Well, I have an electric boost gauge that came with the car with a peak and warn feature. I notice that 90% of the time, it's vac reading is about 4-6 mmhg lower than the mechanical that I hooked up to the nipple on the UIM. I would trust the one I hooked to the manifold more than an electric gauge, and I was curious to hear if other noticed this problem as well. The gauge re-calibrates each time I turn the car to accessory, so I have no idea why it would be off so much....

Trev

 

Where is the electronic gauge getting its source from?

 

It is T'd into the MAP sensors line. I haven't moved it from that location since I bought the car...maybe I should run it from a different source? I just don't understand why the mechanical one I have hooked to the extra port on the UIM would be 4-6 in/hg higher than the electronic gauge. SOMETIMES the electronic gauge reads like the mechanical, but only 10% of the time. Maybe it is how I am re-calibrating it each start up or something?

 

Many people have noted slightly different readings from the two different locations. I personally prefer T'ing into the line to the MAP sensor as that gives a better indication at what the car is getting from the sensor. I would trust that reading over the extra nipple on the far side of the UIM.

As a test, you could swap the two sources for the gauges and see if you have the same variance just on opposite gauges.

 

good plan. I will try that. I still think there is more room for error with an electric gauge than one that is going RIGHT to the UIM.