mattkh 0 Posted May 31, 2008 Hi Supplied 12v to the ISV in isolation. All I hear is a click when it opens. What makes it buzz when on the car ? Should it buzz when tested in isolation ? Quote Share this post Link to post Share on other sites
ProdigalSon 1 Posted May 31, 2008 mattkh said: Hi Supplied 12v to the ISV in isolation. All I hear is a click when it opens. What makes it buzz when on the car ? The ECU pulses the 12V line to the ISV, which is why it buzzes when ignition is switched on. mattkh said: Should it buzz when tested in isolation ? No, unless it is really bizarrely broken :lol: As long as it opens and closes quickly when you apply/remove the 12V, then it is probably fine (look in the side when you do it to see the movement)... Proper broken ISVs don't move much/at all when the 12V is pulsed. HTH :wink: Quote Share this post Link to post Share on other sites
mattkh 0 Posted May 31, 2008 ProdigalSon said: The ECU pulses the 12V line to the ISV, which is why it buzzes when ignition is switched on. Hi Most grateful to you. What frequency are the pulses ? Are the pulses matching the chatter of the injectors ? Quote Share this post Link to post Share on other sites
ProdigalSon 1 Posted June 2, 2008 mattkh said: ProdigalSon said: The ECU pulses the 12V line to the ISV, which is why it buzzes when ignition is switched on. Hi Most grateful to you. What frequency are the pulses ? No idea, sorry, didn't do a frequency reading on it... Would guess it to be several hundred Hertz/times per second, but that's judging by feel alone :cuckoo: mattkh said: Are the pulses matching the chatter of the injectors ? If they do match it is probably entirely coincidental - the pulsing of the fuel injectors is linked to the rpm I think (they fire twice every revolution IIRC), but the ISV frequency is pretty steady... Both ISV and injectors vary their 'open' duration to allow a carefully measured amount of air or fuel (respectively) to be delivered to the inlet, so there is a relationship there it just isn't necessarily one of pulse frequency/regularity. Quote Share this post Link to post Share on other sites
Supercharged 2 Posted June 2, 2008 Sounds like it working electrically but they fail due to dirt etc mixing with oil and causing a 'cutting paste' that wears the shaft... very difficult thing to test really. Quote Share this post Link to post Share on other sites