2000 Grand Marquis with idle control valve problems
2000 Grand marquis - same as crown Vic, have 4.6 with 125,000 miles on it. Have had no problems with the car with general maintenance and upkeep until a year ago, started making a howling noise coming from the air intake / air filter box area. Had it diagnosed and asked on this forum and got the answer that it was a idle air control valve. Bought an after market - not Ford product.
I then drove it after turning off the check engine light - noticed the engine running extremely cold - but the noise was still there - light came on again and the code said the temp was too low - replaced thermostat - reset light erased codes and then drove it - temp is fine now but the noise is still there and intermittent - at a light at normal operating temperature pull up and stop, the engine idle will speed up and noise starts as the idle control vale speeds up the idle - but for no reason - then it stops and returns idle to normal - sounds like it is working but this happens repeatedly and gas mileage now sucks because the idle is too fast about half the time.
Any suggestions ?- it's almost like the computer tests the control valve and says - OK - your working but it just is completely annoying - and not just the noise which can freak people out next to you at a light or parking lot. The codes which it originally came up with were 1504 or 1506 depending upon my unplugging or plugging and which control vale (the original or the new) that I installed.
appreciate any help as I am trying to avoid taking it to the shop - rather do it myself.