Upgrading a 280Z EFI to Spitronics Mercury 2 ECU

[grannyknot]

Chas, do you think it's maybe time to flush your clutch fluid or are you going for the original look?

[EuroDat]

Most probably due for a change. I changed it 5 years ago and the new fluid was a greenish colour. Should have replaced, or striped the master cylinder down and shrub the inside clean, when I did the slave and hose. So many things on my to do list atm.

[EuroDat]

Hi All.

I ordered the connector plug from vintage connectors. http://www.vintageconnections.com

It's the connector plug that connects the main harness to the efi harness under the dash.

Very efficient. Ordered the connectors on the 25th and they came in today the 31st. They shipped through USPS which also kept the costs down low.

I should have my exhaust fitting for the O2 sensor welded by tomorrow. All goes well I can try to start it up over the weekend.

[EuroDat]

A quick update.

I have been buzy, but not making a lot of progress.

The O2 sensor is fitted and I calibrated the air temperature, water temperature, map sensor and tps in the ecu.

The engine started and ran for about a minute and stopped. When I checked the components, I found the coil driver wasn't working. How did that happen?

It took me about 4 hours playing with the system and swapping components, but I found my problem is in the trigger coil in the distributor. It produces about 0.35 to 0.45Volts AC and the ecu needs between 0.5 and 1.0 volt AC.

Thinking about my options.

1. Find another model trigger coil that will fit in the distributor without too much modifications.

2. Go to a 60.2 crank wheel with wasted spark. I was planning to go with a bosch 3x2 coil pack 0 221 503 02 later, but I could fast track that project.

3. Use a HEI module to trigger the ECU. I might try this tomorrow and see if that cures my problem with the trigger.

Also need a new coil driver. Luckely they only cost €12. Hope to have the replacement by the end of the week.

[Chickenman]

What kills coil drivers is usually to much dwell. Check your dwell settings. Weak signal from VR sensor shouldn't affect driver life. It may cause sync loss but it shouldn't kill the coil driver in the ECU. 

[Zed Head]

Not sure but I think that he was saying that the coil driver wasn't "triggering" or being driven by the VR signal.  It's not damaged.

But not really clear why it worked once with the same low voltage pulses.

[EuroDat]

I think the coil driver gave up through my own doing. Its a combination relay and coil driver and I connected the relay section wrong for a brief second, but like all HEI modules etc, they don't like it. It still worked, but gave up after a minute or so running the car.

Because the Spitronics comes in module form, the Coil driver is an external unit and lucky for me can be replaced for €15.

I am planning on using one of my spare HEI module to amplify the trigger signal. That should clear all the error messages Im getting from the pickup. Just waiting for a new coil driver to turn up. It's now in Londen, and probably here early next week.

 

Project costs:

I kept a note of all the costs so far and its now at €771. Add another €26 for the combo coil driver including shipping and it will come out at €800. That is about $900.

Ill probably go over the €1000 before Im finisded. I still want to tape the harness once all the bugs are out, make a new mounting bracket for the ECU so the kick panel will fit correctly and then odd nickle and dime stuff that adds up along the way.

I could have saved a little by using the original AFM temerature sensor and leaving the AFM in place. Releasing the AFM spring tension on the flap so it will be always open. Spitronics comes with an App for your mobile. I don't think it's available for Apple yet, but it works well on android. 

 

ECU Project.pdf

[Captain Obvious]

In theory, the amplitude of the reluctor coil pickup should be proportional to the speed of rotation. The faster you change the field, the higher the pulse amplitude.

With that in mind... Was the missing issue only at idle? I would expect the pulse height to be plenty high once the RPM's are up.

Also, I assume you checked the pickup gap was within spec, but someone has to ask. 

 

[EuroDat]

Hi Captain,

I am having this discussion spitronics as well. The ecu generates an alarm if the voltage doesn't reach 0.5vac. It will start an run, but it keeps genarating an alarm every time you start or if it goes above 0.5 and goes back under. It's not absolutly necessary, because when I crank the engine the fuel pump runs and I can hear the injectors pulsing. Everything appears to be doing what it should do. Im just trying to get it solved while waiting for a new coil driver.

I fryed a HEI module when I modified my TIU. So it seems to be a habit of mine.

Spitronics also have a whatapp group. That is handy, because you just hit record and explain your problem, leave a message or a photo. I even managed to help someone with a wiring issue. Thats surprising since I am a beginner on these systems.

About the pickup coil. I have checked all three pick-ups (2 spare). The new LX-507 is measuring 724ohms at room temperature and the old original was 708ohm. Can't remember the value ot the third one, but I have not used it.

Both were adjusted to 0.3mm and were generating 0.35 to 0.40vac with the occasional 0.45vac peak. The new unit is in the car now.

[Captain Obvious]

I haven't measured it, but I'm surprised at how low your AC readings are for the VR output. Kinda makes me wonder if maybe you're dragging the voltage level down by asking the coil to drive something of lower impedance than it was designed to interface to.

In your drawing above, you mentioned "Hall pickup"... If the coil signal input of the system was designed to be driven by a Hall Effect sensor, then it's conceivable that it's expecting to be connected to an active driver instead of a passive pickup? Maybe they're driving a pulse transformer or the LED input of an optocoupler with the ignition input signal, and the VR pickup just doesn't have the ummph to provide the power at low RPMs?

If I were designing the ignition input section of a system like that, I would want to provide galvanic isolation of the signal pickup, but I would buffer it on the non-isolated side first and then run it through an isolating device like an optocoupler or transformer... AFTER I had amplified and buffered it.

Kinda hard to test (because the distributor has to be spinning), but I wonder what the pickup coil signal looks like when it's NOT connected to the Spitronic module. If it's a lot higher when running open circuit, then maybe the Spitronic input impedance is dragging it down.

[EuroDat]

I have not had a lot of time on the datsun lately. Summer holidays and paving the driveway and some other little projects keeping me occupied.

I did some more testing on the VR output. With the dissy out of the car running in a lathe at engine speed 1200rpm engine speed, it produced around 1 vac. At 350rpm, during cranking, the 0.45vac is just not enough for the mercury and that generates an error.

I wanted to eventually go to a wasted spart system, using a crank sensor in the backing plate and notches in the flywheel. Now with this error problem, I decided to fast track that idea and ordered the multy coil driver and coil packs. For the time being, Ill fit it to the front pulley.

It took a couple atempts to find the best position for the sensor and clear the belts and fan. It mounted nicly in between the alternator belt. Fitted the trigger wheel and set it to +/- 60 degrees btc. I can fine tune it in the software later. You can set it just about anywhere, but it the ECU goes in limp mode, it will go to 10 degrees btc. That doesn't work it you set it anywhere other than 60degrees btc.

A couple of while Im at it projects. The AC compressor seal needed replacing and I sent the radiator off for cleaning. hope that will be back by the end of the week. Cleaning and painting all the brackets.

 

[Zed Head]

That VR unit is the 77 unit right, with the single pickup coil and one tooth causing the voltage?  I wonder if that's why Nissan went to the six tooth setup with the ZX distributor, beside giving a more consistent trigger pulse.

Sounds like you've already moved on. but maybe a ZX distributor could get you going quicker, in the meantime.