Protection Relay Conversion and Fuel Distributor Starting Alignment

(Starting a thread from a PM because I need to post an attachment)

Steve:

I received the newer relay and moved the wiring around in the socket and the FV is now buzzing away as it is supposed to. Many thanks.

I am afraid I need to trouble you further. As I mentioned earlier, my car was heavily "compensated" by the previous owner/mechanic in terms of mixture and idle adjustment. I am having a rough time finding a starting point in terms of the mixture and idle setting to keep the car running so I can get a good reading and start tweaking the mixture/idle settings.

I am also not sure what is going on with my duty-cycle meter. IT seems to indicate between 12-14%. Not sure if it the inverse since I beleive the FV valve is negative slope.

Do you know how to set a good starting point to keep the car running and to begin the mixture tuning ?

Thx, again

Oleh

 

Oleh -- You should get a copy of the Mondial8/QV WSM 281/83 and read Chapter D. I can't recall where, but others have put this Mondial WSM up on websites as a .pdf file (if someone knows where Oleh can download this Mondial WSM file please post where).

This jpeg describes the "rough" starting alignement of the mixture screw given on page D29:
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Can't comment on your duty cycle measurement seeming strange.

 

Thanks Steve,

I gather from all the research I have done on the issue of trying to set mixture based on duty-cycle is the following:

"Don't bother monkeying around with the mixture screw until you get 50% duty cycle with the O2 Sensor disconnected ... because something else (thermal switch ,etc) is preventing you from achieving this critical baseline"

Is this a fair conclusion ? If I am not getting 50% duty cycle with the O2 sensor disconnected and the engine idling stably at ~1000 RPM, I must have another signaling/electrical issue at play ?

Thx

Oleh

 

Yes (but only if you trust your duty cycle measurement )

If the duty cycle does seem "wrong", check if the oil temp switch and the water temp switch are open (they both should be when warm).

 

Indeed, trusting the duty-cycle meter is a variable I need to solve. It seems stuck on 11-14 % when set for duty-cycle and 88 when switched to dwell on the 4 cyl scale so something is hokey.

I used the procedure you show above to initialy set the mixture, then I teaewd the idle for 1000. It seem sto be running OK, However, my duty cycle measurements seem odd. I will need to use another meter as a reference.

The water temp switch tested OK, not sure where the oil temp switch is yet.,

Thx,

Oleh

 

Another gem from Steve!

How do you measure the duty cycle? The black probe goes to ground, where does the red probe connect to?

I have digital dwell meter that I used to measure the dwell angle on my truck until I got rid of the point and converted to Petronix Ignitor, can't believe I can use it for my Ferrari.

 

To the AG (light blue/yellow) wire of the frequency valve (while it is plugged in and working).

Oleh -- You might try this too. If you are now measuring the "dwell" between the PN (beige/black) wire and the AG (light blue/yellow) wire of the FV, try measuring between the AG wire (the "+" lead of the dwell meter) and ground (the "-" lead of the dwell meter). Mathematically, they should give the same result, but perhaps your meter needs the reference ("-") signal to be ground (rather than the +12V of the PN wire) -- just a thought...

 

Thanks Steve, will try that.

I am wondering if I put the big black protection diode in backwards and that is preventing me from seeing the 50% baseline with the O2 sensor disconnected. Like a dope I did not note the orientation when I took it out to check it and the markings are in Italian with not clear cathode/anode annotation.

O

 

Didn't you use the simple test with a light bulb and the battery that Paul recommended here to determine cathode vs anode:

http://ferrarichat.com/forum/showpost.php?p=138962539&postcount=6

If it was in backwards, I think that the biggest flaw it would cause is to prevent the cold start injector from firing during cold cranking. You could just unplug it during warm idle to see if it makes any difference in the duty cycle measurement (but I'd be very surprised if it did).

 

After setting the mixture using the visual base method of removing a fuel line and rotating the screw CW until I got the hole to fill up, and then backing out 1/2 turn. I got he car to run and adjusted the idle to 1000. The car runs good and stable, and I took for a ride and wow what a difference wit the buzzer actually working.

Well, I am starting to have more confidence in the duty cycle measurement and it seems to hover around 85%.

However, after the test drive I wanted to disconnect the O2 sensor to see if I can get that elusive fixed 50% reading. When I pulled the O2 sensor, the car stumbled and died. It restarted but would not hold idle.

Any ideas on what the next step should be ?

Thx,

Oleh

 

Obviously, the mixture is not quite right because it should run OKish even with the O2 sensor unplugged (although it is a clear sign that the FV duty cycle is changing when you unplug the O2 sensor).

One thing you might try is unplugging the safety switch (this way the FV will keep running even if the engine stops running) and then measure the FV duty cycle when the engine is running with the O2 sensor plugged in, and then unplug the O2 sensor and see if the FV duty cycle changes (it should if the engine dies). If your measurement detects no change in the FV duty cycle when the engine dies, then I still wouldn't trust your FV duty cycle measurements.

Alternatively, you could try arbitrarily adding a little richness (1/32~1/16 of a turn CW on the mixture screw) and see if that keeps the engine running when the O2 sensor is unplugged.

 

Well, I found another analog duty cycle meter and unfortunatly it corraborates my duty cycle that seems to be fixed at 85% whether the O2 sensor is plugged in or not. The thermo switch that is on the expansion tank is operating OK so that cant be holding the FV at a fixed value. I could not test the one behind the oil filter but I did disconnect it to emulate a warm run and it still sticks at 85% with or without the O2 sensor. Running out of ideas.

Perhaps I am connecting the meters wrong. I am connecting the meter to the leads that go to the FV, leaving is connected and buzzing but sticking the sharp-tipped leads thorugh the back. Is this correct ?

Oleh

 

Has anyone used an oscilloscope for this measurement? Looking at a high voltage (above several millivolts is high) and slow times (less than 1millisecond is slow) is easy and cheap scopes are out there.

 

Try as described in post #7.

 

Steve,

Yes, I did try various combinations of connections as suggested. I only got a signal when both leads are connected to the 2 leads leading to the FV.

I am going to look at the diode again, I know its a long shot but that is one variable that I was never sure of when I re-inserted it. Will also check all connections etc under there since there tends to be allot of moisture down there. Would any of the other 2 relays cause this kind of issue. THey looked kind of oxidized on their casings from the moisture.

I won an analog duty cycle meter on Ebay and am awaiting its delivery so as to have a third reference.

Thx for all the help

O

 

I can't accept this answer yet Just as you get ~6 VAC when measuring between the two wires on the FV when it is running, if you measure the AC voltage between the AG (light blue/yellow) wire of the FV and ground you should also get ~6 VAC when the FV is running (and a finite dwell value when using a dwell meter). Can you please measure the AC voltage between the AG wire and ground when the FV is running to confirm that that does measure ~6 VAC?

Unlikely IMO, as those two relays are used to control the air injection system and the cold start injector functions, but maybe you should ensure that your air injection system is really "off" as, if it isn't, (during warm-running) the O2 sensor will "tell" the injection ECU to (wrongly) add more fuel by increasing the FV duty cycle. Not sure the easiset way to do this on your model, but (see page 73 in your 307/84 OM) what you want to do is physically block the air line that runs from the airbox to the cut-off valve "A" and onto the check valves "B" -- i.e., you want to ensure that no air is allowed to enter the check valves (which is what the cut-off valve should be doing when it is "off").

 

Steve:

I will check the AC voltage this afternoon.

I will also pinch off the fabric covered air hose that runs from under the airbox to the valves you mentioned during warm run. Incidentally, I had to replace one of the check valves last year as it rusted to pieces.

Oleh

 

OK, I checked the AC voltage betwen the AG (blue/yellow) wire of the FV and ground and got a steady reading of 5.19 VAC.

I also used my dwell meter and connected it also between the AG wire and ground and it gave me a reading of about 20 on the DWELL scale.

I had a new thermo time switch laying around so I went ahead and changed that as well, but no changes.

Thx,

Oleh

 

I like that AC voltage measurement result much better than "not geting any signal", but am still doubtful of your corresponding dwell measurements. The US 328 technical documents (which also uses a K-Jet with Lambda system) gives the following relationship between dwell and AC voltage when measuring between the two terminals of the FV:

6.4 VAC = 50 % duty cycle

7.4 VAC = 60% duty cycle

7.6 VAC = 65% duty cycle

Mathematically, this makes sense for a rectangular wave switching between 0V and 12V, so I have to conclude either:

1. the waveform is flawed, and is not a rectangular wave shape (I guess you'd need an oscilloscope to confirm/deny), or

2. something is still wrong with your dwell meter device(s)/method -- are you sure that your dwell meter is reading directly in duty cycle? If you are on an 8 cyl scale (i.e., the device thinks you have an octagonal cam lobe shape), and the dwell meter is reading 22.5 degrees that would be roughly a 50% duty cycle.

Feel free to give a shout if you need something else, but I don't have any better idea right now.

 

Thanks Steve:

I am awaiting delivery of another meter which should be in today. ITs a Snap-On MT917 which is an analog DWELL and Duty cycle meter, Perhaps I can get to the bottom of this. To summarize: if I am using a DWELL meter, I should connect it between the AG wire of the FV and ground, NOT the other lead of the FV ? Also, I should have the DWELL meter on the 4 cyl scale. Is this correct ?

Oleh

 

Dwell meters designed to work specifically on a points based ignition system should be hooked up with with the "+" lead of the dwell meter on the AG wire and the "-" lead of the dwell meter on ground to be used in the exact same manner. Doesn't mean that you couldn't get a meaningful measurement using the two terminals on the the FV, but this might give the complemetary (open) reading rather than the closed reading (i.e., "dwell" is defined as the degrees of cam lobe rotation during which the points are closed).

It doesn't matter what cylinder scale you use if you are measuring dwell as long as you know how to translate from degrees to duty cycle -- i.e.,

on the 4 cyl scale: 45 degress = 50% duty cycle

on the 6 cyl scale: 30 deg = 50% duty cycle

on the 8 cyl scale: 22.5 deg = 50% duty cycle

Hopefully, you new meter will have a direct "duty cycle" output so you can avoid this confusing translation

 

hey Steve,

I was trying to locate the O2 sensor today and the only wires to the cat I saw were to the thermocouple. THere was a bung plugged up with what looks to be a 19mm bolt. (see pic). Someone must of removed it and clipped the wires because the green signal wire and 12v heater wire ends are where they should be which is under the air filter box. I wonder if the previous owner/mechanic shorted the wires. Could that be why the car will not run with the signal wire disconnected.

The symptoms I am having are similar to this guys'

http://www.ferrarichat.com/forum/showthread.php?t=123042&highlight=O2+sensor+location

Where I have a near 90% duty cycle no matter what.


I need to verify if that was indeed where the O2 sensor was or is that just a test port and the O2 sensor is somewhere else.

Oleh
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Well Steve, it official, the O2 sensor is missing !!!! What the green lead and the 12v heater leads are connected to is the next mystery. Maybe they are just cut them off and stuffed up into the chassis. I still dont understand why the car dies when I disconnect the green lead since there is no O2 sensor. I have a new and correct O2 sensor for the car which I will attempt to install tonight. I just hope all this did not fry the ECU.

Oleh

 

I have been misinformed. the plug is for a test port. The O2 sensor is installed and wired correctly. I have no choice but to assume the ECU is bad. I have verified the following:

1. The duty cycle is indeed fixed at 90%. I used 3 different meters including a Snap-On MT917A, all corraborate a fixed 90% duty cycle whether the O2 sensor is connected or not.

2. The engine stalls when I disconnect the O2 sensor. I got the reading with the O2 sensor disconnected by peddling the throttle to keep the motor going enough to get a measurement.

Unless anyone has any other ideas, i think i am going to hunt for an ECU

Thanks for all the help,

Oleh

 

Aaack! I hate it when we start to get near here

I still don't like that the engine behavior changes (it stalls) when you unplug the O2 sensor, but you don't detect any change at all in the duty cycle at the FV. AFAIK, the only way the injection ECU can change how the engine runs is by changing the duty cycle of the FV.

Have you tried measuring the voltage on the O2 sensor single wire when plugged in and the engine at warm idle? If the voltage on this wire is wandering between 0.1V DC (lean) and 0.9V DC (rich), that would show that the FV duty cycle must be changing.

Have you tried just adding some richness by tweaking the mixture screw to see if you can get it to stay running at warm idle with the O2 sensor unplugged?

Also, how is your cold-running immediately after cold start-up? -- does that idle OK?

I would suggest that you confirm/deny the health of the oil temperature switch before pursuing a different injection ECU. See fig 68 on page 77 of your 307/84 OM. This oil thermoswitch should be closed when cold (below 15 deg C) and open when warm (above 25 deg C). You can just manually unplug it to simulate an "open"/warm condition if it seem wrongly closed when warm.