alright.. so here we go i have bought this truck recently and now i am stumped and want a second opinion before i go and get a new IAC valve.. when i turn on my truck she idles up at about 1500 rpms.. first i want to know if that is a normal idle range for these 4.9 5 speeds? if it is cool no worries.. had an explorer that would idle really low and it needed an IAC valve so thats why i am thinking it is the IAC on this one.. i cleaned the electrical connections and inspected my throttle cable and everything looks to be good.. like i said just wanting a second opinion before i buy another IAC valve

Nick

 

When the truck first starts up 1500 RPM is not too bad. Does it idle back down to a normal RPM or does it remain high? It is stays high then I suspect a vacuum leak or something is telling the PCM to bump up the idle RPM. If the idle drops back down, then everything sounds like it is okay. If it remains high then try unplugging the IAC. If the idle remains high you have either a vacuum leak or a stuck IAC. If the idle drops then you have a sensor issue.

 

i'll try it out once it stops raining.. we may get a tornado today too..

 

unplugged IAC and it remained at 1500.. i see another guy with a similar problem on the forums.. when i first start it up the idles go to like 2000-2500 then drop to 1500 almost instantly.. then when throwing into gear and engaging clutch the idles drop down to about 1k right when it bites.. i know my rpms are going to be a little bit higher then a 2wd but i think 1500 is high.. will take off the IAC valve completely and hit it with some brake cleaner tomorrow when the weather clears up.. i have replaced a ton of vacuum lines just because they were cracked and i thought that was my high idle issue but i think i have replaced all the visible vacuum lines that were bad.. when i take my IAC off i will also go back through and make sure i replaced all the bad tubing and see what i come up with

 

The "High Idle" issue is probably the most common one on this forum. We need a "sticky" at the top of the first page.

 

well thanks for your input.. it is POURING right now.. hate this NC weather.. it is very bi polar.. we had snow the other day and now we are having tornado weather.. make up your mind mother nature.. another note, did ford offer sunroofs factory in their trucks in 88? anybody know? i have a sunroof in a 1988 f150 4.9 4x4 long bed..

 

a sunroof? does it open up or its just a piece of glass in the roof? ive never heard of one of these trucks with a sunroof.

 

yeah opens up.. not power sunroof but it has a latch and you can open it and the back side pops up about 2-3 inches..

 

hmm. never heard of one from the factory. that sounds like an awesome feature though. is it a standard cab?

 

yeah sure is, no AC has sliding rear glass and the sunroof thing.. (which leaks) need to re do the weather stripping which i will do when i have a dry day to take it off and re do it all without having to rush.. right now some good ol duct tape is keeping my seat dry.. i actually really enjoy the sun roof and it makes it kind of unique