Intermittent high idle issue

[NavyVet88]

2002 Ford Ranger Edge 3.0L 104k

Randomly while driving I’ll come to a stop at a light or stop sign and notice the truck is setting around 12-1500 rpm instead of the normal 700ish. At first I put the truck in neutral to see how it would react at a stop sign and it shot up to just over 2k rpm’s and putting it back in driving of course caused a hard jerk due to load. After restarting when leaving the store it was normal and no issues for the rest of the drive home.

IACV was replaced about a year and a half ago due to failure. A vacuum leak be constant I think.

 

[Lubener]

I would look for an intermittent vacuum leak. Look at the brake booster or PCV vacuum lines. A code scan could reveal something. Fuel trims would go highly positive with a bad vacuum leak as well..

 

[partspro]

I think the IACV could be defective or you have an air leak somewhere

 

[billt460]

Can you "kick it down" in neutral when it does this?

 

[NavyVet88]

I would look for an intermittent vacuum leak. Look at the brake booster or PCV vacuum lines. A code scan could reveal something. Fuel trims would go highly positive with a bad vacuum leak as well..

I plan on hooking up my reader a bit later after my little boy wakes up from his nap and I’ll post back with what I find.

 

[NavyVet88]

I think the IACV could be defective or you have an air leak somewhere

It was an auto zone branded valve so that is a possibility. I’ll give it a good look when I can.

 

[HankHill]

2002 Ford Ranger Edge 3.0L 104k

Randomly while driving I’ll come to a stop at a light or stop sign and notice the truck is setting around 12-1500 rpm instead of the normal 700ish. At first I put the truck in neutral to see how it would react at a stop sign and it shot up to just over 2k rpm’s and putting it back in driving of course caused a hard jerk due to load. After restarting when leaving the store it was normal and no issues for the rest of the drive home.

IACV was replaced about a year and a half ago due to failure. A vacuum leak be constant I think.

Check your PCV hose and valve. Aftermarket PCV valves are garbage, get a motorcraft one for proper operation.. Check out the ford taurus forum, they have TONS of avalible solutions for the 3.0 OHV motor:

https://www.taurusclub.com/forums/

 

[The_Eric]

Also look at tps. If you've got access to a decent scan tool/live data, look to see if it thinks it's at part throttle when it's doing it.. If it thinks it's at part throttle, then it will open the iac to cushion the drop in revs when you close the throttle.. This is done to prevent a rich condition.

 

[HankHill]

Also look at tps. If you've got access to a decent scan tool/live data, look to see if it thinks it's at part throttle when it's doing it.. If it thinks it's at part throttle, then it will open the iac to cushion the drop in revs when you close the throttle.. This is done to prevent a rich condition.

Live data feed is awesome for detecting sensor issues.. Best thing ever.

 

[NavyVet88]

Sorry guys, been pulling daddy duty today plus the weather is crappy. I haven’t had a chance to check the live data on my reader. What should I look for in the data? I’ll be honest I’ve never pulled live data to troubleshoot an engine. Most all of my experience has been mechanical and obvious type stuff.

 

[NavyVet88]

Check your PCV hose and valve. Aftermarket PCV valves are garbage, get a motorcraft one for proper operation.. Check out the ford taurus forum, they have TONS of avalible solutions for the 3.0 OHV motor:

https://www.taurusclub.com/forums/

The hose and cable are both motorcraft OEM as of two years ago. I avoid aftermarket unless it’s an absolute emergency.

 

[NavyVet88]

Can you "kick it down" in neutral when it does this?

By kicking it down do you mean fast like shifting?

 

[NavyVet88]

Check your PCV hose and valve. Aftermarket PCV valves are garbage, get a motorcraft one for proper operation.. Check out the ford taurus forum, they have TONS of avalible solutions for the 3.0 OHV motor:

https://www.taurusclub.com/forums/

Thanks! I just created an account and posted.

 

[billt460]

By kicking it down do you mean fast like shifting?

A bit like the way you started a carbureted engine with an automatic choke. Once it started cold it ran at high idle, until you "kicked it down" by stabbing the accelerator pedal.

This would disengage the fast idle cam, allowing the vehicle's idle to drop down. I can do that with my 1991 F-150, even though it has electronic throttle body fuel injection. But not with my Jeep, (2015) or my Toyota Camry, (2018). They are totally controlled by the computer.

You just have to wait until the computer lowers the idle. That takes longer than it should with my Toyota. Once the engines are hot, they will drop to a 650 RPM idle almost immediately after starting.

 

[Junk]

Sorry guys, been pulling daddy duty today plus the weather is crappy. I haven’t had a chance to check the live data on my reader. What should I look for in the data? I’ll be honest I’ve never pulled live data to troubleshoot an engine. Most all of my experience has been mechanical and obvious type stuff.

I'd check for codes, but the live data I'd be looking at would mainly be short term and long term fuel trim, banks 1 and 2. The total of short and long term trim per bank should ideally be +/- 10%. If you have a vacuum leak your number will be way positive. Common vacuum leak points on the 3.0 are mainly the PCV hose/elbow assembly that goes from the rear of the intake manifold to the PCV valve in the driver side valve cover. If that's the problem it'll be mushy, and if it's causing an intermittent vacuum leak it'll probably be split as well. Have seen these cause weird intermittent issues quite a bit.

 

[HankHill]

I'd check for codes, but the live data I'd be looking at would mainly be short term and long term fuel trim, banks 1 and 2. The total of short and long term trim per bank should ideally be +/- 10%. If you have a vacuum leak your number will be way positive. Common vacuum leak points on the 3.0 are mainly the PCV hose/elbow assembly that goes from the rear of the intake manifold to the PCV valve in the driver side valve cover. If that's the problem it'll be mushy, and if it's causing an intermittent vacuum leak it'll probably be split as well. Have seen these cause weird intermittent issues quite a bit.

Every one of the 02-05 older 3.0 ohv's high mileage motors I've seen there has been either elbow issues, original plugged PCV valves at 150k, or sometimes leaks in the stiff plastic colored emissions control lines. I avoid like the plague touching them, but you have to for the intake manifold removal. Known issues are so depressing when you know somethings coming at you soon.

 

[The_Eric]

Sorry guys, been pulling daddy duty today plus the weather is crappy. I haven’t had a chance to check the live data on my reader. What should I look for in the data? I’ll be honest I’ve never pulled live data to troubleshoot an engine. Most all of my experience has been mechanical and obvious type stuff.

You'll be looking at tp voltage - don't remember the exact number but it should be under 1.1 ish volts. Also in the lines of data, there should be one that looks something like "Throttle (or throttle position)" CLOSED or PART THROTTLE. If you see part throttle, then you know the computer is purposely hanging the throttle open because it thinks you're driving with the throttle off the idle position. It hangs it open like that because if you're driving and close the throttle, the engine will go momentarily rich and thats bad for emissions and catalyst life. So what it does is open the iac in anticipation of you closing the throttle. Then it will slowly lower the engine speed to idle.

 

[partspro]

You'll be looking at tp voltage - don't remember the exact number but it should be under 1.1 ish volts. Also in the lines of data, there should be one that looks something like "Throttle (or throttle position)" CLOSED or PART THROTTLE. If you see part throttle, then you know the computer is purposely hanging the throttle open because it thinks you're driving with the throttle off the idle position. It hangs it open like that because if you're driving and close the throttle, the engine will go momentarily rich and thats bad for emissions and catalyst life. So what it does is open the iac in anticipation of you closing the throttle. Then it will slowly lower the engine speed to idle.

Since my name is Eric I agree with Eric, the engine computer and the other computers on the CAN network all talk to each other to determine what should happen. Since many have 'Adaptive Learning' the continually evolve to match your driving style .

 

[NavyVet88]

I'd check for codes, but the live data I'd be looking at would mainly be short term and long term fuel trim, banks 1 and 2. The total of short and long term trim per bank should ideally be +/- 10%. If you have a vacuum leak your number will be way positive. Common vacuum leak points on the 3.0 are mainly the PCV hose/elbow assembly that goes from the rear of the intake manifold to the PCV valve in the driver side valve cover. If that's the problem it'll be mushy, and if it's causing an intermittent vacuum leak it'll probably be split as well. Have seen these cause weird intermittent issues quite a bit.

 

[NavyVet88]

The images above are the truck idling at running temp WITHOUT the high idle issue. I couldn’t replicate the high idle to save my life. Does anything in my data pull catch your eye?