[gpa]

Originally Posted by SS-Traveller

Choosing a lower gear while towing/going up inclines doesn't just preserve the clutch - it reduces wear and tear of the engine and transmission system as a whole.

To add to what SS-Traveller has said. Lugging was evident in the era of carb engines where all they had for ignition timing were points and advance weights. Timing was pretty stationary at lower RPM's and with a high load and low RPM, there was a lot of pre-detonation (ping) which could destroy a piston or valve seat, and a lot of stress on a cast iron crank shaft.

Today, while the same physics occur, ECU's control ignition timing using knock sensors as well as knowing the engine load and RPM. So the stress lies on the crankshaft and bearings. It also places stress on the head gaskets.

Some long term negative effects:

1. Prematurely worn rod bearings and crankshaft
2. Poor oil pressure as a result of excessive rod bearing clearances.
3. If done excessively you can weaken and break a crankshaft, rod or a piston.

[SS-Traveller]

Originally Posted by gpa

Timing was pretty stationary at lower RPM's and with a high load and low RPM, there was a lot of pre-detonation (ping) which could destroy a piston or valve seat, and a lot of stress on a cast iron crank shaft.

Today, while the same physics occur, ECU's control ignition timing using knock sensors as well as knowing the engine load and RPM. So the stress lies on the crankshaft and bearings. It also places stress on the head gaskets.

Yes, and because the pinging (pre-ignition) does not occur due to the knock sensors, the tendency to unnecessarily lug the engine is greater nowadays. The damage gets shifted from the pistons downwards into the crank.

[clevermax]

Originally Posted by SS-Traveller

Driveline shunt is a shuddering or jerking that is felt due to the small amounts of play through the transmission system - each union joint has a tiny amount of play - the clutch spline drive, each gear mesh, including the differential, each cv joint and finally the wheel hubs. If they were all tight, there would be no drive line shunt at all, but in practice every one has a tolerance.
Even if none of them are badly worn, that's a lot of gears/joints etc in the system, and these can add up to give a noticeable lurch when powering on / lifting off.

Thanks for the explanation, My car has this issue for sometime now, and I was finding it difficult to explain it to others, especially service guys. I think it could be due to a worn clutch. The problem is more noticeable when I release the accelerator fully in second and third gears and let the car move on momentum - it is not smooth.

If this is not due to a bad clutch, what else could be the common causes and how to address these issues?

[k_nitin_r]

Originally Posted by Atlblkz06

There is no clear definition for this since the parameters are different for all cars. For the average gasoline engine, anything below 1750rpm in 3rd or higher hears is lugging. With diesels the RPM range drops to 1250rpm or so.

When in gear, if you accelerate and the car is unable to accelerate - that is lugging.

With the AC running, the Esteem Di cannot accelerate when driving at the recommended speeds for the gear and does require shifting down. However, that isn't really lugging. Try the lower gear and engine/transmission braking will slow you down.

Originally Posted by Zahir

Absolutely 100% Correct! It gets on my nerves when ppl do this! Its either drive in a low rpm zone or rip. Anyone heard of 2-3000rmp power bands in diesels? Apparently not.

I'm in 2k-3k range when I need to overtake but not for regular driving. It's noisy, but that's when the turbo kicks in.

Originally Posted by theMAG

While extremes are never recommended, the manufacturer recommended gear shifts are perfectly doable at the same time. I've heard many people ask how it is possible to drive in 5th gear at 45 kmph (as an example) simply because Maruti says so in their manual. It is possible if you know how and dont overdo it.

There are people at the Maruti customers' meet who claim that their Marutis cannot do the recommended speeds. However, I find the Maruti recommended speeds to be perfectly doable unless you are going uphill. Besides, when doing downhill, you would use a lower gear than recommended for engine/transmission brake or a higher gear for an almost 'free-fall' down a not-so-sleep slope without the engine complaining.

Originally Posted by sujaylahiri

I don't think lugging affects modern day engines anymore.
If you have a wide open throttle at a low rpm, the engine computers these days are smart enough to decrease the amount of fuel injected into the intake port (or the cylinder in case of GDI) so that there is no incomplete combustion in the cylinder.

I have never seen smoke pouring out of the exhaust when lugging but when over-revving there's a great deal of black stuff pouring out to remind you of the buses and trucks in the city.

[rohanak1]

Sometimes when I am driving at a decent speed in 5Th gear and know that I need to slow down after some distance either for a hump or a crossing I take my foot of the accelerator which reduces speed gradually but do not shift the gear down and do not acccelerate as well. I brake and shift to 2nd gear when I approach the hump. Is this also lugging ? If I need to accelerate I shift down to the appropriate gear and then accelerate .

[Suraj25]

Originally Posted by rohanak1

Is this also lugging ? If I need to accelerate I shift down to the appropriate gear and then accelerate .

When you lift your foot off the the accelerator, is there a point when the car starts putting on its own in 5th? This happens when the speeds are too low for the gear. If this is the case then you're lugging the engine. Else, if the car is slowing down gradually and you depress the clutch before this begins to happen, you're not lugging!
I hope you understand what I'm trying to say.. Not sure if I've conveyed it clearly :/

[anupmathur]

Originally Posted by rohanak1

.... I brake and shift to 2nd gear when I approach the hump. Is this also lugging ? ....

No, this is not lugging. However you would do well to shift down a tad earlier; you can then avoid using the brake before shifting down.

[Metallicar]

I follow the simple rule.

Higher the speeds ---> Higher the gear.

Lower the speed --> Lower the gear.

This gives the best FE and also comfort.

When you need to overtake then just bring it to a smaller gear.