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> L-Jet: Over My Head, Bad ECU, car's back on the road.
Mike Sanford
post Sep 23 2013, 12:43 PM
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Found a diagram online. Checking now.
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Mike Sanford
post Sep 23 2013, 01:01 PM
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Good voltage across all the pins you listed. This is first time I've used the resistance function on the meter, looked like 5K ohms if I'm reading it right.
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timothy_nd28
post Sep 23 2013, 01:15 PM
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It should read 0 ohms.
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malcolm2
post Sep 23 2013, 01:21 PM
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QUOTE(Mike Sanford @ Sep 23 2013, 01:43 PM) *

Found a diagram online. Checking now.



bowlsby diagram

Was it this one? I found it to be perfect. Page 2 has the ECU connector.
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timothy_nd28
post Sep 23 2013, 01:24 PM
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When the meter is set to resistance, touch together the meter leads. What resistance is shown?

Whatever is shown on the meter, recheck pin 1 to the neg side of the ignition coil. The meter should show the same resistance.

Since you have the ECU connector off, measure pins 14 to 5,,15 to 5,,, 32 to 5 and 33 to 5. Do this with the ignition switch set to the ON position. What are these voltages?
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Mike Sanford
post Sep 23 2013, 01:59 PM
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I hadn't zeroed out the meter while checking resistance. After watching a couple of multimeter videos on youtube, zeroed the meter, and there is 0 resistance from 1 to the coil.

All of the pins you've suggested are reading 11.7-11.8.

I'm not that old, but the connected world still amazes me, I've got my Kindle Fire sitting on the engine and I'm reading instructions while testing things.
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timothy_nd28
post Sep 23 2013, 02:06 PM
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That last step verifies that the resistor pack is hooked up and is showing continuity. Pull each injector out, but leave the fuel hose connector as well as the electrical connector. Obtain a length of wire and turn the ignition key to the "ON" position. With this length of wire, tie one side to the negative side of the battery. The other side of this wire, touch pin 14 on the ECU connector. You should have a fuel injector spraying fuel like crazy. Do this for pins 14,15,32,and 33. Make sure the injectors click and you see a spray of fuel.

No smoking for this test procedure. (IMG:style_emoticons/default/blowup.gif)

After that test, check the resistance from pin 13 to pin 5
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Mike Sanford
post Sep 23 2013, 02:14 PM
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I'm grateful for all the help, but at this point I'm really going to have to go to work, and resume testing tomorrow morning. I'll get back on here then, and let you know what I find.

Thank you, thank you, thank you.
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timothy_nd28
post Sep 23 2013, 02:18 PM
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Very welcome. I have a exam in a hour, so this works out for me as well.
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Mike Sanford
post Oct 2 2013, 11:21 AM
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Didn't get to play with the car for over a week. Doing a whole-house remodel and it doesn't leave much time for the 914.

When I jumped the pins straight to the battery, the injectors squirted. Put the connector back on the ECU, cranked the engine, no squirt.

Does this mean the ECU is a goner?
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timothy_nd28
post Oct 2 2013, 12:00 PM
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It's going in that direction in a hurry. At the ECU plug, check the resistance between pin 13 and pin 5. This is your CHT sensor, I have heard rumors that a bad CHT sensor will keep a Ljet from starting.

The ECU receives power via pin 10 from the dual relay and the grounds pin 5,16,17. This has been confirmed in a previous test. Continuity of the fuel injector loop including the resistor pack has been confirmed with another test we did. The last thing the ECU needs is a trigger pulse on pin 1. We tested the continuity of this wire to the ignition coil, which checked good. The last thing we need to verify is the CHT and you are indeed getting spark.

If you are getting spark as you said earlier, you should be able to run the car (temporarily) off some starting fluid. If the car does run using starting fluid, then it makes me believe you have a faulty ECU.
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Mike Sanford
post Oct 2 2013, 12:34 PM
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No resistance between 13 and 5. Definite spark.
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timothy_nd28
post Oct 2 2013, 12:39 PM
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Find and disconnect the CHT connector. Ohm out at the connector and engine ground
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Mike Sanford
post Oct 2 2013, 12:46 PM
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Headed out to work, car bank on hold. Thanks,
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Mike Sanford
post Oct 3 2013, 01:33 PM
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Gal on Craigslist had two 1.8 ecu's for sale. Got her to bring them by, the car fired right up when they were plugged in.

If anyone else needs the other unit, PM me and I'll get you her number.

2nd time 914 world has talked me through getting the car back on the road. It would be hard to keep the car running without this forum.

Thanks,
Mike
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X911IC
post Oct 3 2013, 01:42 PM
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Timothy! You are awesome. I have bookmarked this thread for the future. I kow that i will be needing it at some point during my build. Thanks
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KELTY360
post Oct 3 2013, 02:43 PM
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QUOTE(Mike Sanford @ Oct 3 2013, 12:33 PM) *

Gal on Craigslist had two 1.8 ecu's for sale. Got her to bring them by, the car fired right up when they were plugged in.

If anyone else needs the other unit, PM me and I'll get you her number.

2nd time 914 world has talked me through getting the car back on the road. It would be hard to keep the car running without this forum.

Thanks,
Mike


Should have bought both of them and you'd have a backup or could sell to someone here who needed one.

Glad to hear your problem is resolved. Very impressive diagnosis exchange.
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timothy_nd28
post Oct 3 2013, 05:08 PM
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Glad to hear this, but we still have to address a few house keeping issues. The CHT sensor, did you ever recheck this? Either pin 13 to ground with your multimeter, or by disconnecting the CHT connector and checking the resistance there? I personally would like to know if a failed CHT sensor would keep a Ljet from firing up, just for my own knowledge.

Now going back to post #10. I had you check the voltage at the dual relay for pin 88y, and you reported back with 11volts (battery voltage). So far so good, but then I had you check pin 88d and you reported back with 8-9 volts. This part isn't so good, which shows a drop across the contact points inside the dual relay. See red circle in the attached picture

Attached Image

To put this to bed, lets do one more test. With the car off (ignition off) set your multimeter for DC and put the red meter lead on 88y and the black meter lead on pin 88d. You should see 12vdc or whatever the current battery voltage is. Now, go ahead and start the car. With the car running, you should see 0vdc on the meter. If your meter shows anything higher than 0.5vdc, it will be imperative that you replace the dual relay soon, as it could leave you stranded on some desert highway.

If you wouldn't mind, I would love to have your failed ECU. These things rarely fail, and I would like to take it apart to see what exactly went wrong. (IMG:style_emoticons/default/beerchug.gif)
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larryM
post Oct 3 2013, 09:13 PM
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http://www.hiperformancestore.com/Ljetronic.htm

http://www.international-auto.com/afla-rom...-of-sensors.cfm

http://www.ratwell.com/mirror/potts/

http://www.nichols.nu/tip540.htm
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stugray
post Oct 3 2013, 09:20 PM
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Nice work!

Any chance you can pay tumamilhem a visit with your multimeter?

http://www.914world.com/bbs2/index.php?showtopic=216237
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