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996 C4 running lumpy

t.j.hall

New member
Hi

Can I have some suggestions, when the winter weather turned rather wet, I put my 2001 996 C4 way for the winter, the car has remained unused from late December until last weekend, to stop the battery going flat, I removed the battery.

After checking the oil, water, etc. I started the car, which it did without any trouble, however after leaving it for a while, I drove it just under 1 mile to the petrol station, it felt "˜lumpy', when idling it now hunts between 800-1200 revs

There is a strong smell of petrol particularly from the left hand side exhaust

The car has only done 69,000 miles and has a full service history either from Porsche or a Porsche Specialist - Any ideas what is wrong and the best approach to resolving it?
 
Using it[:D]

69k & Porsche service history or not, that's got to have some serious cob webs.
I sooner 200k and redlined once a week that left to rust.
No offense but is it a surprise that it runs ruff?
If you locked a race horse away in its stable for three months I doubt it would do very well in a race.
My advise would be take it out first for a good hour RAG IT then see if its lumpy.

P.S was the Battery on a maintainer? surely yes? if not it sure would run lumpy if you managed to turn it over.

Hopefully after a run alls well, Good luck.
 
Hi

I read somewhere that there is a procedure to follow after re-connecting the battery. It won't idle correctly until it's been carried out. I'll see if I can look it up.
 
If battery power is lost to the DME (ECU) the idle speed may be higher than normal and fluctuating (hunting). This will remain until the throttle adjusting unit and the mixture are put through a simple re-adapting process.

Switch on the ignition for 60 sec without starting the engine or touching the accelerator pedal. Switch off the ignition for 10 secs. This completes the basic adaptation of the throttle systems. Then run the engine (this is a must do) for several minutes to allow the DME to relearn the idle speed and mixture adaptation values.

I hope thi helps.
 
If the problem persists for much longer, the best bet is to get a diagnostic check done. Adaption might help, but it doesn't usually affect the idle in that way.

There could be several culprits, ranging from a coil pack to a Variiocam solenoid, but you are shooting in the dark without getting a diagnostic check and the fault codes read.
 
In my experience a faulty coil pack will cause the engine warning lamp to come on, on the dash. I take it there are no warning lights on?
 
I would always say that lumpy running and smell of fuel = coil pack. Be careful though as if you get petrol in your cat you will ruin it and it could go on fire and make the exhaust very hot, so much so that it can melt the back bumper.
 
thanks, I have ordered an OBDII diagnostic checker, should arrive today; as soon as I have the codes I will let you know

 

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