1G Electronic Boost Data Logging

[cbatters]

New thread regarding MMCd enhancements.

MMCd New Features

[BLACK94TT]

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[LeMoN1438]

Can you make this a little bit more clear for me? You can hotwire something to go into the unused port to input values into the ecu, or does it take values from the ecu and output it?

[cbatters]

Originally Posted by LeMoN1438

Can you make this a little bit more clear for me? You can hotwire something to go into the unused port to input values into the ecu, or does it take values from the ecu and output it?

Please re-read the first post ..... description is pretty simple / clear (provided you are already familiar with data logging. Otherwise you may want to do some searches/reading on datalogging.

Installation is on par with an A/F gage. You need to identify a couple of wires but there are only 3 connections.

MAP pressure is great for troubleshooting / alarming.





Clint

[BLACK94TT]

Clint,

I just realized that my electronic Autometer boost gauge utilizes the GM map sensor. Can I tap its signal wire and take it to A22-green/black? And do the same with its ground, going to A22-black?

Not knowing enough about electronics, will tapping the already in use sensor degrade the signal causing erroneous readings at both the gauge and logger?

Looks like I'm over here now.

[cbatters]

Originally Posted by BLACK94TT

Clint,

I just realized that my electronic Autometer boost gauge utilizes the GM map sensor. Can I tap its signal wire and take it to A22-green/black? And do the same with its ground, going to A22-black?

Not knowing enough about electronics, will tapping the already in use sensor degrade the signal causing erroneous readings at both the gauge and logger?

Looks like I'm over here now.

Short answer - Only connect the signal line, not the ground line. More details below.

SIGNAL LINE
Output impedance of the GM map sensor is quite low and the input impedance on the ECU is relatively high so it should not load the MAP output. (Autometer gage input should also be a relatively high input impedance.)

GROUND LINE
This one is a bit more complicated. Depends on what "Ground" you used for your autometer install. If you used "Signal Ground" of the ECU you are all set and there is no need to connect the ground lines.

And if you used a different "Gound", you still don't want to connect the ground wire because this can form a "ground loop" where current is flowing in the ground lines.

Quick DC measurement between Ground of the MAP sensor and Sensor Ground of the ECU A22-black will tell you how much error you would have. (ECU input has 8 bits of resolution so a .020 volt error will produce a 1 bit or ~.2 PSI error.)

SIMPLER EXPLANATION (No DVM required)
Start car and observe Autometer pressure at idle. Connect signal wire of MAP sensor to EGRT input.

1. Note whether there was any change in Autometer gage reading

2. Compare pressure of Automater gage and the display on the logger. If they are within +/- .2 PSI you are good to go.


NOTE - I will add a note at the beginning of this post to highlight the fact that if you already have an AutoMater Boost Gage, you can have boost logging for the cost of about 36" of 18 gage wire and a couple crimp on connectors! PICS of your AutoMeter install would be appreciated.

[skunkworks]

I have been meaning to post this here. This is my install using the digikey 2.5 bar sensor.
http://rocky.digikey.com/WebLib/Moto...A%20SERIES.pdf
It has been working great. It is a temperary perminant install

[cbatters]

Originally Posted by samco

I have been meaning to post this here. This is my install using the digikey 2.5 bar sensor.
http://rocky.digikey.com/WebLib/Moto...A%20SERIES.pdf
It has been working great. It is a temperary perminant install

LOL - "TPI" - Temporary Permanent Install

I'll have to post my "TPI". Given the low mass of the sensor, I didn't bother with the tie-wrap - the sensor is just suspended from the vacuum line.

One note about the Motorolla sensor - probably a good idea to provide some protection against water/oil infiltration. I wash my engine on a pretty regular basis and have not had any problems with the Motorolla sensor with just some electrical tape wrapped around it for protection.


Clint

[BLACK94TT]

I don't remember exactly where I grounded the Autometer gauge. I guess it doesn't matter anyway, since you say the only connection I'm concerned with is the signal to A-22. I have no idea why A-22 doesn't even need a ground.

I'm going to check this out tonight. To be able to log boost will be a huge help when tuning. I'd like to go out there right now and try this.

I'll post back with results.

[cbatters]

Originally Posted by BLACK94TT

I don't remember exactly where I grounded the Autometer gauge. I guess it doesn't matter anyway, since you say the only connection I'm concerned with is the signal to A-22. I have no idea why A-22 doesn't even need a ground.

I'm going to check this out tonight. To be able to log boost will be a huge help when tuning. I'd like to go out there right now and try this.

I'll post back with results.

The ground lead of A22 is ECU Signal Ground. You don't want to tie Chassis ground to Signal ground at the MAP sensor because it would create a ground loop. (Chassis ground and Signal ground should only be tied at one point which in this case is at the ECU.)

Low power instrumentation like A/F and Boost meters should be connected to signal ground. Incorrect ground reference of an A/F meter for example, could cause your A/F to change everytime you step on the brakes or turn on your blinkers.



Clint