Periodic Surging Idle
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Logistics Pro
Joined: Oct 2008
Posts: 4,818
Likes: 1
From: Avilla, IN
Periodic Surging Idle
Here's how it goes:
Start the truck up after its had enough time to be cool.
Easy Start, Smooth Constant Idle,
As the engine warms up, it begins to sound like it running poorly, like its sputtering or something. When this happens the idle will be surging up and down like 100 rpms. It seems random, but it never goes below the normal idle speed, it only surges up. (I would think if it really was a sputter the rpm would decrease, right???) When I drive it hard to see how it acts, it feels like I've only got about 50 horsepower.
Once the engine is fully warm, it runs fine, has a steady idle, and seems to have the correct amount of power.
The fuel filter was changed 1500 miles ago, and the oil and oil filter 800 miles ago. Motorcraft 15W-40.
Also it doesn't seem to matter if its 100* or 60* outside.
Ideas???
Start the truck up after its had enough time to be cool.
Easy Start, Smooth Constant Idle,
As the engine warms up, it begins to sound like it running poorly, like its sputtering or something. When this happens the idle will be surging up and down like 100 rpms. It seems random, but it never goes below the normal idle speed, it only surges up. (I would think if it really was a sputter the rpm would decrease, right???) When I drive it hard to see how it acts, it feels like I've only got about 50 horsepower.
Once the engine is fully warm, it runs fine, has a steady idle, and seems to have the correct amount of power.
The fuel filter was changed 1500 miles ago, and the oil and oil filter 800 miles ago. Motorcraft 15W-40.
Also it doesn't seem to matter if its 100* or 60* outside.
Ideas???
Hotshot
Joined: Jun 2007
Posts: 10,008
Likes: 7
From: Austin, TX
Sounds kind of like what mine is doing, but I haven't taken time to look into it. Mine has all the power it should at all times, but idle will surge every now and then when it's warming up. Check ICP and see if it's jumping with the idle. My ICP will jump up and down around 100psi quickly and this is when the idle will start jumping around. I haven't figured out what is causing it, but I'm leaning towards my injectors being the cause of mine.
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Logistics Pro
Joined: Oct 2008
Posts: 4,818
Likes: 1
From: Avilla, IN
I replaced the ipr o-rings about a year and a half ago.
Maybe the ipr itself is briefly sticking?
I don't have a scan gauge, would a hydraulic pressure gauge react fast enough to see it?
Travis, does your truck seem powerless while thats happening?
Maybe the ipr itself is briefly sticking?
I don't have a scan gauge, would a hydraulic pressure gauge react fast enough to see it?
Travis, does your truck seem powerless while thats happening?
Post Fiend
Joined: Dec 2010
Posts: 10,121
Likes: 3
From: Orrville, Ohio
I believe a liquid filled hydraulic gauge will work so long as it is a 3000lb gauge. Somebody on here just had a thread bout that a week or so ago. I guess it cost them about $70 or so to build the lines and gauge.
Hotshot
Joined: Jun 2007
Posts: 10,008
Likes: 7
From: Austin, TX
I'd say the next step would be to verify that your getting sufficient high pressure oil pressure.. Most of us use a scanner to check things like this, but you can also build a mechanical gauge to do this and watch it while cranking. The injectors need around 600psi of oil pressure in order for the engine to start.
The gauge will have about 3 feet of hose. On one end of the hose you will have a 4000psi liquid filled gauge and the other end the hose will connect into one of the ports in the oil rail that you have been loosening to let air out of the system. Find a hydraulic shop and have them set you up with this stuff.
What you'll need:
Just run the line and gauge away from moving parts and up towards the cowl. You can lay it up under one of the windshield wipers so you can look at it while you crank the engine. You can also do this while driving for those of you looking to check pressure while driving and don't have a scanner.
The gauge will have about 3 feet of hose. On one end of the hose you will have a 4000psi liquid filled gauge and the other end the hose will connect into one of the ports in the oil rail that you have been loosening to let air out of the system. Find a hydraulic shop and have them set you up with this stuff.
What you'll need:
- 0-4000psi liquid filled gauge
- About 3' of hose rated for (minimum) 3000psi working pressure (12k psi burst rating!) with the gauge on one end, and a #6 female JIC swivel fitting crimped onto the other.
- You will also need an individual fitting to screw into the head to go from the head to the hose. This single fitting will be a 45 or 90degree fitting # 5 "male boss" (sometimes called # 5 o-ring) on one end of the 45, and a # 6 male JIC on the other end of the 45.
Just run the line and gauge away from moving parts and up towards the cowl. You can lay it up under one of the windshield wipers so you can look at it while you crank the engine. You can also do this while driving for those of you looking to check pressure while driving and don't have a scanner.
My truck doesn't lose power. It will just bounce around at idle like a bobble head doll sometimes. Once it's warmed up it doesn't do it and dead cold it doesn't do it. Always does it while it's warming up. Like after it gets over 100* oil temp. It's weird, but I haven't felt the need to chase down the problem on mine.
Try unplugging the ICP while it's idling like that and see what happens.
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