Boost Gauge Question

[MN Cummins Lvr]

I know this has been touched on before, but just want to confirm.



I installed an Isspro boost gauge today. It reads 0 while cruising at 50 MPH and I got it up to about 16 or 17 with my foot heavy into the pedal. Also, when I really put my foot into it, I could hear air hissing from the gauge. Everything sound normal or do I have a leak?



Can't wait to tow something heavy to really test it. By the way, engine is stock.



Thanks,

Paul

 

[EMDDIESEL]

Your readings sound pretty normal, at WOT i get 19psi and idle 0. Cruising about 55mph its only a few psi. , only when you really get on it will you see a rise. The hissing does NOT sound normal though, mine is totally silent, i would check your fittings.

 

[SLightfoot]

You have a leak

I just installed my guages today.

No hissing sound from the guages, and there should NOT be either.



If you hear hissing from the guage, you had better go and check the pipe fitting... . cuz it must be leaking.



Cruising down the road, I see about 5 lbs boost all the time at 60MPH.



Shawn

 

[Fireman Dave]

Paul, you should see 4-6 lbs at 50 mph - more on a hill. Your hiss may be the culpret.



Dave

 

[Archive]

Fireman and Shawn are correct... running down the road, not uphill, you should see between 4-6lbs of boost. 0 boost at that speed is not normal. Re-check your fittings on the back of the gauge, and while you are at it, at the other end, also.

 

[John]

Paul, if you are hearing a hissing sound from your boost gauge you have a leak! It could be the gauge itself or the connection. . most likely the compression fitting (either too tight or too loose).



This may sound stupid but...

are you sure it's a hissing sound you are hearing from the boost gauge or could it be turbo whine transmitting up through the nylon tubing? VDO warned against using their own nylon tubing installation kit on turbocharged vehicles for this reason. I can absolutely substantiate this... I used a pressure gauge to initially set the back pressure level on my BD exhaust brake. I also left it connected, laying it on the seat in the cab during my first test run (to the mountains and back). I immediately discovered that what the VDO tech. had told me was true, I could hear the turbine whine telegraphed through the nylon boost line. I believe it is masked to some extent by routing the line under and behind materials that have a tendency to dampen noise. However, different levels of driver auditory perception can vary the threshhold of any perceived turbine whine through the nylon boost line... or not.

 

[MN Cummins Lvr]

I tightened the fitting on the gauge and guess what? Hissing is gone!



I am seeing about 17 to 18 at WOT, about 7 at 70 MPH, 5 at 60 MPH. Gauge is more sensitive now being that the fitting is tight. Maybe the installer has a leak in his brain!



Thanks everyone for the help!



Paul