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Hi All, First time poster here so go gentle with me Bought a 2007 997 2S about a month ago (65k miles), and had some fairly major issues with it straight away. The engine had a load of work doing (£4k+) in the 18 months before I purchased it, which was a bit of a warning sign I guess but I also figured that maybe it was good that it had had a load of independents looking through things. Anyway, I drove about 400 miles and triggered the check engine & warning lights. Took it to the garage and they replaced coil packs, spark plugs and actuators, re-ran the diagnostics and all seemed OK. Took it out again this week for about 30-40 miles and all seemed fine but then had the same issue 3 times under hard acceleration. Engine revs up to around 5.5k RPM in 3rd gear as normal, and then just at the point at which it feels like it's going to shift up (Tiptronic, in auto mode), limp mode kicks in it shifts to 4th (to protect). Then when the engine revs down and shifts down to 3rd again, with gentle acceleration it turns off an normal service is resumed... until the next hard acceleration anyway. Am going to take it in to a specialist as soon as I get it organised but any ideas/suggestions? Good news (for me anyway) is that this all happened very soon after purchase from the dealership so am protected under both UK consumer regs as well as their own 3-month warranty. The first round of repairs (coils, plugs & actuators) was about £1k... hoping this isn't going to be as bad (but prepared for the worst). Video is here for those interested:
Im just here to say I have no idea, but I bet thats very distressing and I hope you get it figured out. Weve got some very experienced guys on the forum that should be able to point you in the right direction soon. Good luck.
Thanks! Thankfully in the UK you are protected such that if you bought it from a registered dealer and there is a pre-existing fault within 30 days of purchase, you can basically just hand the keys back and get a full refund. So the dealer's been fine about paying for everything (but the alternative for them is worse). But I don't want to return it because it makes me very happy (when it's working properly anyway...)
That is nice!! Ive never had to deal with it, but we have lemon laws over here which are sort of supposed to work like that, kinda. Not sure. But it seems to be a hassle anytime you get a lemon and try to return it.
Open the engine lid and look at the motor mounts are they stock or aftermarket semi solid versions. It's possible that the engine is vibrating at higher RPMs and semi solid mounts can trip the knock sensors which will do what you've described.
OK, next would be to check the condition of the transmission mounts as vibration there can trigger the same things. If they look worn, I think I have a brand new pair of Torque Solutions Street trans mounts that only fit the Tiptronic equipped car I'd sell at a discount. I bought them by mistake for my 6 speed manual car and have no use for them.
Really, we're going to need to run some live values with a scanning tool when this is occuring, like misfire tracking by cylinder number, engine roughness, maybe mean fuel trims for both banks, camshaft deviation both banks, etc.
Thanks - yeah trying to arrange a diagnostic at the moment. I'll update the thread when I know more but thank you for your help and if I need those trans mounts I'll give you a shout!
Have the specialist scan the code if you don't have the tool for it. Since the CEL came on, the code is supposed to be stored. That will tell you straight away that is wrong.
Was the accelerator floored the entire time during the first acceleration in the video? If yes, the car was already accelerating abnormally slowly even before the limp mode kicked in at 5.5k rpm.
I had this issue once. The codes I got were:
P0300 Misfiring, checksum error
P1 095 Air mass (HEM) ahead of throttle valve - implausible
P21 21 Throttle adjusting unit potentiometer 1
P21 26 Throttle adjusting unit potentiometer 2
P21 02 Throttle actuator control motor circuit low
Basically, the potentiometers went bad in the throttle body. The problem went away completely, after I replaced the throttle body with a new one.
Thanks J.Tan - no it wasn't fully floored as I had a car a little way ahead of me when I was filming it and didn't want to turn a small problem in to a big one! Probably around 2/3rds of the way I'd think.
I have a 2006 997S, am original owner, 74,097 miles on it as of today - M97 engine, manual transmission. First time I had the problem was in August of 2013 at 46,185 miles (I had the first set of plugs replaced at around 30,000 miles). Every time I pressed the accelerator, the engine would miss; I barely got it back to the dealer - it would stall on me. The dealer replaced the coils and plugs - coils were actually crumbling, falling apart. Had to get them replaced a second time, a little over six years later, at 68,188 miles when I had to get the starter replaced. That time, the coils were falling apart again but I didn't have the engine missing under acceleration. I was told by the dealer that Porsche had upgraded the coils because of past problems like mine. What I am wondering is this: could it be that the coils can't withstand the heat generated in the engine compartment? Hope you are able to get it fixed. With so little mileage since you got the coils replaced, It's a puzzle.
What I am wondering is this: could it be that the coils can't withstand the heat generated in the engine compartment?
Yes, the new coil design has a much thicker insulator on the back so it.lasts longer. That's why they require longer fasteners (often included in the box) the first time you make the change.
Yes, the new coil design has a much thicker insulator on the back so it.lasts longer. That's why they require longer fasteners (often included in the box) the first time you make the change.
Many thanks for the info - I was really steamed that it took so long for Porsche to engineer and produce a critical component like the coils.
Hey all - thanks for contributing to this thread. Here were the fault codes:
P0300-01 Random/Multiple Misfire detected exceeds limit value
P0303-01 Misfire, Cylinder 3 exceeds limit value
P0303-01 Misfire, Cylinder 2 exceeds limit value
P0303-01 Misfire, Cylinder 1 exceeds limit value
P0420-01 Catalyst System Efficiency below threshold, Bank 1 exceeds limit value
So... catalytic converters were shot, and under heavy acceleration they couldn't get rid of the exhaust quickly enough, hence why it was happening at high revs but not at lower revs. Solution is unfortunately expensive (around £2k for one side) but the dealer is paying for it. Didn't manage to convince them to pay for the other side though, the car is still under warranty for 6 weeks so I might drive it like hell and hope the other side goes next .
10-11-2021, 05:36 AM
'07 997 2S limp mode under hard acceleration
Bought a 2007 997 2S about a month ago (65k miles), and had some fairly major issues with it straight away. The engine had a load of work doing (£4k+) in the 18 months before I purchased it, which was a bit of a warning sign I guess but I also figured that maybe it was good that it had had a load of independents looking through things. Anyway, I drove about 400 miles and triggered the check engine & warning lights. Took it to the garage and they replaced coil packs, spark plugs and actuators, re-ran the diagnostics and all seemed OK. Took it out again this week for about 30-40 miles and all seemed fine but then had the same issue 3 times under hard acceleration. Engine revs up to around 5.5k RPM in 3rd gear as normal, and then just at the point at which it feels like it's going to shift up (Tiptronic, in auto mode), limp mode kicks in it shifts to 4th (to protect). Then when the engine revs down and shifts down to 3rd again, with gentle acceleration it turns off an normal service is resumed... until the next hard acceleration anyway. Am going to take it in to a specialist as soon as I get it organised but any ideas/suggestions? Good news (for me anyway) is that this all happened very soon after purchase from the dealership so am protected under both UK consumer regs as well as their own 3-month warranty. The first round of repairs (coils, plugs & actuators) was about £1k... hoping this isn't going to be as bad (but prepared for the worst). Video is here for those interested:
Limp mode kicks in around 0:15 and then back to "normal" again at 1:10.Thank you for reading/watching!
