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I hope someone will be able to help me out here. This is going to be a
little long, but I want to give the background of what I've done over the
last few of weeks.
A couple of weeks ago, while changing the oil on my '86 GT (AOD) I noticed
that there was some coolant leaking from the "weep hole" on my waterpump.
Not wanting to wait until the last minute, I went out and bought a new
waterpump and 180 degree thermostat. When I started the teardown to replace the waterpump, I saw that
my fan blades were seriously cracked (original nylon fan), and that the fan
clutch was shot. I had been having ongoing overheating problems, so I
decided to yank out the fan and clutch assembly, and replce it with an
electric fan set-up. So I installed the electric fan, the new waterpump and
the 180 degree thermostat. I adjusted the knob on he fan to come on when the
(stock) gauge reached the mid-point in the normal range. Fast forward one
week...
I started getting a surging idle while stopped at stop lights or while
sitting in traffic (L.A. traffic sucks!). No big deal, I'd replaced the idle
air bypass valve just last month for the same thing, so I would just pull it
off and clean it. I pulled it off, and it was still clean, but cleaned it anyway just to be safe. The
surging continued, and got worse, along with serious hesitation while accelerating
and at speed. It almost felt like the engine was dying for a split second
while I was doing 60mph. I started doing it worse and worse the more I drove
the car. It also started bucking when the AOD was trying to shift into high gear, almost like it was trying to go into high but couldn't quite make it. By the time I limped it home it sounded like an old neglected
1970's POS land yacht ( picture: chug chug chug chug). Not good! My fuel
milage started to really dropped at the same time. I normally get 18mph mixed
city and highway...this time I was at 12.5mpg. so anyways I got it home,
pulled a plug and they were very heavily carbon coated. I replaced the
plugs, cleaned the cap and rotor and it ran better. The next day I could
tell it was happening all over again. It started running VERY rich (it
sucked down 1/2 tank of gas in 11 miles).Okay it sounded like it was (at the very least) time for a
tune up. I replaced the PCV valve, cleaned the PCV filter screen, new plugs
again(motorcraft, gap .050), new ford Motorsport 9mm wires,MSD cap and
rotor, and a new MSD Blaster coil. I checked the TPS and it checked out ok,
then reset the computer. So tonight after I finished this all up, I start up
the car and it sounds like it should except for the occasional missing. I
took it out, filled up the tank and drove for 10 minutes of so, and now it's
doing it all again. I just chug chug chuged it back to my house (my eyes are
still burning from the unburned gas in the exhaust smoke..light grey) and am now pleading
with you for some ideas. HELP!!!
Rich
:confused:
 

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I had similar effects, and it was the fuel pump on its way out....not sure if all of the symptoms match yours though....sorry if this is not correct
 

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Before you changed out the waterpump and fan you were all right and never had these symptoms? I would suspect that the electric fan could be causing you a problem, What does the voltage gauge read while the fan is on ? You might want to just disconnect the fan and see if that makes any difference.

Also have you checked for codes? Could be that you ECT is acting up and causing the EEC to try to compensate.


Bill
 

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rich

I had the same problem when i put on my electric fan. When i hooked itup It was wired through the air conditoining so when the a/c came on the fan came on. One day when i had my a/c on it did the same thing. Like you said chuig,chug, chug, and it barely wanted to move. When i turned the a/c off it cleared up and ran fine. I would say if it was anything its something with the wiring on yours. But i dont know what type of fan you put on or how you've got the thing wired. It never repeated itself during normal operations. Hope this helps ya out. (I had a blackmagic fan)
 

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I had similar symtoms a while ago, surging, extremely rich, it turned out the problem was the air charge temp sensor. It's in the #5 intake runner, check it with an ohm meter, from the terminal to ground, resistance should not be infinite.
Hope this helps
 

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I agree with the guy that mentioned it is probably due to modifications you have made. I also saw someone found a prob with it wired to ac compressor. When your ac comes on-idle goes up right. So there is a connection between ac-fan-idle control. Maybe there is some backfeed causing problems for your ecm. Whenever you are running rich-check your fuel pressure first-this is common among fords-more on exploders and rangers but still I would check it. If you have a wire spliced into ac clutch wires I would pull it out and go for a test drive. Good Luck
 
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