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here is a engine problem for you, some one please help.
i have a 1997 f150 with a 4.6 and about 190K miles on it. the problem is, is that when i come to a stop and the truck is idleing it is only at 490- 510 rpms, and sometimes i will stop and it will drop down to 200-300 then jump back up to 500, when it idles at 490-510 it shakes, not terably but it does have a "rithim" to it. also this only happens when the truck has fully heated up, when the temp gauge says anything lower than it's usual running temp. when in park and neutral, and fully heated it's rpms are at about 550.
i thought it was the IAC and so a couple months ago i replaced the IAC and i pretty much solved the problem, the rpms still weren't at 700 but were alot better and never droped down, and just recently i changed the oil and started running it on premium it sarted doing it again.
could running it on premium be causing the problem? should i replace the IAC again? could it be the TPS? or some other problem?
Any kind of help would be greatly appreciated. thank you
p.s i looked undernieth my hood, to see if anything looked wrong and i noticed that a couple of my spark plug wires a resting on the head covers, somone told me your wires should not toch any hot part of your engine, could this be it?
I would be inclined to agree that it may be the TPS sensor.
I would thoroughly inspect for a vacuum leak first. Check the PCV hose real good, mine went bad at 32,000 miles.
Jimmy
I believe that it has just deteriorized and got a hole in it back near the throttlebody. The dealer replaced it under warranty so I never really saw it.
Usually if it is the EGR or DPFE sensor, you will get a code for them.
Jimmy
at least the EGR and DPFE are easy to get to! just get a good repair manual. you really don't even need a good one, if you're in a pinch a Haynes will do. fifteen bucks and available at any Autozone or Advance Auto! Chilton manuals are more in depth, but they are also a bit harder to comprehend and can be harder to find.
i am going to have my friend look at it this weekend when i go racing, he was the one the helped me replace the IAC and has saved me about $500 so far, i will see what he says. what does the EGR and DPFE do? i don't know if i said this before but i had 2 o2 sensors replaced a year and half ago, could the others be going bad? bec when the others went bad, they made the check engine light come on.
Differential Pressure Feedback sensor. it's part of the EGR system. pretty likely you'll have to get this from Ford. NAPA doesn't even list it.
you'll find it just to right of the throttle body. it's a 3"X4" silver box w/ an electrical connector and two vacuum hoses attached to it. one of those hoses connects to the EGR valve.
Yes that sounds like the right part.
With all the problems that DPFEs are prone to I'd buy a genuine Ford one which has been updated, even if it cost more.