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CEL and Rough Idle after standing for 3 months


pingping010101

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I've just returned from overseas and I'm having a few dramas with the 986.

I had no choice but to leave the car stood in a multi-storey car park for the last three months. I went to start it yesterday and the battery was completely dead. This has now been replaced and the car started and driven for just 4 miles to get it home. 

The car has a really rough idle - when depressing the clutch whilst approaching a speed bump and slowing down the rpm will dip right down to the lowest marker and then back up. It can only idea for a minute or two before it stalls. At the point where I arrived home the car threw a check engine light and then refused to start in to idle, although would start and run with the accelerator depressed slightly. 

Any fast resolutions before I start the google-fest? I don't have an ODB reader. 

Thanks

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You can check the condition of the coilpacks by removing and inspecting them. With it being late afternoon though unless you have a lit garage space you might be of of luck for now. 

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If it's been stood for a while though I would do all the usual fluid checks and get some fresh petrol in it. 

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get a fault code reader on it,if theres a misfire you run the risk of damaging the cats.

you could remove the plugs to give you a clue to any misfires,but in all honesty it could be a number of things.

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I just went out for a longer journey - around 16 miles - to get a better idea of the symptoms and to see if it was going to blow up. 

The CEL flashes only at idle when stationary. After beginning to drive the CEL becomes solid and stays that way for the duration of the trip. As soon as the engine is switched off and restarted the CEL flashes and then turns solid again a few seconds after pulling away. At the end of the journey, whilst in the car park, I held the car at idle again without turing it off first and it took about 30 seconds to begin flashing again. The engine was then turned off. 

There's no loss of power and throttle response is just fine.

I had disconnected the battery again just before the drive to clear the CEL and see how long it took to return. (Immediate!) At the start of the drive, only when depressing the clutch whilst decelerating - approaching a roundabout or at a junction - the RPM took a nose dive and the car stalled a couple of times. (Changing up doesn't have the same problem.) At the end of the journey this had stopped happening - the RPM would still dive but only as far as around 800rpm and wouldn't stall. 

I will have to get an ODB2 reader. I'm only in the UK for another couple of weeks and I intend to get the wife to drive the car whilst I am away so as to avoid a repetition of these dramas. I need to real sort the idle issue though as she isn't particularly mechanically minded and would need the AA to rescue her as soon as it throws a light while I am gone. 

 

 

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If you have Home Start you could always call the AA and say it won't start, amazingly when he gets there it starts but rough......he may well read the codes for you as the CEL is on?

Well you have paid for it.......;)

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Bit of a coincidence but it could be a MAF issue. Poor idle is a symptom. Try connecting the electrical connection to the MAF and take the car for a run. Any improvement? If so then the MAF is on the candidate list for replacement.

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In my experience, right back after mine had been sat around for months with a duff battery, it would stall completely at junctions.

 

After 5 miles or so, it had adapted and was fine - this was with various vac leaks, a big hole in cat, potentially duff MAF, dodgy O2 sensors etc. etc.

 

The only time I saw a CEL was when the car wash place it came from had bump started it (code for misfire or something).

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8 minutes ago, pingping010101 said:

Thanks Chris.

I'll get some new coils on order plus an ODB2 reader and go from there.

 

I would suggest that you think about changing the fuel filter.  It's a candidate for the symptoms and the fact it's been standing, imo.  Less than £20 to do, if you do it yourself, but a bit of a faff.

 

I don't think it would be coil related unless you had a bit of hesitation/power loss under load, or a misfire.  I had a blinking/solid EML when my coil plug connector popped off, and it sounded like an Impreza! 

Could be vaccum leak related (which is the normal fluctuating revs first check), but I don't know why it would suddenly start from nowhere.

 

Only other thing I can possibly suggest (assuming it's been stored somewhere dry) is that there has been an underlying issue there the whole time, the ECU had already adapted to it, and since the battery has been flat it has lost the adaption settings (in other words, it had adjusted previously to a vac leak/duff sensor, and now everything has been reset, it's reacting to the original issue?). 

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Stale fuel for sure.

Also if the battery died then the ecu will have to relearn the parameters of the engine which normally means the car will do a few weird things for a while. Couple that with the stale fuel and i'd put my money on it being the combination of the two.

Fresh fuel and and a good drive will probably sort it out.

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