Ford EEC-IV data logger

Bob T

Hi everyone,
Looking for some feedback on an idea I have.· First off, I'm a long time programmer, hands on auto mechanic, but newbie at electronics.
I would like to build a datalogger for the ECU in my mustang.· I want to be able to log a bunch of sensors (TPS,ECP MAP, 02, etc.) and track the ECU output (injector duty cycle, timing advance), for the purpose of tuning/diagnosing the fuel injection on this car. The sensors are all variable voltage based on vRef 5v.
The idea is the put the datalogger between the ECO and the wiring harness and operate passively collecting the data.··I'm thinking of packeting up the sensor data and xmitting them via serial (or bluetooth) to and external visual display (think dash)

I've looked at the basic stamp before for other stuff and I thought it could do the trick.· So my questions are:

Which processor would be best
What is best way to do the a/d conversions
Any projects documented that would be a good jumpstart
Or is it just crazy talk?

Thanks,
Bob

Larry~

1 not sure how fast you want to do this so processor is up in the air
2 if your taking info off the ECU you don't need A\D converters this is already done
3 there is a chip that interfaces with ECU, and you just need to interface to that chip ( forgot the name)
4 crazy maybe, maybe not

Jonathan

Search for "OLM OBII" and you will find some chips designed to talk to an ECU. I used one to talk to my Subaru, and it was easy to use and works well.

You can easily make a data logger out of it. On thing to bear in mind is the limited read/write capabilities of the EEPROM on a Stamp (or any other eeprom). The number of cycles varies, but is usually in the 10k to 100k range. Not a problem for most uses, but if it is going to be in continous service, you might want to consider other storage options.

Jonathan

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Jonathan

oops, make that "ELM OBII".

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Bob T

As fast as I can get it?· I'd be happy with round robin poll of data points (say 15 of them), packaged up and xmitted out 10 times per second.
There is a service port on the back of the ECU, maybe thats what you are refering to by saying these values could read out ot the ECU's memory.· I was thinking of sampling voltage levels on the ECM wiring harness.

Bob T

To Jonathan,
Thanks very much for your response. However, these chips are OBDII and EEC-IV is OBD-I, or am I missing something?

Bob T

Oops, the EEC_IV is basically ODB_nothing.

Jonathan

Bob,

I don't know Jack about OBDII or the other protocols or what vehicles use what. I just found out what my car uses and worked with that [noparse]:)[/noparse] There are several forums out there that you could ask vehicle specific questions on.

As far as sampling voltages go, that is easy enough. A car is a rugged enviroment in terms of electrical noise and vibrations and so on, but totally do-able, you just need to bear that in mind when designing.

I quite like the TLC2543 for ADC. It has 11 channels, +/- vref pins and can be used by any of the Stamp series. One thing is that it is limited to 5V input, so you will have to use voltage dividers to drop the voltage on any voltages above 5V. This is very important, as you can destroy the ADC otherwise. I just roasted one that way [noparse]:)[/noparse]

If you go this route, read the information Tracy has on the TLC2543 at: http://www.emesystems.com/OL2tlc2543.htm
Great page with lots of info about using this chip with a Stamp.

HTH,

Jonathan

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www.madlabs.info - Home of the Hydrogen Fuel Cell Robot

Bob T

Thanks Jonathan!