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Hi,
I have a 1991 VW Golf MK2 1.8 gti petrol, and I am having some idle and low mpg issues, which I hope you can help with.
When i start my car (Cold start) it starts up fine, but as soon as I give it gas, the idle drops to around 600 rpm, and then goes back up to around 800rpm.
I have no vacuum leaks, cleaned throttle body, serviced the car, changed fuel pressure regulator, changed lambda o2 sensor and knock sensor.
The car also failed its co emission test, and I am getting very poor mpg and slight backfire after driving on the highway or revving the car sometimes.
It’s quite weird as when i’m driving on the highway I get around 27mpg and local city driving I get about 19mpg…. but the weird bit is that at idle I am only getting 12mpg, and the car temp goes quite high.
I also at times get a smell of fuel, but I cannot find any leaks. I have ran out of ideas, and would be grateful for advice.
Here is a quick video link of the cold start idle.
Many thanks.
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Hi, spark plugs are in good shape, and there are no signs of fuel leaks. I have also got my fuel injectors tested, and they are all good.
I am in the process of changing the fuel hoses as some are quite old and worn. But this will not help with the idle issue. Any other suggestions are welcome.“…the weird bit is that at idle I am only getting 12mpg, and the car temp goes quite high.”
That’s weird. At idle, you should be getting 0 mpg, at least in this universe.
If your car is in danger of overheating at idle, it could be a malfunction of the cooling fan, or the water pump. (I remember that VW went through a phase when it had water pump issues, but I don’t know if that history applies to your car’s year.) It could also be restricted coolant flow within the cooling system, or restricted air flow through the radiator.
As for the little hiccup at idle, I wouldn’t make that my highest priority right now. Your car is over a quarter of a century old, and it’s bound to show its age from time to time. It might be nothing more than a tired old throttle cable with a bit of slack in it. I’d concentrate on the cooling issue, as it may worsen and become an issue that will leave you stranded somewhere. And who knows, maybe getting the cooling system right might help with your mileage concerns.
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