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dawsieboy84

should a MAP sensor buzz??

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Ignition on without car running there is a buzzing from the turbo pressure sensor? Is this normal?

Been told I have a fault and it they think it is this sensor? Before I go and spend £155 on a new one would the buzzing indicate it is shorting/faulty?

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Is anyone able to help out here? Could someone who owns a MK2 lift the bonnet and have a listen?

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Buzzing apart - it's quite easy to crudely test the sensor to ascertain if it's responding. Check that the constant voltage connection to the sensor is 5V with the ignition switched on. Having identified the constant terminal - connect a voltmeter between the earth wire and the signal wire (with the connector attached to the sensor). Check for a voltage change as the throttle is opened and closed slowly. It's usually the diaphragm that fails within the sensor - so either you'll get no response with changing engine speed or the voltage will briefly change and fall back with each change in throttle position.

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I have done this and it all works fine so now I am completely stumped! 

Its the dreaded hesitation and kangarooing under hard acceleration and hard starting which is throwing up random fault codes i.e. P1251 P2226 I even had one for Glow Plug Circuit but glowplugs harness and relay all fine.

so far the below has been tested and cleaned/replaced

MAP SENSOR, MAF SENSOR, EGR VALVE, TURBO VANES, TURBO ACTUATOR, Battery, VACUUM PIPES, GLOW PLUGS AND ALL CONNECTING PARTS, INJECTORS, Oil, Oil FILTER AND FUEL FILTER.

I am now down to my last thing which I have suspected for a while! 

The in tank fuel filter, it just feels like a fuel starvation thing! under steady acceleration and when it is going its fine, but when you ask it for some more it all goes wrong, even worse in hot weather.

I saw someone on here actually did this fix as the mesh filter can clog with deposits and wax from poor diesel or diesel being sat in the tank for a while. I will be doing this tonight failing that I will have to give up on this car which I really do not want to!

Even Toyota ran a diagnostic and told me there were no fault codes showing up for anything?

 

 

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