Turbo boost oscillations while towing

[Fishstxy]

When towing a 5,000lb trailer in both normal and tow/haul mode, at low RPM with mid boost demand ( low throttle demand) the boost pressure will start to oscillate violently. I assume this is the waste gate flapping. I can break the condition by either adding or removing throttle input.

I noticed it originally by the strange chirping should from the engine. When I switched to the boost gauge view (Lariat dash) I could see the boost pressure oscillating at about 3 times a second. Seems to consistently kick in cruising at highway speeds at constant power

Anyone else seen this? It can’t be good for the turbos so I’m tuned in to try to avoid it.

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[superfordman]

My truck will do the exact same thing at just the right times, sometimes towing or not. Seems to depend really on the conditions, load (head wind for me usually), speed and throttle. Just like you said the BOV starts fluttering back and forth and so do the boost gauge slightly, then just a simple tap of the throttle and goes away. No idea why it does it, but has since day one and have almost 66K right now and no issues, so I don't worry about it too much. It really seems to do it more when I have my big wheels and tires on, more load essentially.

 

[TheGoatman]

Octane?

 

[Fishstxy]

Octane?

93

 

[TheGoatman]

Do you go wide open throttle every so often?

if it’s a 21, an ecm update at the dealer may help too

 

[DT400]

When your boost is pulsing have you noticed the rpm's bouncing in rhythm? Mine does this but it has been attributed to a bad torque converter (locking/unlocking) unfortunately they are on back order and no deliver time is even estimated.

Darrell

 

[Gros Ventre]

The symptoms, I believe, point directly at a flaw in the computer coding.

 

[GIjoe]

I’ve noticed my mpg’s doing the same thing. I’ll have to pay more attention to my turbo gauge and see if it’s related

 

[Fishstxy]

Do you go wide open throttle every so often?

if it’s a 21, an ecm update at the dealer may help too

Rarely. I can try this next time I'm towing. I have experimented with WOT unloaded in Sport mode a few times, but that's it.

 

[Fishstxy]

When your boost is pulsing have you noticed the rpm's bouncing in rhythm? Mine does this but it has been attributed to a bad torque converter (locking/unlocking) unfortunately they are on back order and no deliver time is even estimated.

Darrell

No change in RPM, just chirping from the turbo which sounds like waste gate flapping. I noticed it happened a lot less with cruise control on, but not 100%.

I'll try to get a CarScan data record next time.

 

[TheGoatman]

If you catch it early enough a fluid change may help. I am planning on doing a fluid change at the dealer at 20k miles. Using the ford pass points I got at delivery

 

[RuggedGoods]

Just a weak spot in the engine calibration, basically. The control loop for requested/actual boost isn't very sophisticated.

Easy way to solve it is probably to avoid low rpm when towing (lock out your high gears). Or get a Livernois tune.

 

[powerbeast]

I noticed mine would oscillate engine output during low rpm high load when running low Octane, which was further exacerbated during the summer temps. Almost like timing was being retarded. 91Octane solved this issue.

 

[GIjoe]

Just noticed this today going uphill with low rpm and moderate throttle. Sounded like a belt slipping at first but I could make it worse/louder with more throttle. Forced a downshift and went away.

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