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Petrol cap and engine management?
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Old 05 Jul 2008, 06:41 PM   #1 (permalink)
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Petrol cap and engine management?

Hi there,,
Am I going NUTS??

I've got what I think is a weird link between my Engine management light and my petrol tank / cap...

If I fill my car to FULL tank and drive around I have found that by the time the needle shows half a tank remaining (which doesn't take long, Ha, Ha) the engine management light sometimes comes on.. BUT, if I unscrew the petrol cap and replace it the next time I start the car the light is gone ..

This has happened on a few occasions now and it seems like a link to me..?
I've had the light come on and off a few times since I've owned the vehicle (about 18months). I had an ECU check done about a year ago, but it returned as UNKNOWN cause.. and cleared?

The car doesn't seem to show any symptoms i.e. it drives and idles perfectly, it's also recently been on a rolling road and come back as everthing is satisfactory - 225bhp - Considering it's standard apart from a stainless steel back box.
Also,
A lot of my mates also drive the bugeye and they too seem to have problems with their engine management light coming on.. But, my mates with the classic Scooby never seem to have trouble??? Are Bugeye Scooby’s more sensitive????
Cheers...
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Old 06 Jul 2008, 04:17 PM   #2 (permalink)
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Hi.

When you have a loose petrol cap or faulty seal on the cap you can get a CEL. Triggered by pressure in the tank.


Quote:
It is a meaningless code
Meant to alert you that the cap is leaking releasing a small amount of fuel vapor into Earth's pristine atmosphere

Code P0457 EVAP LEAK DETECTED (FUEL CAP)
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Old 04 Aug 2008, 07:34 PM   #3 (permalink)
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Re: Petrol cap and engine management?

Just wanted to keep this thread alive as its just saved me a trip to the dealer. Last saturday filled up as normal and shortly after the MIL came on, panicked a little as Ive had the car for only a month-6 weeks tops. Its under a proven warranty and to be far they were very helpful and advised me to get it booked in advising they would replace the said part etc but I may have to cover the diagnostics. Checked my petrol cap after reading this thread and its sorted now, I hadnt closed it to the point of hearing the click. Closed it properly to the click and it went out straight away.
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Old 09 Aug 2008, 10:56 AM   #4 (permalink)
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Re: Petrol cap and engine management?

Baffling! JUst in case anyone else has/is/did experience this, petrol level dropped just below quarter and light went on again. Stopped and checked the petrol cap, light still on. Filled tank to 3/4 and its gone straight away! At no point did the car run any different to normal, any thoughts guys?

Cheers, Ben.
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Old 12 Aug 2008, 09:25 PM   #5 (permalink)
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Re: Petrol cap and engine management?

strange one! perhaps worth getting it plugged in just to put your mind at rest as it could be coming on as a coincidence{prob not} but my bugeye was always off and on with various things, seemed to suffer badly with cel where as my replacement 04 dosent???
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Old 16 Aug 2008, 11:00 AM   #6 (permalink)
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Re: Petrol cap and engine management?

i take it you havent got a small leak in any of the fuel lines or tank? It would produce the same results as the petrol cap if the petrol level was below the leak.
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