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Discussion Starter · #1 ·
I'm having an issue with my 2007 F250 6.0 surging on light acceleration. The surging seems to be lessened when the engine has reached operating temperature, and on some cold days, can be noticeably felt by me and my passengers. It's also very rhythmic, moving about +-100rpm every second. The surging seems to start after 2nd gear, but once the torque converter locks, the issue appears to disappear.

The problem doesn't present itself when cruising at a steady pace, and I think this is because the locked converter prevents any rapid RPM changes.

I have an additional problem of an occasional rough idle. The truck will idle smooth and fine, then get into a fit of +-200RPM variance, then return to normal. A/C being on or off makes no difference during this rough idle.

I've performed the following recent maintenance on the truck:
- New FICM power supply (shows 47.5v at all times)
- New Motorcraft fuel filter
- Recent oil change with Motorcraft filters and oil

I have a laptop with AutoEnginuity. I've verified that:
- ICP pressure matches ICP desired(closely, but not exact?)
- FICM power supply voltage is 47.5v
- The live data meter shows the drop in RPM's on acceleration(to rule out the gauge, even though I can feel it)

Other quick Information:
- The truck does not seem down on power. A full throttle acceleration at cruise seems to pull as much as I would expect.
- I don't think this is a HPO leak as the truck barely cranks on a hot start and fires.
- The truck otherwise runs fine. Sometimes this surging seems to dissipate completely.
- Absolutely no smoke unless it's a snap WOT at low speed, where a small haze will be left.

Some ideas I've had:
- Replace the ICP sensor, based on the rough idle...
- Possibly the turbo vanes need cleaned, but I don't see how this would create a rough idle.
- I've ordered a fitting to test the fuel pressure, but since the truck accelerated fine at WOT, this wouldn't seem to be the case to me.
- I'll be pulling the EGR valve to check it's condition, though I don't feel these are the typical symptoms of a plugged EGR.

I've searched and searched on this issue but haven't quite found a topic with the same symptoms. Many deal with ICP sensors and rough idles, but my idle is not nearly as rough as some of the YouTube videos. I would explain it as a momentary stutter. If anyone has some input or has seen these symptoms before, please let me know.
 

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Discussion Starter · #2 ·
I ended up taking a look at the EGR valve just in case. It looks pretty clean compared to what I've seen online, and there wasn't any noticeable fluid inside the intake. Gave the EGR valve a quick cleaning anyways. Also replaced the ICP sensor with a known good one. No change. Worth the 5 minutes it took I suppose.

Also figured out the issue is present with the truck in parked and revved to around 1800-2500 RPM. The truck is unable to maintain a consistent RPM and has the same surging even with no load.
 

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My first guess would have been EGR valve. Also check fuel pressure at the pressure regulator.
 

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Discussion Starter · #4 ·
My first guess would have been EGR valve. Also check fuel pressure at the pressure regulator.
Thanks! Decided to check it now, found a buddy with a fuel pressure test fitting. Fuel pressure looks good at idle and on snap WOT acceleration, though at the time I was not encountering any surging! Did have a breakthrough though, the truck threw it's first code today, P0263(Cylinder #1 circuit Contribution/Balance fault). After an oil change and a useless contribution test, took the truck on the freeway and beat on it and that seemed to finally get the truck to notice an issue. I'll be going through the harness tomorrow in case there's a short, might even try some RevX everyone seems to be on about, but I think I'll be doing the injectors next week. If I had to guess this one is sticking open too long or something.

I'm guessing this is related to my FICM failure I drove on for a couple days :frown2: Hopefully this leads somewhere.
 

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I like Archoil myself, but I doubt that will help your problem.
 

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Discussion Starter · #6 · (Edited)
wI'm at a loss and haven't made any progress on this issue.

I tore the truck apart, did the standpipes and dummy plugs, and replaced injector #1. Truck now has a very smooth idle and sounds great. I again verified fuel pressure just in case. However, this ridiculous surging is still present.

This guy seems to have an identical problem to mine, but unfortunately never posted a solution:
http://www.thedieselstop.com/forums/f23/irregular-jumpy-rpms-while-accelerating-climbing-294301/
I notice an irregular pattern in the RPMs. While accelerating/climbing the RPMs go up in a stepwise fashion. It is not when shifting gears, which is smooth. It goes up 2-300 RPMs, then jumps up another 200, etc. You can feel the truck pull forward in this stepwise fashion.
The only difference being he never mentions a surging in park when reving 1800-2500 RPM's.

So far I've verified the EGR Valve and EBP sensor are clean. Unplugging either has no effect on the surging. Again, the truck has no loss of power and otherwise runs and drives completely fine.

Equally as annoying, this TSB explains my issue perfectly, but apparently doesn't apply to my 07...
Some 2004-2006 E-Series/F-Super Duty and 2004-2005 Excursion vehicles built before 8/22/2005 and equipped with a 6.0L diesel engine may exhibit various light surging concerns upon light acceleration from stop to 50 MPH (80 Km/h) typically on cold start, 1800 to 2800 RPM in drive or neutral, or under high load typically pulling a trailer and/or going up a grade (prolonged light surge). The concern normally occurs right before a transmission upshift event, or if transmission is held in gear where engine speed is steady 1800 to 2800 RPM.
If anyone would like to see some datalogging from AutoEnginuity or has any other advice, please let me know. I'm grasping at straws trying to figure this problem out.
 

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It sounds like you're on top of this. I found it to be a good read up to the point there was no ultimate outcome.

Have you considered checking the Throttle Position Sensor(s)?
 

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A similar surging I had recently let me to an failed vgt solenoid. Swapped it out with my buddy problem solved got a new one coming.
 

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I was thinking TPS too. Sometimes they don't set a code.
 

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Discussion Starter · #10 · (Edited)
Still having the issue, just haven't had much time to mess with the truck lately. Still drives absolutely fine, though the colder the truck is in the morning, the worse the surging will be until it warms up.

I'm torn on the throttle position sensor, I feel like the issue wouldn't be present with cruise control if that was the case. I do think I can view the TPS output in AutoEnginuity, I'll give that a try tomorrow. I'm super hesitant since the peddle seems to work fine at all other RPM ranges. I'd rather try just replacing the VGT Solenoid before spending the money on a new peddle. The only doubt I have on the VGT Solenoid is that I don't feel like much boost is used in neutral while revving, yet that's when the surging is also present.

It's been in the back of my mind that this could be turbo related(IE VGT Solenoid or sticking vanes). Now that's it has finally gotten cold here in Arizona and the problem has worsened in the morning, I've noticed the turbo whistle changes pitch with the change in RPM's. Really seems to be a chicken or the egg situation on whether that's related. Since I'll be updating the STC fitting I planned on cracking open the turbo this weekend anyways to run through that idea.

I'll post if I reach a resolution between the two ideas.
 

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Discussion Starter · #11 ·
Finally had some time to tear into the truck! Pulled the turbo this morning, cracked it open and found a slightly worn unison ring where the actuator hole is ovaled out. I've read this normally occurs due to rust however my unison ring and housing actually look like they're in pretty good condition. I'll be polishing it into a shine and have a new unison ring on the way tomorrow for $150 from Amazon. If I don't post here again this was the solution!
 

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Discussion Starter · #12 ·
I'm stuck on this truck. Cleaning the turbo veins and replacing the unison ring had no effect on the surging issue. I am now leaning towards the VGT Solenoid or the EBP sensor.

I am very hesitant to just throw parts at the truck. I'm again trying to diagnose this through Autoenginuity. The only anomaly I have found on my truck is a consistent surging in the EBP sensor. I've attached the output from AutoEnginuity. If anyone knows if this is indicative of a specific problem, please let me know.
 

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No idea about test but sending you more lucks to found the issue, it will sure save more people dealing this situation.
 

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Discussion Starter · #14 · (Edited)
Unplugged the EBP sensor hoping it would go to an 'inferred' reading. Knew from the start something was better, what used to be an incredibly 'noisy' truck had the smoothest idle I could only remember driving off the lot. Took the truck for a drive and the surging was history, acceleration was as smooth as I could ever want it to be, and the sound from the turbo was absolutely amazing. The truck was experiencing a very slight delay when building boost and a similar delay when dumping boost(I suppose they're called turbo farts? The sure sound good to me!).

Obviously not looking to continue driving a truck with unplugged sensors. My research is telling me this is actually a symptom of a bad VGT solenoid.

Similar explanation of issue, same 'problem solved' with the EBP sensor unplugged here(there's even a video!):
6.0 surging help!!!! - PowerStrokeArmy
Sorry if external links are bad. :(

I have a VGT solenoid on order from someone who's willing to take it back if it doesn't correct the issue(yay!). My logic is the sensor seems accurate and 'recording' the varying back pressure and adjusting turbo speed accordingly. My other theory is the EBP is giving erratic output and the turbo is being adjusted for that. The other avenues I'll be exploring are the EBP sensor and checking for large exhaust leaks. Will post back with resolution.
 

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Thanks very much for keeping this thread updated, this is the stuff we all go searching for when we have trouble. Threads with a happy ending are very valuable around here!
 

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Discussion Starter · #16 ·
Issue was in fact the VGT actuator solenoid. Attached is the readout from the EBP sensor after the swap. Truck is now running great. Too bad I didn't mess with the EBP readouts beyond the basic Key ON Engine Off voltage testing sooner.

Thanks everyone for your input.
 

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Good news! Thanks for updating us!
 

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Glad you got it sorted out. When my VGT solenoid went south, the truck just died and refused to run for very long.
 

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I was thinking TPS too. Sometimes they don't set a code.
I know this thread is old but I had same problem. But both batteries were bad (bad cells) took em out replaced them, it worked ok for the first 10 min or so. Then problem came back. Wento to dealer price for TPS pedal $365.00 went to local pick-n-pull got it for $45.00. Disconnected batteries, replaced the pedal (has to be original not the AutoZone one) let it run on park for about 30 min then drove it for about 20-30 miles and the problem is gone no more surging no more idle cycling. Maybe it was just a fluke or I got luck or maybe the problem will come back but it seems to be working ok for now.
 
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