Boost Gauge Question

[Dgc333]

This question is directed to those that have installed a boost gauge that directly reads manifold pressure (not one reading the CAN bus via the OBD port).

I finally got my gauge pod installed on the top of my dash where the upfitter switches were and noticed an unusual behavior of the boost/vacuum gauge when on the vacuum side. Looking to see if others have the same phenomenon happening.

When cruising at a speed that has the throttle open enough for manifold vacuum to be in the 0 to 10"Hg range the gauge needle is very steady. But when I slow down and the throttle is barely open with manifold vacuum in the 10 to 20"Hg range the needle oscillates rapidly about 1 to 2"Hg. If I remove my foot completely from the throttle and coast the manifold vacuum will go to 20 to 24"Hg and be steady.

I suspect what is happening is a very small throttle openings the ECU cycles the throttle open and closed rapidly to maintain speed which changes the manifold vacuum and is being measured by the gauge. Just wanting to know if others with a boost gauge are seeing the same thing.

Other than being a distraction I am concerned if this is not normal what impact will it have on the long term reliability of the throttle body and boost/vacuum gauge. I can fix the gauge by putting a capacity tank in the line (already a very small size restrictor in the gauge fitting).

Look forward to comments. ?

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[Muscleford]

I like the gauge cluster. What are gauges? Where did you get it? Cost?

 

[Zetterbeard]

This question is directed to those that have installed a boost gauge that directly reads manifold pressure (not one reading the CAN bus via the OBD port).

I finally got my gauge pod installed on the top of my dash where the upfitter switches were and noticed an unusual behavior of the boost/vacuum gauge when on the vacuum side. Looking to see if others have the same phenomenon happening.

When cruising at a speed that has the throttle open enough for manifold vacuum to be in the 0 to 10"Hg range the gauge needle is very steady. But when I slow down and the throttle is barely open with manifold vacuum in the 10 to 20"Hg range the needle oscillates rapidly about 1 to 2"Hg. If I remove my foot completely from the throttle and coast the manifold vacuum will go to 20 to 24"Hg and be steady.

I suspect what is happening is a very small throttle openings the ECU cycles the throttle open and closed rapidly to maintain speed which changes the manifold vacuum and is being measured by the gauge. Just wanting to know if others with a boost gauge are seeing the same thing.

Other than being a distraction I am concerned if this is not normal what impact will it have on the long term reliability of the throttle body and boost/vacuum gauge. I can fix the gauge by putting a capacity tank in the line (already a very small size restrictor in the gauge fitting).

Look forward to comments. ?

The pulsing is related to the number of intake strokes per revolution. Inline boost pressure restrictors exist to attempt to remove the vibration. Apparently some gauges have a built in restrictor (my $85 Auto Meter still vibrated). I attempted to install this one, but the needle still pulsed and the restrictor actually whistled very loud when building boost. I removed it.

 

[machinist85]

I installed a Gloshift boost gauge in mine and it came with a brass restrictor to prevent flutter. It was a small brass cylinder with a tiny pinhole hole through it. The restrictor gets pushed into the hose about an inch or so before where it connects to the engine. It completely stopped the flutter.

 

[Frenchy]

This question is directed to those that have installed a boost gauge that directly reads manifold pressure (not one reading the CAN bus via the OBD port).

I finally got my gauge pod installed on the top of my dash where the upfitter switches were and noticed an unusual behavior of the boost/vacuum gauge when on the vacuum side. Looking to see if others have the same phenomenon happening.

When cruising at a speed that has the throttle open enough for manifold vacuum to be in the 0 to 10"Hg range the gauge needle is very steady. But when I slow down and the throttle is barely open with manifold vacuum in the 10 to 20"Hg range the needle oscillates rapidly about 1 to 2"Hg. If I remove my foot completely from the throttle and coast the manifold vacuum will go to 20 to 24"Hg and be steady.

I suspect what is happening is a very small throttle openings the ECU cycles the throttle open and closed rapidly to maintain speed which changes the manifold vacuum and is being measured by the gauge. Just wanting to know if others with a boost gauge are seeing the same thing.

Other than being a distraction I am concerned if this is not normal what impact will it have on the long term reliability of the throttle body and boost/vacuum gauge. I can fix the gauge by putting a capacity tank in the line (already a very small size restrictor in the gauge fitting).

Look forward to comments. ?

As one who already understands turbocharged vehicles I can assure you that this is normal. It really depends on the current conditions to what the Boost/Vacuum gauge will be doing. Just remember that if you are in Vacuum over boost you will generally be getting better Fuel Mileage.

 

[Dgc333]

The pulsing is related to the number of intake strokes per revolution. Inline boost pressure restrictors exist to attempt to remove the vibration. Apparently some gauges have a built in restrictor (my $85 Auto Meter still vibrated). I attempted to install this one, but the needle still pulsed and the restrictor actually whistled very loud when building boost. I removed it.

If it was related to intake strokes per revolution I would expect it to happen at all throttle positions and vacuum levels. This only happens at very very light throttle. The gauge is rock steady from 0 to 10"Hg.

Something to think about, Thanks for the response.

 

[Dgc333]

I installed a Gloshift boost gauge in mine and it came with a brass restrictor to prevent flutter. It was a small brass cylinder with a tiny pinhole hole through it. The restrictor gets pushed into the hose about an inch or so before where it connects to the engine. It completely stopped the flutter.

Mine is a Glowshift too, it didn't come with a separate restrictor but the fitting on the gauge itself has a pin hole restrictor.

 

[Dgc333]

As one who already understands turbocharged vehicles I can assure you that this is normal. It really depends on the current conditions to what the Boost/Vacuum gauge will be doing. Just remember that if you are in Vacuum over boost you will generally be getting better Fuel Mileage.

I have been driving turbocharged 4cyl vehicles continuously for the past 37 years. All of them have had boost gauges, either from the factory or installed by me. None of them have exhibited this particular phenomena. One of the main reasons for installing the boost/vacuum gauge is the ability to maximize mileage when I want to get the best mpg.

One of the things I have already noticed compared to my two Ecoboost Mustangs is with the Mustangs you can easily drive the vehicle and keep up with traffic without ever going into boost. For the Ranger to keep up with traffic you need to let it develop about 5 psi of boost. I imagine that it's do to the Ranger being almost 1000 l s heavier and less aerodynamic.

 

[machinist85]

Mine is a Glowshift too, it didn't come with a separate restrictor but the fitting on the gauge itself has a pin hole restrictor.

It's been a couple years since I put mine in. I may have made my own restrictor. I do remember having a flutter problem at low rpm when I first put the gauge in. I have the version with the rubber hose. I know they also make the same gauge with plastic line and compression fittings. I'm not sure if that one has a restrictor or not.

 

[Dgc333]

I like the gauge cluster. What are gauges? Where did you get it? Cost?

The gauges are Glowshift 7 color black series gauges. The volt and vacuum/boost were approximately $50 each and the oil pressure was $90 (comes with the sensor and weather pak harness). Also had to buy from Glowshift an oil filter sandwich adapter ($30) for a place to install the sensor. The gauge pod was from Autometer and was $100. Also needed a tee block in order to tap into the manifold with out cutting any factory lines ($30).

I normally buy Autometer gauges but wanted something that integrated with the interior and the Glowshift gauges are LED back lit and have 7 color choices and seemed to fit my needs the best.

The Autometer gauge pod has a pedalstil on the bottom that is about 3/4" thick. It made for a simple mount to the bottom of the dash tray and aced the gauges just above the surface of the dash.

 

[Dgc333]

It's been a couple years since I put mine in. I may have made my own restrictor. I do remember having a flutter problem at low rpm when I first put the gauge in. I have the version with the rubber hose. I know they also make the same gauge with plastic line and compression fittings. I'm not sure if that one has a restrictor or not.

Mine is like the bottom picture. The silicone hose is way to soft and is easily kinked cutting off manifold pressure from the gauge. Could make a 90 onto the gauge fitting inside the pod without it kinking. Wound up using 1/8 nylon tubing. I used a 90 degree fitting at the gauge and a short piece of the supplied tubing to couple the nylon hose to the barb fitting on the adapter block under the hood.

 

[t4thfavor]

If it was related to intake strokes per revolution I would expect it to happen at all throttle positions and vacuum levels. This only happens at very very light throttle. The gauge is rock steady from 0 to 10"Hg.

Something to think about, Thanks for the response.

It does happen all the time, but it’s happening too fast at higher revs for your gauge to read. It’s normal from my experience too.

 

[machinist85]

Mine is like the bottom picture. The silicone hose is way to soft and is easily kinked cutting off manifold pressure from the gauge. Could make a 90 onto the gauge fitting inside the pod without it kinking. Wound up using 1/8 nylon tubing. I used a 90 degree fitting at the gauge and a short piece of the supplied tubing to couple the nylon hose to the barb fitting on the adapter block under the hood.

If your piece of silicone tubing is long enough you could try pinching it most of the way closed with a clamp and see if the flutter stops. If so a restrictor would help you.

 

[Dgc333]

If your piece of silicone tubing is long enough you could try pinching it most of the way closed with a clamp and see if the flutter stops. If so a restrictor would help you.

That's a good idea! ?

 

[Dgc333]

It's been a couple years since I put mine in. I may have made my own restrictor. I do remember having a flutter problem at low rpm when I first put the gauge in. I have the version with the rubber hose. I know they also make the same gauge with plastic line and compression fittings. I'm not sure if that one has a restrictor or not.

Well I was out in the garage cleaning up and noticed the white plastic Tee that came with the gauge had a restrictor in it. I capped one leg and installed it at the tee block under the hood.

Still getting a little pulsation at 20"Hg but it is solid every where else and it did not noticeably impact how quickly it reacted to changing manifold pressure.

Thanks everyone for the tips and inside.

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