Misfiring 991 997.1

[brian.pilgrim]

Please can someone help!!!. My porsche 911.997.1 2007, keeps misfiring, the garage has checked for bore score, changed the timing chain, replaced a bent valve, replaced the wiring loom, spark, plugs coil pack have all been changed, it's been going on for 3 years. I'm going crazy. Please help !!!

 

[Motorhead]

Hi Brian,

Sorry to hear about your long-term problem. I suppose the first thing to ask is if your garage has run some Porsche-specific diagnostics [PIWIS or equivalent] to see if any error codes are flagged-up, since this is the most reliable and cost-effective way to track any problems?

If the misfire is associated with a particular cylinder you’d have to assume a spark plug or coil pack issue, but it seems as though your garage has taken that route without success. If a cylinder bank is involved [cylinders 1-3 or 4-6] a VarioCam solenoid usually is faulty. The problem could be fuel rather than ignition-related, in which case a dodgy fuel injector could be the cause, and you could try using one of the proprietary injector-cleaning products to see if that helps.

Jeff

 

[brian.pilgrim]

Hi Brian,

Sorry to hear about your long-term problem. I suppose the first thing to ask is if your garage has run some Porsche-specific diagnostics [PIWIS or equivalent] to see if any error codes are flagged-up, since this is the most reliable and cost-effective way to track any problems?

If the misfire is associated with a particular cylinder you’d have to assume a spark plug or coil pack issue, but it seems as though your garage has taken that route without success. If a cylinder bank is involved [cylinders 1-3 or 4-6] a VarioCam solenoid usually is faulty. The problem could be fuel rather than ignition-related, in which case a dodgy fuel injector could be the cause, and you could try using one of the proprietary injector-cleaning products to see if that helps.

Jeff

Thanks Jeff I'll check with the garage about the vario cam solenoid, all coil packs have been changed many thanks for your suggestions

 

[Motorhead]

Brian,

You mentioned that a bent valve was replaced, which is a bit of a concern … especially if the misfire is associated with that cylinder. Do you know why it was replaced?

Note that a proper Porsche diagnostic check should identify any issues with the VarioCam solenoids.

Jeff

 

[brian.pilgrim]

Brian,

You mentioned that a bent valve was replaced, which is a bit of a concern … especially if the misfire is associated with that cylinder. Do you know why it was replaced?

Note that a proper Porsche diagnostic check should identify any issues with the VarioCam solenoids.

Jeff

Jeff I'm getting a bit despondent about the independent porsche mechanic I'm using, I'm getting a second opinion on Monday and will let you know the outcome. Thanks

 

[Motorhead]

Good idea Brian, but just to say that it’s worth approaching a reputable Porsche Independent who should have the necessary experience and diagnostic tools to help you.

Note that this isn’t really the appropriate section for your post because it’s for the air-cooled 911s, and there’s a dedicated section for 997s on the forum where you should get a better response:

997 (inc. turbo)

www.porscheclubgb.com

Jeff

 

[Peter_Bull]

Thread moved to 997 area.