Engine trembles

[blucubic]

My 2004 3.2 V6 Cayenne trembles when I start the car.

The trembling started a while back when I refuel the car. Upon refueling, I will have to rev the engine or it dies off. After a few revs, the engine stabilizes and I am able to drive on. I lived with that but the problem has now gotten to almost every time I start the car, particularly the first start of the day. That happens even under scorching sun.

No fault code appears.

What can the problem be? Can I DIY this repair?

Edited May 2, 2012 by blucubic

[wvicary]

Impossible to tell if it's a DIY without knowing the cause of the issue. What tool are you using to retrieve fault codes? I find it hard to believe there are not fault codes present.

I would start by inspecting the spark plugs/ignition coils, EVAP system then fuel pump pressure/volume in that order.

[blucubic]

wvicary,

When I mentioned 'no fault code', I meant no warning light.

Sorry for the misunderstanding.

[wvicary]

Even though there is no check engine light you may have fault codes stored. Does the check engine light come on when you turn the ignition key on/engine off?

[blucubic]

Nope. The check engine light does not come one.

[wvicary]

Nope. The check engine light does not come one.

Then you have a faulty bulb, wiring or DME issue but bulb is the first thing to inspect. You really need to have the fault codes checked.

[bigbuzuki]

The V8s had an issue with the fuel tank vent valve being faulty.

This caused the engine to have a starting problem, especially after refueling without the CEL illuminating.

Faulty fuel caps caused these type of issues as well.

Does the V6 also have some type of fuel tank vent valve or fuel cap issue causing a similar issue?

Edited May 8, 2012 by bigbuzuki

[wvicary]

The V8s had an issue with the fuel tank vent valve being faulty.

This caused the engine to have a starting problem, especially after refueling without the CEL illuminating.

Faulty fuel caps caused these type of issues as well.

Does the V6 also have some type of fuel tank vent valve or fuel cap issue causing a similar issue?

Yes the V6 can suffer from the mentioned faults but not as much as the V8. As a matter of fact I have replaced many EVAP flow control solenoids on various makes over the years so it's not just a Porsche thing incase someone was planning on starting a class action lawsuit.

[blucubic]

Thanks guys.

Will share here once I idnetify the problem.

[blucubic]

Got the car inspected. Was told that the mass airflow sensor is faulty.

[wvicary]

Odd. It doesn't sound like a MAF sensor problem. Have you replaced the unit and did it fix the problem?

[blucubic]

I thought it odd too. But according to my guy, the fault code on the MAF sensor would not go away.

Edited May 19, 2012 by blucubic

[blucubic]

wvicary,

Do you think I should stick to an ori replacement unit? My guy has recommended one by Bosch. Am told that it's a better performer and obviously, cheaper.

Thx.

[wvicary]

Bosch make the OEM unit. Be sure it's the newest part number and you should be fine. I'm curious to what fault codes they got to point the finger at the MAF sensor..... something along the lines of lean condition or ???