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'07 Boost gauge reading 15psi ?


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Finally took possession of our new to us 2007 GT500 last night.


This is a three owner car. Very little owner history from the first 2 owners.

No obvious signs of any aftermarket work, or FFRP dealer installed packages seen so far.


On the 60 mile drive home last night, my wife noticed the boost gauge is reading to the far right as in, 15 psi.


So couple of possibilities.

Aftermarket pulley with stock look.

Gauge is faulty.

Gauge is working as delivered, but just not accurate, as many OEM gauges are known to be(many are just idiots lights with a needle in place of the light,, so not a real gauge)


I did some searching here and another popular GT500 forum,, not finding many hits at all on the OEM boost gauge, and none that talk about OEM inaccurate readings, or failed gauges.


I really don’t think this car has been modified, and though I have not seen it in person yet, my wife has, and is very experienced in spotting aftermarket work…… it’s part of her job (service advisor)


So, are the OEM boost gauges in the ’07 known to read high?

Is there a known common failure of this gauge?

It’s a pretty simple mechanical gauge with a direct line to vac source from what I can see in the OEM Service manual and on line.


Is there something else I’m missing?





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Thanks, ya Im tracking there are OEM STOCK looking smaller pulleys, My son is going to go over the house tonight and put a caliper on the pulley, and check for a CAI and anything else that is not represented in the pictures i have (showing a completely stock looking engine)

My bet is a faulty gauge. ..

I’m told it’s running great, tons of power. So my only concern is, it has a tune, or aftermarket components and a PO did not include the tuner, or worse, removed the tune, but not the pulley, CAI, ect.

It’ll be hooked up to a World Diagnostic system on Friday, so the tune question will be answered then. Hopefully the pulley question tonight,, err Texas tonight, not my tonight.

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The boost gauge is not mechanical. It's electronic and doesn't even read boost. It calculates what boost should be based on other parameters. It's pretty much guaranteed to be inaccurate. Having said that, it seldom is 15 lbs inaccurate. One thing that really does increase boost is plugged cats. Hope this helps.



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I just read through this and one thing that is confusing is the amount of boost. If you are cruising, there shouldn't hardly be any boost, maybe a pound or two. Now when you punch it, the higher the RPM the more boost you should get. I have the Steigemeir Snake Bite kit on mine and my boost reaches just about 15 pounds in the upper RPM range but that is usaully around 6K RPM. My pulley still looks stock but it is under the snout where gears are changed to make it the rotors spin faster. So even if your pulley is still stock and you have that much boost, you may want to ask the previous owner about that.


Now if you are just cruising and you have that much boost, I would definately get it checked out.

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The pegged OEM boost gauge was noticed in a passing event.. so exactly when there should be boost present.


I was not tracking the gauge was electronic.. I thought from reading it was mechanical.. have to go back to the service manual… THANK YOU.


This car has had to previous owners, talking to them is not an option. We bought it from a dealer, who bought the car from one of his customers… bottom line on that I’m on my own as far as PO history.. In the Army we call it “Discover Learning”


I’m leaning towards faulty gauge, as it was confirmed there is no tune installed, and the pulley is stock.

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Call or go by a Ford Dealer and have them run an "Oasis Report". You'll need to give them the Vin #, it will show you all of the service life done through Ford Dealers, and if there is any factory or extended warranty left. A good thing to check out




Thanks Done and Done, before we bought it. ESB valid though DEC 12.. Paid the transfer fee today.

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