For some reason when I get on it, my boost gauge doesn't read- it stays at 0. I even installed a cheap HF boost gauge in parallel, T'ed off the same line, and the car is in fact making the boost it should. If I bench test both the gauges by supplying regulated shop air to the vacuum lines, the HF gauge reads exactly what my calibration gauge reads, and the stock gauge reads what it did when I calibrated it when I put the Hilton boost overlay on it- accurate at 0-10 psi, 2psi low at 23psi. Has anyone else run into this?
Boost gauge not functioning?
- Thread starter SecondhandSnake
- Start date
Sounds like you have a leak somewhere or have the boost line hooked up incorrectly behind the blower.
That's what I would have thought but I put a T fitting just behind the gauge cluster and ran one line to the stock gauge, the other to the HF gauge. The HF gauge reads exactly what I would expect.
The other possibility is when you pulled the boost needle off to do the over lay, you might have pushed it on too far and the needle is stuck and will not sweep.
That's the odd part- as I stated above, I tested it a few times with shop air. First when I was installing it to calibrate it, and just yesterday. It sweeps fine.
When you say you T'd off the line, did you do it behind the glove box or on the line that plugs into the gauge behind the dash?
I've got it done right behind the gauge cluster. It goes from the line that normally goes to the gauge, a T fitting, then a 3" long hose from the fitting to each of the gauges. It's one of the multi size T fittings that have steps and barbs for every diameter so it's very snug on every connection.
Something is not right with one of the lines then. If you are saying you tested both gauges and they work, then....they work. Problem has to be with the line or t-fitting.
this, if it works running a T right behind the gauge then something happened to the vacuum line from gauge to motor or wherever it's tapped in
This is what has me stumped-
If I disconnect the hose in the engine bay that goes to both gauges and supply shop air to it, they both work. This suggests the lines to both gauges work.
Out on the road driving with that hose connected to the lower manifold as it should be, only the HF gauge works- the cluster gauge reads 0. This suggests that the lines from the engine to the gauge(s) work.
Something is defying logic, unless there's something in the behavior of the engine/operating vehicle that the affects the cluster gauge but not the HF gauge.
How much shop air pressure are you applying to the gauge line? If it us more than your supercharger then the needle might be stuck but you are apply enough force with shop air to still move it.
Are you sure you are reading boost and not vacuum on the HF gauge? Stock gauge only reads boost, could be why you are only seeing one gauge "work".
Are you sure you are reading boost and not vacuum on the HF gauge? Stock gauge only reads boost, could be why you are only seeing one gauge "work".
Definitely building boost. Datalogs are well above 1.0 volumetric efficiency when I get on it.
Bypass valve was reconfigured and tested awhile back when I was concerned that the reference (bottom) line was causing it to open due to seeing boost. Now it's just referenced to atmosphere.
I was varying shop pressure all the way from 0 to 25psi. Current adjustment had the car making 20psi. Both moved together, along with the reference gauge I had.
The HF gauge is boost and vacuum. I can hardly even see the vacuum portion while driving- it's mostly obstructed by the steering wheel. As mentioned before it's definitely seeing/showing boost based on the datalogs.
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