Rough idle, occasional cold start smoke, 987 .2

[911hillclimber]

Starting to get a bit niggled by my 2009 gen 2 987, 41k old.
i had some severe smoke on start up several months back which PCT fixed with a change of oil temp switch.
smoke did go away.
rough idle appears when cold warm or hot after, say, standing at traffic lights.
never cuts out, rocks the car.
car goes like stink or will do 36 mpg.
Getting occasional start up smoke again, but I think it is down to start up, and switch off shortly after, but a bit inconsistent.
any thoughts please, close to selling the car now after a year.

 

[Geoff_Fields]

Random amounts of smoke on start up is a normal and very common phenomenon of all the flat 6 engines, nothing to worry about. Severe smoke is more likely to be air/oil separator failure. I cannot see how changing oil temp switch is going to fix that but am always willing to learn. As for the rough idle I would be looking at coil packs.

 

[911hillclimber]

Thanks Geoff.
I have an old 1973 911 with an equally old 3.2 in it, smoke free compared to this!
I was baffled why the oil switch would do anything, but for months it stopped smoking.
Seems rough idle belongs in the They all do that bubble, but not all do.
time to let this car go.
it really is a nice design, but these things annoy me.

 

[Gordon Attar]

Hopefully not the case.

Last Boxster I had with rough idle required bore scoping and then a rebuild.

 

[Motorhead]

Graham,

As said, a failing AOS or coil pack could be the cause or maybe it's just a contaminated mass airflow sensor.

It might be worth running some diagnostics for a better insight into the exact cause of your problem.

Jeff

 

[Boxbrownie]

I have just cured months of rough idle at start up and very subtle rough running when hard accel, everyone and thier brother said "coil packs" no doubt about it, change them and all will be OK...........well coil packs investigated (amongst other things) and my local specialist could only find slight drop in fuel pressure, no fault codes as such.

Last week finally bit the bullet and had the fuel pump changed (ouch!) and it starts like it reads my mind now as before it turned over for quite a few seconds before it would "catch", and settles down immediately to a steady low idle, drives smoother too, not that I really noticed before just thinking it was the character of the flat six boxer config.

Only on the 987.2 though as it has DFI with which the correct high pressure is vital.

FYI

 

[Motorhead]

As David has pointed out, it could be the HPFP if it's a 3.4L (the 2.9L wasn't DFI).

My 2009 Cayman S was the subject of a recall where the pump was replaced, although it didn't display any symptoms of imminent failure. It would be worth checking to confirm whether or not it was replaced on your Boxster, if appropriate.

Jeff

 

[jmaddox]

Worth checking oil level. Mine smoked on start up when I first had it. The dealer had the oil level right at the top of the display. I changed the oil and filter and topped the level carefully so not to overfill it and it's fine now.

 

[bellaboots]

Same car same year same problem same fix same cure

 

[carnaby35]

Is your car by any chance parked up on a sideways slope. Had it with ours where smoke was embarrassing, all warning lights came on and cut engine out. Started ok again after a few mins and then ran like a dream. It seems that oil enters cylinders due to being parked on slope then burns off.

 

[911hillclimber]

Thank you all.
I decided to simply move the car along the drive and switch it off before the cold start high tick over period and switched it off. Left it for 3 days.
Drive is very level, oil level on the dash is right 'full' and I would be happier with a 'bar' vacant at the top, but PCT did the change so should know where to fill it..
Started it up yesterday, small amount of oil smoke as I was expecting.
Moved it a bit more to another part of the same level drive. and after a minute switched off (engine ticking over).

Washed and used the car this morning, quite a lot of oil smoke and the car ran fine, but smoke.
I'm sure this smoke on start up is all down to these short moves where the engine is not fully cleared and residues of oil are still around.

After a 30 min run, nice and hot parked on level drive and switched it off from tick-over.

will use the car again on Thursday to take it for the A/C test which has stopped working at a very local indie.
Might see if they do a complete run through the car diagnostics to reveal any fuel pressure issues.

It's a nice car to use and to have, but...not sure it is really for me anymore.

 

[Briggy]

Can you clarify the oil level? Are you saying all bars are lit? If so, it's overfilled. Even good places make mistakes and overfilling is possible.

Cheers,
Bryan

 

[Motorhead]

I'd agree with Bryan - the level should be one bar down.

While it's with the Indie, get them to drain off a bit of oil and see if that helps. It's worth a try, especially if all appears well with diagnostic test.

Jeff

 

[jmaddox]

Absolutely agree with last two posts. If all segments are lit then definitely overfilled. This increases the likelihood of smoke on startup in my experience.

 

[Boris the spyder]

Just had an oil change at OPC and all bars lit. So is that a problem then ? Surely it is going to be filled with the amount shown in the workshop manual and if that happens to light all bars then I cant see a problem. I have never had anything else but all bars lit and its got full OPC history

 

[jmaddox]

Probably not a problem. The trouble is once all bars are lit you have no idea if it is slightly overfilled or whether it is overfilled by a litre or even more. If it was mine I would drain some out.

This is is why so many of us do our own oil and filter changes. It takes quite a lot of care and time to get it right which no garage can realistically do.

 

[Boris the spyder]

I think its 7.75ltr of oil for a 2008 / 3.4S. I dont know how many home oil change folks jack their cars up level to drain them, I have watched a few videos on You Tube where they simply lift the rear of the car to drain it. a garage ramp lifts it level. There cant be much residual oil left in a warmed up engine jacked up level and drained, then 7.75lts measured out and refilled.

 

[Motorhead]

I think it depends upon how long the technician allows the system to drain Graham. I seem to remember reading somewhere that Porsche recommends about an hour during an oil and filter change, which is probably about right if the tech does this first and then carries out all the other service procedures before refilling. If not then who knows how much residual oil there will be?

The correct level is to the maximum mark, ie one bar down on the display, each segment representing ~0.4 litre. How accurate are the garage's oil dispensers; and do the techs have time to check the oil level after the service, bearing in mind that the engine has to be up to temperature to check the level?

Jeff

 

[Boris the spyder]

I take your point, really I think the problem is compounded by these electronic readout devices. I really do not understand the need for them. What on earth can be more accurate than a dipstick. People that care about their cars as we all do would dip on a regular basis and get a 100% accurate readout. Maybe the electronic and dipstick would be better. The electronic one to give you a reasonable idea every time you start and the stick for changes.

 

[Boris the spyder]

I am maybe blurring out here. Just read mine and indeed it is on the top arrow mark one segment down. I guess I was assuming folks here meant 1 segment down from the full arrow. Maybe I am the dipstick. Used to golden oldie devices. [8|]