is it ok to let a car roll on idle revs in traffic?

[Boobonman]

Absolutely fine.

[kambites]

Modern engines are very tolerant to all sorts of abuse. It might use a bit more fuel than changing down, but it's not going to do any harm.

[anonymous-user]

If it isn't struggling then it's fine.

[Boobonman]

I spend a lot of time in traffic in various vehicles, do this all the time in 1st, 2nd, 3rd and sometimes even 4th.

[kambites]

maverickdrives said:

kambites said:

Modern engines are very tolerant to all sorts of abuse. It might use a bit more fuel than changing down, but it's not going to do any harm.

lol i cant go any lower than first gear in traffic :P Im usually rolling at idle revs in first gear on flat

Ah, missed that bit. No it wont do any harm.

[smokeey]

Boobonman said:

I spend a lot of time in traffic in various vehicles, do this all the time in 1st, 2nd, 3rd and sometimes even 4th.

What the hell are you driving that will idle in 4th with the clutch out?

[ismellburning]

smokeey said:

What the hell are you driving that will idle in 4th with the clutch out?

All cars, surely – it'll just idle while moving fairly fast.

[Dog Star]

smokeey said:

What the hell are you driving that will idle in 4th with the clutch out?

My SLK cruises at about 65mph at 1200rpm; it's an auto so it's not like it's me abusing it or anything.

[james_gt3rs]

ismellburning said:

smokeey said:

What the hell are you driving that will idle in 4th with the clutch out?

All cars, surely – it'll just idle while moving fairly fast.

I think a lot of cars would stall in 4th gear!

[mnkiboy]

You'd be surprised actually - modern computer controlled fuel injection cars will increase the throttle when the engine speed drops below idle, so it will probably idle in 3rd absolutely fine. There's a limit obviously - it won't keep it from stalling on a steep hill.

[ouch]

Guess it depends on how sophisticated the idle control system is, some have a lot more scope for increasing air & fuelling to deal with the load of idle-whilst-in-gear - whereas others don't. My '96 TDI will happily idle along in 4th on a flat road, for example.

[mnkiboy]

maverickdrives said:

mine is a 13 year old car, do they still count those as modern cars ? I know its not a classic.

Yes

[fjord]

Don't auto's do this all the time?

[Mr2Mike]

ismellburning said:

All cars, surely – it'll just idle while moving fairly fast.

Some idle control systems have greater range than others, i.e. can correct for more engine load.

My ZS180 would pull ~30mph in 5th with no trouble at all when the engine was cold because of the high idle speed, but I wouldn't expect a small engined car to be able to do that.

[thatdude]

I will let my car (civic 1.6) roll along at idle in 1st and 2nd gear. Not third, because it dosnt feel right. But it's a perfectly safe practice. Just dont boot it too hard from idle; high loads at low rpm isnt great for an engine

[Krikkit]

fjord said:

Don't auto's do this all the time?

Yes, but that's with a torque converter... They don't have a fully locked connection to the engine, it'd rotating a viscous coupling that allows varying degrees of slip so the engine can't be laboured.

thatdude said:

I will let my car (civic 1.6) roll along at idle in 1st and 2nd gear. Not third, because it dosnt feel right. But it's a perfectly safe practice. Just dont boot it too hard from idle; high loads at low rpm isnt great for an engine

Citation needed.

[E30Addict]

I was told that doing this can cause problems if you have a car with a dual mass flywheel, and you should always apply some throttle. This could be complete rubbish though...Anyone else heard this?

[zeppelin101]

maverickdrives said:

not sure I doubt my car has a DMF, usually diesel engines have that.

A lot of petrols from the last 10 years have them too. All new ones will.

[Lazygraduate]

Seem to remember Harry Metcalfe driving his Zonda without using the throttle in one of his videos. Got to about 30 in 6th if I remember correctly!