Boost signal on ECU-EGR input for logging

[cbatters]

7/15/04 Update

Summary of Boost Logging at the following link...

1G Electronic Boost Data Logging

and more info on MMCd developments at this link

MMCd New Features


Start of original thread
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Has anyone hooked up an electronic pressure tranducer (0-5V) to the ECU-EGR temperature input for datalogging?

I saw a reference to this on Jeff's site (related to TMO) but have not seen anyone taking about it. (nor have I ever seen any logs posted with boost pressures)

Seems like a slick way to get boost pressure into the cockpit and use the logger to display boost (and use alarms to constantly monitor boost.)




Clint

[cbatters]

Gotta keep my own thread going....

Current plan is to order one of these Motorolla MPX4250 sensors (2.5 bar) and mount it in a small box under the dash. I will either mount a small +5V regulator in the same box or steal +5V sensor excitation from the ECU. (I am guessing the ECU's A/D converter is ratiometrically tied to this voltage which is used for sensors like TPS.)

http://rocky.digikey.com/WebLib/Moto...A%20SERIES.pdf

Should work.... (famous last words before the puff of smoke!)

The other choice is to find a tougher MAP sensor and mount it under the hood and tie it into the existing EGR temperature wiring... would be slick if you could simply mount a MAP sensor near the exising boost solenoid but I am still trying to find the the A22 EGR temp sensor connector on my car.



Clint

[Jeff Lucius]

I think the GM MAP sensor uses the Motorola sensor. Check out the web page below. What they show is the GM MAP sensor (I have one, but not bought from them). Might save you some time.

http://www.aquamist.co.uk/sl/plist/p...6/806-666.html

[cbatters]

Originally Posted by Jeff Lucius

I think the GM MAP sensor uses the Motorola sensor. Check out the web page below. What they show is the GM MAP sensor (I have one, but not bought from them). Might save you some time.

http://www.aquamist.co.uk/sl/plist/p...6/806-666.html

Thanks... output drive specs on the GM sensor are more robust than the MPX4250 - I still have to measure the input impedance characteristics of the ECU-EGR to determine an appropriate interface.

Found the A-22 connector (near the injector resistor module taped up with some alarm wiring) According to the schematic, the A-22 connector should have sensor excitation and the signal return path for the EGR sensor to the ECU.

This is quickly heading towards a simple mod to get boost pressure into the logger for display / alarming without running any new wires/hoses.


Clint

[J-Ville VR-4]

Please keep us updated, this is interesting!

[Jeff Lucius]

The GM 3-bar MAP sensor is available from MSD Ignition. Search google for MSD2313 or MSD-2313. The store below sells it for $49.70

http://www.tognottisautoworld.com/se...UCT_ID=MSD2313

You'll also need a socket/harness connector. Conduct Tite (PN 85146) sells some that are a close match or that may need only a little bit of knife work to make the correct notch for the key on the sensor connector. See middle pic and red rectangle in the web page below for where notch needs to be added.

http://www.hondata.com/3barinstall.html

[FaceGarden]

Originally Posted by Jeff Lucius

The GM 3-bar MAP sensor is available from MSD Ignition. Search google for MSD2313 or MSD-2313. The store below sells it for $49.70

http://www.tognottisautoworld.com/se...UCT_ID=MSD2313

Digikey sells them for $18.19. Never buy components from anyone but the component dealers. I bet that website buys them from digikey too. here's the link: http://www.digikey.com/scripts/DkSea...0AP-ND&Site=US

EDIT: I just realized that that is only the pressure transducer, not the whole MAP unit, but all you need is the tranducer anyway.

Also note that I am working on building my own electronic boost gontroller/guage. It will have a nice display and i could sell them for $130-150. I need to develop it first, but I am going to buy my parts soon. If people would be interested in buying them, I can hurry up. Just figured I'd mention this. Thanks for the thread though, now I know what transducer to use!
-Taylor Alexander

[cbatters]

Update:

Input impedance of the ECU is ~10K ohms pulled to +4.5VDC

The MPX4250 has fairly limited .1 mA output Source capability (which is not a problem because of the ECU pullup) but there is no Sink specification. (Need to be at least .5 mA) Might work OK but you could not be sure from the datasheet.

Probably time for a quick test.



Clint

[cbatters]

Ordered parts.. will report back in a week or so with results. If it comes together as planned, this could be one of the easiest (and cheapest) boost monitoring mods for anyone with a 1st gen that is already using a data logger.

(Biggest open issue is whether there is an appropriate source of +5V under the hood where I steal 10 mA of current. If not, I will have to add a small voltage regulator and tie into +12V. TPS looks promising but it depends on the impedance / circuitry used by the ECU to protect the +5V line.)

Note: I have already pinged SHiVeR-91VR4 and Dm1try (MCCd) to find out what it will take to get their SW to scale the EGR input in boost (PSI/ATM) instead of temperature.

Pocketlogger - Would also like to find out if pocketlogger allows custom scaling for the EGR input (or user defined registers/scaling.)



Clint

[cbatters]

Lunch update:

1. TPS +5V is rock solid measuring 4.989V - adding a 10 mA load did not produce any attenuation. (The ECU is apparently not using impedance protection and either has active circuitry or NO protection on the +5V signal. I need to do a little more testing to make sure this is not close to any current limit foldbacks.)

2. Measured input impedance on ERG-ECU line matches calculate impedance of 10K

3. 0 to +5V input on the EGR temperature input produces 0-255 courts on the logger!!

4. No CEL produced by having very high and very low "EGR temperatures"

If they had a 3Bar sensor at autozone, I would have driven back with the boost gage gerry rigged under the hood!!

Technical risks have been reduced to near zero. Only a few details regarding mounting and the best place to tap into the +5V TPS line remain.



Clint