Idle sticks during shifting, motor overspeeding

[green2000]

Hey guys,
My first post. I have a 2000 Ranger with the 3.0 and its driving me crazy! I cant hardly drive my truck right now. So here is the story:

Everything starts out fine when I drive to work in the morning, until I get above 45mph or so or get on the highway. When I get to a stoplight or off the highway and come to a stop the idle stays at the level it was when I was flying down the highway!!
From then on when I shift the Idle speed stays at shifting levels (2000-2500ish) when I depress the clutch to shift gears. So Im slamming the truck into the next gear like I never took my foot off the gas!!
Then at a stop light it sounds like my truck is gonna explode because it is revved up so high, while I sit there and I cant fix it. Tapping the gas wont do it, just makes it worse. Only way to lower the RPMs is to shift to 5th Gear prior to coming to a stop.
By the way the CEL has been on for a long time.

What I have done:
Changed the IAC....TWICE!!! No change.
Cleaned the MAF, no change.
Got the codes read at Advance Auto and it throws a "DPFE low voltage" and thats it.

Any help is appreciated.

 

[monsterchuck]

Just off the top of my head, but an erratic throttle position sensor could cause that. Also, you may not have lean exhaust codes(P0171 and P0174), but look for vacuum leaks anyway.

 

[green2000]

Sounds like a TPS issue to me,,,,but Im ignorant! Makes sense though. If the throttle wont return to original position, then it kinda makes sense.
Is the TPS easily changed and where is it in relation to the DPFE/IAC?
Thanks for the response monsterchuck!

 

[naford]

The DPFE is an easy fix and has to do with the EGR. So I'd start there first.

 

[90jurassic2]

My truck was doing this. It was just a vacuum leak for me.

 

[green2000]

How did you find the vacuum leak?
Where did you start looking and did you use Carb cleaner or soap?

 

[GentleRF]

When I first got my '86, it had the same issue. What I ended up doing was add a throttle return spring. It made the accelerator a bit stiffer but then it did stop the over revving. Later on, I put a throttle body on it which was the better solution.

Rick in East Bremerton

 

[RonD]

What I would check first is the throttle plate return spring.
From your statement "Tapping the gas wont do it, just makes it worse"
It reads like once you have opened the throttle plate to a certain point the engine RPM is holding it open via air flow, you could get more RPM but not less by tapping the gas pedal.
Once you slowed the RPM, via 5th gear, the air flow would be less and throttle plate could close.
Could be the spring or bushings are worn so there is a stiff part when plate opens and can't easily close again.

Check the throttle cable and cruise cable if so equipped.

 

[Earl43P]

Clean the IAC. It controls idle. (Edit: replaced twice, DOH)
Leave some carb cleaner in the body of it.
Thwock it against your palm repeatedly so that the plunger slides along the shaft you just cleaned. Cover the ports while doing this to agitate the carb cleaner inside.

Here's good info on vacuum leaks: http://www.therangerstation.com/Magazine/Summer2003/VacuumLeaks.shtml

A very common leak point on the 3.0 is the PCV elbow on the rear of the head. Pretty hard to see it without a mirror since it is so close to the firewall.

Disconnect the battery and turn on/off headlamps. Reconnect battery. This will clear the codes and make it re-learn its idle strategy.
Start the truck in neutral, apply brake, don't touch the gas pedal for 4 min.
Turn on AC, wait another 4 min.
Drive the truck normally for a couple days. See if that helps.

Normal idle behavior for your 2000 3.0 is like this:
Idle is boosted so rpms hang high when above 5mph and shifting.
If you put it in neutral and coast to a stop, the idle will hang at 1200-1500 until you pass through 5 mph, then it should drop to about 800-900. If it's not doing that, you have a problem.

Fixing the bad DPFE may help ($45 part). Pay attention to where each hose goes, it matters. One is SIG the other is REF. Inspect the hoses for cracks.
Do the same battery disconnection to reset the computer when you replace that part.

 

[green2000]

Thanks for the detailed troubleshooting process!! I will be giving that a try for sure.

Heres a weird update. I checked out the throttle return spring and sprayed the crap out of it with carb cleaner.....truck drove all day like nothing was ever wrong!
Next day it was back to its old tricks.So I sprayed it down again with carb cleaner.
Today it ran fine all day.
Didnt find any vacuum leaks yet, but still looking.

 

[WindChaser]

I had (so far so good) the same issue on my '93 2.3L. I replaced the throttle return spring (didn't fix), then the TPS (didn't fix it), and yesterday I put a spare (used) IAC on and it seems to have fixed it. I hope anyway.

 

[90jurassic2]

Mine was on the throttle body, the little thingy (don't know what it's called) that stuck out. It might not be a vacuum leak. It just was for me. Sorry I can't help more hoss.