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HELP RICK ! VREF Map info
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pdai11 Offline
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Post: #1
HELP RICK ! VREF Map info
Hi Rick, i am trying build the VREF Map adjuster from your Tuning For Mileage information but got stuck half way. The part that says ' Run a ground wire to one of the outside legs of the pot' presumed this is connected to a ground ? Other part ' Run the right leg to a Key-on/ Crank battery voltage' is this the leg from the Voltage Regulator or the leg from the POT ? I cannot understand what wire goes to the MAP sensor ? and lastly, after cutting the wire to the MAP sensor, connect one end and leave the other end (from ECU) taped up disconnected ?

Thanks
08-13-2009 02:52 PM
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colchiro Offline
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Post: #2
RE: HELP RICK ! VREF Map info
Hi pd.

First of it, it's my link, but not my document.Wink Tuning for Mileage was written by mpgmike (not our Mike), but our Mike did a little editing and added the pics.

I think what's confusing you is the written part and if you look at the schematic it's a little clearer.

[Image: map_sensor_handler.jpg]

The ground is on the trim pot above, which Mike shows one of the 20 turn pots like he uses on the narrow band efies. Yes it goes to a good ground.

The "right leg" is your 12 v supply as shown on the voltage regulator. It needs to connect to a wire that is hot only when the ignition is on.

The Map wires you cut will go to the SPDT switch.

I have a problem with this statement, it doesn't seem to work with the diagram: "DO NOT TAP THE VREF WIRE COMING OUT OF THE ECU! This will affect all sensors using the same 5 volt signal and will deliver disastrous results. After you cut the wire, connect your adjusted voltage wire to the MAP sensor and tuck and tape the other end of the cut wire back into the harness."

I can see not cutting the wire if it goes to other sensors, but not cutting it and tucking it away, if the diagram doesn't show that.

Maybe Mike can comment on this.

Rick

Links: Documents / Tuning for Mileage | Toyota Sensors | Autoshop Sensor Tutorials
08-13-2009 03:38 PM
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pdai11 Offline
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RE: HELP RICK ! VREF Map info
Dear Rick, it is much much clearer now, and this setup looks more realistic, setup looks very much like a Map Enhancer ?
Thank you once again.

Mike
08-14-2009 04:51 AM
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colchiro Offline
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RE: HELP RICK ! VREF Map info
Good. Please update this post with your results if there's a problem.

Rick

Links: Documents / Tuning for Mileage | Toyota Sensors | Autoshop Sensor Tutorials
08-14-2009 12:29 PM
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pdai11 Offline
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RE: HELP RICK ! VREF Map info
(08-14-2009 12:29 PM)colchiro Wrote:  Good. Please update this post with your results if there's a problem.


Got it all connected, checked over several times with the diagram. Connected to a battery and a voltmeter, adjusted POT both way, flick SPDT switch either way, no voltage movement ?
08-15-2009 03:33 AM
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pdai11 Offline
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RE: HELP RICK ! VREF Map info
(08-15-2009 03:33 AM)pdai11 Wrote:  
(08-14-2009 12:29 PM)colchiro Wrote:  Good. Please update this post with your results if there's a problem.


Got it all connected, checked over several times with the diagram. Connected to a battery and a voltmeter, adjusted POT both way, flick SPDT switch either way, no voltage movement ?


Sorry, i forgot to mention or state, does it have to be connected to the MAP sensor for any readings ?
How do i attach photos to this message ?
08-15-2009 05:07 AM
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colchiro Offline
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RE: HELP RICK ! VREF Map info
The switch just switches the map adjuster in/out of the circuit. In other words, turning it off restores the map sensor to normal. In my mind, it should also turn off the VR, but that's a minor problem.

You'd want to measure from the output wire to ground with your meter. You shouldn't need a sensor connected.

To attach pictures, just upload them to any free online service (sorry, not here), get the exact url to the pic and then add to them here using the "insert image" button.
If you're using the multi-turn pot, it probably has about 20 turns end to end. You'll hear it click when it reaches the ends. You might need to turn it a few turns to see the meter move.

BTW, what does your voltmeter read? It should be set to 20 VDC.

Rick

Links: Documents / Tuning for Mileage | Toyota Sensors | Autoshop Sensor Tutorials
(This post was last modified: 08-15-2009 05:27 AM by colchiro.)
08-15-2009 05:21 AM
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pdai11 Offline
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Post: #8
RE: HELP RICK ! VREF Map info
(08-15-2009 05:21 AM)colchiro Wrote:  The switch just switches the map adjuster in/out of the circuit. In other words, turning it off restores the map sensor to normal. In my mind, it should also turn off the VR, but that's a minor problem.

You'd want to measure from the output wire to ground with your meter. You shouldn't need a sensor connected.

To attach pictures, just upload them to any free online service (sorry, not here), get the exact url to the pic and then add to them here using the "insert image" button.
If you're using the multi-turn pot, it probably has about 20 turns end to end. You'll hear it click when it reaches the ends. You might need to turn it a few turns to see the meter move.

BTW, what does your voltmeter read? It should be set to 20 VDC.


I have a 3/4 turn 1k POT, would this be the problem which i should use a multi turn POT ?
I have found a Sensor on the firewall which looks like a MAP sensor, there's a vacuum hose connects to the inlet manifold, on the sensor it states ' sensor assy vacuum' there are 3 wires, 2 wires reads 0.2 volt, 1 wire fluctuates from 4.4 down to 0.4 and up and down
08-15-2009 05:47 AM
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colchiro Offline
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RE: HELP RICK ! VREF Map info
This is a link to pressure sensors (from my Autoshop link). It might help you figure out how your MAP sensor works and which wires you need: http://www.autoshop101.com/forms/h35.pdf

I would think you'd have a ground, +5v and an output. Assuming the 4.4 is your output, there should be a +5 input.

A pot is a pot, as long as you have a resistance that changes, that's all you need. You're using the center and an outside terminal, right?

What voltage do you read on each of the VR terminals (as measured to ground)?

Rick

Links: Documents / Tuning for Mileage | Toyota Sensors | Autoshop Sensor Tutorials
08-15-2009 06:05 AM
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pdai11 Offline
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RE: HELP RICK ! VREF Map info
(08-15-2009 06:05 AM)colchiro Wrote:  This is a link to pressure sensors (from my Autoshop link). It might help you figure out how your MAP sensor works and which wires you need: http://www.autoshop101.com/forms/h35.pdf

I would think you'd have a ground, +5v and an output. Assuming the 4.4 is your output, there should be a +5 input.

A pot is a pot, as long as you have a resistance that changes, that's all you need. You're using the center and an outside terminal, right?

What voltage do you read on each of the VR terminals (as measured to ground)?

I managed to source the +5 volt wire on the MAP sensor, had connected the enhancer on. No adjustment can be done through the POT, tested the voltage from the MAP wire which is showing 1.8 volt and idling is very low and no power when revving, turn the SPDT switch to other side and voltage is 0 and idling is normal, presume it's now switched off. I had checked all the connections against the diagram over and over again which is spot on. Could there be a fault on one of the components and has many members used this setup before ?
Thanks
08-16-2009 05:08 AM
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