Help! i just installed all new plugs and wires on my truck last night, i started it up, and it ran fine for a while then i took it around the block to test drive it and then i hit a stop sign and my truck dropped to about 400 rpm then died. i dont know why, but i had a bunch of lines disconected to make for easier acsess to the plugs, but i checked and double checked that all vaccum lines were re-installed. My truck is a 97 with 323,000 miles on it, so i know its tired but it ran beatifully before i changed the plugs and wires last night. any ideas???

 

Did you gap the plugs correctly? Are the wires installed properly? Is it firing on all cyclinders? If the above work checks out install your old wires and see if it helps. If not, try the old plugs with new wires. Last resort, old plugs, old wires and figure out why the new stuff doesn't work.

 

ive been working on it all day and i dont think its the plugs and wires, because it runs fine and doesnt misfire at all. how can i change the idle to make it idle higher? maybe my iac is bad, i dont know i can try getting one of a truck at the junkyard for a few bucks. i dont want to take the time to change out the wires and plugs again, that took a while cause there is no room to work with in there. any more ideas why it idles so low?

 

Can anyone tell me how to adjust the idle on my 4.6L f-150 to get it back around 600 rpm?

 

Did you try tapping on the idle speed control motor??

Try cleaning it too. Before changing it.

 

Either the IAC (Idle air control) is bad or those vacuum hoses you disconnected are reconnected incorrectly or leaking or some vacuum hose is still not connected. Since the engine ran ok before you worked on it I would suspect that it is in those vacuum hoses/lines you disconnected.

 

Did you try disconnecting the battery and resetting the computer. These trucks have to "learn" their idle. You can also try removing the IAC and cleaning it with throttle body cleaner.