {on Gatorbacks}on all factory parts by using 87 intakes,tb,egr,exhaust and some head work.So I know for fact they wil allow some degree of mods. Yes I used a LM1 Wideband and a Kirban fuel reg to fine tune it,it ran like a stocker around town and like a raped ape when you stood on it!
That being said, my plan is to use the cam and upper intake setup off my buddys 93lx, a 87 GT ecm{SD} and the T-bird harness I have off a non-HO 5.0 car. I am using the stock T-bird manifolds and I will build a single 3" exhaust.These mods in no way will be past what the SD ecm can handle.
I guess my only question is reguarding the order the injectors fire. Are all efi 5.0 injector harness the same and the order they fire controled by the ecm or did Ford wire the harnesses different for HO and non HO ?
That being said, my plan is to use the cam and upper intake setup off my buddys 93lx, a 87 GT ecm{SD} and the T-bird harness I have off a non-HO 5.0 car. I am using the stock T-bird manifolds and I will build a single 3" exhaust.These mods in no way will be past what the SD ecm can handle.
I guess my only question is reguarding the order the injectors fire. Are all efi 5.0 injector harness the same and the order they fire controled by the ecm or did Ford wire the harnesses different for HO and non HO ?
#9
09-04-2008
IIRC the non H.O. ECU's were bank fire, not sequential. Not a big deal, because even their high end EPEC ECU used a bank fire strategy.
There is a benefit of the sequential system, it does give better bottom end driveability.
I'm not sure of wiring, but that should be fairly easy to check. I will check my service manuals when I get a chance.
And there is nothing wrong with SD. Having run the same car both ways for extended periods I actully found SD to have a better throttle response (your mileage may vary). It's back to the stock SD computer and I'm plenty happy with it.
There is a benefit of the sequential system, it does give better bottom end driveability.
I'm not sure of wiring, but that should be fairly easy to check. I will check my service manuals when I get a chance.
And there is nothing wrong with SD. Having run the same car both ways for extended periods I actully found SD to have a better throttle response (your mileage may vary). It's back to the stock SD computer and I'm plenty happy with it.
#10
09-04-2008
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#11
09-05-2008
Alright,
All I have is the 88 car/truck supplement. The cougar/tbird/mustang all shared the same wiring, and all where sequential EFI. I would assume 87 would be similar.
The only vehicles that used a bank fire where the trucks, so you should be fine.
Clicky here. I've checked the pinouts listed and they seem to match the Ford manual. There's also plenty of other resources at that site.
Don't forget, that the HO and non HO had different firing orders, and although the wiring was the same, the ECU would have been programmed for a different injector firing order. I have run a statndard 302 cam with an A9L and just swapped the injector wiring to follow the firing order. I've read somewhere that not doing so forces one bank to go lean, but don't quote me on that. Some one can correct me if I'm wrong, but as I see it, there's nothing to tell the ECU actually where the engine is in it's firing order anyway
All I have is the 88 car/truck supplement. The cougar/tbird/mustang all shared the same wiring, and all where sequential EFI. I would assume 87 would be similar.
The only vehicles that used a bank fire where the trucks, so you should be fine.
Clicky here. I've checked the pinouts listed and they seem to match the Ford manual. There's also plenty of other resources at that site.
Don't forget, that the HO and non HO had different firing orders, and although the wiring was the same, the ECU would have been programmed for a different injector firing order. I have run a statndard 302 cam with an A9L and just swapped the injector wiring to follow the firing order. I've read somewhere that not doing so forces one bank to go lean, but don't quote me on that. Some one can correct me if I'm wrong, but as I see it, there's nothing to tell the ECU actually where the engine is in it's firing order anyway
Last edited by gt40; 09-05-2008 at 10:45 AM.
#12
09-05-2008
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