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Posted by: Mike Sanford Sep 23 2013, 10:03 AM

I'm a little above my skill set playing with this stuff.

Took the wife out yardsale-ing Saturday morning. This is Tucson, maybe 85 degrees at 8am. Drove two blocks from home, stopped at one. Drove another 5 blocks, car acted as if it ran out of gas. Gas tank is full. Key on, pulled fuel line off of rail and opened air flow meter, squirts fuel. Pulled injector out of a cylinder, moved air flow meter, no fuel.

Shoved my analog voltmeter into injector plug, no sign of a signal at the injector.

Played on the internet looking up l-jet trouble shooting, decided to start with checking the relay because it seemed less intimidating. From what I'm seeing there should be voltage between 88a, 88b, 88c, and 88z and 85 (the ground). I have voltage everywhere except 88c. Come back inside, back on the internet, 88c looks like it powers the auxilary air valve. Would this cause the whole system to shut down? Is there something else I should be checking?

Thanks,
Mike

Posted by: timothy_nd28 Sep 23 2013, 10:14 AM

Everything sounds right. You will not have voltage at pin 88c unless the key is turned to the "start" position or the engine is running. 88c is tied to 88d which supplies power to the fuel pump. Also, the air flow meter does not send a signal to fire the fuel injectors.

Is the car still in its failed no start mode?

Posted by: Mike Sanford Sep 23 2013, 10:19 AM

[quote name='timothy_nd28' date='Sep 23 2013, 09:14 AM' post='1930574'

Is the car still in its failed no start mode?
[/quote]

It's still dead.

Posted by: timothy_nd28 Sep 23 2013, 10:22 AM

Good, it's easier to troubleshoot it this way. With your multimeter, probe pin 88d on the dual relay with one meter lead. Put the other meter lead on the negative battery post. Have some one attempt to start the car, while you are watching the meter.

Posted by: Mike Sanford Sep 23 2013, 10:33 AM

Home alone, but was able to watch meter through the window. About 9 volts.

Posted by: timothy_nd28 Sep 23 2013, 10:37 AM

Seems abit low. Check the voltage at the battery. Next, go ahead and put one meter lead on pin 86a and the other meter lead to the negative battery post. You will need to attempt to start the car while watching the meter again. What voltage do you have here?

Posted by: Mike Sanford Sep 23 2013, 10:46 AM

Battery is at 11v, but there have been multiple attempts to start the car in the last few days. 86a is at 8v.

88c does power up when the starter engages.

Posted by: timothy_nd28 Sep 23 2013, 10:49 AM

Okay, now check pin 88y. You won't need to start the car for this test

Posted by: Mike Sanford Sep 23 2013, 10:56 AM

11v.

Posted by: timothy_nd28 Sep 23 2013, 11:03 AM

How accurate are these readings? Are you still using the analog meter or is it digital?
Pin 88y is battery voltage on the dual relay. The test confirms that you do have the same voltage on that pin as you do on the battery. So far so good, but I don't like the voltage on pin 88d (9v). This shows you had a 2volt drop across the contact points inside the dual relay. If this is true, it's time for a new dual relay.

Posted by: Mike Sanford Sep 23 2013, 11:30 AM

This is a cheap analog meter. 11v is kind of a guess, I'm using the 10v scale and its a about that distance past the 10, not yet maxing out. Just checked 88d again, and (this time) 8v is exactly what its pointing to.

I'll try to find my digital meter and double check my numbers.

Real time cross country electrical trouble shooting, more help than I expected this morning, I'm grateful for your time.

Posted by: timothy_nd28 Sep 23 2013, 11:51 AM

Not a problem. Anyways you have 11v going in and 8v going out, still shows a drop inside the relay and will need to be replaced. Time being, run a jumper wire from 88d to the positive battery post. Does the car run with this configuration?

Posted by: Mike Sanford Sep 23 2013, 12:06 PM

Checked things out with the digital meter. 11.8 at battery. 11.8 at 88y. Numbers jumping between 7 and 9 at 88d.

Jumper kicks the fuel pump on, but I'm pretty sure that wasn't the problem. I'd checked it earlier this morning by pulling a line off the rail, and it was squirting fuel both with the key on and the AFM opened, and when cranking the starter.

Posted by: Mike Sanford Sep 23 2013, 12:10 PM

Just to clarify, it wouldn't start with the jumper in place.

Posted by: rhodyguy Sep 23 2013, 12:14 PM

great, straight forward advice!! nice work!

Posted by: timothy_nd28 Sep 23 2013, 12:14 PM

I identified a problem, but it maynot be the problem. With the jumper on and the fuel pump running 24-7 does the car run, or are we still in a no run mode? Also, do you have mechanical points or a pointless module?

Posted by: Mike Sanford Sep 23 2013, 12:19 PM

With the jumper in place, we're still in a no run mode. Petronix instead of points.

Posted by: timothy_nd28 Sep 23 2013, 12:24 PM

K, verify you still have spark. Next pull off the ECU connector. With the key set to the "on" position, check pin 10 with the positive meter lead and put the negative meter lead on pin 5. What is the voltage? Do the test again, but now measure pin 10 to pin 16. Finally, check pin 10 to pin 17

If you have a strong 12 volts on all the above, set your meter to measure resistance. Measure the resistance between pin 1 on the ECU plug to the negative side of the ignition coil

Posted by: malcolm2 Sep 23 2013, 12:24 PM

Tim is so good, he changed his avatar in mid post!

Posted by: Mike Sanford Sep 23 2013, 12:40 PM

This is the part that intimidated me, and why I started with the relay.

Have spark.

Pulled connector off or ECU.

How are the pins numbered?

Posted by: Mike Sanford Sep 23 2013, 12:43 PM

Found a diagram online. Checking now.

Posted by: Mike Sanford Sep 23 2013, 01:01 PM

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.

Posted by: timothy_nd28 Sep 23 2013, 01:15 PM

It should read 0 ohms.

Posted by: malcolm2 Sep 23 2013, 01:21 PM

http://bowlsby.net/914/WiringHarnesses/HarnDia_FI_EC75-1.8.pdf

Was it this one? I found it to be perfect. Page 2 has the ECU connector.

Posted by: timothy_nd28 Sep 23 2013, 01:24 PM

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?

Posted by: Mike Sanford Sep 23 2013, 01:59 PM

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.

Posted by: timothy_nd28 Sep 23 2013, 02:06 PM

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.

After that test, check the resistance from pin 13 to pin 5

Posted by: Mike Sanford Sep 23 2013, 02:14 PM

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.

Posted by: timothy_nd28 Sep 23 2013, 02:18 PM

Very welcome. I have a exam in a hour, so this works out for me as well.

Posted by: Mike Sanford Oct 2 2013, 11:21 AM

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?

Posted by: timothy_nd28 Oct 2 2013, 12:00 PM

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.

Posted by: Mike Sanford Oct 2 2013, 12:34 PM

No resistance between 13 and 5. Definite spark.

Posted by: timothy_nd28 Oct 2 2013, 12:39 PM

Find and disconnect the CHT connector. Ohm out at the connector and engine ground

Posted by: Mike Sanford Oct 2 2013, 12:46 PM

Headed out to work, car bank on hold. Thanks,

Posted by: Mike Sanford Oct 3 2013, 01:33 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

Posted by: X911IC Oct 3 2013, 01:42 PM

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

Posted by: KELTY360 Oct 3 2013, 02:43 PM

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.

Posted by: timothy_nd28 Oct 3 2013, 05:08 PM

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



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.

Posted by: larryM Oct 3 2013, 09:13 PM

http://www.hiperformancestore.com/Ljetronic.htm

http://www.international-auto.com/afla-romeo-fuel-and-emissions-system/alfa-romeo-bosch-l-jetronic-making-sense-of-sensors.cfm

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

http://www.nichols.nu/tip540.htm

Posted by: stugray Oct 3 2013, 09:20 PM

Nice work!

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

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

Posted by: Mike Sanford Oct 3 2013, 10:46 PM

When I found the units on Craigslist, I thought I could skip the CHT test and just plug another computer in, if it worked it was a computer problem. Guess that was oversimplifying things? Probably won't have time to run the rest of the tests until Sunday, but will let you know what I find out.

PM me about the ECU.