I was reading through my repair manual and found a section titled "Vacuum gauge diagnostic checks". It says that you can use a vacuum gauge to check for worn rings/cylinder walls, leaking head gaskets, weak valve springs, improper ignition or valve timing and the list goes on. It says you can check all this just by connecting the gauge directly to intake manifold vacuum and watching the rate of needle movement. My question is, can I do all the same checks using a simple aftermarket boost gauge (one that shows vacuum pressure along with boost pressure) instead of using a hand-held vacuum gauge like the one described in my manual? or would a small aftermarket gauge not be precise enough to accurately determine engine problems?

 

Yes they are the same thing. The gauge will really only tell you if you have strong or weak vacuum and most of the time its from a vacuum leak. However I find them to make certian diagnostics much easier and would install a vacuum gauge on my 2.8 if I was putting gauges in and needed one more.

 

Cool, thanks.

 

A boost/vac gauge isn't a very good diagnostic tool unless you have a serious problem, like somebody says... The kind of diagnostic vac gauge they are talking about gives more detailed readings (milimeters of mercury compared to inches)and is most likely more accurate than a boost gauge. Some also come with an additional scale within the gauge and hookup for checking fuel pressure. Of course vag com is the ultimate diagnostic tool for us.

 

So vag-com could give me just as much information as a vacuum gauge check? Is there anything vag-com can't do? Cylinder compression check, oil pressure check, etc.? I'm really considering getting the software, but is there anything else I'll need to buy? Is it easy to use?

 

vagcom will give you the readings of all the sensors in the car, so the only things it cant do, is what you dont have a sensor for. you just need the software and a cable to connect the obd-II port to your computers serial or usb port. the software is the expensive part.

 

Their website suggested getting the Bently service manual along with either their Hex-USB+CAN or thier KII-USB interface. Which of these interfaces should I get? Are the Bently manual and Vag-com software easy to understand for someone who's somewhat new to automotive maintenance and not all that computer inclined? I really don't know anything about Vag-com other than what I just posted. Is there anything else I should know before purchasing the software, manual, and usb cable?

 

Bump.