I have a 94 full size Bronco w/5.8 engine that has problem running when engine is cold. After engine warms up - it is fine. I have had it at 2 differn't Ford Dealers and they are unable to fix it. 1st shop replaced hegar sensor and cleaned throttle body. 2nd shop replaced fuel filter, fule pump and fuel regulator and swapped many diff parts. They had it for 3wks and finally called me to pick it up and said they could not fix it. It does not show any codes...I am out of money and very frustrated....any suggestions would be greatly app.

 

[font size="1" color="#FF0000"]LAST EDITED ON 21-Jun-00 AT 09:41 AM (EST)[/font][p]Check the engine temperature sensor's connector. If any corrosion is there, the coolant temp input to the computer will be off high (it will think the engine is warmer than it really is). Clean the corrosion off the connector and sparingly apply new silicone dielectric inside the connector. If the corrosion is on the pins of the coolant temp sensor, replace it.

Another common problem with this vintage 351 is the upper intake plenum gasket going brittle and cracking. This causes a vacuum leak right into the lower intake manifold.

The gasket is easy to replace and cheap. You only remove the 2 air intake hoses, the PCV hose at the back, throttle and other linkages, and one screw and nut combination on the passenger side (plenum support bracket). Then remove the 6 bolts holding the plenum (the snail-looking thing) and it should pull right off.

The gasket will have 8 holes in a line, each corresponding to each cylinder. It will likely be paper thin, brown with heat, and cracked. Replace it with a good gasket (I bought mine at a CarQuest store). For about 30 mins work and $3 for the gasket, you've got a much better seal.

Good luck.
Mike