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Model specific boards => Golf mk3 => Topic started by: gizago on 23 September 2012, 17:41
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My mk3 8valve is running rich- any common faults that cause this?? It idles fine, drives fine, but smells strongly of petrol. There are no leaks etc anywhere, its definitely just running rich. Is this something that can be adjusted out, or is it likely to be a sensor playing up??
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Could well be the hall sensor on the distributor needing set up. Best to get a code reader or vagcom hooked upto it.
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I would change the temp sensor
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Could well be the hall sensor on the distributor needing set up. Best to get a code reader or vagcom hooked upto it.
Ive had a fault code reader on it to try and trace an intermittent fault which turned out to be the crank sensor, which ive now replaced. I'll check back over the codes and put them up here.
I would change the temp sensor
I did wonder about that, but when the blue temp sensor went on my mk2 it was different symptoms, wouldnt idle, cut out if you came off the power quickly etc. Worth a try though.
Cheers guys.
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Fault codes it had were-
65535:- (control module defective faulty static)
00513:- (engine speed sensor G28 signal outside tolerance intermittent)
00515:- (camshaft position sensor G40 signal outside tolerance intermittent)
00523:- (intake air temp sensor G42 open circuit/short circuit to B+ intermittent)
If anyone can shed any light on any of those.....
Since then I've fitted a new crank sensor and swapped the maf for a different one. If these re-set the same as mk2 digi's then ive resert it too. (ie revved it to over 3k 3 times when stationery)
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Camshaft position sensor (g40) is the hall sensor on the side of the distributor but not sure what would cause it be intermittent, could be faulty or the wires going to it have become brittle which is a coomon issue. Mine was out of tolerance when I rebuilt my engine and it was running so rich my down pipes were glowing red hot. Not usre on what the rest of the codes mean.
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Excellent, hopefully a new one will sort it then. Its been reluctant to start from cold too, spinning over but not firing which is probably caused by the same sensor I guess. Cheers mate, much appreciated.
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Camshaft position sensor (g40) is the hall sensor on the side of the distributor but not sure what would cause it be intermittent, could be faulty or the wires going to it have become brittle which is a coomon issue. Mine was out of tolerance when I rebuilt my engine and it was running so rich my down pipes were glowing red hot. Not usre on what the rest of the codes mean.
They wouldn't do that if its rich. To much fuel and it will cool the motor. So it would have been very lean!!
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Camshaft position sensor (g40) is the hall sensor on the side of the distributor but not sure what would cause it be intermittent, could be faulty or the wires going to it have become brittle which is a coomon issue. Mine was out of tolerance when I rebuilt my engine and it was running so rich my down pipes were glowing red hot. Not usre on what the rest of the codes mean.
They wouldn't do that if its rich. To much fuel and it will cool the motor. So it would have been very lean!!
Was definately running rich like, the smell of fuel was horrific and popping and banging.
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Not saying it is in this case, but very lean can seem like very rich due to lean misfire not burning the fuel = sends unburnt fuel into the exhaust
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Rich=poor performance
Lean= good performance
But to much either way is bad!
Why do you think after a remap your bhp and mpg increase? Because a lean it out
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This explains it:
When there is lean combustion, fuel is the limiting reactant and there is excess oxygen. This means that ideally, there will be complete combustion of the fuel and air, which results in an exhaust mixture primarily of CO2, H2O, and N2. When the fuel and air mixture is extremely lean (equivalence ratio << 1), there is a chance of lean misfire because there is not enough fuel in the tank to ignite the mixture. The unburned fuel will exit the cylinder during the exhaust stroke, thus releasing hydrocarbons (VOCs) into the atmosphere.
Smell of fuel, plus "popping and banging" would occur with the above