Bonco with 302

[cj41foley]

I picked up a 86' Bronco 4x4 with a 302 and fuel injection about a month ago. I drove about 3 hours to go get it and got there and it would start and idle fine but driving down the road it would spit and sputter under mild acceleration. Got it back home and checked the fuel pressure and it was at 30 psi but it was dropping down to about 10 psi when it was acting up. Replaced the in tank and frame rail fuel pump along with fuel filter and fuel pressure regulator. Problem solved. It still had a little skip in it but it acted like a firing problem like plugs or wires etc. Well I went out to the barn the other day and was just going to drive it on the property a litte bit. I cranked it up and let it idle a bit and noticed it was idling pretty rough and putting a little bit of black smoke out of the exhaust. Now I love black smoke but not out of a gas burner...lol..it's acting like a carburetor with the choke closed, ,what to do? Maybe Idle Air Control, mass air flow??? I don't have a clue on all this fuel injected mess. I've got to get it running right and get that top off for summer. I only paid $800 for it and the body is rust free and straight and everything works fine. It's a little dull and the inside is a little used but it appears to be very solid. I want to put about a 6" lift with 36's on it and wheel the mess out of it. This is my 3rd Bronco but my other's were a good ole carburetor. Any advice? TIA sorry for the long post

[bigcountrysg]

Originally Posted by cj41foley

I picked up a 86' Bronco 4x4 with a 302 and fuel injection about a month ago. I drove about 3 hours to go get it and got there and it would start and idle fine but driving down the road it would spit and sputter under mild acceleration. Got it back home and checked the fuel pressure and it was at 30 psi but it was dropping down to about 10 psi when it was acting up. Replaced the in tank and frame rail fuel pump along with fuel filter and fuel pressure regulator. Problem solved. It still had a little skip in it but it acted like a firing problem like plugs or wires etc. Well I went out to the barn the other day and was just going to drive it on the property a litte bit. I cranked it up and let it idle a bit and noticed it was idling pretty rough and putting a little bit of black smoke out of the exhaust. Now I love black smoke but not out of a gas burner...lol..it's acting like a carburetor with the choke closed, ,what to do? Maybe Idle Air Control, mass air flow??? I don't have a clue on all this fuel injected mess. I've got to get it running right and get that top off for summer. I only paid $800 for it and the body is rust free and straight and everything works fine. It's a little dull and the inside is a little used but it appears to be very solid. I want to put about a 6" lift with 36's on it and wheel the mess out of it. This is my 3rd Bronco but my other's were a good ole carburetor. Any advice? TIA sorry for the long post

Make it carburated, replace intake, with a 4 barrell intake and through a carb on it. Get an ignition box like msd or something and get rid of all that electronic crap. But on another note O2 sensors may need replaced, mass air sensor maybe bad, Cats maybe clogged. Just some ideas for ya.

[cj41foley]

Well a carburetor would be an easy thing to do but I like to be able to bounce around off road and climb steep hills without the carburetor flooding out and sputtering. fuel injection is gonna stay just got to get it right, it's nice to be climbing a big steep hill and stop on it and not have your motor stall out

[jngreen]

I don't think that in 86 the 302 had a Mass Air Flow sensor.
I think it had a MAP sensor (manifold air pressure).
I had a 91 F350 with the 351 and it had the same symptoms (smoke, rough idle). I had to replace the O2 sensor to fix the problem. Be prepared, they are usually a PITA to get out and are not cheap to replace but prolly less than $100. Your cat might also be plugged. Some people can get away with taking out the cat completely but you run the risk of throwing check engine lights, but I do know a few that don't. (Mine did.)

Basically, If all of your mechanical parts are functioning properly, then you have a sensor problem. Most likely in your intake or exhaust system. If you could get a good scanner to run tests, it could possibly point you to the sensor that is causing the problems.

[cj41foley]

yeah I'm gonna get rid of the cats, and look into it more this week when I'm off

[MrJohnWayne]

you can gut the cat and nix the 02 sensors. Don't remember who but someone makes some dummy 02 sensors to replace the factory ones.

[cj41foley]

nix the 02 sensors???????????

[MrJohnWayne]

Yeah instead of replacing the 02 sensor in the pipe you can plug in a dummy 02 sensor that will always give the computer the same reading. They kinda take away while the motor is cold, but once it hits op temp you're good to go.

[cj41foley]

what would it hurt if I just unplugged them, I'm not worried about emmissions or tickets or anything, I just want to get it offroad able

[pipelayerjdh]

You could try an EEC-1V Code reader and see if anything is outta wack. I have never had any lights come on after removing the cats.