Spagolli94

I've been notice a very slight chugging sensation and I didn't know if this was considered normal. It only seems to happen when I'm the highway, in slower traffic, going about 50. I'm in manual mode, in 5th gear and when the traffic clears, I'll slowly roll on the throttle until, say about 50% or so. The RPMs are fairly low and I sense a faint chugging, like the engine isn't happy pulling from lower RPMs.

At first I just thought it was a windy day, or maybe just really slight bumps in the road or my mind was playing tricks on me. It feels kinda like a 4 cylinder manual tranny car when you try to go up a hill in a high gear. But not nearly that bad - it's a very subtle sensation.

I would expect this to occur if I had it in 5th gear, floored, at 900 RPMs. However, my RPMs are in an acceptable range and I'm only trying to accelerate moderately. In fact, it doesn't seem to get any more or less noticeable if I floor it.

I don't notice it as much in auto mode because when I give it gas, it will just downshift for me. Has anybody else experienced this or something similar? I'm wondering if it's normal or I'm just crazy.

hovik92

What a timely post! I felt this on my way to work about 1 hour ago for the first time ever! I tried to re-create it but I wasn't successful. I'm guessing 5th gear is too big for the power coming out of the engine. Mine is a IS250 though.

cFoo

I notice it in auto-mode in all driving modes, eco, normal, sport, and sport+ on my 350 F. The feeling is identical to when you're driving stick and you're in a lower gear than you should be. I'm a bit concern because it feels exactly like you're lugging the engine. You can feel this on a flat surface as well. Just let off complete, then ease back into it very gently. I think the transmission is over zealous in fuel saving mode, it up-shifts, because you didn't smash the pedal it stayed in the gear but does not have enough power.

Loe

5th gear in manual mode at 50mph is like 2,500rpm, its not in a lugging zone and there should be plenty of torque to move the car at a good pace.

Having said that, O/P I notice this too. Doesnt feel like the tradtional misfire since is softer and smoother in sensation.

Hermes

Can you record this? I don't really understand by what you mean as a "chugging" sound.

Spagolli94

Whew - so I'm not crazy after all? The fact that others are experiencing the same thing makes me thing it's "normal" and perhaps some fuel-saving feature. It kinds makes me feel a bit motion sick though. If it is some sort of fuel saving engine management thing going on, I wish it would happen in eco mode only. I'd rather use a little more gas and not get the sensation that my engine is subtly sputtering while maintaining a constant speed or gently accelerating in high gears.

And you're right - at 2,500 rpm there shouldn't be any lugging. The sensation reminds me of driving an old underpowered Civic up a hill in a high gear. The engine would start to lug, then you'd give up a select a lower gear to get up the rest of the hill. It's a similar sensation but nowhere as severe. It doesn't feel like the engine is going to stall, nor is it as severe as a misfire. It just feels like the engine isn't running quite right or it has crappy gas. It almost feels like some sort of cylinder deactivation. Very subtle, but noticeable.

It's funny though, I tend to notice it in 5th gear more so than 6th gear. If it was lugging due to too much gas at low RPMs, I would think 6th gear would be the worst.

Unfortunately, as others are experiencing the same thing, I guess this is a "feature" of our cars, thus not something that can be fixed by the service dept. Has anybody asked their service dept about this issue?

Spagolli94

It's not a sound. You can't hear anything abnormal. It feels like a subtle misfire when you're cruising in 5th or 6th gear on the highway. I notice it most when I'm in 5th gear, gently accelerating. I'm not sure if you've ever driven a stick shift before. If you are going up hill and are in too high of a gear, the engine will start to lug. Eventually, if you don't downshift and continue to lose momentum up the hill, I guess the engine would stall if you didn't downshift. It feels like this but MUCH more subtle.

Ironically, if I floor it - intentionally trying to make the engine lug - then it goes away.

The other day, I thought it was the wind subtly moving the car around. There's no sound. Just the sensation of inconsistent power coming from the engine.

Hermes

Ah I understand what you mean now. Have you talked to the dealer? That's quite concerning

Spagolli94

I just emailed the dealer to see what they say. I probably won't worry about taking it in for a closer look until the car is ready for its 5k service. It's going to be tough for them to troubleshoot, however, as the sensation is quite subtle and somewhat intermittent.

Spagolli94

I think I figured out this out. It’s just an illusion caused by a very responsive, connected suspension, whisper-quiet engine running at low RPMs and poorly maintained roads.

Many of our crappy highways, especially the concrete ones, have subtle bumps and dips. The car is so glued to the road and you can feel this subtle up and down motion. The engine is so quiet and running at such a low RPM that it feels like a lugging sensation. But I’m 90% sure that it’s not coming from the engine. In fact, in a particularly bumpy section of highway, I actually let off the gas and the lugging sensation remained even when the car was coasting.

This also explains why it’s intermittent - because some stretches of road are actually good and properly graded.

I never noticed this lugging sensation in my BWM before, even though that suspension was very firm and responsive as well. I think it was because the engine was taching higher and I could actually hear it - I could hear that the engine wasn't lugging.

link13

I've been told any perceived lugging is because I got the small motor car and that I deserve it :-)