Hey all,
Im tyring to figure out if its possible to bypass the exchange solenoid permanently. Ive found this thread:
viewtopic.php?f=4&t=11978&hilit=exchange+solenoid&start=20

It seems to state that there is a barometric pressure test from the ecu every couple of minutes and this may effect Base maps for fuel or spark?
Reason for my interest is my car behaves very differently to these different scenarios:

1-With everything normal, (yellow wire connected, Vac lines to exchange solenoid normal) The car runs best & the stock dash boost gauge works correctly.

2-With Yellow Wire Cut, The car runs great as above and the stock boost gauge works for a while then for no apparent reason the stock boost gauge stops working correctly, And performance/driveability is affected. When this occurs the pressure exchange solenoid shuts and doesn't allow air through to the MAP sensor. (touching yellow wires together restarts the vac thru the solenoid!)

3-With Yellow wire cut but vac line straight from manifold to Map, Doesnt really seem that different from above wexcept for a small improvement in driveability, Performance still down and stock boost gauge doesnt work.

So.... What i have derived from all this is that when the dash gauge is working, The car runs significantly better, but i have boost cut.
Has anyone found a way around boost cut? Is it possible using the stock ECU and Map setup?

Please any ideas/comments will be appreciated.
Cheers, James.

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"BESSY"
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i am retardedlyt atm drunk but i think ur map sensor might be stuffed just get ur car runing good are reliable on 14 PSI and go from there

once ur car is perfect and quick on 14 maybe look at cutting yellow wire but seriously boost isnt the anweser all the time.


my always ran 14 psi once it was pefect never cut yellow wire and was reallly fun to drive! dont worry about high boost untill u hae a decent cool and car is running perect

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"hahhahahhaa its good its got straw for a pipe frontn.... the bigger that hole gets the more money falls out of ur wallet... "



Epic i must say.

LMFAO What??????
I have a decent cooler and car is running good. But 16Psi is WAAAAAY better than 14 man!

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"BESSY"
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James,
There is no reason why your boost meter wont work with the yellow wire cut...........once the signal from the map sensor reaches 5volt it will "cut" the ignition. The meter is not related so it should work independently.

Check out the diagram:



Sounds like your MAP sensor is stuffed.

So, where does the stock gauge recieve its input from?

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"BESSY"
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Pin 7 is the signal from the ECU.

Pin 7 is the pressure signal and pin 3 is the pressure exchange solenoid signal or is it a feed?

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"BESSY"
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So am i correct in saying pin 2 (pressure switch) is the Yellow wire?

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"BESSY"
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It's a feed from the ECU



Yes.

Ok. Im getting ideas..... But if pin 3 is a feed from the ECU to the Exchange solenoid then what is causing a loss of this signal?
Also could i run a seperate or "teed in" feed to pin2 at the MAP and pin1 at the E101 to effectively bypass its readings? Keepeing both MAP and E101 thinking they are still connected but not allowing the 5volts to travel and Reduce ignition? Thereby eliminating boost cut but retaining my stock boost gauge and driveability?

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"BESSY"
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Could the ECU be shutting off feed to the Exchange Solenoid Which im going to call the PES, When it does its "test" on Barometric pressure reading and realises that the feed from the MAP to the E-101 isnt there?
That would explain why the solenoid and my boost gauge work for a while after disconnecting the yellow wire, then drop out later.
Which also explains the affect on performance and driveability because when this happens the exchange solenoid seems to be "closed" and not allowing vac to the MAP sensor. Could this "closed" issue actually be that the ECU is stuck taking its barometric pressure reading or is the not possible?

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"BESSY"
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Try this first............it will determine your issues.

Wow! Do you have the 3rd page? The one that continues on the boost sensor backprobing?
Cheers man, That is gonna take me ages!!!!!
So............. What you doing tomorrow...... Lol!

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"BESSY"
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That's it...........number 1 just says check for correct piping and manifold pressure.

I scanned both leaded and unleaded versions.......both are the same.

I can help you tomorrow no troubles..........let's hope the weather is a little better.

No worries! That stuff is awesome! Whered you get it from? Ill be in touch tonight about tomorrow.
Thanks again

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"BESSY"
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I have a manual from Trade school, believe me it's over 15 years old!

My understanding of the system is that pin 7 (the yellow wire) is the output from the boost sensor which goes to the ecu. Pin 3 is the pressure exchange signal, when the ecu wants to check atmospheric pressure, it grounds the exchange solenoid and pin 3. That way the boost sensor knows not to give the boost gauge a reading of atmospheric pressure. Pin 4 is the output from the boost sensor to the gauge. I am guessing that when the ecu no longer receives a signal from the boost sensor, it stops switching the exchange solenoid and boost sensor. And the sensor stops outputting a voltage to the gauge.

You can't expect to have the best air/fuel mixture when an important sensor like the boost sensor stops giving an output to the ecu.

The only way that I can think of running higher boost with the yellow wire connected, is to use a voltage clamp on the boost sensor output or regulate the air pressure to the sensor to a maximum of 13/14psi.

thats it! I could run a bleed valve between the manifold and the map sensor and tee off my boost gauge after it (for testing only) to get the bleed close to 14psi. This should in effect trick the system so i can retain everyday driveability and still get the mixtures nearly spot on considering im only running 2psi over what the ecu thinks im running. And ive set my afm to rich by unplugin the bypass holes too so i should definately be on the safe side of the mixture scale.

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"BESSY"
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thats it! I could run a bleed valve between the manifold and the map sensor and tee off my boost gauge after it (for testing only) to get the bleed close to 14psi. This should in effect trick the system so i can retain everyday driveability and still get the mixtures nearly spot on considering im only running 2psi over what the ecu thinks im running. And ive set my afm to rich by unplugin the bypass holes too so i should definately be on the safe side of the mixture scale.

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"BESSY"
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Or fit one of these:

http://www.jaycar.com.au/productView.asp?ID=KC5439