looking for TR mechanic

David Feinberg at Ferrari Service of Bedford www.fluentinferrari.com

 

What's your situation? You had a problem, someone turned every adjustment screw on it (before knowing what was really wrong), and it still runs badly?

 

Jim Magee. Pocono Sportscar. Top notch and he is aces.

R

 

And (if US version or late euro F113B) what about the protection relay operation (or lack of operation)? Or do you have an early euro F113A?

 

This is a US-spec car. I spoke with he owner briefly about it yesterday afternoon. From what I gathered, the 7-12 bank runs colder, car seems low on power...and that bank's plugs were wet. We did discuss (swapping of) the ignition amps. Evidently, this was done and the problem appears to remain the same, although the car is now harder to start, I believe. We did not discuss the protection relay.

 

Have you confirmed that you do have spark occurring in the spark plug wires on both banks when the engine is running (even if poorly)?

Was the previous "CO adjustment" done with a known working protection relay?

Does the engine run any better when warm with the single signal wire from the O2 sensors unplugged? (leave the 2-pin heater connections for the O2 sensors plugged in)

At warm idle, what does the voltage measure on the unplugged single signal wire from the O2 sensors relative to ground? (should be something between 0V DC and 1V DC)

 

Good -- one less thing to worry about

Unfortunately, this is a seemingly impossible value so I just can't believe it (especially on your 1-6 bank that seems to be working). With the car at warm idle, and the O2 sensor single signal wire unplugged, by turning the mixture adjustment screw back-and-forth by something like only 1/32 of a turn, this value should swing from ~0.1V (too lean) to 0.9V (too rich). Unless you can do this manually by turning the mixture adjustment screw, the system can't possible work well closed-loop.

See Fig 62 page D83 of the TR WSM for a graph of O2 sensor output vs AFR -- 1.4V does not exist!

This is a more condemning result (and if you have spark on the 7-12 bank, it must be no, or the wrong amount of, fuel). If you have fuel pressure on the 7-12 bank -- do you? The initial test is to just press down on the airflow metering plate after engine shutoff to see if they feel the same -- a more conclusive test is to have the fuel pumps running (with the engine not running) and do this same force test on the airflow metering plates (but don't do this much, or for long, as you don't want to squirt a bunch of liquid fuel into a non-running engine). About the only way the 7-12 bank can have no fuel delivered (if there is suffiicient fuel pressure and the system adjustment isn't totally wacky) is if the orifice from the lower chamber outlet inside the fuel distributor is blocked -- this causes the upper chamber pressure to never be able to exceed the lower chamber pressure, so (all) the differential pressure values inside the fuel distributor stay closed and no fuel goes to the injectors. One downside of having a very low mileage TR like yours is that it's had plenty of stationary time for fuel varnish deposits to form (which can then get dislodged and cause havoc). From here (unless you have something simple, like the fuel pump "buzzes" normally, but really isn't making pressure) you are really to the point where you (or the Mechanic) need to measure:

1) the regulated supply pressure, and

2) the lower chamber pressure -- this requires a special bit of plumbing to connect the lower chamber sampling port on the fuel distributor to the Bosch CIS pressure gauge (and this really can't be done unless you remove the upper intake plenum first). Let me know if you (or the Shop you go to for further diagnosis ) need it, and I'll be glad to sell, or lend, you this special bit of plumbing.

At 80 deg after 4 minutes = you have one bank not running...

 

sounds like fuel issue with the 7/12 bank. would be most likely.

I would start with a fuel pressure check of the failing bank.

Regards, Jim

 

Yes, that would confirm that (almost unfortunately) the regulated supply pressure is OK (I use the same port on the FD to make that measurement). The lower chamber pressure should be something like ~0.4 bar less than the regulated supply pressure when the fuel pumps are running and the EHA current is 0 mA (i.e., protection relay not closed) and maybe another 0.1 bar less when the EHA current is the default 10 mA (i.e., fuel pumps running and protection relay closed).

Another way to check the lower chamber operation is to measure the amount of fuel returned down the fuel return line from the FD lower chambers back to the fuel pressure regulator -- although this again requires some special hardware (a ball and a threaded cap) to block off the return port on the fuel pressure regulator (and removal of the upper intake plenum for reasonable access). I can't recall if the typical value is ~130 mL in 30 secs or ~130 mL in 60 secs (Larry Fletcher was kind enough to share this information with me when I was having trouble), but would dig it out if your Mechanic needs to get to this level.

Still have to say "impossible" here -- are you putting the "+" lead from the DC voltmeter on the single unplugged wire from the O2 sensor and the "-" lead from the DC voltmeter to the bare cylinder head? That's what I'd recommend.

 

If real, this would still be an unexplainable problem

It's not that simple. On KE-Jet, you need the regulated supply pressure (which might be ~5.6 bar) to be > upper chamber pressure (which might be ~5.3 bar and is unmeasurable) to be > lower chamber pressure (which might be ~5.1 bar) to have fuel delivery to the injectors occur (and all three of these pressures are much greater than the injector opening pressure of ~3.5 bar -- because the fuel injector has no role in determining how much fuel is delivered) -- hence, my prior recommendation to measure the lower chamber pressure vs the regulated supply pressure and/or confirm if a reasonable amount of fuel is exiting the lower chambers back to the tank (i.e., to the pressure regulator exit port).

I realize that this is getting a bit complicated so you might want to send the car to David or Jim.

 

Steve,
Mentioned it in another thread but wanted to thank you for all the help that you have given members, including myself, over the years.

Jim McGee - Great local Independent Ferrari Mechanic - Took my own TR to him

Robbie(Mr. Chairman) - Great guy, knows his stuff but is horrible at spelling lol
Reference: Jim Magee

 

No, I wouldn't think this would matter that much in how the engine runs. The tachometric relay's output function is to close the fuel pump relays and to close the protection relay. As long as the voltage leaving terminal 87 on the tachomteric relay is sufficient to close these other relays, that's all that's required.

 

When the starter motor is cranking, it's normal for the battery voltage to droop down to ~10V. Often when we say "12V", what we really mean is "whatever the normal + battery voltage is" -- which can vary from ~10V (when the starter motor is cranking) to ~14V (when the alternator is working). You can always just add a direct jumper wire from the + battery terminal to the backside of violet wire connector in the x connector to see if it makes any change.

I'd be back to the basics:

1. Do you have spark on both banks during starter motor cranking?

2. Are the fuel pumps running during starter motor cranking (i.e., is the tachometric relay working)?

3. Is the protection relay working during starter motor cranking (i.e., do you have "12V" on the red wire at the water thermoswitch)?