981 PDK hesitation/shunt - Page 3 - Boxster/Cayman - PistonHeads UK

I'm pretty sure I'm not imagining it - I'm convinced that when I'm in a high gear (say 4th or above, may happen lower but it's difficult to tell) at medium revs (say 3k or so) if I'm cruising and suddenly plant my foot (in manual mode or without the car changing gear) there seems to be a hesitation/shunting/bumping for a sec or so before the car accelerates cleanly. At first I thought it was just the little bumps in the road you feel fooling me as I was obsessing - it's that mild, difficult to tell whether it's vertical or longitudinal - but the "bumps" always seem to happen more for the first second or so when accelerating as described. Anyone else had this problem? Either feels like the engine is hesitating or that the PDK clutch is slipping...or that I'm going nuts. Car is booked to go for its first service in July, so trying to work out whether to wait until then to get it looked at, or take it in before. Feel quite bad about doing the latter as it's already been in twice for warranty stuff and one of those was me being an idiot :/

Not had anything like that.

Someone on here posted that they had had their dynamic engine mounts replaced 3 times. Could it be that?

Not experienced anything like that. Does it happen in all situations i.e. Normal/Sport/Sport plus if applicable?

Mario149 said: in a high gear at medium revs (say 3k or so) if I'm cruising and suddenly plant my foot (in manual mode or without the car changing gear) there seems to be a hesitation/shunting/bumping for a sec or so before the car accelerates cleanly. It's sudden high torque bouncing the springs in the clutches and you can get the same effect in a manual car. If you leave the PDK in auto it will engage the right gear and this won't happen. The only place I've ever noticed a difference between PDK and a torque converter auto is crawling in traffic, where occasionally there will be a slight jerk as clutches engage/disengage. The classic way to test a manual car for a worn clutch is to drive exactly in the way you have described; plant foot at medium rpm in high gear. The high torque will cause a worn clutch to slip.

We have the same problem on our GTS, its going into the dealer on Monday to look at this and a couple of other bits. Feels a bit like a fuelling issue as I initially thought it was the traction control kicking in.

Is it not transmission shunt? Drove a few Porsches and no matter how carefully you apply the throttle there is evident shunting of the gearbox and transmission, especially on the motorway.

ellesmereFNC said: We have the same problem on our GTS, its going into the dealer on Monday to look at this and a couple of other bits. Feels a bit like a fuelling issue as I initially thought it was the traction control kicking in. Thanks for the comments so far. To be honest if if had to put money on it I'd say it was engine rather than transmission related, maybe fuelling as suggested above^^. Like I said, feels like hesitation. I've driven cars where there's drivetrain shunt and the slack is taken up only once I.e. one bump rather than a series of them.

This to me sounds like you are confusing the PDK gearbox. Say you are in 4th it thinks you are going to change to 5th next, but you plant the throttle, the car needs to change down but you have 5th selected at the 2nd clutch, so has to swap that out and put third in, at the same time the engine is trying to deliver more torque and revs. Hence you get a jerk/shunt. PDKs Get it right 90% of the time but not always. Sorry just reread your post, it seems you are in manual mode, so cannot be this- not sure then.

JC360 said: Is it not transmission shunt? Drove a few Porsches and no matter how carefully you apply the throttle there is evident shunting of the gearbox and transmission, especially on the motorway. Certainly not true of mine - but it hasn't got Chronosport and the dynamic engine mounts that go with it. I still wonder if that is a factor.

Just dropped the CGTS off at the local OPC, went out with the technician and the initial thoughts are either a failing coil pack or a sticking / failing valve train solenoid... Guess i'll know later on, also this happens in auto or manual and makes no difference if its in standard, sport or sport +

ellesmereFNC said: Just dropped the CGTS off at the local OPC, went out with the technician and the initial thoughts are either a failing coil pack or a sticking / failing valve train solenoid... Guess i'll know later on, also this happens in auto or manual and makes no difference if its in standard, sport or sport + Good to know, I may try and get mine in then before its service in July.

Had something like that on my boxster, bit like a misfire, eventually it triggered a cel light on the dash. Turned out to be a loose connection on one coil pack.

Have bitten the bullet and booked mine in for Friday. They'll look at the exhaust tips as well while they're at it as they appear to have the par for the course corrosion on them.

Quick update...now looks like it might be the high pressure fuel pump.

Well that didn't sort it...! Technician can feel the problem but car has no fault codes, the search will continue.

ellesmereFNC said: Well that didn't sort it...! Technician can feel the problem but car has no fault codes, the search will continue. Oh no! What a pain! The hesitation on my car now seems to be intermittent, could feel it yesterday but not the day before

I've noticed a small problem with mine. When I'm going slowly in say 3rd and I start to brake gently I feel a shove or shunt as it downshifts to say 2nd. These downshifts used to be smoother than a smooth thing. Now they are noticeable.

ATM said: I've noticed a small problem with mine. When I'm going slowly in say 3rd and I start to brake gently I feel a shove or shunt as it downshifts to say 2nd. These downshifts used to be smoother than a smooth thing. Now they are noticeable. Funny you should mention it, but I was also thinking that some of the gear shifts weren't as smooth as they used be.

Mario149 said: ATM said: I've noticed a small problem with mine. When I'm going slowly in say 3rd and I start to brake gently I feel a shove or shunt as it downshifts to say 2nd. These downshifts used to be smoother than a smooth thing. Now they are noticeable. Funny you should mention it, but I was also thinking that some of the gear shifts weren't as smooth as they used be. Right If I bought the car today I would not think anything of it. But I have experienced better 12 months ago. Is there any adjustment for the clutch [as it ages] or is this all automatic / computer controlled.

ATM said: Mario149 said: ATM said: I've noticed a small problem with mine. When I'm going slowly in say 3rd and I start to brake gently I feel a shove or shunt as it downshifts to say 2nd. These downshifts used to be smoother than a smooth thing. Now they are noticeable. Funny you should mention it, but I was also thinking that some of the gear shifts weren't as smooth as they used be. Right If I bought the car today I would not think anything of it. But I have experienced better 12 months ago. Is there any adjustment for the clutch [as it ages] or is this all automatic / computer controlled. Have no idea.

Two things, 1. Have you got the sport button pressed? 2. Have you been driving the car more enthusiastically? IIRC the PDK transmission has several shift maps and it will switch between them either if it is told to or if it "learns" how the driver is driving. I think the transmission has more "maps" than there are switch positions. The maps control both when the transmission shifts and how firmly it shifts. I have heard of cases where people take modern auto cars back to the dealer complaining that it's changing gear incorrectly. Dealer simply asks, "Has someone else been driving the car?". If the answer is "yes" then that's often the explanation; the car has simply learnt someone else's driving style. Eventually it will either default back to its normal mode or learn the style of the next driver. Some extracts from a PDK driver's manual, Select position D for "normal" driving. The gears are shifted automatically according to the accelerator position and speed. Depending on the way the vehicle is driven (economical, comfortable or sporty driving style) and on the resistance (e.g. uphill), the gearchanging points are shifted towards higher or lower engine-speed ranges. The accelerator position, driving speed, engine speed, longitudinal and lateral acceleration and the road profile all have an influence on the gearchanging characteristic. When you brake, and depending on the amount of deceleration, the PDK transmission changes down earlier. With a sporty driving style, downshifts are already initiated when the brake pedal is touched lightly. This further enhances a dynamic driving style. The PDK transmission temporarily changes to the sportiest gear-changing map, i.e. to the highest possible gear-changing points, if the accelerator pedal is pressed quickly. The transmission accordingly shifts down immediately by one or two gears (temporary downshift). "Sport" mode activated: The PDK transmission switches to a sporty gearchanging map and shortens the shifting times. A sporty driving style is recognised more quickly and the gear-changing speeds are adapted to driving performance. Braking downshifts are initiated earlier. Downshifts occur for small decelerations, even at higher revs. "Sport Plus" mode activated: In "Sport Plus" mode, the PDK transmission changes to a shift programme designed for driving on race circuits. 7th gear is not selected. The gear-changing performance is enhanced significantly again compared with "Sport" mode. Please see the chapter ""SPORT" AND "SPORT PLUS" MODE" on page 167.

Thanks for the explanation Rockin, but the hesitation happens in normal, sport, sport plus, manual mode or auto. Wouldn't say it's the PDK as the engine is also pinking slightly under a light throttle as the hesitation happens. I'd say fuelling or ignition related or maybe the emissions system having a fit. Whatever it is I can see a battle coming on as the dealer says they can't fix the issue as there are no fault codes, even though they have driven it and acknowledge there is an issue. Edited by ellesmereFNC on Friday 17th March 04:52

ellesmereFNC said: Thanks for the explanation Rockin, but the hesitation happens in normal, sport, sport plus, manual mode or auto. ....the engine is also pinking slightly under a light throttle as the hesitation happens. Hmmm. On my manual car if I'm going slightly up-hill at 40-45 mph in 6th gear I sometimes think I can hear it pinking slightly. I've talked to the OPC about this and they say, "no, a modern car won't suffer from pinking because the knock sensors will automatically correct the ignition timing if it's detected. And there are no codes." Anyway, I simply change down a gear on the odd occasions that it happens which obviously makes it go away. Just to clarify, this isn't driving in too high a gear and the gear indicator light certainly doesn't ask for a gear change anywhere near that speed. These cars will easily pull from 30 mph in 6th. The only other thing I would add is that in gentle driving you can occasionally feel when the fuel supply is cut in or out by the injection system. IIRC these engines do not receive fuel all the time, only when needed. As regards PDK transmission this is interesting from, http://autoweek.com/article/car-reviews/porsches-b... "PDK adds a trick coasting feature that automatically drops engine revs to idle levels when you ease completely off the throttle. On long downhill grades, for example, the engine will stay in coasting mode until you step back on the gas or shift. Porsche says this feature, combined with stop/start, helps the Boxster lineup see a roughly 15 percent improvement in fuel economy."

rockin said: Hmmm. On my manual car if I'm going slightly up-hill at 40-45 mph in 6th gear I sometimes think I can hear it pinking slightly. I've talked to the OPC about this and they say, "no, a modern car won't suffer from pinking because the knock sensors will automatically correct the ignition timing if it's detected. And there are no codes." The tech at my OPC said the same thing, but it still does it! I turn off the coasting function most of the time, I prefer engine braking when going downhill and into corners...saves the brake too! Sometimes cars can try to be too clever...and trip themselves up...which is what i think is happening here, one sensor is reacting to a minor fault off another and trying to cancel it out. So knock sensor is altering the timing due to the pinking, which alters the fuelling, which the drops power, which could confuse the PDK software, which etc...Did I say I once knew an old woman who swallowed a fly!!!

Might sound like a daft one, but where are you buying fuel? There can be some pretty substantial differences between the way engines behave, and although they are often set up to run safely on regular unleaded, Super often helps, especially when there is a bit of transient pinking. Haven't tried supermarket fuel in a long while, but last time I did a back-to-back of Morrison's vs. Esso on an engine dyno, I was stunned at just how much performance difference there was. Have avoided it even for road cars ever since. Liam

LiamH66 said: Might sound like a daft one, but where are you buying fuel? There can be some pretty substantial differences between the way engines behave, and although they are often set up to run safely on regular unleaded, Super often helps, especially when there is a bit of transient pinking. Haven't tried supermarket fuel in a long while, but last time I did a back-to-back of Morrison's vs. Esso on an engine dyno, I was stunned at just how much performance difference there was. Have avoided it even for road cars ever since. Liam I Dont buy cheap fuel, use Shell V-power and BP Ultimate...only had the car 3 weeks so only filled it twice and its now been in dry dock for a week now. At least its keeping the miles down...apparently the Techs are now asking Germany for advice as they can't solve why its doing what it does...wouldn't of bought it if we'd noticed the issue on test drive!

Okay, update on my car. It went into Porsche Guildford today and chatting to the service chap it seems it is a known "feature". According to him it's due to the cam variator switching the cam profile to a high power one as you get on the loud pedal. Apparently they had a Cayman in last year with the owner giving the exact same symptoms. They had it it for 2 weeks, changed ECU etc etc, couldn't find anything wrong and found that other cars they had did the same. Then Porsche in Germany confirmed it was expected behaviour. They're going to plug it into diagnostics anyway to check, and I also mentioned the PDK not shifting quite as cleanly as I thought it used to, so they'll take a look at that as well. Given that the hesitation is so minor the explanation makes sense to me, but we'll see if they come up with anything else.

Well our GTS now been at the dealer for 2 weeks, Germany involved but not sure yet whet they think it is...maybe they'll just swap it for a GT3!

ellesmereFNC said: Well our GTS now been at the dealer for 2 weeks, Germany involved but not sure yet whet they think it is...maybe they'll just swap it for a GT3! Update on mine: dealer checked it over, no faults anywhere. I've driven it quite a bit since and I can still feel it occasionally and it's very very mild. If your issue is genuinely more noticeable (you have to really be looking for it to feel it on mine) it sounds like either your issue is different or that maybe your cam variator isn't "variating" quite as swiftly as mine i.e. not "broken enough" to trigger an error somewhere. As I said before, Guildford told me they went right round the houses for a couple of week with this last year on a Cayman and in the end Germany said "that's expected".

Well we're now into week 3 of not having the car...just had the below from the OPC, so at least there is a problem, it's not normal and they are trying to sort it. have spoken to our senior technician again regarding the progress and he has advised the following. In the beginning we confirmed the fault with hesitation under part throttle and it seemed to occur between 2000 & 3000 rpm but was worse in sport plus. The initial thought was fuel starvation as the vehicle judders until it exceeds 3000 rpm. No relevant faults were showing in the system tester and in actual values the mid-range fuel trim was high but not enough to flag a fault. During another road test using data logger a noticeable dip in fuel pressure occurred at the same time as the fault. We checked the low pressure delivery rate which was 4400ml over 60 seconds, this was way over the 2.91 minimum, we have tried a fuel pump control unit which has had no effect on the fault, we have replaced the high pressure pump and carried out the relevant adaptions but the fault remains. We noticed 2 misfire counts on the 1000rpm per misfire section on cylinder 2 and also a timing retardation on this cylinder but not on any of the other 5, we removed the ignition coils and plugs but no visual faults found so we have swopped coil 2 to cylinder 3 then carried out a second retardation data log and found cylinder 2 now not retarding at all. We have sent all the data logs and screen shots back to Germany on the PRMS ticket and are now waiting for a response from them. So a number of issues seem to have raised there heads...jus hope iits not to long to wait...boiught the car 6 weeks ago and actually had it on the drive for 3 of them!

Sounds like they should take the car back and do you a nice little deal on something else. Getting a 981 in a spec you like could be a challenge but there could well be something within that dealer group...

Maxym said: Sounds like they should take the car back and do you a nice little deal on something else. Getting a 981 in a spec you like could be a challenge but there could well be something within that dealer group... We're beginning to think the same...money back or an attractive deal on something else...we went for the GTS as it was more special than an S, but right now we wouldn't care about not seeing it again. Dealer doing what they can but patience running out with what is obviously a faulty car. Edited by ellesmereFNC on Wednesday 29th March 12:22

I have a similar issue on mine, (manual, non S) more noticeable when you turn the PSE on. Accelerate up to 3k steadily, lift of and the accelerate steady again and you get what I've started calling a "Sneeze", sounds like a miss or brief stutter before carrying on as normal. Probably happens at different revs but much easier to spot at this range. It's off into the OPC next week for them to have a look. Not sure where I stand with no warranty if they start claiming I need this and that changing but that doesn't cure the fault, do I still have to pay for those items even if it doesn't cure the fault, can I just request the refit the old part back?

Guys, did anyone manage to solve this? My 981 PDK is behaving exactly how other posters have described and to be honest it is spoiling the car for me, even though it is very subtle and not something a passenger would notice. I'm not sure how to go about fixing it, personally it feels fuel or ignition related to me but I have no doubt that OPC will say "no fault codes, nothing wrong".

My 981S PDK has never suffered from these issues- and, although I've now switched from Tesco Momentum to Shell for (tested) economy reasons I've never had these issues whatever fuel I've used - including the odd dose of 95 octane when I couldn't get the proper stuff.

SkinnyPete said: Guys, did anyone manage to solve this? My 981 PDK is behaving exactly how other posters have described and to be honest it is spoiling the car for me, even though it is very subtle and not something a passenger would notice. I'm not sure how to go about fixing it, personally it feels fuel or ignition related to me but I have no doubt that OPC will say "no fault codes, nothing wrong". Hi Nope unfortunately we never got to the bottom of this issue, our dealer at the time based near Chester spent 4 months trying without and success to fix the problem that all their technicians agreed was present. Then one day they took in another GTS which did the same and their attitude changed. Suddenly it was a characteristic of the car and they would do no more...so in total we were without our car for 16 week from purchasing it when we were handed the keys and told nothing more would be done...No Sorry for your trouble, here’s a toy car or umbrella as compensation, just a bugger of from the service manager...sales even had the cheek to email to tell us to forget the issue and enjoy the car. A car which we bought from then to take on a road trip down to Tuscany, but ended up going in our Audi A4. So it still hesitates but maybe not as bad if I keep the oil level up, the engine can be heard to pink under load on 97 octane, with 95 if we hav to put it in it sounds like a tin can rattling. The Porsche dealer near Chester have ruined our experience of the brand. Hopefully the dealer near Wolverhampton will be better, as they seem to of been up to now...much better.

ellesmereFNC said: Hi Nope unfortunately we never got to the bottom of this issue, our dealer at the time based near Chester spent 4 months trying without and success to fix the problem that all their technicians agreed was present. Then one day they took in another GTS which did the same and their attitude changed. Suddenly it was a characteristic of the car and they would do no more...so in total we were without our car for 16 week from purchasing it when we were handed the keys and told nothing more would be done...No Sorry for your trouble, here’s a toy car or umbrella as compensation, just a bugger of from the service manager...sales even had the cheek to email to tell us to forget the issue and enjoy the car. A car which we bought from then to take on a road trip down to Tuscany, but ended up going in our Audi A4. So it still hesitates but maybe not as bad if I keep the oil level up, the engine can be heard to pink under load on 97 octane, with 95 if we hav to put it in it sounds like a tin can rattling. The Porsche dealer near Chester have ruined our experience of the brand. Hopefully the dealer near Wolverhampton will be better, as they seem to of been up to now...much better. Thanks for replying, unfortunately your answer does not come as a surprise nor does the dealer - one who I refuse to give another penny to. So what's next? Are you just going to live with the 'characteristic'? I find mine is fine towards higher revs or when making good progress, it's the partial throttle in higher gears when negotiating traffic that its most noticeable. Considering a lot of my driving is motorway rush-hour it is evident the majority of the time.

Not mentioned yet on this thread, but could it be drive-by noise or emmissions regulations related? I.e a part of the engine map at certain rpm/road speed? There was an absoutely huge thread on here a few years ago from a guy with a Cayman R, the engine misfired/hesitated continually at 3k rpm in a certain gear, and was finally confirmed by Porsche as expected due to emmissions and/or noise regulations.

Olivera said: Not mentioned yet on this thread, but could it be drive-by noise or emmissions regulations related? I.e a part of the engine map at certain rpm/road speed? There was an absoutely huge thread on here a few years ago from a guy with a Cayman R, the engine misfired/hesitated continually at 3k rpm in a certain gear, and was finally confirmed by Porsche as expected due to emmissions and/or noise regulations. Sounds plausible. Motorbikes (almost universally) suddenly got a flat spot at 5500 rpm when stiffer noise regulations were introduced (quite a long time ago now). There is a dip in the torque curve of all 981 engines at 3000rpm which may point to the same conclusion. That said this issue seems to be limited to GTSs. Anyone with an S or 2.7 have the issue?

anonymous said: [redacted] I used to use Tesco 99 on the odd occasion but ever since my wife's BMW X1 threw an error message and I got talking to the highly experienced technician sent out to sort it I've kept away. He was 100% certain the EGR blockage was due to "supermarket fuel" and filled me in on how only Shell, Texaco & BP refine their fuels differently.

SkinnyPete said: Thanks for replying, unfortunately your answer does not come as a surprise nor does the dealer - one who I refuse to give another penny to. So what's next? Are you just going to live with the 'characteristic'? I find mine is fine towards higher revs or when making good progress, it's the partial throttle in higher gears when negotiating traffic that its most noticeable. Considering a lot of my driving is motorway rush-hour it is evident the majority of the time. Hi, ours is the same, higher in the rev range its better but between 2-3k rpm on light or partial throttle it hesitates. We're due tyres soon so will get it checked over again at Wolverhampton at the same time. I'm sure its the timing not adjusting properly as it does pink even with high octane fuel. We'll never darken the doors at Chester again...ever.

I have just come across this thread. I have a 981 GTS with similar symptoms, where typically if trickling along and you then ask for significantly more throttle, the acceleration increases and after a moment I get what appears to be a gentle but firm boot up the backside. To me it feels like the exhaust mounts tightening, as the change is felt more physically than is the case with cam variations, but still investigating. My car is a manual. It is not a transmission issue as far as I can see.

Possibly related, possibly not, I did read somewhere that (on PDK cars) coming out of coast mode could be a bit jerky. On my car it's completely seemless, but if it isn't it may be a related issue, as my car doesn't have any shunt issues either.

bcr5784 said: Possibly related, possibly not, I did read somewhere that (on PDK cars) coming out of coast mode could be a bit jerky. On my car it's completely seemless, but if it isn't it may be a related issue, as my car doesn't have any shunt issues either. I light my start stop button to prevent coast.

Always drive in Sport and the only time the gearbox gets clunky, is if driving with big throttle inputs then coming to a rapid halt, the car can seem to 'slam' into 1st a bit hard, but otherwise it's pretty smooth?

nsm3 said: Always drive in Sport and the only time the gearbox gets clunky, is if driving with big throttle inputs then coming to a rapid halt, the car can seem to 'slam' into 1st a bit hard, but otherwise it's pretty smooth? Yeah i also get this so i flick to manual when coming to a hard stop because the down shifting is always a bit too vigorous for my liking.

This thread is old, so likely those that contributed to it may not pick this up. I have a 2016 981 Cayman (non S) manual - pretty much last-of-the-line. Have much the same issue as described here; slight engine faltering (mostly at c.1600-200rpm) under light load, worse when cold. Dealer had the car for two months and replaced 6 Spark Plugs, 6 Coil Packs, Valve Lift Solenoid, High Pressure Fuel Pump under warrantee. Fault remains. Just been advised subsequently that 'they all do this' as the Variocam tips from one to the other mode (or similar). I had thought that the Variocam would change at higher rpm (say 3500 rpm); but the main question here to those that had this issue is: did this fault it worsen / develop into something more? Thanks in advance for any repossess here, Sam.

OP here. I never got to the bottom of it other than the dealer saying cam variator. From memory since it was so mild and a bit intermittent I just lived with it. I sold the car a few months later and swapped into a 997 GTS manual (because children, not due to the issue). samliv said: This thread is old, so likely those that contributed to it may not pick this up. I have a 2016 981 Cayman (non S) manual - pretty much last-of-the-line. Have much the same issue as described here; slight engine faltering (mostly at c.1600-200rpm) under light load, worse when cold. Dealer had the car for two months and replaced 6 Spark Plugs, 6 Coil Packs, Valve Lift Solenoid, High Pressure Fuel Pump under warrantee. Fault remains. Just been advised subsequently that 'they all do this' as the Variocam tips from one to the other mode (or similar). I had thought that the Variocam would change at higher rpm (say 3500 rpm); but the main question here to those that had this issue is: did this fault it worsen / develop into something more? Thanks in advance for any repossess here, Sam.