Can anyone tell me why I now get overboost (CEL comes on plus rapid deceleration) with a boost guage connected?

I'm running a Dawes Device which is switchable in circuit or out of circuit via solenoids, so I can use standard setup or extra boost. The overboost only occurs if I add the boost guage to the setup and have the Dawes operating. Without the guage but with Dawes on I do not get overboost.

The only way at present with the guage in circuit that I can avoid this is to reduce the Dawes boost, but even at 12 psi I get the CEL coming on due to overboost in 4th gear.

Any clues?

Ive tried the gauge either side of the Dawes. One side reads correctly but with overboost occurring, whilst the other side only reads up to 5 psi but I don't get overboost...so I'm guessing the boost guage is the problem - causing fluctuations in pressure?? (have double checked the connections and they are all sealed inside with pft tape or whatever you call it )

Any answers much appreciated as it is annoying and I'd rather do without the boost gauge if it's going to cause these problems.

Tony

 

Try tapping the boost gauge off the vac line to the dumpvalve instead..

Could be the gauge / connection is leaking?

JGM

 

sounds like the extra void space in the the length of pipe going all the way to the boost gauge is probably causing a spike which pushes it just over the limit. it then quickly goes back under, even for a fraction of a second a surge is all it needs to cause an overboost warning...

hope that helps!

 

Ta for the replies.

I'll try the dump valve method and if that fails I'll assume it's the 2nd response...and the gauge can head towards the bin...So much for the Indiglo group buy

 

Tony,
Can you not get a pipe off the manifold, rather than anywhere near the dawes??

Ron.

 

The blanked off nipple is where mine's fitted, without problem. Makes sense to keep it away from the Dawes connection, else you're adding another variable to the "potential problem equation"...

 

Can you give me directions as to where the nipple is? The car is an MY2002 WRX.

Cheers

Tony

p.s. The dump valve pipework is much thicker and I am not going to cut it or fiddle with it, so it will have to be tweaking with a nipple or lob it in the bin

 

Try lookng at the front of the inlet manifold, there are a few pipes that go onto the inlet, there may be a spare one that has a little rubber cap on it, use that one if it's there, that'll give you a true manifold pressure reading!!

 

Just a note, MY2001 onwards 'bug/new age' do NOT have a spare nipple, unlike my previous MY00 (and earlier versions).

If your interested in how I've fitted my gauge see the Where to fit a boost gauge pipe on a WRX MY03 thread.
-Steve

[Edited by stevecrisp - 12/12/2003 8:19:37 PM]

 

So, you'll need to put a tee in one of the other pipes then!

 

And we are back to the dump valve line again.. lol

 

Thanks for all the repsonses..

Scoobynet never fails!

Once I've unpacked all my boxes from moving, I'll have a fiddle with the Scoob.

Cheers

Tony