Cayman S, surging while accelerating?

[paterson12]

Earlier today while pulling out of a junction I noticed the car surging while accelerating. I only accelerated lightly and was changing gear at about 2.5k rpm, the car seemed to surge repeatedly (only lightly) and then stopped.
It has done it in the past but I thought it was my imagination.
My thoughts are maybe the drive-by-wire, throttle body, MAF or I'm going crazy?

Anyone heard/experienced this?

Thanks

 

[AndrewCS]

I assume a manual ... was it in Sport mode ?

 

[paterson12]

Yes maunal, PASM was in normal.

 

[Motorhead]

Joe,

I presume that you've not had a CEL warning.

I be inclined to check the MAF first. I seem to recall that yours is an early car and it's possibe that the MAF's got contaminated with age, so you could try cleaning it first to see if there's an improvement. If it's not that then your best bet is to get a diagnostic check and see what that throws up, if anything. A Porsche Indy should be able to help.

An intake leak is also a possibility.

Jeff

 

[paterson12]

I think you're right Jeff, I suspect maybe the MAF.

I did have my friend check any faults through the OBD today (not at Porsche but using very expense snap-on diagnostic equipment) which showed no faults. Typically the car has been running perfectly today so any faults may have been wiped before the diagnostics.

This problem has happened on the same tank of fuel, as silly as it sounds I may fill up again and rule out crappy petrol.

 

[Buddy]

Poor fuel is a possibility but also an air leak on the intake and plastic plumbing, my son has a Boxster S and had a crack in the tubes which caused it to hesitate when turning.

 

[Motorhead]

Joe,

Just shot in the dark but if you still experience the problem when you've checked out all of the above, you could try changing the fuel filler cap. It's probably not a bad idea to change it anyway if it's not been replaced previously (£9.24 from Design 911 UK).

Jeff

 

[paterson12]

Funny you should say that Jeff. Ive literally just filled it up and I've noticed that there is quite a lot of pressure when opening up the cap. A rush of air/gas/vapour pressure. It could be my technical ignorance but is that normal? I've not experienced that on any other vehicle.

Intake system and Maf seems fine.

 

[AndrewT]

.... Ive literally just filled it up and I've noticed that there is quite a lot of pressure when opening up the cap. A rush of air/gas/vapour pressure. It could be my technical ignorance but is that normal? ....

That always happens on my 2.9 - I can't say whether it's supposed to do that or not.

 

[Motorhead]

I think that happens to a greater or lesser extent on most modern cars with complex closed fuel tank ventilation systems Joe. Nothing to worry about.

Jeff

 

[AndrewCS]

Funny you should say that Jeff. Ive literally just filled it up and I've noticed that there is quite a lot of pressure when opening up the cap. A rush of air/gas/vapour pressure. It could be my technical ignorance but is that normal? I've not experienced that on any other vehicle.

Nor me ... one of our`s (non Porsche) has an issue when filling the tank, eventually traced to the carbon canister / system.

 

[Buddy]

On my Gen1 I did have a fuel filling problem where the fuel would blow back as soon as it started to pump in! The OPC said no it can't do that but I pointed out that I had owned four Porsches before and this was doing it! I insisted on their senior tech coming to the fuel station and he got splashed, he also agreed there was a fault and then confided that it's fault we don't like to do as it can be twenty minutes or hours depending which way round a clip was fitted in the factory no problem to me it was under warranty.

If it blows back get it sorted before running out of warranty!