[s-cars] Does this sound like the N75 valve?

[Jared Robinson]

I have a mechanical boost gauge
when the car is off it sits at 0

I will say that the gauge seems a little 'slow' in vacuum... Maybe not slow,
but REALLY REALLY smooth. When I turn the car off, it SLOWLY goes back to 0
Most gauges I've had just snap to 0

Also, on part throttle under vacuum, it's pretty slow to respond. it
normally sits right at about 30cm Hg (11.8in) when under normal acceleration
and goes to about 40cm Hg (15.7in) when decelerating. However, because it's
a 3bar boost gauge, the vacuum readings are scaled to fit down to 80cm...
which is strange because I've never seen a car pull 80cm of vacuum (31in)

This is the gauge
http://www.sw-performance.com/upload/114337.jpg

Gauge only comes in 1 bar and 3 bar

The car is going on the dyno tomorrow morning and I'm going to hook it
directly to the MAP sensor on the dyno to see if the boost is good... I only
see two scenarios:
1) boost is on, gauge is crap
2) boost is off, time to start digging.

On Fri, Oct 2, 2009 at 12:39 PM, Robert Myers <bob at chips-ur-s.com> wrote:

> *This message was transferred with a trial version of CommuniGate(r) Pro*
>
> Jared,
>
> If the car is pulling more or less right at WOT there is no way for
> manifold pressure to be below ambient.  Hmmm...  What does your boost gauge
> read with the engine off?  Zero or ~1?  If it reads zero then your
> observations might be appropriate.  If it reads 1 then your observations are
> impossible and something is bad outawhack.  Mechanical gauge or electronic?
>  Certainly not the old trip computer boost display.  If that's what you are
> using then all bets are off because that "gauge" is a useless piece of
> trash.
>
> Yes, it's possible that your WGFV (N75 valve) might be screwed up somehow.
>
> Bob
>
> At 11:15 AM 10/2/2009, you wrote:
>
>> *This message was transferred with a trial version of CommuniGate(r) Pro*
>>
>> So, we flashed the ECU back to normal on Wednesday night
>> I was seeing 1.2 solid for the few pulls I took afterwards. It was a nice
>> crisp cold night too... but ever since then it's been erratic
>> the sporadicness of my boost is confusing. I'm not sure if it's a kinked
>> line to the boost gauge or what...
>> But at full throttle the needle was jumping between 1.1 and .8 all
>> morning.
>> It would spike to 1.1, bounce back down to .8 then back up to 1.0 then
>> back
>> down to .9... it was just everywhere.
>> The car FEELS fine, but the boost readings are just everywhere.
>>
>> --
>> Jared Robinson
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>


-- 
Jared Robinson