» » »

Ford Q&A

Ask Your Question

2003 Ford Ranger Question: I'm having high idle and revving issues, suspect vacuum leak but lines are solid

 

Question

toughtruck, 4.0L V6, Trabuco Canyon, CA, November 15, 2013, 21:43
 Rookie

I just spent the last two days working on my truck, checking the lines, replacing a couple parts, and researching trying to fix her. But nothing seems to help.Research around and found a few that sounded like the problem I am having and tried what was recommended, but nothing seems to make any real changes. So here it goes, I'm tired of throwing money away with no resultsTruck started to idle and run real rough, loss of power, loss of throttle response, feels like I'm towing a fully load trailer behind me while driving. She sounds like she is idling real high ( almost what it would sound like when it is revved up to 5000 RPM's ), and whistling, but the RMP shows she is only idling at 1200 and I have her set to 800-1000 RPM. While driving if I go over 2100 RPMs sounds like the engine is going to blow. Worst part about this is it's not even throwing any codes, I can force a code to be thrown, and yes the check engine light works.I've checked, cleaned and even replace the Idle Air Control (IAC) valve. Replaced after covering the ports and noticed it wasn't opening when the truck would start and could feel it trying to engage. The symptoms reduced a little after replacing.It was recommended to replace the Throttle Position Sensor. No change.Truck will idle and sound perfect once the IAC valve is unplugged and still attached, but once you give her any gas the over revving and whistling sounds return for a few seconds but goes away. Also with it unplugged the truck RMP gauge shows her idling between 800 and 1000.

1 Answer
Flag This
  • Answer #1

    cardocIII from Gillespie's Auto Service, November 16, 2013, 01:56
    Profile_thumbnail
     Master

    Its one thing to pull codes with a cheap puller, its completely different to use a fully functional scan tool that can report all the possible data and perform bi-directional control commands. For one thing, you really don't have control of where you set the idle speed. You can try and change the throttle plate angle, but the PCM will simply turn around and change the command to the IAC to try and get the idle speed that it wants. If you open the throttle plate too wide manually, to the PCM that simply looks like you want to speed the engine up or even accelerate in gear, and then it commands the IAC open as a dashpot function to prevent a stall when the throttle plate gets closed. If you can get the data, what is the current idle speed, and what is the IAC command and the TPS voltage being reported?

    I can't hear the excessive noise you mentioned, but a locked up clutch fan will sound like an airplane . making a significant roar, and I've found a few of the fans with cracks that make them vibrate. Inspect that carefully because it could break with the engine running and result in pieces flying out.

    One last thought, you said it feels like your dragging a fully loaded trailer behind you, as in the truck has no power? A restricted exhaust is a possibility. That being said the best way to continue is with a technician who has the experience and the right equipment to work his/her way through the symptoms. The information you have here is fine to build a picture of what we would expect to see the vehicle doing, but testing is required to confirm what is going on.

    Reply
    Flag This