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Discussion Starter · #1 ·
Hello all,
I have a 1986 Ford Bronco with the 5.0L EFI and a 4 speed manual. My efi fueling is on a base curve as someone before me removed all the sensors for electronic control. The fuel pumps are on a toggle switch and both pumps are brand new. I get around 8-10 mpg with this setup and I am looking for answers on where I should start and if it is worth the swap.
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i dont think a carb will do better. add the stuff back. you still going to be pretty rough with a 4 speed stick since no od.
 

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Discussion Starter · #4 ·
I mean I'm getting the same with my edelbrock carb lol. Why don't you readd all the sensors?


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I would be overjoyed if I could get the sensors replaced and have it running right, but all I know that is for sure missing is the O2 sensor and a couple buddies I know have the EFI that actually works and while they get good mileage they've had nothing but problems with codes and such. Being that mine is nearing 300,000 km or 180,000ish miles I don't want to throw money into the stock motor if I can get parts for a carburetor swap that I can use on another motor when this one dies
 

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Discussion Starter · #5 ·
i dont think a carb will do better. add the stuff back. you still going to be pretty rough with a 4 speed stick since no od.
I mean better mpg would just be an extra, I'm more looking for it not to be running as rich and be easier to work on. I know more about carburetors than I do efi and up in Canada the sensors and computers are stupid expensive with exchange and shipping. I am running 31" tall tires and 3.50 rear gears so 4th gear at 100 km/h or 62 mph rpm is 2300rpm so not great but not terrible.
 

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I mean better mpg would just be an extra, I'm more looking for it not to be running as rich and be easier to work on. I know more about carburetors than I do efi and up in Canada the sensors and computers are stupid expensive with exchange and shipping. I am running 31" tall tires and 3.50 rear gears so 4th gear at 100 km/h or 62 mph rpm is 2300rpm so not great but not terrible.
well im getting 2800 rpms at 55mph lol


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I mean better mpg would just be an extra, I'm more looking for it not to be running as rich and be easier to work on. I know more about carburetors than I do efi and up in Canada the sensors and computers are stupid expensive with exchange and shipping. I am running 31" tall tires and 3.50 rear gears so 4th gear at 100 km/h or 62 mph rpm is 2300rpm so not great but not terrible.
well by the time you buy a new intake carb and associated parts you prob could put that back in. ford efi those years is pretty simple. i think you really only need tps iac and map sensor and dist pick up sensor to run it all. only other ones are the egr and smog pump sensors. egr is worth keeping but the smog pump id delete it if possible. in the us its only about a 100 bucks for all that. idk if it be much more to get it across the border. intake alone will cost triple that unless you find used parts.
 
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Amazing what the "finicky" speed density system will adapt to isnt it? I built up a 94 351 and left the factory computer alone. It got similar mpg to you, but did have good power. A tune would've really helped it though I'm sure.

In my 85 with a 4speed, my 300 is at 3000 rpms at 70mph. It will get 12 mpg at that, with 450 cfm 4bbl. That's with 4.56 gears and 37s.

I'd say if you want, swap it to a 4bbl. You'll need an intake, carb, and a way to regulate the fuel pressure down to 6-7psi. You'll also need to get a duraspark2 distributor and control box for the easiest way to do it right. That stuff can all be found on 83 and back fords. A points style system would also work.

You have a rare filterbox setup being a bullnose with efi. Someone may want it. 87+ all had the filterbox on the driver side fender liner.
 

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What will the new engine be???
If performance oriented, I am going to go against the grain a bit here and say to carb swap this one, as you will then be all set later for the other engine. Especially if it is a 408 stroker or something like that. Something the the Speeddensity stuff would never run anyways.
If it was my own, I would look at a Holley Sniper or like setup to return to efi later, if you want to.
The cost of coverting to MAF, or switching over to megasquirt setup, is about a wash (or more if you have to buy everything) as to go with the Sniper. Though the multiport efi is likely a bit better in terms of efficency.
 

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What will the new engine be???
If performance oriented, I am going to go against the grain a bit here and say to carb swap this one, as you will then be all set later for the other engine. Especially if it is a 408 stroker or something like that. Something the the Speeddensity stuff would never run anyways.
If it was my own, I would look at a Holley Sniper or like setup to return to efi later, if you want to.
The cost of coverting to MAF, or switching over to megasquirt setup, is about a wash (or more if you have to buy everything) as to go with the Sniper. Though the multiport efi is likely a bit better in terms of efficency.
Great point on the aftermarket EFI. Since he already has a high pressure fuel system, it would be almost stupid to not use the Sniper or whatever. @AbandonedBronco converted his 85 with an efi 302 and auto trans to a 300 and zf5, run by a 2bbl Holley sniper. The power, and smoothness of said power was amazing. Made my hopped up, carbed 300 seem like an old tractor engine.
 

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@BigBlue 94 This is exactly my thinking too.
I am also a person whome went down the Mass Air Swap route with the Edelbrock truck EFI intake & such, and If I was going to do that engine/trans/bronco combo again, it would of gotten something like the Sniper (if not the Sniper) for sure. Especially when these systems are tailored to those that are converting from carb. tech to efi. I feel they are a good middle ground, as far as new tech but also simple-ish, and offer room to grow later.
 
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I would be overjoyed if I could get the sensors replaced and have it running right, but all I know that is for sure missing is the O2 sensor and a couple buddies I know have the EFI that actually works and while they get good mileage they've had nothing but problems with codes and such. Being that mine is nearing 300,000 km or 180,000ish miles I don't want to throw money into the stock motor if I can get parts for a carburetor swap that I can use on another motor when this one dies
I mean better mpg would just be an extra, I'm more looking for it not to be running as rich and be easier to work on. I know more about carburetors than I do efi and up in Canada the sensors and computers are stupid expensive with exchange and shipping. I am running 31" tall tires and 3.50 rear gears so 4th gear at 100 km/h or 62 mph rpm is 2300rpm so not great but not terrible.
EFI will ALWAYS be more efficient, perform better,and in most cases be more reliable than a carburetor. The reason yours runs like shit is because the oxygen sensor has been removed. The oxygen sensor is what allows the EFI system to run closed loop and adjust A/F ratios for best performance/ efficiency. It's been neutered to the point where it's basically an electronic carburetor. These EFI systems are actually very simple. Mine has 235k on it and has rarely had an issue. In fact it's been years since I saw a CEL. I have a Trailblazer with 218k on it, even with OBDII and way more going on it rarely has issues either.

You can get all the sensors and any wiring you need from the junkyard, many of the same parts were used until 95 on half tons and 97 on heavy duty trucks.

Make A friend who knows his way around EFI and he'll set you on the right track. I know because I am that guy.
 

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Discussion Starter · #18 ·
@BigBlue 94 @CrazyBRONCOguy Thank you both for your input and suggestions, as for what engine I would plan swapping in the future it would preferably be a 408 stroker but small chance of it being a 347 stroker. I never thought of just getting a sniper or other type of efi system as I already have the pumps and line for it to just drop right in. Absolutely great information being I got this bronco almost 2 years ago. Now if I did go with the sniper or something like it would I be able to transfer that over to a swapped 408? Or does the sniper kit I'd be looking for only work for the 302?

@pfun41 @dash_cam Both great points, that might just be the route I take for this engine with the junkyard harnesses and sensors. I've already changed out my TPS and IAC Valve for new parts, as for doing the O2 sensor it shouldn't be all that hard to find everything I need on a junkyard truck. I feel this motor is on it's last legs so throwing a stupid amount of money at it definitely isn't the best idea. Also if I do put in sensors will the computer just see that automatically and adjust as needed? Or will I have to get it tuned?

Side note, the motor that is in it is as far as I know the stock 302. It does have polished finned aluminum valve covers on it. From what I can see the passenger side cover would be a pain to remove as the manifold top is right there so would it be a logical assumption that maybe the motor has been rebuilt or swapped at some point?
 

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@BigBlue 94 @CrazyBRONCOguy Thank you both for your input and suggestions, as for what engine I would plan swapping in the future it would preferably be a 408 stroker but small chance of it being a 347 stroker. I never thought of just getting a sniper or other type of efi system as I already have the pumps and line for it to just drop right in. Absolutely great information being I got this bronco almost 2 years ago. Now if I did go with the sniper or something like it would I be able to transfer that over to a swapped 408? Or does the sniper kit I'd be looking for only work for the 302?

@pfun41 @dash_cam Both great points, that might just be the route I take for this engine with the junkyard harnesses and sensors. I've already changed out my TPS and IAC Valve for new parts, as for doing the O2 sensor it shouldn't be all that hard to find everything I need on a junkyard truck. I feel this motor is on it's last legs so throwing a stupid amount of money at it definitely isn't the best idea. Also if I do put in sensors will the computer just see that automatically and adjust as needed? Or will I have to get it tuned?

Side note, the motor that is in it is as far as I know the stock 302. It does have polished finned aluminum valve covers on it. From what I can see the passenger side cover would be a pain to remove as the manifold top is right there so would it be a logical assumption that maybe the motor has been rebuilt or swapped at some point?
You can test oil pressure and compression to get an idea of what condition it's in. but it's more likely to run like shit if it's running rich. With some sensors it helps to disconnect the battery after replacement for about 20 min, then let the engine idle for a few minutes so the computer can calibrate. Also Don't blindly throw new sensors on. Many parts store sensors are junk. If you go with a new O2 sensor get a Bosch or NGK. They can be had cheap and make the OEM sensors for many cars (OEM for broncos is bosch but I run NGK as Bosch tends to lean slightly rich).

Different valve covers mean nothing, people swap those for various reasons all the time. All it means is the intake was off at some point.

Nothing you do is gonna make much difference until you get an O2 sensor back on there, as it's stuck open loop running pig rich to compensate for the lack of feedback.
 

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Discussion Starter · #20 ·
You can test oil pressure and compression to get an idea of what condition it's in. but it's more likely to run like shit if it's running rich. With some sensors it helps to disconnect the battery after replacement for about 20 min, then let the engine idle for a few minutes so the computer can calibrate. Also Don't blindly throw new sensors on. Many parts store sensors are junk. If you go with a new O2 sensor get a Bosch or NGK. They can be had cheap and make the OEM sensors for many cars (OEM for broncos is bosch but I run NGK as Bosch tends to lean slightly rich).

Different valve covers mean nothing, people swap those for various reasons all the time. All it means is the intake was off at some point.

Nothing you do is gonna make much difference until you get an O2 sensor back on there, as it's stuck open loop running pig rich to compensate for the lack of feedback.
Oil pressure is 12-15 psi at warm idle. New sensors weren't blindly thrown on, the old TPS wasn't reading accurately and was worn and IAC was replaced as it sporadically idled when it was warm going from where it sits normally at around 1000 rpm dying off to 600 rpm then coming back. These were both cheap sensors and the TPS works fantastic whereas the IAC is now a new one but tells me there is a vacuum leak somewhere cause it didn't fix it. Understandable about the valve covers, just had some hope maybe it was a newer engine than the original. As for the O2 sensors i know there is one downstream sensor but some wiring diagrams I've seen show an upstream one closer to the manifold. Maybe just on a little newer than mine?
 
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