LG John

I've noticed of late when in traffic that the car gives and annoying 'engine braking' jerk when lifting off in 1st gear. Picture a traffic jam and I'm using a tiny bit throttle in 1st to maintain 2500rpm and tottle along. When I lift off (to apply the brake) no matter how smooth I come up when I go to zero throttle the car gives an annoying jerk. I've even noticed it a few times in 2nd gear under similar circumstances and sometimes the 2nd-3rd gearchange can seem jerky. I'm fairly sure this is a recent thing Anyone know what's causing it or is it another 'they all do that sir!'

I've recently put in an ITG that made he-haw difference so it'll be coming back out again soon. Not sure if it is related but when sipie fitted the ITG he was fairly sure when reconnecting a pipe after fitting the filter that he hadn't disconnected the pipe in the first place The pipe in question goes into the large air pipe just after the maf (the one held in place at either end by big clips). I guessed it might be the DV return and that by lying loose it would have vented to the atmosphere and not been a problem? Anyway, this pipe is connected up again and the ITG is correctly fitted but I've got this annoying jerk. If its normal its not a problem as I could live with it but I'm just being careful and posting to see if its an indication of something more sinister.

The only other car I've known to do it is my flatmates old 306 and it ran like a bag of hammers

LG John

Will a shortened version help?:

When I lift of the throttle in 1st the car jerks. Its a pig! What's wrong?

jameswrx

iTrader: (4)

Engine mounts?

Bob Rawle

The pipe is related to emmision control and would not cause the problem, do you have a std dump valve fitted or an aftermarket one? What MY is the car, if it is a MY00 then it could be down to the '802 syndrome

LG John

MY99 with JB Tek 2.5. Dawes is controlling the boost (although this problem is obviously off-boost)

Edited to say, its still on the standard dump valve

[Edited by Saxo Boy - 3/3/2003 10:53:16 PM]

swan

Do you also have a similar problem when getting onto the throttle? I don't understand why but replacing the lambda sensor helped eliminate both problems for me.

David_Wallis

Anti JerkOff Kit made by Kleenex?

LG John

No its fine when you accelerate again (well, I'm fairly sure it is but I'll check). IIRC I picks up nicely and then the boost comes and with a bang (dawes) which I like

Dizzy

just pop in the clutch select neutral and coast Uber bad I know.

JamesS

This is part of the calibration - most likely fuel ramping out and then cutting off with closed throttle decel. Done for drive-feel, fuel economy (!!) and emissions...my 00MY is also not great in traffic! The 4*4 hardware is a pig for good driveability. Tip-out shuffle being the techy term!

LG John

So is the consensus that this is 'normal' Already picked up on the depressing the clutch thing but that means judder city when it comes back up (I think the clutch is about the throw in the towel)

StickyMicky

yeah i depress the clutch and dont let the engine slow me down

mine does it, u have to rember theres 4 wheels dragging the engine speed down not just 2
well thats how i looked at it

brickboy

Don't know about the Scoob fuel injection specifically, but the Bosch systems used on a lot of other cars (VW / Audi / BMW etc) cut fuel completely when you lift off at anything over 2000 rpm, and don't restore fuelling until 1300rpm or similar. It's for emissions control.

Not a problem when you're in 3rd or 4th gear and rolling at decent speed but at low load / high rpm in 1st you get a lot of shunt.