98.5 A4 gas gauge reads empty when off the throttle. While accelerating the gas gauge will give an incorrect reading. Sometimes its about half sometimes its a quarter.

Has anyone seen/heard of this before? Any ideas what it could be?

Also is there a way through vag com to get a direct reading from the sending unit on the pump? This would help me rule out a faulty gauge cluster.

 

your sender unit is bad. replace or repair
http://www.audiworld.com/tech/elec77.shtml

 

Thanks for the link colony.

Anyone know if you can get a direct reading of the sending unit through vag?

 

if your sender is broken, no. that is the only think that reads your fuel level

 

Correct, if it is broken then I wouldn't get a (accurate) reading and know it is broken. I just like to make sure what I am replacing is the culprit. It makes no sense to me how the throttle would affect the sending unit in any way.

 

theres nothing else it could be really. if it was your guage cluster, it would either work, or not. it wouldnt ever move from E. it could be a combination on vapor lock or something. dont replace it, clean it up. its a variable resistor like that article says. any corrosion or anything will change the reading

 

You can take resistance readings, I belive full is 40ohms and empty is 280ohms. If u remove the trap door in the trunk there are 4 wires that go into the tank the 2 thick wires are power to the pump and the two smaller are the sensor, meter probes will fit down in to the connector to the contacts. Resistance is not polarity sensetive so it doesn't matter which probe goes to wich wire.

 

^^^what he said, and those impedance values are correct.

 

just follow the DIY and take the fuel level sending unit out. all you have to do is get a piece of wire that is around half an inch long and solder it in there cuz the old one broke in half... also, when you do this make sure that you dont have a lot of gas in the tank because you dont want to get your hands wet :P i have done this on my car before and its a 30 minute job and i was taking my time. my fuel gauge would only work untill it got to half way, then it would just fall down to 0. replacing that little wire fixed the unit. i recommend that you do this easy process instead of buying a new unit which is over $100.

 

Thanks for all the info guys. I'm still hooked on why the throttle would affect the sending unit though.

I fueled up yesturday and ever since the gauge has been working properly. If it happens again ill be trying the suggestions.

Thanks again everyone.