Shuddering/Stuttering with AC

[j3ff]

Was curious if anyone else has encountered this issue:

FIrst hot day in MO yesterday and turned on the AC while doing some in-town, stop and go driving. Noticed a "vibration" that was unfamiliar to me and then realized that the engine was shuddering/stuttering when stopped in traffic with the AC on... this has never happened in cold/moderate weather with heat or any other system drawing on the engine.

anyone? is this a fuel mapping/ ignition timing issue that can be corrected? my guess is that the added load of the AC compressor is causing the engine to struggle at low RPM.

 

[goblues38]

didn't notice and "stuttering"...but I do notice the AC is sort of weak when the truck is just sitting idle (motor still running). If the auto stop kicks in, it takes forever for the AC to catch back up again because of all the hot humid air it keeps blowing without the compressor.

 

[jabroni619]

How severe is this exactly? Are you sure you're not just feeling some vibration from your radiator fan running while the AC is running in the warmer weather?

 

[Raptorguy1]

Mine vibrates a little running on high. Nothing alarming, just enough that I'm aware it's on and feels different.

 

[j3ff]

How severe is this exactly? Are you sure you're not just feeling some vibration from your radiator fan running while the AC is running in the warmer weather?

Mine vibrates a little running on high. Nothing alarming, just enough that I'm aware it's on and feels different.

it is possible it is as simply as radiator fan vibration; but i have not experienced the same in any other car/truck in the past.

to Raptorguy1's point, it was happening when i had it on "Max AC" and it is not shaking like a pole dancer - but it still is quite noticeable and feels odd/off.

 

[0r30]

Were you able to figure out what was causing this? I’ve been having similar instances since the summer started.


Sent from my iPhone using Tapatalk

 

[WraptorBoy]

Hi. You shouldn't feel any vibrations while the AC is running or starting up, even at idle, in my opinion.

When you turn the AC on, the engine idle is increased to compensate for the additional compressor load. Most of this should be invisible to you except the obvious slight increase in engine RPM.

At idle, the AC is compressing at it's lowest. Generally, you need to be above a specific RPM in order to get maximum cooling from the compressor.

I felt no virbrations in the Raptor I drove and had the start/stop engaged nor any vibrations at idle etc.

Yeah, makes no sense to have start/stop active when the AC is on. The computer should disable the start/stop system when the AC is on...

I would take it in and have them make sure there are no loose bolts on the brackets holding the compressor or any other related component. A defective compressor would cause a vibration or a misaligned drive belt... assuming it's not an electric compressor.

 

[baptizo]

I rarely have to use the A/C (never used the MAX setting) where I live but it hasn't affected how the truck feels or drives but I also always have the start/stop turned off.

Out of curiosity, though, I'm going to test it in MAX and see if it is different.

 

[MHIII]

My 2018 Raptor is in Ford service dept now for engine shudder. Cam phasers have been replaced, ( a week in the shop) then the engine shudder started. Service said they loaded new PCM software, and it seems better. However, now it is throwing a Turbo boost control code. Awaiting a call now on the plan to fix it.

 

[MHIII]

Rountree Ford in Shreveport La fixed the engine shudder issue. Great service and professionalism throughout the process. Ford had a software update for the ECU.