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Black soot and missing @ 2500-3500 rpm


PuebloBroncoII

New Member
Joined
Apr 9, 2008
Messages
2
Vehicle Year
1986 Ford Bronc
Transmission
Manual
I have 86 Bronco II 2.9 engine. About two weeks ago I had a problem with the engine missing. I replaced the MAP sensor and solved the problem. Along the way i Also repalced the EGR valve and the IAC. After I fixed that it now idles perfect and tops out perfect but in between about 3000 rpm it misses bad and seems like its starving for gasor something, but if you push the gas to floor it straightens out. Also i notice when idling it shoots black soot from the tailpipe and has an odor like its running rich. I replaced the fuel filter as well. Any ideas of what this problem may be would be greatly appreciated.
 
Just a couple off the cuff ideas, but I'd check the fuel pressure regulatorand look for kinks in the return line.

Ken
 
Sometimes when MAP sensors go bad, the gel inside the map comes out the vacuum port and goes down the vacuum line. Make sure that vacuum line isn't partially plugged up. Also, about the fuel pressure regulator, pull the vacuum hose off and turn the key on, make sure no fuel comes out from a ruptured diaphram. It would run real bad with a fully ruptured FP regulator, so that probably isn't your problem.
 
I cleaned the vacuum line out and also the ports connecting as well. Still no change. I still need to check the fuel pressure regulator and see where that leads. Would the cat converter have anything to do with the black soot coming from the tail pipe?
 

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