2016 Sport - 3.5L EcoBoost "Chugging" on cold starts

[chartquist]

Greetings. Curious to know if anyone with the 3.5L EcoBoost is experiencing a chugging feeling on cold starts for the first 30 seconds or so. When I pull out of my garage in the morning, my 2016 Sport will chug or buck very slightly when I pull out. It's as if the fuel delivery isn't smooth at that point. It goes away very quickly and then pulls away smoothly and normally off idle at stoplights, etc. Wonder if this could be related to the throttle body issues?

Note, I didn't put this in the throttle body thread since the symptom seems completely different.

 

[613GT500]

What grade of fuel are you using?
The one and only type I experienced shuttering during a cold start, was from bad fuel I pumped from an out of town gas station.
Problem went away after a fresh tank full of 91.

 

[need-a-cage]

What grade of fuel are you using?
The one and only type I experienced shuttering during a cold start, was from bad fuel I pumped from an out of town gas station.
Problem went away after a fresh tank full of 91.

I get the same "surging" at very low throttle positions just after start-up. I feel it when moving from the driveway into the garage and when slowly pulling out of parking lots. Another 16 owner on a different forum has the same issue.

 

[613GT500]

Do you feel that it will stall?
Have you tried letting the car roll without applying gas?

 

[need-a-cage]

It won't move without hitting accelerator. Most noticed when moving from my driveway into the garage which is on a slight incline.

 

[Napalm]

how many miles?

what mods if any?

Some times when you tune a computerized car you can get the tables slightly out of whack and get some odd issues with start up idle until the car is warm enough to go into closed loop mode.

IE until the cat converters are hot enough to be fully functional and good readings coming out of the rear O2 sensors. But that first closed loop run is either too rich or too lean.

I notice your other devices are fairly highly modded so I'm going out on a limb and guessing that's an issue.

 

[copierking]

My 15 is doing it now again. It did it before and they replaced the #1 plug. Its back again so I will bring it back to the dealer. Its fine if I let the car warm up but cold starts it like its bucking down the road for about 300 feet then goes away. Its not weather related does it in hot or cold.

 

[613GT500]

My 15 is doing it now again. It did it before and they replaced the #1 plug. Its back again so I will bring it back to the dealer. Its fine if I let the car warm up but cold starts it like its bucking down the road for about 300 feet then goes away. Its not weather related does it in hot or cold.

Did you even get a CEL during those occurances?

 

[copierking]

No CEL but first time showed up right away at the dealer after they hooked it up . Left it over night so they could check first thing in the morning. Now it only has to set an hour or two.

 

[TwinExes]

My 16' does this also on cold start up. I would characterize it as a rough idle for 15-30 seconds. I read somewhere that this is a brief lean condition, commanded by the PCM, to heat the cats up faster. No CEL or any other issues, and octane doesn't seem to matter either. Doesn't bother me at all.

 

[chartquist]

What grade of fuel are you using?
The one and only type I experienced shuttering during a cold start, was from bad fuel I pumped from an out of town gas station.
Problem went away after a fresh tank full of 91.

Octane rating doesn't seem to make a difference and my Explorer is bone stock. Just hit 4K miles, so the inside of the engine should be perfectly clean too.

 

[chartquist]

My 16' does this also on cold start up. I would characterize it as a rough idle for 15-30 seconds. I read somewhere that this is a brief lean condition, commanded by the PCM, to heat the cats up faster. No CEL or any other issues, and octane doesn't seem to matter either. Doesn't bother me at all.

Agree, it's more of a curiosity than a problem. Never had a CEL come on from it either.

 

[613GT500]

My 16' does this also on cold start up. I would characterize it as a rough idle for 15-30 seconds. I read somewhere that this is a brief lean condition, commanded by the PCM, to heat the cats up faster. No CEL or any other issues, and octane doesn't seem to matter either. Doesn't bother me at all.

If it's running lean for the first 30sec or so, I'm not seeing that on the A/F ratio reading, as I have my EX hooked up to Tourque Pro, via obd and it's reading 14.7 (stoich).

 

[Flatplane]

Normally cold engine start up runs on open loop strategies. Catalytic converter temps during start up do not affect mixtures. There is some discussion across the markets about intake valve/runner deposits causing this anomaly. Normally this does not occur in vehicles with lower mileage. I would gander a guess it is programmed fuel look up tables that may in fact be lean mandated by federal emissions laws.

 

[TwinExes]

No, but mixtures affect converter temps. You may be onto something with the federal regulations. The Platinum my wife drives acts the same way at cold start. Wish I could remember where I read that.

 

[Kpwweb]

We discussed this in a previous thread... Sgt411 compared it to an old carburetor and choke setup. I agree. My 2013 ExSport does this as well. Always has.

 

[xlt03]

Same issue here. Backing vehicle out of garage to driveway. Only for the first 20 seconds. I have 2100 miles on mines. Chugging goes away. Using top tier 85.

 

[peterk9]

Same issue here. Backing vehicle out of garage to driveway. Only for the first 20 seconds. I have 2100 miles on mines. Chugging goes away. Using top tier 85.

The engine requires a minimum octane of 87 according to he manual. I've not even seen 85 around here.

Peter

 

[xlt03]

Typo...meant 87. Sometimes " feel" like a transmission not getting enough pressure similar to 5R55W at startup and goes away after 15-20 seconds.

 

[need-a-cage]

Mine did it from day 1 totally stock. Still stock, but I do have an SCT X4 so I'll look at the AFR and see if it changes from the time I notice it to when it goes away. I am pretty sure these are programmed for a stoich of 14.08 for when lambda is 1 for today's gas mixtures.