997 Gen 2 - flat spot on acceleration

[JGamlin]

Upgraded 997 Cobalt Blue C2 Cab just before factory warranty expired last December to 997 Gen 2 Basalt Black C4S coupe manual.

Problem:- on acceleration in second gear at +/- 2,700 rpm I continually experience "flat spot" or "hesitation".

Local OPC say they can not find a problem on diagnostic and it may correct itself when car run in.

Have now covered 1,100 miles (topped up1.25 lt oil) and the problem persists.
(Jersey is small island with speed limit of 40mph but try to drive not less than 20 miles per trip)

Can anyone please offer an explanation as to what the problem could be ?

 

[Mark Elder]

But you don't get some problem in 1st or 3rd ?(maybe tough to check in 3rd given what you say about speed limit[&:]).

I think the "it'll go away when run in" unreasonable after 1.1K miles. Presumably they can feel it themselves when they drive it?

 

[tscaptain]

Only in 2nd? Do you have Sport Chrono +? If so is it the same in different modes?
My Gen 2 used about the same oil, btw. Don't think running in is an issue.

 

[Black80XSA]

OPC excuse sounds like a load of tosh to me - lack of fault codes is a bit strange, any misfire should be logged. What octane fuel are you using? Is it only in second gear ?

I'd be asking the OPC to have another look, on the premise they have 3 attempts to fix the problem before you can legally reject the car (a bit drastic , but might kick them into action !)

 

[JGamlin]

Hi - thanks for responses

Only in 2nd - as change from 1st before 2,700rpm and below that level in 3rd and higher (40mph limit in Jersey)
I don't have Sports Chrono
Use Super grade octane - highest grade

Will go back to OPC - had hoped Forum might recognise fault - now I am worried.

 

[tscaptain]

To my knowledge none of the Gen 2 owners on the Forum have had any engine issues, so far! Early days, I know. To my simple brain a flat spot would be more likely due to a fuel/air problem rather than electrical? ECU? Like Mark says surely if you take them out in it they can feel it too? Bring it over to the mainland and give it some welly is the other option![]

 

[jonathanw]

I occasionally get a flat spot when starting off and giving it a bit of welly. I have not done too much mileage and wonedr if I should take it back for a checkup - trouble is dont have too much time free at the moment. (I have the PDK and this happens when left in auto mode).

 

[tscaptain]

Give it some launch control. Jonathan. No flat spot then![] Can't say I've noticed anything other than a clean pick up from tiniest of throttle in traffic to more enthusiast pull aways - manual or auto, which is the same thing anyway - isn't it?

 

[JGamlin]

OPC mechanic denied feeling anything when driving - time for a second opinion.

btw - happy birthday

 

[juliany27]

I agree - a second opinion is needed asap. You could insist that the OPC sort this out - or threaten to get an expert to look at it - and also send the OPC the bill if anything wrong is found. IMO, you have the law on your side bearing in mind the age of the vehicle and the amount you paid for it.

 

[JGamlin]

Update on "flat spot" after investigation by local OPC.

Technician found flat spot at 2,800 rpm if throttle angle at 11%. No engine fault showed up on diagnostics.
He was able to replicated the same 11% throttle angle on 3 other new Gen 2 C4S in stock and they all exhibited the same "flat spot" at 2,800 rpm.
A report has been submitted to Porsche UK for further testing and possible submission to factory for decision on whether or not they consider this a problem for possible remapping.

Should I feel better that all other cars tested so far exhibit the same problem and is this a problem ?

I would be interested to hear opinions.
Do the above findings sound plausible to the technically literate who understand these things?

 

[garyw]

Glad that they actually looked into it properly.

I'd personally be pleased that they have found an issue on other cars showing that there is more of a chance that its a manufactures fault. however they may come back with the usual 'characteristic of the car' line we've heard so many times.
At least they have found a issue with the car, much better than them saying, we can't find anything wrong Sir....

Have they not reflashed the mapping and replaced the throttle potentiometer? I'd of thought they would do that as matter of fact in their usual fix by the parts bin options []

garyw

 

[Black80XSA]

If enough cars are affected then i suspect it will be a case of a revised map being uploaded during routine serve visits for cars not complained about, and a 30min fix for those that owners do highlight as an issue.

 

[JGamlin]

Gary, OPC mentioned reflashing the mapping but not testing or replacing the throttle potentiometer - which I have just Googled, as no knowledge of electromechanical devices.
From description sounds as though this could be the faulty component ....

Have to return to OPC as the tyre filling compressor seems to have been "liberated" from its storage slot in luggage compartment.[]

 

[tscaptain]

If the technician managed to replicate the fault on three others it would seem unlikely that they all have faulty potentiometers too? Have they tried to reproduce the fault on C2S's? I presume the throttle system/mapping is identical on the 2's and 4's.

 

[JGamlin]

The other three came into stock at same time as mine. One was sold this weekend so should trace new owner for reaction - it's not a big Island.

 

[tscaptain]

ORIGINAL: JGamlin
- it's not a big Island.

I know - used to go there frequently![] Short runway too [&:]