5.0 Cold Start Bogging

[dmac]

Does anyone experience their 5.0 after a cold start, when slowly accelerating up a slight incline (~5-10 mph), the engine starts to make a really deep, booming (almost buffeting) tone.

It goes away after a few minutes and I can avoid it by bringing revs up manually or being really light on the throttle.

Could it just be a combination of running rich and transmission shifting too early?
I don't think its knock...

I'm going to try running a tank of Chevron (my car was a loaner before), and doing the PCM relearn.

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[lrequa92]

Does anyone experience their 5.0 after a cold start, when slowly accelerating up a slight incline (~5-10 mph), the engine starts to make a really deep, booming (almost buffeting) tone.

It goes away after a few minutes and I can avoid it by bringing revs up manually or being really light on the throttle.

Could it just be a combination of running rich and transmission shifting too early?
I don't think its knock...

I'm going to try running a tank of Chevron (my car was a loaner before), and doing the PCM relearn.

What octane fuel do you run?

 

[dmac]

What octane fuel do you run?

I run 87. Sometimes e85 which is 100+ octane. It has happened on both, but more often 87.

 

[tony72cutlass's']

Does anyone experience their 5.0 after a cold start, when slowly accelerating up a slight incline (~5-10 mph), the engine starts to make a really deep, booming (almost buffeting) tone.

It goes away after a few minutes and I can avoid it by bringing revs up manually or being really light on the throttle.

Could it just be a combination of running rich and transmission shifting too early?
I don't think its knock...

I'm going to try running a tank of Chevron (my car was a loaner before), and doing the PCM relearn.

Sounds like cylinder deactivation kicking in to me.

Try this, next time you hear the sound, press a bit more into the gas, if you hear the truck all of a sudden "come alive" and not switch gears, then you just switch from i-4 to V8 mode. This happens to me when i roll up a very light incline after turning a corner.

More often then not now i hammer it lol

 

[dmac]

Sounds like cylinder deactivation kicking in to me.

Try this, next time you hear the sound, press a bit more into the gas, if you hear the truck all of a sudden "come alive" and not switch gears, then you just switch from i-4 to V8 mode.

Yeah that is what it feels like, but would be shocked if CD kicks in while still warming up.

 

[JExpedition07]

Do you have an exhaust on it?

 

[dmac]

Do you have an exhaust on it?

Factory exhaust. I dont prod it too hard when I feel it for obvious reasons. Usually off pedal then slowly on and it goes away.

 

[dmac]

Soon I'll be putting penzoil Platinum full synthetic in, maybe that will help...

 

[JExpedition07]

I’d take it in for that concern, with the rental history of the truck who knows. I’d get it documented and see if they can replicate. Maybe it’s something up with software telling CD to kick in when it shouldn’t. Could also be running rich for some reason.

 

[tony72cutlass's']

Soon I'll be putting penzoil Platinum full synthetic in, maybe that will help...

my truck is running 10X better with Mobil 1 full synthetic. Way quieter than the motorcraft factory stuff i used for the first 25K miles

i was a die-hard mobil 1 fan for 20 years, figured why not use the motorcraft stuff. Anyways, i'm back to being a die-hard fan

 

[tony72cutlass's']

Yeah that is what it feels like, but would be shocked if CD kicks in while still warming up.

CD is deactivated in tow-haul and sport mode. Try that next time you are going up the hill

 

[dmac]

CD is deactivated in tow-haul and sport mode. Try that next time you are going up the hill

Yup thats a good test Ill run before getting a dealer to help.

 

[dmac]

I’d take it in for that concern, with the rental history of the truck who knows. I’d get it documented and see if they can replicate. Maybe it’s something up with software telling CD to kick in when it shouldn’t. Could also be running rich for some reason.

Definitely runs rich. My old 15 5.0 ran super rich and sounded similar on cold start but didn't bog. Ive looked into it before and they just dump fuel in there on the factory tune until things warm up.

 

[dmac]

Appreciate all the thoughts guys. Will keep you all updated.

 

[tony72cutlass's']

Let us know how it goes

My f-150 sounds like a shaking box of marbles on startup compared to my old pushrod V8 from 72 that’s so smooth you could cut diamonds on the dash, progress doesn’t always make sense to me

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