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Jerking on deceleration
https://forums.tipec.net/viewtopic.php?f=25&t=25398		 Page 1 of 1
Author:  Austin09 [ Sun Jun 01, 2025 1:55 pm ]
Post subject:  Jerking on deceleration
944 turbo jerking at slow speeds on deceleration. Worst in 1st gear but also in 2nd.
Is this normal or is there things I should check for wear?

It happens when driving at slow speeds e.g. if I let off the accelerator to slow for a speed bump it jerks.

I’m looking to get a checklist I can go through and narrow down the problem. I’m thinking perhaps:

- throttle side. It’s got a new TPS.
- I’m ruling out air flow or fuel mix because it’s not at revs where it would stall
- could it be CV joints
- clutch is strong it’s not got a high bite point but at least 25k miles and 15 years old maybe more

Advice on what I can check myself please before going to a specialist
Author:  scam75 [ Mon Jun 02, 2025 10:37 am ]
Post subject:  Re: Jerking on deceleration
Hi Austin

My money would be on CV joints, mine was doing this until I replaced all 4 CV's and the issue went away completely.

If you dip the clutch when approaching speed bumps, and it doesn't jerk, bad CV's will be confirmed.

Stuart
Author:  Austin09 [ Mon Jun 02, 2025 3:00 pm ]
Post subject:  Re: Jerking on deceleration
Thanks,

I’ll start my inspection there then and look for a split boots and feel for play on the rear wheels.

The CVs were new 10 years ago c. 10k miles ago

No jerk when I dip the clutch it’s decelerating in gear 1st or 2nd coming up to speed bumps and the like it’s most noticeable
Author:  scam75 [ Mon Jun 02, 2025 6:08 pm ]
Post subject:  Re: Jerking on deceleration
No worries. I suppose miles is a big factor but I've found new CV's last about 10 years with me, about 60k miles. Had one knocking a couple of years back but upon inspection all 4 had seen better days, the one nearest the exhaust tends to go first.

4 CV's (GKN OEM) were about £160 from ECP and solved my issue. Only ever replaced them singly before but doing all 4 made things so much better and IMO worth doing.

Stuart
Author:  Austin09 [ Mon Jun 02, 2025 6:22 pm ]
Post subject:  Re: Jerking on deceleration
Thanks
I’ll let you know how I get on. If the grease escaped then perhaps they have worn prematurely but barely done any miles.
I’ll also test my TPS with my multimeter cos that’s newish but I don’t recall this issue after fitting it only the other day for my first drive of the year
Author:  Austin09 [ Thu Jun 05, 2025 10:56 am ]
Post subject:  Re: Jerking on deceleration
I jacked up the car and inspected the boots and checked for noises and play on the wheels and no indications there are issues with either driveshafts.

TPS is making an audible click when off the throttle and the resistance readings is as you'd expect in line with clarks garage. Its new so can rule that out.

I need to do drive shaft seals so I will probably pull the CVs off and inspect and regrease but think I need to look elsewhere.

Any other suggestions?
Author:  briggy [ Sun Jun 08, 2025 11:17 am ]
Post subject:  Re: Jerking on deceleration
Does it also jerk when accelerating as well as decelarating? If so, it could be the clutch. The rubber centre disintegrates over time. This is exactly what happened with my old S2, years ago.
Author:  tr7v8 [ Sun Jun 08, 2025 1:52 pm ]
Post subject:  Re: Jerking on deceleration
The drive shaft that dies soonest is the one above the exhaust as the grease gets cooked out. I've done a few and on one the grease was like cement!
Author:  Austin09 [ Sun Jun 08, 2025 1:55 pm ]
Post subject:  Re: Jerking on deceleration
Interesting. I’ll take it off and do the drive shaft seal in the next couple of days and see if it needs regreasing.
It’s not too expensive for a new drive shaft but I don’t want to replace if I don’t need to if the problem lies elsewhere.
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