Okay - So all of the ECM issues... I haz them...

I'm trying to get teh engine into shape so that I can pass smog. There is another thread on that. (See: https://www.thirdgen.org/forums/tpi/...ow-vaccum.html) I thought I was close to done, but I wanted the check the ECM.

I purchased the cable from Red Devil River. (http://www.reddevilriver.com/aldl.html) I installed the drivers and hooked it up.

When the car is running, I don't get a full set of data. If I stop the car, I get the full set until the power drains. I made a video of it here:


To try to fix it, I reattached the ground from the engine to the body. I checked the grounds in the ECM bundle, and I also checked to make sure that there is continuity on the signal lines. I cleaned the contacts and put everything back together.

Another thing that I noticed is that the engine runs differently with the cable attached than without it.

I'm about to just order a new computer, but before I do, I would like to be confident that this is actually a computer problem, and that replacing the computer will allow me to read the sensors.

I've read all of the ALDL posts that I could find, but I didn't see anything about this particular issue. Thanks in advance for any suggestions.

 

IF anyone runs across this thread with the same problem. I did order a new computer, which came from the manufacturer faulty. I spent a while chasing down a bad computer code.

In the end, it turned out that the red devil river cable while assembled correctly doesn't read the car correctly once the engine is running. Go figure. I ran down to the local electronics store, soldered up a board with the two transistor solution, found a computer with an old school serial port and it works great. ( Well the board works great - computers with serial ports don't have the best batteries any more. )

 

If you ever need a TRUE serial port and only have USB holes, check out the Belkin F5U409 adapter. The unit contains an actual 16550 UART and can be configured for true, old-school serial protocols. I have them as an absolute MUST for connecting to older PLCs, HMIs, CNCs, and other industrial controls. I tried several other types which claimed to be actual serial ports and they failed. Allen-Bradley PLCs can be pretty damned picky about true serial handshaking, and this is the only thing I've ever found to work reliably.

Incidentally, they're are still available: qid=1506732872&sr=8-1&keywords=belkin+f5u409

 

That’s a great tip! I’m going to order one - it should solve a bunch of serial interface issues with other equipment too! Thanks!

 

You can find the vacuum leak easily with a spray can of starter fluid, carb cleaner, or apparently propane.

And I'm with you on these ECM's. Seems like its always something.

 

The correct serial to USB connection makes all of the difference. I can datalog while I drive and evaluate when I get back home.

I'm still looking for a vacuum leak ( tried both propane and carb cleaner ) might be time for a cigar smoking friend to help me out. I did find that the AIR valve was not working, so it was pumping fresh air into the top of the intake manifold, which would seem to confuse the o2 sensor...