Butty

iTrader: (2)

Had an ongoing problem with an SPA gauge reading boost spikes.
I get max tell tale figures typically 16.4 psi, but have been up to 17.5 psi, but I get no fuel cut.
Idle vacumn is -10 psi and with engine off it is 0 psi.

The mods are very basic exhaust ones (no d/pipe decat) and I run Optimax with NF.

At a PE dyno session last week, the target psi was said to be about 14 psi and none of the readings taken during the run was above this.

So do I have some sort of problem with the SPA gauge, the OEM pressure sensor for the ECU or perhaps does the ECU sample pressure less frequently, average out the pressure over a longer period than the SPA?

The SPA pressure take off point is Teed at the manifold with the 2 port solenoid hose.
A Dawes is waiting to be installed, but if I rely on the SPA "over readings" then I won't be able to set it up correctly.

Nick
1997 Forester S/tb

R19KET

Nick,

It will be due to the "sampling" rate of the SpA compared to that of the ECU. You will always get spikes, and I imagine the ECU is just missing them, but I wouldn't worry about it.

You should be able to change the sampling rate of the SpA, so that it damps out the spikes.

Mark.

Butty

iTrader: (2)

Lovely job Mark.
Gauge default is with fastest av. period. I'll tweak this until I get figures that tally.

Nick
1997 Forester S/tb

R19KET

IIRC, I use 4 x pc.

AlanG

Nick

Default sampling rate on the gauge is 0.4 seconds.

If you can imagine using an analogue gauge which has no damping, you will get a wide variation in readings until it stabilises (so you will see high peaks), so as Mark says, alter the sampling rate to say for example, one second to dampen the reading out.

There is an issue at the moment with software on the type of gauge i run which SPA are taking action on and should be rectified in the near future.

However, this may not be applicable in your circumstance dependant on the type of gauge you have in your car.

Alan

Butty

iTrader: (2)

Thanks Alan,
My gauge is a DG206 Boost & temp combo.

Nick
1997 Forester S/tb

AlanG

A week late but....

I've been told the gauge you are using will be fine since it's a pressure/temperature gauge.

There is an issue with the software relating to pressure/pressure gauges which they are attending to.

Sorry, i was late getting back to you.

Alan

T-uk

alan,

what is the press/press issue?

I know mine would not read boost due to a wrong feed being fitted.I think they suspected a 5v had been soldered instead of a 12v so I sent mine back but have not tried it again yet to see if it now works.

was this the issue or is there another we should be aware of.

Butty

iTrader: (2)

OK Alan.
I've played around with the sample rate and have am working at the 1.0 setting.

Nick

AlanG

No problem Nick. Just give it a check to confirm the setting is there, the next time you go in, but make sure you go to rEt and reboot the gauge and not just switch off, as any setting you look at has to be flashed back to EEPROM, even if you don't change it.

John
There is a software issue but only on certain gauges when you try to alter parameters, not a display issue.

Alan

Butty

iTrader: (2)

3ugger.
I did a long run today and still got 17.1 psi with the sampling rate at 1.0 (seconds??).
Anyone know if the max display value is also calculated on the sampling rate or is it an instantaneous value, regardless of what the rate is set at?
I can't believe that this is a real value as I have no fuel cut defender, yet the car was puling nicely.
Is it true that the fuel cut sets in if the max pressure above target for the ECU is seen for more than 1/2 sec?

The display valves have settled down and are a pretty constant 11 psi from about 3000 rpm through to the red line.

I'll also try SpA tomorrow.


Nick

AlanG

Where have you mounted the pressure sender?

Alan

Added to say don't answer. Just re-read your first post. Doh!!

I felt it was better to fit at the manifold where the brake servo's vacuum hose fits, with a suitable "T" piece.

[Edited by AlanG - 10/30/2003 8:23:30 PM]

AlanG

I should also have said that adjusting the sampling rate is a bit like putting a damper on an analogue gauge.
If you have a gauge which is undamped the needle would swing about wildly and you would basically read the average of the variation.

The SPA gauge with the sampling rate extended will reduce the fluctuations in readings on the gauge, so that the user doesn't get distracted by the figures *bouncing* about, but your peak will still show and nothing to be worried about IMO.

What to do is watch the pressure on the gauge as you accelerate and see what it shows. You might find what you see on the gauge is different to what the peak reading has been logged by the gauge.

Alan

T-uk

well I thought I better try my boost gauge today , since I had not checked it since SPA returned it.

I had been using the SPA oil pressure gauge I also have but plugged into the boost sensor to keep me going , while the problem with the boost/fuel pressure gauge , was getting repaired. the fuel side of the gauge has always worked fine.

the problem I had originally was it under read , so Boost pressure read -0.3 bar at idle when it is really about -0.6 bar. on full boost it would read about 0.5bar too low.

with the oil gauge used short term as a boost gauge everything worked as expected.

my proper boost gauge is now reading 1.2bar at idle

looks like it will have to go back again.

[Edited by T-uk - 10/30/2003 9:12:00 PM]

AlanG

John

I'm back up in your neck of the woods today.(Tuesday)

Want to try my gauge and see the figures it gives?

Text if you want to go ahead.

Alan

T-uk

huge thanks to alang.

he did not make it up yesterday but managed up today.

we never actually tried his gauge in my car but he went into the settings menu and adjusted a few things and now everything is spot on. I had never adjusted anything since it came back from SPA but the gauge is now working fine.

cheers again