997:Uneven Idle when cold

It's been happening for a while now, once in a while my car will develop an uneven idle, and the engine check light will come up. It's been back to Porsche Melbourne twice and they've found nothing wrong. Yesterday it happened twice! Seems to do it when it's cold, and not when it's fully warm. Ideas? Fuel injectors? Spark Plugs? Coil Packs? the 997 doesn't use spark plug leads anymore does it? Time to jack up the car and pull the plugs? are the spark plugs easily reached? Thanks.

Have you had air oil separator issues lately? Mine did similar after the AOS was replaced. Got it checked out, nothing found, gave it a good enthusiastic run and it hasn't happened since.

After a bit of googling, I am figuring on changing the coil packs and the plugs, and giving the injectors a good clean.

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Try putting a bottle of injector cleaner in the tank and giving it a good thrashing (ie. An Italian tune up)

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So it suddenly got worse last Friday and the car started running on 5 cylinders... a few panic calls to PCM, but all the people I know were unavailable. Left messages. sigh. Called Michael from Autoart, drove it down to him after lunch. By this time the car has decided to run on all 6 cylinders again, tank was low so I refilled with BP 98 octane. He connects the iPad, hey it's wireless connection ! cool Multiple misfires in multiple cylinders. So not like one bank or anything. Maybe it was a bad batch of fuel? Injectors? So after much talk, he sold me bottle of strong industrial strength injector cleaner, $25, I put it into the tank and drove home. Took the girl swimming, got a call from the wife... some lady driver has T boned my Subaru at a T intersection, apparently the lady didn't see my big grey subaru liberty and just drove out into the side. No injuries but the car is badly damaged. Sigh, had plans to drive off to Torquay that night! Put poor Liberty in garage, repacked bags into the 997, left things out of course, left dogs at home, took the 997 on a long drive. So now she's running better. Diagnosis... a bad batch of fuel? dirty injectors? combination of the two? Anyway she's running okay at the moment, I might get the injectors and plugs looked at next year by Autoart. I am still annoyed with PCM for just plugging in the computer, confirming I have a problem and not actually doing anything to fix it. And the Subaru is a write off..... sigh.

Stick a bottle in once a year at least, not only does it give the injectors a clean it also dissipates any water that has  accumulated in the tank.

Just an update, $1200 later I've replaced all 6 coil packs, and gotten a carbon clean and injector clean. Result, car is idling fine now, touch wood, and the hesitation off idle seems to be gone, i.e. better throttle response from idle.

From time to time you might need to red-line your car, say in 2nd gear, then throttle off still in 2nd and let the car slow down naturally.  Do this with a hot/warm engine only.  This will mean heat, no fuel and the plugs get a good cleaning as the car slows down.   I used to do this to my old air-cooled car and also seems to work on the 997 ok.   Flat sixes need to be driven through the full rev range - so a couple of mandatory red-lines on the drive home from work is required

I think in my case the coil packs were going, and maybe the 9 months the car sat in the dealer didn't help the injectors.

Okay, update, After cleaning injectors and changing spark plug leads and spending $$, the problem came back !!! Also my fuel economy was sh*t So after more googling, I decided to clean the MAF sensor, and wouldn't you know it, it sort of fixes the problem. Sort of as in it's mostly gone away but hic-cups once in a while so not a 100% fix. I might have to change the MAF sensor, guess I should look at Pelican parts. And I need to clear the engine check light !

Orion, out of interest how many klmns on your car??? i had a 997.2 3.6ltr & thrashed it regularly without issue but it was a low K car.

Just over 80,000 km I think.

What fault codes show up? Is the engine light still on?

ECL is still on, I just got a bluetooth OBD2 module that'll I'll be plugging in. Basically misfire in random cylinders was what I've been told by PCM and my other mechanic, At the moment I am thinking maybe a clean of the Carby and the idle setting valve, What do you guys think?

Just got my bluetooth OBD2 adaptor, worked great with Torque app on my phone, engine code is P0302, which is a misfire on cylinder 2, Hmm last time it was all random cylinders now it's down to cylinder 2?

which bluetooth adapter did you get.. link?

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Possibly a coil playing up. Try swapping a coil with one of the other cylinders and see if the fault follows the current no. 2 coil.

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This one: http://www.ebay.com.au/itm/111231021421?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT There are cheaper ones on ebay but I didn't want a lemon. I just had all the coils changed around Christmas. Sigh.

Is it easy to access the coils and spark plugs in a 997?

clear the fault and re check if it is in fact just no. 2,or random

cleared fault, and yes no 2 came back again.

swap the coil to another cylinder and see if the fault follows the coil

It could be a faulty air mass meter if a misfire is detect at random cylinders. If it's only logging a misfire at cylinder 2 then swap both spark plug and coil pack to another cylinder. Re-check and see the codes come up after. Accessing coils and spark plugs in a 997 will be much easier with a hoist but can be on the floor with a floor jack and jack stands.

so far so good, new plugs + coils + sticky lifter cleaner = very smooth idle Also cured the occasional problem I had, which was after I've revved the engine hard.. the idle was lumpy. so maybe it was sticky variocam lifters playing a part in my bad idle. cross fingers it's all going to be fine for a while.

What sticky lifter cleaner did you use? The idle on my 996 is just barley within the tolerance of +-20rpm. Maybe this cleaner will help make it smoother.

I used this one: http://www.nulon.com.au/products/Engine_Treatments/Lifter-Free_and_Tune-Up/#.VW5cJ8-qr5k but really the plugs have to be changed sooner then recommended 30K, they are only standard copper plugs not platinums or anything. Also I think I had the combination of coils, plugs and sticky lifters. Sticky lifters symptom for me is after a hard rev the car didn't want to idle cleanly

My plugs are fairly new. My understanding is coils usually trigger a missfire fualt codes if they misbehave. And I only get this code when i simulate a miss fire. Sticky lifters cleaner on the other hand...wow. The engine is as quite as an empty Brisbane church on the night of State of Origin. I did not find nulon brand in the local shop thu. So bought Liquid Moly. Cleaner is supposed to take full effect after 14 days of use. It has been only 3 and the rev needle is rock solid. I am impressed. thanx.

LOL it's a far cheaper solution then the alternative: 1) drop engine 2) open valve covers 3) remove cams 4) change out lifters ($400 each) 5) replace it all and put engine back in Yeah... that sounded like lots and lots of $$ I figure that with these "new" variocam engines, there's so much happening via hydraulics, and actually using engine oil for hydraulics is a shit idea, what with the temperature, combustion, carbon etc, and then they put on a super long maintenance period ! So it'll get pretty dirty in those hydraulic channels and the "sticky lifter cleaners" are needed. That's my current thinking.

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Orion03 I've been following your posts for a while. Did you buy the car from Porsche Parramatta? I test drove the atlas grey 997 they had at around the same time. I would hope not to get hit with any large costs soon after buying an approved model.

Yes I got the car from Porsche Parramatta, and yes it came with the 1 year warranty. I took the car home to Melbourne, and the warranty transferred here okay. But I have complained about this uneven idle and ECL light many times, took it back to PCM about say 3 times complaining about it. i.e. I drive normally, then the car hesitates and ECL at the lights. PCM said basically, oh yes we see the misfire on the computer, very interesting, don't know what it is, and left it at that. On and on it went until my warranty ran out. Then wanted to charge me min $600 to change the spark plugs ! Oh yeah at this point it started to get bad so I started to spend $$ with Autoart, near $3K by the end including a new water pump. So I am NOT happy with PCM, I thought they didn't take the problem seriously and waited for me to run out of warranty. On the other hand, the car runs very very nicely now and weird flats in the power delivery is now gone ! I LOVE this car now. I feel the LOVE again.

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That's what you need to be feeling. Nothing worse than looking at your car and having a feeling of worry or regret.

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I must defend Porsche by highlighting that these problems are on engines +10years old. Still not bad for a finely tuned beast of a machine. On my engine there is over 2200 house of frustrated/angry/mother in law issues/suicidal tendencise/career not going anywhere driving. And yet all it needed is a bit of vitamin C lean.

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Oh yes of course, it's that these systems are relatively new.... i.e. only now are they hitting 10 years + hence the cures to the problems that come up are "new" to us owners and the mechanics.