Acceleration In First Gear

[peteo48]

Good post embee. I did a bit of reading around the subject of CVT boxes and how to drive them because I was convinced I was "doing it" wrong. I now apply gentle linear inputs on the throttle and this avoids that rubber band effect where the revs surge but it takes a bit of time for the car to find the right ratio. I still get that on the increasingly rare situations where I need to accelerate briskly but mashing the pedal simply doesn't suit the CVT.

The best comment I read was to the effect that the CVT was designed for effortless driving, mostly in urban settings but absolutely not for aggressive driving styles.

[Jocko]

I find my DSi throttle has no lag on depression but seems to delay on lift-off. When I lift off the throttle, the revs die slower than I would like.

[SuperCNJ]

IMHO the iDSi twin spark was a much underrated engine and perfect for the Jazz,  it was capable ( as you have shown ) of great MPG and was a much easier drive than the later engines, which although of higher power on paper need to be revved to get to that power.  The Jazz is not a sports car, my wife would love the Idsi engine in her MK2 Si.

Yes the old iDSi Engine was super reliable, it was completely faultless in the 10 or so years we had it. Suffered the usual low end torque but we got used to it. It was a capable engine, perfect for the Jazz imo. My only small gripe with it was the economy, it wasn't bad but compared to its main rival at the time, the Yaris it was noticeably more thirsty. My cousin and I did a few long trips and both filling up together before setting off and found that our Jazz consumed more fuel at the end of the trip despite being in convoy all the time.

[Jocko]

Suffered the usual low end torque but we got used to it. My only small gripe with it was the economy

I have to disagree with both these points. My 1,2 i-DSi has wonderful low down torque and, on a level road, will pull happily from 20 mph in 5th. As for economy, the figure beside my avatar (as I type 55.3 mpg) is my AVERAGE mpg for the almost 5 years and approaching 52,000 miles. My best tankful was an unbelievable 69.9 mpg.



As you can see, the torque between 2,000 rpm and 5,500 rpm is excellent.

[peteo48]

IMHO the iDSi twin spark was a much underrated engine and perfect for the Jazz,  it was capable ( as you have shown ) of great MPG and was a much easier drive than the later engines, which although of higher power on paper need to be revved to get to that power.  The Jazz is not a sports car, my wife would love the Idsi engine in her MK2 Si.

Yes the old iDSi Engine was super reliable, it was completely faultless in the 10 or so years we had it. Suffered the usual low end torque but we got used to it. It was a capable engine, perfect for the Jazz imo. My only small gripe with it was the economy, it wasn't bad but compared to its main rival at the time, the Yaris it was noticeably more thirsty. My cousin and I did a few long trips and both filling up together before setting off and found that our Jazz consumed more fuel at the end of the trip despite being in convoy all the time.

Just on the economy thing could it be that the Yaris had a smaller engine? I don't know the answer to this btw.

[E27006]

Suffered the usual low end torque but we got used to it. My only small gripe with it was the economy

I have to disagree with both these points. My 1,2 i-DSi has wonderful low down torque and, on a level road, will pull happily from 20 mph in 5th. As for economy, the figure beside my avatar (as I type 55.3 mpg) is my AVERAGE mpg for the almost 5 years and approaching 52,000 miles. My best tankful was an unbelievable 69.9 mpg.



As you can see, the torque between 2,000 rpm and 5,500 rpm is excellent.

 The graph traces start at 1000rpm, yet the Jazz Dsi has a very low idle of 500 rpm, extrapolate the orange torque   trace down to 500 rpm and you can estimate quite low figures for torque at 500 rpm.  As rpm  increases from idling, torque grows rapidly, note how the  torque at 2000 rpm  is 300% of torque at 1000 rpm.
The  Jazz 500 rpm idle speed  is possibly why drivers new to a Dsi tend to stall the engine on setting off, (I'm guilty of stalling  too), and the sense of missing bottom  end torque, applying throttle the engine has to build up more revs
 Many other makes of cars idle at 800 rpm,    It used to be a benchmark for a carburettor aspirated engine, how you could turn down the idle speed  on the carburettor until the engine would not self-sustain, the lower the better the engine.

[culzean]

 The graph plots and traces start at 1000rpm, yet the Jazz Dsi has a very low idle of 500 rpm, extrapolate the traces down to 500 rpm and you can estimate quite low figures for torque at 500 rpm.  As rpm  increases from idling, torque grows rapidly, the  torque at 2000 rpm  is 400% of torque at 1000 rpm.
 Many other makes of cars idle at 800 rpm,  that Jazz 500 rpm idle speed  is possibly why drivers new to a Dsi tend to stall the engine on setting off, (I'm guilty of stalling  too), and the sense of missing bottom  end torque, applying throttle the engine has to build up more revs,   It used to be a benchmark for a carburettor aspirated engine, how you could turn down the idle speed  on the carburettor until the engine would not self-sustain, the lower the better the engine.

Never stalled any of our iDSi MK1's,  wish I could say the same for wifes present MK2 VTEC.  I always thought of the iDSi as a diesel that ran on petrol,  its low down tractability and 'lazy gear changes' were great.  Just as a comparison my brother had a Honda VFR750 ( non-VTEC carbed version ) and his mate had a newer VFR800 VTEC with injection,  his mate was always complaining about stalling the 800, so my bro suggested they swap bikes for a few miles,  my bro also stalled the 800,  but his mate was so impressed with the 750 ( 8 years older ) that he wanted to swap bikes with my bro., who politely declined.... 

[Kenneve]

One thing for sure is that Honda have certainly removed this issue in the new hybrid cars. I've read and watched several reviews of the Mk4 and the Cross star and the almost doubling in torque from previous models is, apparently, very evident to the point that wheel spin can be an issue!

I can certainly agree with that, when I surprised myself recently.
I was stopped in lane 2 of a 3 lane road, at traffic lights, when ‘white van man’ pulled up alongside in lane 3.
Now i knew that the road dropped to 2 lanes and the other side of the junction, so it was obvious that he was going to cut in.
I just pressed the throttle rather more than usual and the car took of like a scolded cat, leaving him aghast that an old duffer like me would attempt to take him on, in what is generally regarded as an old mans car.
Yes, with twice the torque of the Mk3, the Mk4 certainly goes.

[Jocko]

L12A1 engine: Idle speed should be: 700±50 rpm (min-1)

According to my ScanGauge mine ticks over at 740 rpm.

And as for waiting for the revs to build up. I just have to touch my throttle and the revs are around 1,200 rpm. Takes off like a boy racer if you are not careful.

[SuperCNJ]

Suffered the usual low end torque but we got used to it. My only small gripe with it was the economy

I have to disagree with both these points. My 1,2 i-DSi has wonderful low down torque and, on a level road, will pull happily from 20 mph in 5th. As for economy, the figure beside my avatar (as I type 55.3 mpg) is my AVERAGE mpg for the almost 5 years and approaching 52,000 miles. My best tankful was an unbelievable 69.9 mpg.



As you can see, the torque between 2,000 rpm and 5,500 rpm is excellent.

I think this may be a slightly subjective topic, one person's perception of good low down torque may be different to another. Despite how much I love the Jazz (we've had 4 in the family and still have 3) I do feel the low end torque on all our Jazz's except the MK3 1.5 sport are all pretty weak although it seemed to improve with newer versions.

Our 1.4 MK1 was the one I was referring to earlier and although it is a slightly larger engine than the one you have, it still felt quite sluggish off the line at low rpm. Once it gets going though, it's fine.

As someone mentioned, looking at your graph, you really don't have much torque at low engine speeds. Yes I agree at higher engine speeds you do get some decent torque but unless you're prepared to use high revs every time you're pushing off it's just not really ideal. It could be that the Jazz has a lighter flywheel than say European cars which gives the feeling of lacking torque. Again, this is just my view which I appreciate is different from yours. 

On the fuel economy, this was just our experience of the Jazz, it wasn't by any means poor, but when we did a few straight comparisons with the Yaris, I kept having to fill up more at the end of the trip.

[SuperCNJ]

IMHO the iDSi twin spark was a much underrated engine and perfect for the Jazz,  it was capable ( as you have shown ) of great MPG and was a much easier drive than the later engines, which although of higher power on paper need to be revved to get to that power.  The Jazz is not a sports car, my wife would love the Idsi engine in her MK2 Si.

Yes the old iDSi Engine was super reliable, it was completely faultless in the 10 or so years we had it. Suffered the usual low end torque but we got used to it. It was a capable engine, perfect for the Jazz imo. My only small gripe with it was the economy, it wasn't bad but compared to its main rival at the time, the Yaris it was noticeably more thirsty. My cousin and I did a few long trips and both filling up together before setting off and found that our Jazz consumed more fuel at the end of the trip despite being in convoy all the time.

Just on the economy thing could it be that the Yaris had a smaller engine? I don't know the answer to this btw.

I think it was about the same. I seem to recall it was a 1.3, our Jazz was a 1.4 on paper but it was actually 1339cc if I recall correctly - so no meaningful difference in engine size. But it could be down to the difference in weight - I don't know.

[Jocko]

on a level road, will pull happily from 20 mph in 5th.

That takes low-end torque. It is not just subjective. Regarding economy, perhaps your mate is just a more frugal driver than you are. What sort of mpg do you currently get?

[SuperCNJ]

on a level road, will pull happily from 20 mph in 5th.

I'm sorry but that doesn't prove much as most if not all modern cars will be able to pull in 5th from 20mph.

That takes low-end torque. It is not just subjective. Regarding economy, perhaps your mate is just a more frugal driver than you are. What sort of mpg do you currently get?

Possibly, but I generally drive sensibly to get decent mpg in the Jazz. Given we were in convoy (with me mostly following) on the several hundred-mile trips, I think the small differences in driving styles (if any) is a bit of a moot point.

No idea what mpg we were getting, my guess would be around 40 around town. We sold the car a few years ago now so can't really tell you exactly but I just noticed it wasn't as economical as the Yaris - although I'd still have the Jazz over the Yaris any day!

[Jocko]

Given we were in convoy (with me mostly following) on the several hundred-mile trips, I think the small differences in driving styles (if any) is a bit of a moot point.

I'm not trying to get in a pi$$ing contest here but anyone who has driven in a convoy knows that the first vehicle tootles along at 30 mph, the second one has to do 20 mph to 40 mph and the poor sod at the rear of a large convoy is either stopped or driving like a lunatic to keep up. I have done it on bus trips (especially when the only driver who knows the route is at the front) and any army driver has experienced it many times.

[SuperCNJ]

Given we were in convoy (with me mostly following) on the several hundred-mile trips, I think the small differences in driving styles (if any) is a bit of a moot point.

I'm not trying to get in a pi$$ing contest here but anyone who has driven in a convoy knows that the first vehicle tootles along at 30 mph, the second one has to do 20 mph to 40 mph and the poor sod at the rear of a large convoy is either stopped or driving like a lunatic to keep up. I have done it on bus trips (especially when the only driver who knows the route is at the front) and any army driver has experienced it many times.

Ok   I don't think that happened.

I think we're going off-topic now, so suggest we leave it there.