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I have a 89F150 4x4 with the 300. It is a new jasper with virtually everything replaced on it. When it is cold out and it is first started it runs fine for about 45 seconds and then it starts surging and will usually die. If it doesn't die it will quit after a few minutes. I took it to a very good mechanic and he replaced the idle sensor, computer, cleaned the throttle body and a few other things I can't remember. He said that there is a sensor for the temperature but it checked out ok. He is stumped. I'm out a lot of money and still have a truck that doesn't run right. Any suggestions?
Donald
TFI = Thick Film Integrated ignition module. It is right on the base of the distributer. My experience is that if this goes bad, it won't start at all. Mine decided to go at a pitstop in Coalinga, CA in the middle of a trip from Seattle to San Diego. Good thing there was a Motel 6 right there. Anyway, mine also has a problem with hesitation/stumble. I found a tech service bulletin on the Mitchel Repair CD ROM that addressed it. It wsaid it can many times be caused by the EGR opening up too fast going from a stop especially when it is cold out. It details a fix that has you install a ported vacuum switch in the thermostat housing which prevents the EGR from getting vacuum until the coolant is warm. It gives ford part numbers of the things you'll need right in it. I haven't done it yet for other reasons (money/living in warm SoCal) and I can live with it. It only does it very briefly so if I just push it the clutch and take it easy for the first few minutes, I am fine. It probably applies to your injected '89 as well. I can send you a scanned copy (and anyone else too) if you email me at rpspwp@home.com. Good luck.
It could also be a problem with the EGR itself sticking open. You may want to pull it off and knock the carbon off the seat or just replace it all-together. When I swapped mine after failing a smog test in '94, they gave me a different style that used an extra diaphram btwn the EGR solenoid and the EGR valve. It is a back pressure transducer type EGR that uses exhaust pressure to modulate the vacuum signal to the EGR so it opens/closes more smoothly. Just a thought.
Not sure if this is the same thing or not but, my 87 F-150 was surging and running like crap, numerous "good mechanics" with the computers telling them the "MAP sensor was out of range", but they knew better because those things never go bad. After I got tired of the experts I was refered to a friend of a friend who worked at Ford and had a used MAP sensor laying around, we plugged in the new one and Problem Solved! Sometimes the "experts" experience is their worse ememy. Hope this helps.
I have had the same problem w/ my 89 F-150, 300-I6, with 115,000 miles on it. (Up in the cold MI climate) The problem started up right around 100,000 mi (engine overhauled at 95,000). I've found that the best fix is to start the truck, and when the surging starts, I get on the gas and hold the engine at about 1500 RPM for another 30 seconds to a minute. After that it'll idle down fine.