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91' 4.0l idle and throttle trouble

Joined
Mar 3, 2012
Messages
84
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6
Location
Virginia
Vehicle Year
1987
Make / Model
Ford Bronco ii
Engine Size
2.9
Transmission
Manual
recently i swapped my blown up automatic for a manual, rebuilt the motor and put headers on. ran great! exhuast leak happened and blew a gasket. yanked motor and two of the stage 8 locking header bolts broke! many others bent just buy unbolting them. dont buy them if you value your truck cuz they are junk!!!! getting to the point, i got diff bolts and dropped the motor back in. now it idles way to high and chokes down when i push the clutch in. it has no throttle responce either. at wot it has nothing and after more than a few agonizing seconds i get the power but lose it when i change gears. its also died on me a few times goin down the road. so today i got a tps, iac, coil pack, and icm. put the tps on first and nothing. then leaving the tps on i threw the iac on and it idled down to 500, too low for the motor, then i put the coil pack on and it was even worse. lastly i put the icm on. seems about the same. on flat ground now it has power but on hills it wants to die still. after each sensor id unhook the battery for a while. it hesitated less at wot this time after a while. the computer may be learning how to operate, im not sure. the idle did smoothe out over time and got up to 700. right now its outside idling. it died once out there. im almost at a complete loss. ive cleaned the enitre air intake tube system and air box, cleaned my filter with that k & n filter recharger -great stuff btw- replaced the maf sensor. the battery is a 65 series(biggest thing they put in fords-i work at fisher auto parts). i had the factory altenator rebuilt. i run pure gas(right now its got high test in), ive replaced the fuel filter. got new autolight pro series wires and motorcraft single platinum plugs. starting to think this thing is pos.
 
Last edited:


Handlin_Business

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Jan 5, 2013
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Vehicle Year
1992
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Ford
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Manual
Check out your mass airflow sensor. Mine was half unplugged, previous owner had broken the clip, it was attached with silicone. i was pulling my hair out for weeks limping it to school and back. (poor throttle response, bogging down especially in lower gears, stalling between shifts or at stoplights) all kinds of problems. take a look. might need to spray a bit of electric parts cleaner in there too if youve got some debris or grime
 
Joined
Mar 3, 2012
Messages
84
Reaction score
0
Points
6
Location
Virginia
Vehicle Year
1987
Make / Model
Ford Bronco ii
Engine Size
2.9
Transmission
Manual
its new and ive already pulled the sensor out of the housing and cleaned it. starting to think this junkyard ecu has gone bad. self tested the system and it was throwin every code at me. think the tps is faulty, no volt reading at all and the plug is showing readings
 
Joined
Mar 3, 2012
Messages
84
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Points
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Location
Virginia
Vehicle Year
1987
Make / Model
Ford Bronco ii
Engine Size
2.9
Transmission
Manual
Problem found and fixed.
 

PanamaExpat

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May 28, 2011
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Location
Panama City, Rep. of Panama
Vehicle Year
1994
Make / Model
Mazda
Engine Size
4 liter
Transmission
Manual
So what was the problem? My next suggestion was going to be loose bolts or bad gasket on lower intake.
 
Joined
Mar 3, 2012
Messages
84
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0
Points
6
Location
Virginia
Vehicle Year
1987
Make / Model
Ford Bronco ii
Engine Size
2.9
Transmission
Manual
Nah lol I sprayed carb cleaner everywhere and none was suckd up. Besides I have all new gaskets. The tps was grounding out somewhere between the ecu and the sensor. Multimeter found it. The sensor was getn like 7 volts and reading wot at closed throttle. Backpropbed the sensor w a safty ping and tied a ground wire to the eyelet and grounding the wire to the battery was a insta fix!!!!. I need a carburetor'd motor.
 

Andy D

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Jul 9, 2011
Messages
1,940
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Location
Marshfield MA
Vehicle Year
94
Make / Model
The Rat
Engine Size
4.0 OHV
Transmission
Manual
My credo
to prevent Found On the Road Dead, Fix Or Repair Daily
Good job finding trouble.
 

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