84 vs 85
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Senior User
Joined: Feb 2005
Posts: 234
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From: Vancouver, Canada
84 vs 85
I have an 84 bronco II which I was having some major problems with my rebuilt carbs. I moved to Canada where auto wreckers are far more plentiful than in California and picked up a used carb off an 85 bronco II. Needless to say my truck runs amazing, good power I'm only throwing a few codes, one for the knock sensor and another for the EGR no seating properly. Any who my question is that my 84s air cleaner assembly is different than the one on the 85. My 84 air cleaner has a vacuum motor connected to the heater door that is activated to divert air from over the exhaust manifold in order to heat the Truck up faster. Both model years have this feature but all the 85s I have seen do not have the vacuum motor that has a vacuum motor attached to the back of the carb. Instead it is directly activated by a vacuum solenoid attached to the passenger side fender well. Am I able to switch my older 84 system out for the 84 without any modifications to the computer system.
I know this all kind of sounds confusing, please ask me if you need any extra information.
-Thank You
I know this all kind of sounds confusing, please ask me if you need any extra information.
-Thank You
Post Fiend
Joined: Jun 2002
Posts: 13,873
Likes: 3
From: Atlanta GA
Basically, yes, because the 84/85 are dumb systems and are not looking at the vacuum system directly and it is more spark control then anything else.
> one for the knock sensor and another for the EGR no seating properly.
Fix the knock sensor! I don't know where it is on the 2.8, 2.9L it is lower driver's side. A bad knock sensor will cause the vehicle to run poorly because the computer goes in default mod and will not advance the spark. Which is pretty much SOP for most Fords, so I imagine the 2.8L is the same way.
re:EGR
Could be dirty, but, more likely it has a vacuum tee or hose broken somewhere. Last one I worked on/owned (1984) was back 2002 and I can tell you I think 3 dozen connections is what I counted ... or it seemed it
If you do not have vacuum, it thinks the EGR is bad.
If you do not have to met emissions, you might want to consider a Duraspark II conversion.
Might try a new PCV.
> one for the knock sensor and another for the EGR no seating properly.
Fix the knock sensor! I don't know where it is on the 2.8, 2.9L it is lower driver's side. A bad knock sensor will cause the vehicle to run poorly because the computer goes in default mod and will not advance the spark. Which is pretty much SOP for most Fords, so I imagine the 2.8L is the same way.
re:EGR
Could be dirty, but, more likely it has a vacuum tee or hose broken somewhere. Last one I worked on/owned (1984) was back 2002 and I can tell you I think 3 dozen connections is what I counted ... or it seemed it
If you do not have vacuum, it thinks the EGR is bad.
If you do not have to met emissions, you might want to consider a Duraspark II conversion.
Might try a new PCV.
