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Bronco II MISSES BAD


Kalebgearhart

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I have a 1987 Ford Bronco II that broke down up the mountain yesterday. I killed it on a steps incline and it would just click instead of starting so we tried jumping it but that didnt work so we pulled it over the crest of the hill and tried push starting it down a hill but still nothing.

Ended up at the end of the day today replaced the ignition control module because it failed autozones test but the coil passed. Still pretty sure I need a starter solenoid cause it just clicks from the key. I arced the solenoid to start it.

It ran rough and the muffler was glowing red with a hole in it then after it cooled down i kept going and now the cat was glowing so we unbolted the cat and that made it idle on its own and not die but any acceleration and its missing really bad. If i can get it to 4500 rpm it sounds fine and smooth but between 800 and there all it does is miss and shake with no power.

Please help, i think it might need plugs and wires but i wasnt sure if they would all go bad at the same time. Thank you in advance
 


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alwaysFlOoReD

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Overheating cat makes me think like it is running rich. Change the o2 sensor.
 

RonD

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Also check the Fuel Pressure Regulator(FPR) vacuum hose
FPR has the return fuel line attached AND a vacuum hose, if FPR starts to leak then raw gasoline will be sucked into the engine via that vacuum hose, causing rich running and flooding out
Pull off vacuum hose and check it for gasoline

Yes, if you can jump fender mounted relay(solenoid) and starter motor works, then replace that relay
Positive battery cable will be on one larger post with ALL the other wires, thats the power distribution point for the whole vehicle, make sure all connectors are clean
The other larger post just has ONE wire(cable), it goes to starter motor

Then there can be 1 or 2 smaller posts, if 1 then its the "S" post, if 2 then it will be "S" and "I" post, they will be marked that way
The "S" post is what activates this relay, it gets 12volts from the ignition switch(thru the neutral switch) when key is turned to START
So if you have an "I" post it won't be used in 1987

Make sure relay is grounded to fender via its bolts, so clean off any rust or ??, on bolts or fender metal where it touches relay's metal housing
 

Kalebgearhart

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Just checked the vaccume hose and its dry so it cant be that right?
 

Kalebgearhart

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Update, unplugged the number 6 injector and nothing changed at idle or with any throttle. Replacing it today and see what happens
 

Kalebgearhart

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The injector didnt do it so I changed the o2 sensor like alwaysFLOoReD said but still nothing. Checked the timing today and it was off but so we adjusted it but it still misses under load except for the higher rpms like 4500. Any help is appreciated
 

Paulos

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Have you pulled any codes off the ECM/ECU? Also, I would clear the ECM after changing any sensors, etc.
 

Kalebgearhart

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I didnt know you could pull codes on something this old, where do you plug in to? Also how do you clear the ECM?
 

Paulos

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Kalebgearhart

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Ill try to check codes in the morning, thank you
 

Kalebgearhart

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Can there still be codes if my cel isnt on?
 

Cees Klumper

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Yes there can be codes.
I would also check for vacuum leaks. They are really sensitive to those. Twice now I forgot to attach a vacuum hose, or plug, and it would run very poorly. One diagnostic method I use is plug a vacuum pump (like Mityvac, for brake bleeding etc) into each hose going FROM the intake manifold to wherever: auto trans modulator, cruise control, heater system, brake booster. They should all hold vacuum pretty good. If not, the ECU gets bad input and can't run the engine properly. Good luck
 

Kalebgearhart

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Couldnt figure it out so I took it to the shop. They diagnosed it distributor
 


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