86 efi 302 idle problem
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86 efi 302 idle problem
I have a 86 4x4 302 efi truck with longtube headers and full true duals, and a cold air intake, stock otherwise. I have had no problems at all out of this truck for the past 2 years, and have not driven it much, just once every week or two, and starting wednesday night, i drove the truck about 40 miles. It drove fine. The next morning, after a 45 mile drive, the truck would not idle, would die at a stop sign. if you rev it up, its fine and driving it is fine. just when it idles, in park or gear, it seems like i have a cam in it, it sounds like it is misfiring. Last night we changed the plugs and cap and rotor, seemed to help for a few minutes, then after driving a few miles, same situation. I have a spare IAC solenoid i am going to try out on it, but anybody have any other suggestions?
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Joined: Jan 2007
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From: Martinsburg, WV
Clean the IAC and check out the voltage at the, make sure it's in spec. Also you or someone else haven't messed with the the Idle stop screw have they? is the rough idle accompanied by a fast clicking sound, like a solenoid or relay?
Fuel Injection Technical Library » Throttle Position Sensor (TPS)
Fuel Injection Technical Library » Throttle Position Sensor (TPS)
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yes, the idle screw had been messed with, just trying to keep it running, and yes there is a fast clicking sound over by the vacuum relays on the pass fender. I dont see any vacuum leaks anywhere either. My next plan was to take off the iac and clean it well, test it out. what voltage should it be at?
Logistics Pro
Joined: Jan 2007
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From: Martinsburg, WV
Follow the link for the specs. You will need to reset the base idle as well, I think that site has info on that as well. I went through this recently on my truck The clicking is the EGR solenoids fluttering the vacum to the EGR valve, keeping it open at idle as well as the ecm dumping more fuel. You will probably find the TPS reading high, making the ecm think the throttle is open further than it is. I had replaced the TPS with an aftermarket unit and it was defective, chased it for over a year off and on. I ended up getting a motorcraft unit, setting the base idle back where it needs to be and has been fine ever since. One of the worst things you can do is mess with that screw.
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