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Juddering when Lifting off

Cater_Racer

Cater_Racer

PCGB Member
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Not normal Graham, I have the identical sister car (1997 993 Targa Manual), and no problems. I'd look at engine mounts?
 
Thanks How easy is it to tell if the mounts are failing/failed? This wouldn't explain the revs holding thou? Graham
 
The rubbers deteriorate over time - if the car's rubber bits have never been replaced, I'd lay odds they've already failed. I'd suggest investigating the Powerflex range of suspension polyurethane bushes. No recommendations for the engine mount replacement other than official Porsche. There is a Porsche RS Engine Mount but this may be a bit much. The revs are obviously a different problem. No idea.
 
As others have suggested Graham - and considering your car's age - the driveline shunt you're describing could well be caused by a failing engine or gearbox mount. Other possible sources could be wear in the driveshafts and a failing dual mass flywheel [do you get a clunking sound when taking off from a standing start?]. It sounds as though the "fast idle" problem you describe is probably unrelated to the driveline shunt but probably isn't helping. Something amiss with the idle control circuit I would think. Jeff
 
I have had this since I have had the car, 11 years and now it's very annoying!
I am hoping others with be able to help if this is normal!
993 Targa 6 Speed Manual with 48500 Miles and serviced every year

When driving and lift off the car judders like your in the wrong gear. It's not all the time, can happen when cold or hot also.
should you be able to slow down and still be in 6th @ 40mph, 5th @ 40 mph, 4th @ 40mph & 4th @ 30 mph might seem daft question
Sometimes when you idle the revs can hold above 1200 for a few mins before dropping

Any ideas would be great

Thanks

Graham
 
Thanks I Spoke to a Tech at Swindon who said the judder & idle issue could be the idle control circuit. There is a part right at the back of the engine, left of the airbox, but a diagnostic should show this [link=https://drive.google.com/open?id=0B4Jf1F4qCNcSMXFlWjVqQVQ4Rjg&authuser=0]Rear View[/link]
 
The clutch was replaced by JZM Porsche before I had it at 30K so should be that then?? The pic from my previous post should of had the arrow pointing as the part I was told could be causing the idle issue! [link=https://drive.google.com/open?id=0B4Jf1F4qCNcSaVlyQ28zZzZaQ2c&authuser=0]Click here for Picture[/link] Graham
 
JZM will have checked out the DMF when the clutch was replaced Graham, so you should be able to discount that as a source of the driveline shunt. If the engine and gearbox mounts and the driveshafts joints are in good condition then you could ensure that the idle stabiliser valve is functioning correctly. Sorry, can't access your pics but his PH post might be of use: http://www.pistonheads.com/gassing/topic.asp?t=977858 Jeff
 
Jeff Great Link. Just had time now to read it "slow return to idle from high revs jerkiness in traffic & mild to more noticeable "kangarooing" sounds familiar now I have read it. I do find it a bit jerky/kangarooing in traffic also. Just thought it was me and my clutch control!!! Will see if I get time tonight to remove it and clean it, nothing to loose! it could explain the juddering/kangarooing
 
Well got the ISV off the other night. Bit of a bitch for the rear Jubilee clip as all were facing to the left! Got it off and gave it a shake and no movement what so ever! Soaked in White spirit as per the instructions over night. It did loosen some dirt but I ended up using carb cleaner to get it completely clean. Now moves freely [link=https://drive.google.com/file/d/0B4Jf1F4qCNcSSmpub3o4SFJrdzg/view?usp=sharing]Click here! ISV in Situ[/link] [link=https://drive.google.com/file/d/0B4Jf1F4qCNcSXzhvRlFvR3dFQ1k/view?usp=sharing]Click here! ISV Unit[/link] [link=https://drive.google.com/file/d/0B4Jf1F4qCNcScWNIOTYxX3hjclk/view?usp=sharing]Click here! ISV Dirty[/link] [link=https://drive.google.com/file/d/0B4Jf1F4qCNcSNTdoR2lWeGprdlE/view?usp=sharing]Click here! ISV More Dirt![/link] Can't seem to get the pictures to show in the post for some reason! ill upload a clean pic tonight Just need to refit tonight and take for a drive tomorrow
 
Cheers Maurice. Back in now. All save and sound. A bitch to get the rear pipe back on as not a lot of hand room! Attached two clean pics [link=https://drive.google.com/file/d/0B4Jf1F4qCNcScTMyS2szYTBudUU/edit?usp=docslist_api]Click here - Inlet[/link] [link=https://drive.google.com/file/d/0B4Jf1F4qCNcSZTNkQ0ZYa1N3SlE/edit?usp=docslist_api]Click here - Outlet[/link] Started car ok and all seems ok. Need to go for a spin tomorrow to see if anything has been fixed by cleaning the ISV
 
The answer is simple don't lift off...... Don't you just love helpful relies like that.........I had the same issue in my 93 non vario and replace engine mounts, gearbox mounts and cleaned the ISV which cured it.......so good chance it I sone of them!
 
Took the car out for a Spin on Saturday after cleaning the ISV. Didn't really notice any difference. Still juddered! [:(]

open


 
That's a pity Graham. It looks as though you'll need to look elsewhere - as above.

Are you still getting the fast idle or has cleaning the ISV cured that problem?

Jeff

 
Jeff

Dont' know. It didn't happen all the time. Will be going to the Bugatti Breakfast meet /Cornbury House F1 Sunday so will see. Hopefully that will be fixed as it was stuck and dirty

Graham

 
I have now done 100+ miles over the last 10 days and have noticed the following

Every time I lift off there is a Judder. Sometime it is only just noticeable but it is there.

If I push the clutch in at what ever speed the idle only drops to the 1st marker above 1000 rmp and then after about 6 secs or so then drops to 850 rmp. Is this normal??

In traffic crawling along (eg 2nd gear 20 mph) it is very hard to keep the car smooth and not judder.

Graham

 
Graham,

Sorry to hear that you're still living with the problem.

Other than reiterating my previous comments about engine mounts, driveshafts and clutch/DMF, I believe that the 993 uses electronic throttle actuation and I'm wondering if it's malfunctioning. It might be worth checking out but probably will require some appropriate diagnostic equipment.

Jeff

 
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