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Cold start idling

H

h4x0r7000

New member
Hi guys,

Noticed lately and hoping it's just because it's been really cold recently but, when starting the car I notice that the revs bounce around more often. Not to extreme just slight above and below 1000 RPM and only lasts for maybe 30secs before it settles. Tonight the car stalled twice in a row and I wasn't even in gear when it happened, just conked out.

Just found it Abit strange and was wondering if anyone could give me advice on to look out for anything?

Cheers :)
 
Hi Gareth, You don't give any details about your car - age, mileage, etc. - but idling problems are often related to MAF failure or contamination. If you disconnect the MAF the engine will run with a default setting, so you could try that to see if the problem disappears. Sometimes a faulty AOS can contribute to erratic idling, usuallly accompanied by a lot of smoke in the exhaust. I presume that you're not getting misfires or CEL warnings and that once warmed up the engine behaves normally. Of course, it could be that one of the air temperature sensors is misbehaving in the cold weather. The best way to check that out is to run a diagnostic check, so you'd need to contact either a PC or Porsche Indy for help with that. Jeff
 
Just anther thought Gareth. The problem is obviously related to the "fast idle" rather than normal idling, so obviously there's a different DME control setting. I think that you're going to need to get a proper diagnostic check. Jeff
 
Hi guys, Cheers for the responses. So you think this is more to do with the engine management than the engine itself? There hasn't been any warning lights or anything and it drives fine. It's only when it's a cold start that it happens and I don't remember it always being like that. To describe the situation and hopefully people might say mine does that and it's nothing to worry about. First I turn the key to let the oil check finish, once done I turn it over. Starts pretty normal and revs. As it's coming down, it gets to 1100 revs, then bounces below to 900 then 1100 again. After leaving it for 30secs it then drop to about 800 to a normal idle. What do you guys think?
 
How long does it take to clear the problem? Part way through warm up? Or does it persist further?
 
It just does it the once as described above. Once warmed up, if I turn off and start it again, it won't happen. Only on cold starts it would.
 
Gareth, I'm sure that your engine hunting problem is fuelling/throttle related since it only occurs during the initial 30-second fast idle stage and is therefore an electronic control problem involving the cold-start circuit. The engine electronics are very complex and, as I said in my previous post, you're best getting a full diagnostic check which should indicate the source of the problem. Keep us posted if you get a result. Jeff
 
Hi Jeff, Cheers for the advice. I recorded a video of it last night and will upload it later to see what you guys think. It's not a bad in the video this time round but you will see the revs drop where it normal does.
 
Here's the video, ignore the ! It's only the water for washers. https://www.dropbox.com/s/97zmqg16pbqt66a/Video%2026-01-2015%2021%2009%2036.mov?dl=0
 
From the video there seems to be little wrong, possibly just a little damp from the chilled air and it soon clears. From the soundtrack it sounds as mine did before I had new coil packs fitted, the coil packs in the case of my car were originals and the car had covered in excess of 80,000 miles so dependent on the type of road use the engine and coils could have had a similar amount of running hours. But my coils had already been assessed as corroded but operating to an acceptable level, that was about 1,000 miles before three failed but the soundtrack was as yours for many miles before that and the plugs had only been changed 4,000 miles previously. Do you know the history of spark plug changes? Or has there been a warranty inspection? This will give some indication of how often the plugs and coils have been disturbed and since they are to be changed each 4 yrs at max yours should have been charged recently presuming they weren't changed early due to mileage etc.
 
Hi Kevan, Cheers for posting. Coil pack got replaced 2 years ago and had a major service done in July 2013. In the past year I've took it to Porsche dealers, had coolant flush, numerous health checks and mostly recently took it to ninemeister and they did a check too. Being honest, it started a couple days after it was there.
 
Just watched the video again, tbh the sound is appalling and does not sound like that. It could be muffled with the way I was holding my phone.
 
Yes Gareth, very difficult to understand the nature of the problem from your video but the fast idle ~1,000 rpm seems to be fairly robust. However, it seems that it's the sound the engine makes during this period that concerns you. Is that right; and does it change significantly once the engine settles down to the normal idling speed? Jeff
 
Hi Jeff, Na the sound doesn't bother me, its just a bad recording. Around 5-7 seconds, the rev needle bounces around before settling which is my concern. Previously, it use to start, rev to 1800, and settle at 1100 without the needle bouncing. The needle only really bounces on cold starts. If you say what's on the video is normal and nothing to worry about, then I'll be happy. I guess I could be worried over nothing if its to do with the recent cold weather.
 
Three points I'd like to raise on this, first is that the oil level seems to be indicating above the max level mark so maybe you are not on level ground, next the movement on the needle, personally I wouldn't be concerned about it clears rapidly as the engine begins to warm up and third, noise is relative to where the car is, inside a garage can sound horrendous against a wall a little better and so on they always sound better in a clear space or better still going along the road.
 
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