I have a 1997 Ford F-150 6-cyl 4.6 liter with a few miles short of 200,000. It now has a very low idle speed , sometimes dropping below 500 rpm. At times, the idle gets so low, it feels like it is running out of gas and about to die. I can hear a stream of wind (maybe an air leak in the intake manifold) but cannot locate it. I have replaced the IAC sensor as well as cleaned the MAF sensor but am not sure if I want to put out another hundred dollars on a part that will not fix the problem. Anyone have any ideas as to what may be causing the problm before I replace the MAF?

 

Sounds like a vacuum leak. check all the PCV lines, you can spray them with TB cleaner and if the idle comes back up you found the leak, but it should be loud enough to get pretty close just by sound. I'd clean the MAF long before I'd just replace it.

 

If you do clean the MAF sensor, make sure you are very careful in how you do it. They are very fragile and can be broken easily. I would only use a electronics spray cleaner on it and don't try and use a brush on it. If you know someone with a scan tool that gives live data can tell you if it is working properly.

 

Yep, and I am guessing it is a 4.2L since you said it is a V6.

 

thanks for the help, i am going to clean the MAF sensor again and try to find that leak if there is one, i will post what happens

 

Has your check engine light came on? If not you may want to get your fuel pressure checked?

 

yes the check engine light is on, but it could be a whole list of things because my engine overheats, my slave cylinder is busted and i dont get much pressure to my clutch, and the abs light is on as well. i am just fixing it one at a time but dont know which (or if all) problems are making the check engine light come on. The truck runs fine when it is not idling, so i dont think its the fuel system, however.

 

hi, if it is the v6 try the 90 degree rubber boot under the inlet manifold in the middle. there is a pipe that goes right to the back of the passinger side rocker cover. the rubber perishes badly. bokker.