i have a 03 2wd ranger edge with the 3.0 5 spd. it revs its self up on its own and i cant figure out why. at a stoplight it will rev up to 3500 at times without touching anything. i have already put on a new tps and iac, cleaned the throttle body, and checked everything with the throttle linkage and it still does it. thoughts?

 

Got a cracked vacuum line somewhere? Flaky wire connector for TPS?

 

checked the vacuum they all look pretty good except one. and it still isnt that bad but will replace this next week. and wire connectors looked fine

 

it doesn't do it consistently. rpm usually stays between 2000-3500 but sometimes will idle normal. will sometimes do it in while moving to and it will cruse at around 45 mph without touching the gas

 

Welcome to the forum

RPMs are set by air flow, thats the point of the throttle plate/"gas" pedal setup, its an "air" pedal
If you add more gasoline to an engine without adding more air all you get is a flooded engine

After engine is warmed up and idling, unplug the 2 wires on IAC Valve
It will close an RPMs should drop to 500 or so, engine may even stall, either is good it means no air leaks at idle.
If RPMs do not drop then there is an air leak

TPS(throttle position sensor) reports throttle position to computer, it doesn't control air flow, it is a mechanical part not electronic, so can wear out, replacing it when its older is fine

Computer issue, could be computer is loosing its sanity, lol.
Get a OBD reader and check for communications with computer and then any codes, there should be a few.
You are looking for odd ball codes or no communications, meaning computer is failing.
Also disconnect MAF sensor, its a main sensor, and make sure computer now shows a MAF circuit problem, so is correctly reporting codes


You can get BlueTooth OBD2 readers for under $40, they connect wirelessly to your smart phone or tablet, APPs are free or $5
They can be use to get codes of course but also to watch LIVE DATA while you are driving, which can be helpful when diagnosing a problem.

OBD2 is not a Ford thing, ALL vehicles sold in US or Canada from 1996 to now were required by Law to use OBD2, so these readers will work on any vehicle 1996 and up

 

no codes are given when i went through the vaccum lines the hose between the pcv and the pcv elbow basically fell apart when i touched it but i can't find a new one anywhere. its about 3'' long and one end has an id of 3/8 and the other side has an id of 5/8. i can't find a replacement anywhere

 

does the pcv have to have vacuum pressure? can i just close off the hole on the intake and run a hose down for it to drip out of?

 

You should be able to find a short heater hose that is molded for the angle, I assume 90deg bend
Then cut it to fit
get 5/8" and then use plastic tape or ??, to build up diameter of small connection and use a hose clamp.


No you need it connected, it is a "Known/Planned" vacuum leak, less at idle more at speed, so computer is set up for that

 

i'm not talking about about the elbow its a straight line that runs between the elbow and the valve cover. tried generic ones but they won't fit

 

ok i got that figured out so now all the vacuum new and it still does it. will test the brain box tomorrow

 

update i ended up braking down and taking it to a shop. the reflashed the computer and it ran great fro like 3 days then started doing it again. looks like it needs the brainbox, thanks for the help

 

Not a common issue but can happen, considering the amount of engine computers out there, one in every vehicle since around 1985, there are not that many failures.

Thanks for the update

 

I've been having this high idle issue for quite a long time. Over a year to be exact. I have replaced the IAC the MAF the PCV and all the vacuum lines that looked like they needed attention with no solution. But I finally found it. It was the IAC. The part I replaced it with was an aftermarket part from AutoZone. The bolts lined up. The connector fit. But it still idled high. So I thought that it could not be the IAC. But after looking at all the forms and everyone pointing to the IAC. I decided to go with a Motorcraft branded unit. After replacing it, it immediately solve my problem. comparing the innards of the two, they are very different in design and quality.

Life lesson: buy oem

Hope this helps

 

Good work

Thanks for that diagnosis, yes some OEM parts are just better

 

After reading this thread and some light troubleshooting, I picked up a new IAC. Worked great! Such an easy fix, I’m kind of scared

Thanks again!