Besides right at the ECU...where under the "hood" of the car can you "T" for a boost gauge?
07-06-2003, 08:08 PM
#1
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Besides right at the ECU...where under the "hood" of the car can you "T" for a boost gauge?
<center><img src="http://pictureposter.audiworld.com/9882/pic00042.jpg"></center><p>
07-06-2003, 10:48 PM
#2
I think that a good place is just downstream of the.....
analogue pressure transducer, aka (incorrectly) "moisture trap". This is the same signal as the ECU gets (only a bit - milliseconds - earlier). Then your challenge is to find a suitable rubber grommet in the firewall to put your pressure tubing through. You might have to have a T and a 90 deg elbow to get the tubing pointed over to the drivers side.
I have seen an intake manifold drilled and tapped to take brass pressure tube fittings. However, without the benefit of the pressure transducer, this means that air/fuel mixture is being (sort of through diffusion) brought into the interior of the car, into an electrical device with the potential for sparking. This sounds like trouble to me. Hence the first suggestion sounds better to me.
What do the boys at ASW (Dave Jones?) suggest? What do the Colorado S-car Mafia, e.g. Hap or Frank do?
Dave F.
I have seen an intake manifold drilled and tapped to take brass pressure tube fittings. However, without the benefit of the pressure transducer, this means that air/fuel mixture is being (sort of through diffusion) brought into the interior of the car, into an electrical device with the potential for sparking. This sounds like trouble to me. Hence the first suggestion sounds better to me.
What do the boys at ASW (Dave Jones?) suggest? What do the Colorado S-car Mafia, e.g. Hap or Frank do?
Dave F.
07-07-2003, 06:07 AM
#3
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The ECU pressure signal
is given by the pressure transducer located inside the ECU, nothing else gives it a pressure signal.
IMHO/IME the best location is a T at the ECU.
HTH,
Mihnea
IMHO/IME the best location is a T at the ECU.
HTH,
Mihnea
07-07-2003, 07:26 AM
#6
Mihnea, what we have here is failure to communicate....
The "moisture trap" (which is the wrong name for it) is an analogue to analogue pressure transducer, i.e. there is a air/fuel mixture pressure "signal" from the intake manifold side of a fuel resistant diaphram which is translated to an air-only pressure "signal" in theplastic tube leading to the ECU. The pressure transducer (2.5 BAR or 3 BAR) inside the ECU box is analogue (pressure) to electrical and translates the analogue pressure signal (can be read on an analogue gauge) to a millivolt electrical signal (that can be read with a multimeter - as you well know) that is read by the chips in the ECU. (The one thing I don't know is whether the ECU pressure transducer also creates a digital output from the millivolt pressure translation or there is something else that does this before the chips).
In any event, to install an analogue pressure gauge, it should be fine to T' off anywhere downstream of the analogue pressure transducer and before the ECU box. The advantage of T-ing near the ECU is the analogue pressure signal tube has already gone through the firewall and into the passenger cabin.
Dave F.
In any event, to install an analogue pressure gauge, it should be fine to T' off anywhere downstream of the analogue pressure transducer and before the ECU box. The advantage of T-ing near the ECU is the analogue pressure signal tube has already gone through the firewall and into the passenger cabin.
Dave F.
07-07-2003, 08:55 AM
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Nope.....
What I mean is that there's no such thing as an analogue to analogue pressure transducer in our cars. What's going out of the intake manifold through the moisture trap (which BTW isn't the wrong name for it, it's just that, an empty fuel filter so fuel residues don't go inside the ECU's pressure transducer) is just air, the fuel is being sprayed into the IM runners and due to the air flow that's never going backwards, the fuel could never find itself inside the vacuum line leading to the moisture trap and to the ECU. The moisture trap is mainly there because of the fuel vapors from the evaporator valve, nothing more, nothing less.
No offense intended,
Mihnea
No offense intended,
Mihnea
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07-07-2003, 09:57 AM
#8
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But isnt that a LONG run from the A-Pillar to the ECU? Which route did you take?
The FW is actually pretty easy to punch through as there is a plug that is unused under the steering column. My question is where does the T get placed? As I can see where there is Boost "like" vac. line right there at the FW near the Moisture Trap...but not sure if that is appropriate to tap.
07-07-2003, 09:59 AM
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So is it OK to T off there near or "at" the moisture trap? See Pic:
<center><img src="http://pictureposter.audiworld.com/9882/pic00042.jpg"></center><p>
Left side of picture...see vacuum hoses
Left side of picture...see vacuum hoses