EFI 460 high idle
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Senior User
Joined: Feb 2004
Posts: 180
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From: Vancouver
EFI 460 high idle
well this has bin buggin me for a while now.. the truck idles at 1000-900.. this is kinda high.. i would like it around 800.. but how do u adjust the idle on these computer controlled motors?? thanx
Junior User
Joined: Jan 2001
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EFI idle setting
The idle RPM is set in the computer. It is not adjustable. Your high idle is a symtom of another problem. Try checking your ECT sensor. If your ECT always tells the computer the engine is very cold, the idle will stay high. Have you checked if you have any stored trouble codes in the computer? Like a bad ECT sensor code?
Just some random thoughts...
John
Just some random thoughts...
John
Junior User
Joined: Jan 2001
Posts: 81
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MIL trouble codes
You may not need a programmer. On my 1994 you can jumper a wire on the test connector under the hood near the brake master cylinder and the Check Ingine light on the dash will flash out the trouble codes. The proceedure and codes are on many websites. This may or may not work on your newer (OBD-II) truck.
Hope this helps...
-john
Hope this helps...
-john
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Senior User
Joined: Feb 2004
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From: Vancouver
hmm well the thing is.. i have no service engine soon light on the dash?? it works.. but its not on when the truck is running.. so the computer thinks the truck is running fine right?? so theres gota be somethin thats makin the idle raise... hard to say
Post Fiend
Joined: Jun 2003
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From: Black Hills of SD
I had a bronco 2 come to my shop from a dealership with a similiar problem. Routine troubleshooting following the reccomended flowcharts came up with nothing. When I got into it with the breakout box I found they had the connectors for the coolant temperatur sender and the air charge temperature senders swapped. Both had the exact same connecter. The aircharge sender doesn't return the right voltage signal for the computor to see a warm engine and keeps it on high idle. That was pre-obd 2. They had just did a head swap on this vehicle. If your problem arose after repairs it may be related. The coolant sensor is cheap and easy to replace so you might try a new one if you don't have the diagnostics available. I would reccomend paying extra for OEM parts from the dealer.
You might also check for vacuum leaks. The computor can only close the throttle so far or the IAC valve. If there is false air being introduced the O2 sensor will provide the fuel for the extra air and keep the mixture right so it may not have much of a drivability problem.
You might also check for vacuum leaks. The computor can only close the throttle so far or the IAC valve. If there is false air being introduced the O2 sensor will provide the fuel for the extra air and keep the mixture right so it may not have much of a drivability problem.
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Senior User
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From: Vancouver
well i took a good look at the 2 different sensors.. u were right about them being the same.. but the connection is very slightly different so they didn't fit not to mention the wires wernt long enough to swap them to over.. this is really bothering me now.. i looked many times for vacum leaks also.. but found none.. 
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Senior User
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From: Vancouver
ok this really sux.. today i replaced the IAC and TBS... also not to mention i put a MSD coil in.. still idleing same as before.. i don't understand... the old IAC was a little carboned up.. but that doesnt explain y the new one aint doing its job right.. time to get a computer code reader i guess... looked at one today.. for $300.. ouch...
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Senior User
Joined: Feb 2004
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From: Vancouver
k after day 2 of installing that new IAC sensor im getting a check engine light after the truck warms up..... its like im just makin things worse bye trying to fix the problem... no one have anymore ideas? is there a way i can reset the computer?? maybe it needs to relearn the new sensors?? just a thought... 
Posting Guru
Joined: Mar 2003
Posts: 1,349
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From: Cloud USA
My 93 460 idles at 900-1000 RPM. I cant figure out the problem either. Maybe thats just the way they are programmed. I know my Cam shaft is really worn and when I put the new motor in this spring I hope it will help. When I cost to a stop from say 40mph and just push in the clutch it stays about 1200rpm until I come to a complete stop. 210,000 miles might have something to do with it. I replace the timing chain and gears last summer but didnt correct the idle speed.
Elder User
Joined: May 2003
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Check the TPS. There is a spec on what it should be at idle. On my old 302 it was 1.0 olms resistance. It might or might not be the problem, but, it was on my 302. If you have a meter, it doesn't cost anything to check it. Just pull the plug on it and check the resistance.
Cargo Master
Joined: May 2001
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Definitely get after the vacume leak search. The idle on the fuelies is controlled by how much air goes around the throttle plates via the IAC valve. Ie: a controlled vacume leak. You can plug the line going to the IAC and see if the idle changes. If it doesn't then it is getting air some where else. I have seen bad PVC valves do this or bad air plenum gaskets usually if and intake port is leaking bad you will have a cly that misses.
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From: Vancouver
well i have replaced the PVC... did nothin.. but maybe the air plenum gasket?? is that the one that goes between the throttle body? or th eone between the intake and manifold? i do have a slight miss at low rpm...