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Honda Jazz, HR-V & Hybrid Forums => Honda Jazz Mk1 2002-2008 => Topic started by: JackH on May 15, 2018, 10:04:20 PM

Title: GD 1.4 Not Holding Revs on Gear Changes etc
Post by: JackH on May 15, 2018, 10:04:20 PM
Iíve just bought a manual GD off my dad. High miles but drives well overall.

The last manual GD we had seemed to hold the revs between gear changes etc - when you lift off the throttle in this one, the revs drop immediately to idle and it can lead to gear changes / pull away sometimes being a bit jerky.

Is there anything known for causing this?

Starts and idles fine. Appears to have a drive by wire throttle rather than cable.

TIA

(Comversely, the GE that my dad now has seems to hold the revs for longer than needed.)
Title: Re: GD 1.4 Not Holding Revs on Gear Changes etc
Post by: Jocko on May 16, 2018, 06:10:37 AM
My GD5 immediately drops the revs between changes. That is the way every manual car I have ever had behaved. Doesn't seem to be a problem to me.
Title: Re: GD 1.4 Not Holding Revs on Gear Changes etc
Post by: JackH on May 16, 2018, 07:43:14 AM
Well Iím sure the other one we had did it. Iíve driven other modern stuff that does it too - itís to help smooth gear changes more than theyíd otherwise be.

Itís even more pronounced on the GE that my dad has to the point you have to be a bit more measured on the throttle and clutch when changing up than you might usually be.
Title: Re: GD 1.4 Not Holding Revs on Gear Changes etc
Post by: culzean on May 16, 2018, 09:42:37 AM
Well Iím sure the other one we had did it. Iíve driven other modern stuff that does it too - itís to help smooth gear changes more than theyíd otherwise be.

Itís even more pronounced on the GE that my dad has to the point you have to be a bit more measured on the throttle and clutch when changing up than you might usually be.

GD has a cable throttle (physical mechanical cable connection between throttle pedal and throttle body) GE went to drive by wire (variable resistors on the throttle pedal connected to throttle body via the ECU). This means on GE throttle input can be tweaked between loud pedal and throttle body and has a more 'disconnected' feel.
Title: Re: GD 1.4 Not Holding Revs on Gear Changes etc
Post by: JackH on May 16, 2018, 10:13:51 AM
Iíve seen at least one person on here mentioned on here that some GD models have a throttle cable and others have a fly by wire throttle. They went as far to mention the difference in MPG between the two.

I recently sold a GD CVT-7 and that had a throttle cable. We looked under the bonnet of this one too and no cable.

Will check again later(!)
Title: Re: GD 1.4 Not Holding Revs on Gear Changes etc
Post by: Jocko on May 16, 2018, 10:31:15 AM
My 2006 GD5 is fly by wire. There is a short length of cable from the pedal itself to the potentiometer, but the throttle body is controlled electrically.
Title: Re: GD 1.4 Not Holding Revs on Gear Changes etc
Post by: auntyneddy on May 16, 2018, 10:50:47 AM
Whilst a while back, we were taught if you wanted to get a smooth gear change you had to do what was called a sustained rev gear change because when one took one size ten off the throttle the revs dropped. On our EX Ishift as far as I can remember the revs drop when foot removed from throttle. The car definitely has a fly by wire throttle
Title: Re: GD 1.4 Not Holding Revs on Gear Changes etc
Post by: culzean on May 16, 2018, 10:57:00 AM
The revs do drop, but it can be disconcerting that they seem to drop slower on later models, there seems to be a delay somewhere. 
Title: Re: GD 1.4 Not Holding Revs on Gear Changes etc
Post by: auntyneddy on May 16, 2018, 11:04:09 AM
Two points I missed blame it on age: If the revs did not drop on release of the throttle it would be dangerous and of course a sustained rev gear change was for DOWN shifting.
Title: Re: GD 1.4 Not Holding Revs on Gear Changes etc
Post by: Jocko on May 16, 2018, 01:33:12 PM
Some Jazz models have a damper on the clutch. Don't know if that could have an effect.
I was taught to drive when synchromesh was a luxury. I was taught to time my changes and to double-declutch on down shifts (and on some vehicles going up as well). I even had to prove I could double-declutch on my driving test (as I had a three gear car with no synchomesh on first). Like the Driver Assists we have discussed elsewhere, manufacturers are always introducing something to help (and deskill) driving.
Title: Re: GD 1.4 Not Holding Revs on Gear Changes etc
Post by: JackH on May 16, 2018, 09:52:32 PM
Whilst a while back, we were taught if you wanted to get a smooth gear change you had to do what was called a sustained rev gear change because when one took one size ten off the throttle the revs dropped. On our EX Ishift as far as I can remember the revs drop when foot removed from throttle. The car definitely has a fly by wire throttle

The gear change is fine overall. Itís first to second and pulling away that seems to be more the issue - difficult to do it smoothly. That and I noticed today that the engine can jerk a little if you lift off and on the throttle when at low revs in traffic (checked engine mounts and they look fine).

I never experienced any of this in our last manual Jazz (and nigh on everything else I drive and have driven over the last 28 years), so it does suggest maybe thereís a reason why this car isnít as smooth.

Idles fine but I do wonder if itís a little low as it looks like around 700rpm on the Rev counter once warmed up. Thinking about it, it pulls away etc fine when the engine is cold as the car is idling that bit higher.

Have read that maybe thereís a throttle reset procedure involving disconnecting the battery and then reconnecting it, starting the car and then let it idle until the fan kicks in on these so maybe it needs that?

Got 56mpg on a long 70ish run yesterday so there canít be that much wrong with it but I am finding the love isnít flowing for it like the last one as of yet due this issue making it unpleasant to drive round town and especially so in heavy stop start traffic.

As for the GE... quite disconcerting how long this effectively delays the dropping of the revs but itís obviousky a trait of these (the manual, at least).
Title: Re: GD 1.4 Not Holding Revs on Gear Changes etc
Post by: Jocko on May 17, 2018, 07:00:55 AM
Sounds exactly the same as mine. As I have never had a Jazz, and came to the manual after 25 years with automatics, I figured it was just me and changed my driving to suit. If you find an answer, be sure to post it so I can do the same.
Regarding a reset procedure. Nothing in the Haynes manual about it.
Title: Re: GD 1.4 Not Holding Revs on Gear Changes etc
Post by: JackH on May 17, 2018, 09:07:30 AM
Had we not owned one previously, I might have just assumed this is the way they are and would likely be looking to get rid of it as we speak as it really is that unpleasant in heavy traffic.

However we did, it isnít and Iíll persevere with it for the time being whilst we try to find a solution. 👍
Title: Re: GD 1.4 Not Holding Revs on Gear Changes etc
Post by: Jocko on May 17, 2018, 02:35:08 PM
What sort of revs do you pull in 1st before changing into second?
Title: Re: GD 1.4 Not Holding Revs on Gear Changes etc
Post by: Jeffyjazz on May 17, 2018, 02:41:01 PM
change gear quicker ;D

im not sure if the EGR valve issue that some people seam to have would contribute to the revs falling quickly. ive been driving mine for 8 years i couldnt even tell you if the revs drop or not but i cant imagine they have enough time to fall that much in mine
Title: Re: GD 1.4 Not Holding Revs on Gear Changes etc
Post by: JackH on May 17, 2018, 10:00:13 PM
Itís definitely not the EGR as we had that with the last one.

However... Iím glad to say Iíve fixed it today.  8)

Disconnected the battery for a few minutes to reset the ECU then followed the procedure to retrain the idle etc, which is as follows:

1. Turn the ignition so itís on and wait two seconds before starting the car - make sure that everything electrical like the headunit / climate etc is off before you do the latter.
2. Raise the revs to around 3k and hold them until the radiator fan kicks in.
3. Let the car idle for five minutes. If the fan kicks in, donít count any of the time it runs as part of the five minutes.

And thatís it.

Before I did this, if you were driving along, dipped the clutch then released the throttle and the revs straight dropped down to idle.

Now, if youíre quick with the clutch the revs will rise slightly before dropping - in other words, the same as a GE but far less of it, so about right actually.

Then, when the revs drop, they seem to fall off a little slower and pause briefly at 1k RPM before dropping to idle.

Net result is a smoother gear change. Pulling away is now as it should be so this hasnít just made adjustments for idling - the car is now obviously maintaining the revs applied when using light throttle to pull away far better than it was before.

Also smoother on and off when doing a bit of stop start in traffic.

So I is a happy bunny once more and to the point I used some of the time I expected to be still stood by the car scratching my head well - resprayed the wheels (matt black, nice contrast to the metallic grey bodywork) and buffed up the headlight lenses as, like me, they were a bit dull.   ;)
Title: Re: GD 1.4 Not Holding Revs on Gear Changes etc
Post by: sparky Paul on May 17, 2018, 11:36:18 PM
im not sure if the EGR valve issue that some people seam to have would contribute to the revs falling quickly. ive been driving mine for 8 years i couldnt even tell you if the revs drop or not but i cant imagine they have enough time to fall that much in mine

I've been thinking EGR valve all the way through this thread.

A clogged EGR certainly gives you the jerky gear changes, and the revs do plummet as the engine is desperate to stall. I have just cleaned the EGR thoroughly on ours again, and the car now a pleasure to drive again - rather than the nerve-racking operation of slipping revs on the clutch when pulling away and it stalling at the drop of a hat.

If the car drives better when the engine is cold, I would suspect sticking EGR valve.
Title: Re: GD 1.4 Not Holding Revs on Gear Changes etc
Post by: JackH on May 18, 2018, 12:05:37 AM
im not sure if the EGR valve issue that some people seam to have would contribute to the revs falling quickly. ive been driving mine for 8 years i couldnt even tell you if the revs drop or not but i cant imagine they have enough time to fall that much in mine

I've been thinking EGR valve all the way through this thread.

A clogged EGR certainly gives you the jerky gear changes, and the revs do plummet as the engine is desperate to stall. I have just cleaned the EGR thoroughly on ours again, and the car now a pleasure to drive again - rather than the nerve-racking operation of slipping revs on the clutch when pulling away and it stalling at the drop of a hat.

If the car drives better when the engine is cold, I would suspect sticking EGR valve.

As above, disconnecting the battery and then performing a re-train of the idle sorted it.

When our last one had EGR issues it manifested itself by the car occasionally feeling gutless. Sorted in 10 minutes with some brake cleaner and a socket set.
Title: Re: GD 1.4 Not Holding Revs on Gear Changes etc
Post by: Jocko on May 18, 2018, 07:30:43 AM
Disconnected the battery for a few minutes to reset the ECU then followed the procedure to retrain the idle etc, which is as follows:

1. Turn the ignition so itís on and wait two seconds before starting the car - make sure that everything electrical like the headunit / climate etc is off before you do the latter.
2. Raise the revs to around 3k and hold them until the radiator fan kicks in.
3. Let the car idle for five minutes. If the fan kicks in, donít count any of the time it runs as part of the five minutes.

And thatís it.
Is this just a V-TEC thing? Never seen mention of it anywhere for the 1.2 i-DSI.
Title: Re: GD 1.4 Not Holding Revs on Gear Changes etc
Post by: JackH on May 19, 2018, 12:29:38 AM
No... mine is a 1.4 DSi, not VTEC.

Suspect itíll be applicable to anything with a fly by wire throttle.
Title: Re: GD 1.4 Not Holding Revs on Gear Changes etc
Post by: Jocko on May 19, 2018, 08:21:04 AM
Where did you find me the procedure? Can you post a link? I'll have to try the same with my car.