Shudder when coming to a stop.

[devilly]

02 sensors something electrical as it can't be driveline if doing it when stationery can't be brakes or rotors. have you checked the brake booster rubber and the check value. I used a heap of gasket goo around the rubber on the check value. Egr also springs to mind maybe give it a few hard revs to clean it all out. injector cleaner and run it at high revs for a bit could just be stuff that needs a few hard revs to remove. how does it idle if you remove the iac plug then the tps plug. you could also check the l/h. maybe post a video hope you find it and get it sorted out.

 

[accentstencil]

02 sensors something electrical as it can't be driveline if doing it when stationery can't be brakes or rotors. have you checked the brake booster rubber and the check value. I used a heap of gasket goo around the rubber on the check value. Egr also springs to mind maybe give it a few hard revs to clean it all out. injector cleaner and run it at high revs for a bit could just be stuff that needs a few hard revs to remove. how does it idle if you remove the iac plug then the tps plug. you could also check the l/h. maybe post a video hope you find it and get it sorted out.

I also thought of the check valve and grommet as it felt a bit loose, replaced both items two weeks ago.
Replaced both O2 sensors about three years ago, about a month before I posted this thread so the problem was still there with new sensors.
I put in reconditioned engine about six months before that so it should be nothing to do with with the engine internals.
Each time I replace something or do some maintenance I'm hoping to strike it lucky.
It's not a major issue, just one of those annoying things.

 

[devilly]

some ideas on what to check if haven't already. what about gearbox mount, accelerator cable adjustment, knock sensors. vacuum leak or even cracked headers which is slowly getting bigger so the problem is getting a bit worse.my mind keeps telling me shudder is normal uni joints or diff U shape rubber housing thingo. I hate little problems I know with my luck it turns into something bad lol I hope you find it before its a bigger problem. I dunno your motor could it be as easy as a tune. thinking old school of timing light and points here and dizzy they would shudder and engine if not set properly. I have a brain ach now lol coffee time.

 

[Immortality]

Not 100% on the LS TB adjustment but try opening the butterfly a touch using the butterfly stop screw that way the IAC has has to open less to maintain the idle and the idle rpm is less likely to drop to far. I'd try 1/2 a turn and see what it does that way if it doesn't work it's easy enough to adjust back to the original setting.

 

[accentstencil]

some ideas on what to check if haven't already. what about gearbox mount, accelerator cable adjustment, knock sensors. vacuum leak or even cracked headers which is slowly getting bigger so the problem is getting a bit worse.my mind keeps telling me shudder is normal uni joints or diff U shape rubber housing thingo. I hate little problems I know with my luck it turns into something bad lol I hope you find it before its a bigger problem. I dunno your motor could it be as easy as a tune. thinking old school of timing light and points here and dizzy they would shudder and engine if not set properly. I have a brain ach now lol coffee time.

Transmission mount replaced about a year ago.
Throttle cable can't really be adjusted.
I'm thinking IAC is slow to respond, could be an issue with the PCM

 

[accentstencil]

Not 100% on the LS TB adjustment but try opening the butterfly a touch using the butterfly stop screw that way the IAC has has to open less to maintain the idle and the idle rpm is less likely to drop to far. I'd try 1/2 a turn and see what it does that way if it doesn't work it's easy enough to adjust back to the original setting.

I didn't know there was an adjustment screw, it was well hidden and very difficult to access.
I adjusted it to raise the idle by about 100 RPM and the shudder when stopping has gone.
I am going to adjust it back and try the 40 minute IDLE LEARN PROCEDURE and see how that goes, if that doesn't help I will turn the adjustment screw up again.
https://forums.justcommodores.com.au/threads/idle-learn-procedure.267669/

 

[devilly]

awesome news, sounds like your on to something, hope it fixes it

 

[Christophoon]

how did you go? my VF Evoke may be having a similar issue, did the Idle Re-Learn work out?

 

[accentstencil]

how did you go? my VF Evoke may be having a similar issue, did the Idle Re-Learn work out?

The problem still exists, with all things that have been replaced over the years I thought one of them might have fixed the problem. I think the idle re-learn did help for a little while. The shudder is particularly bad when I first turn on the A/C but seems to improve after driving for a while.

 

[Christophoon]

The problem still exists, with all things that have been replaced over the years I thought one of them might have fixed the problem. I think the idle re-learn did help for a little while. The shudder is particularly bad when I first turn on the A/C but seems to improve after driving for a while.

Did you end up cleaning the IAC? or any of the idle controllers?