today i replaced the plugs and wires on the father inlaws 99 f150 4.6l. not really all that hard at all. with conversation and about 6 beer it took just about 2 hrs to complete. i bought the plugs and wires from a local ford dealership. i did have one unusual thing though. number 1 plug hole was about 1/3 to 1/2 full of oil. all the plugs were in bad shape (over 200,000,km). the electrode end of the plug was fine (no oil was getting past the threads) and the hole was not full. after close inspection i couldn't find any problem and assumed that someone before must have some how spilt oil in to the plug hole. anybody seen this before? also i pulled code "1504" from the computer and my scanner couldn't tell me what that is. i do have the iac unplugged as it was acting up and unpluging it lets the truck idle properly. is the above code just for the iac or is it something else?
thanks.

 

The following is from the"1999 MY OBD System Operation Summary for Gasoline Engines" document available at Motorcraft's website along with model years 1996-2005.

http://www.motorcraftservice.com/vdi...t&menuIndex=28

Engine Outputs
The Idle Air Control (IAC) solenoid is checked electrically for open and shorts (P1504 or P0511) and is functionally checked by monitoring the closed loop idle speed correction required to maintain the desired idle rpm. If the proper idle rpm cannot be maintained and the system has a high rpm (+100) or low rpm error (-200) greater than the malfunction threshold, an IAC malfunction is indicated. (P1506 or P0507, P1507or P0506)

IAC Check Operation:
DTCs : P1504 (opens/shorts)
P1506 (functional - overspeed)
P1507 (functional - underspeed)

Monitor execution: once per driving cycle
Monitor Sequence: None
Sensors OK:
Monitoring Duration: 30 seconds

Typical IAC functional check entry conditions:
Entry Condition___________________________________Minimu m Maximum
Engine Coolant Temp______________________________150 oF
Time since engine start-up_________________________30 seconds
Closed loop fuel____________________________________Yes
Throttle Position (at idle, closed throttle, no dashpot)____Closed Closed

Typical IAC functional check malfunction thresholds:
For underspeed error: Actual rpm 100 rpm below target,
closed-loop IAC correction > 1 lb/min
For overspeed error: Actual rpm 200 rpm above target,
closed-loop IAC correction < .2 lb/min

 

what a great technical site. bookmarked that one. thank you very much jcstratt.