TR air metering device and idleing problems

The amount of fuel delivered to the injectors is directly related to how far the air sensor plate is deflected downwards in the air diffuser housing. If there is more vacuum on the right side, then I would guess that at idle your engine is running almost entirely on the right cylinder bank. That round black device located at the rear end of the left side exhaust cam is the vacuum pump, and it's job is to generate vacuum, I can't imagine that would be the source of your vacuum leak. Check all vacuum hoses connected to the left intake plenum, front and back. Also look at the top of the air diffuser housing, just aft of the fuel distributor itself, to see that the adjuster access hole is plugged - it should be sealed. You might also verify the air bypass screws are set at a similar position for both the left and right banks.

Try to get more information...and come back here and post what you find.

 

Jeff - what if the shaft in that blasted vacuum pump is sheared off like so many do? Any effect?

CC

 

Was the force required to depress each pan about the same, or was the force required very different?

Also, what TR engine family do you have -- F113A, F113A040, F113B, something else?

 

The air meter plates "resistance" to downward motion is caused by fuel pressure in the fuel distributor head. If the plate pushes down easily, there is probably a fuel system problem, either electrical or a bad fuel pump or similar. Check the large white connectors at the fuse panel for burned connections for the fuel pump circuits.

When you depress the air meter plate, more fuel is pushed out to the injectors. So when you depress the left side meter plate, without opening up the throttle, and the engine stumbles, it's probably because you are causing the engine to run very rich for a moment.

As for a vacuum leak, there may - or may not - actually be one. With a vacuum gage hooked up, pinch off each vacuum hose and see if there is a change. Also, with the engine off...carefully screw in the air bypass screw on each side....while counting the number of turns...to see if they are similar....then return the screws to their original positions for now. Have you checked the top of the air diffuser housing, the area between the air meter plate and the fuel distributor head, for an open hole?

In your original post, you state that the vacuum in the RIGHT plenum is 3 times stronger than in the left plenum. You also state that pushing the LEFT side air meter plate stalls the engine - is this correct?

 

The large vacuum hose off the 7-12 plenum (eventually) going to the brake booster should be a "closed" system. As Jeff suggested, for a test, you could just remove this hose and block off the fitting on the plenum and see what happens (those hoses look a little old and brittle and might crack if you try pinching them closed ).

Your depressing the 1-6 airflow metering plate ("pan") at idle, and getting no change at all, is a very strong sign for Jeff's first suggestion that the 1-6 bank really isn't running at idle. It's possible that the vacuum on the 7-12 side is low because it is doing all the work (and was intentionally tweaked that way to get the ~1000 RPM) and the 1-6 side is just operating as a big vacuum pump. Another way to test this would be to remove the fuel pump fuses 1 at a time during warm idle -- if removing 1 causes no change and removing the other stalls the engine, that would confirm that one bank is not really running at idle. On a properly tweaked-up and idling TR engine, disabling either fuel pump would cause the idle RPM to drop from 1000 RPM to ~600 RPM (and it might stuble and stall), but the effect should be the same for each fuse when removed.

Can you please give more prior history? For example, was this car running well, with good power and both banks well-balanced, and something changed instantly to the condition you have now, or has it never run right in your possession and a bunch of other people previously tried tweaking it up without success (i.e., every adjustment screw could be in a random position )?

 

Well, the good news is that the way it is adjusted would explain having a very low vacuum level on the 7-12 bank:

This is clearly wrong -- the throttle plate adjustment screws should barely be opening the throttle plates from their rest positions (something like .003" opening at the plate edge). I can't recall the exact typical amounts, but, from completely backed out from making contact with the lever arm on the throttle shaft plate, these screws shouldn't be turned in hardly at all IIRC (like 1/2~1 turn?). Having the 7-12 screw way in drops the 7-12 vacuum.

This is also way, way out of bounds. Both of the large air bypass screws should only be opened something like 3/4~1.5 turns. 4 turns on the 7-12 bank is way too much (and also lowers the vacuum level on the 7-12 side), and no turns on the 1-6 side is not enough. When the engine is properly adjusted and warm idling at 1000 RPM with equal vacuum in both banks, the test is to fully close both large air bypass screw -- the RPM should drop to ~700 RPM and the vacuum levels (while maybe different than when running at 1000 RPM) should still be the same in both banks. The air bypass screws are then returned to their 1000 RPM positions (and the vacuum level in each bank should still be equal).

This gets a maybe. If the 1-6 side is dead, the engine RPM would still increase when you open the throttle plate on the 1-6 side because this reduces the overall drag (with the 1-6 throttle plate opened, the engine works less hard to draw air into the 1-6 side so the RPM increases).

Bottom line IMO is that you need to go back to the basics first:

1) Confirm that you are getting spark on both banks when the engine is now running (even if running poorly) -- if that's OK,

2) (With the key "off" and the engine not running) Remove each fuel pump relay and place a jumper wire between the female terminal 30 in the relay socket to the female terminal 87 in the relay socket as shown in this jpeg:
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When the jumper wire is in place you should hear the corresponding fuel pump run. If one doesn't run when the jumper is in place, unplug and check the white connectors at the bottom of the fuse-relay panel for any "burned" connections, as Jeff suggested earlier. If those look good, but the pump still doesn't run when the jumper is in place, then you have to check the pump itself. (and be warned that the relay labeled as "7-12" on the fuse-relay panel is physically mounted on the 7-12 side of the chassis, but actually feeds the 1-6 bank and vice-versa).

If spark is OK on both banks and both fuel pumps run with the jumper, but you can't achieve a good result with the adjustments in the ballparks described above (and with the mixture screws in the right places -- which is another huge variable ), then you've got to start doing things like actually measuring the fuel pressure, etc. -- but do the simple things first and report back.

 

Also, being a US version TR F113A040 (KE-Jet with Lambda), you need to confirm/deny if there is +12V power present from the protection relay to run the "E" part of the KE system (we've had many reported cases of people wrongly trying to tweak the adjustments when the real problem was electrical) -- here's how to check:
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Those results are almost all generally good news -- my comments:

1. Good

2. This is good in that it still corresponds to your reported adjustments -- with the throttle plate and air bypass screw on the 7-12 side both being much more "open" than those on the 1-6 side, the vacuum on the 7-12 side should be lower; however, if these values are markedly different than before (when everything was hooked up) then you must have a (big) air leak somewhere. If you reconnect the large hose going to the brake system and the vacuum in the 7-12 side goes down further, you must find the source of the leak in that system. Same for the smaller hoses (but they are so small that I'd be surprised if they could make a huge difference even if left completely open).

3. Good

4. This is Good -- "+12V" in those instructions really means "the output of the alternator" -- when the engine is running, +13~14V is the proper result; using the other method, with the engine not running, a good result is ~12V (the battery voltage). In this test, you are really looking for "something" (like +12~13~14V) or "nothing" (0V).

5. This is a good result in that: A) it indicates that the 1-6 side is at least doing something (as I indicated before the labeling refers to the physical mounting location of the fuel pumps, not their function -- the LEFT fuel pump fuse runs the fuel pump serving the 1-6 bank), and B) it shows that the 7-12 bank is doing more of the work, which corresponds to your vacuum measurements that things are presently unbalanced (a lower vacuum level indicates more air entering 7-12 bank; therefore, it is doing more work).

With regard to: "Had not checked yet the overload relay (with a 10 Amps fuse) in the KE-Jetronic box behind the ECUs." -- no need to do this, step #4 (measuring the voltage on the red wire) is checking the output from the protection/overload relay -- you're good.

If you can figure out what's going on in step 2, I'd say that there's nothing obvious preventing you from being able to tweak it up correctly/balanced.

 

The fuel pressure regulator could certainly be a problem, but I doubt the fuel distributor is at this point, you will have to use a fuel pressure gage, on the return line I think...???...to verify that. As Steve said earlier...it's time to return everything to the basic settings. That means set both throttle plates to "just barely open" and set both air bypass screws to the same positions, and go from there. I'm sorry to be a pain and ask this question again, but can you confirm the mixture adjustment screw holes are capped off? If one of these is open....it causes a massive vacuum leak and makes tuning impossible.

There have been (I think....?) 2 threads in the past, that pretty much describe the sequence of operations, for tuning up the TR fuel system.

 

My comments:

I agree that this seems strange (but you were in an incredibly unbalanced condition with the 1-6 side doing little work), and would not discourage you from getting the proper CIS pressure gauge to measure the regulated fuel pressure at the fuel distributor (I use the port on the FD where the cold start injector attaches). The "feel" test for how much force it takes to depress the pan is the easy/crude test to determine if you have some or none, but having the gauge is best. Let me warn you that the real bottom line overall test of a CIS system is to measure the actual flow volume of fuel exiting the injectors at different pan deflections -- which ain't easy

I don't believe so. If you look at the mechanical layout of the levers, if the pan moves down, the plunger must move up. If the pan moves well, the plunger can really only stick in the "up" position, and, if it did stick in the up position, you would feel very little force at the pan when you press it downwards (which is not what you report).

The electro-hydraulic actuator (EHA) provides only a very fine tweak on the system. Even if it is completely open or completely closed, the fuel volume delivered by the FD should still be strongly proportional to the pan deflection. As I mentioned before, if the +12V signal from the protection relay is missing (which leaves the EHA fully closed and slightly leans out the system by raising the lower chamber pressure), the engine will still almost run OK (which leads people to wrongly try making screw adjustments). In fact, if the EHA is dead and you add a little richness by turning the mixture screw, the engine will run fairly well (as a K-Jet) when warm, but all other modes suffer.

Yes, that is the pressure regulator. Making the supply pressure measurement at the FD will confirm/deny if this componets is working correctly (and the gauge is way cheaper than the pressure regulator).

 

The 2 upper pictures are the throttle plate adjusters, these should be set to just barely keep the throttle plates from totally closed...just barely....like Steve said earlier, the plates should have a distance from closed of about .003". The lower 2 pics are the mixture screw access holes....yes they are definately sealed up.

 

The large-headed brass screws are the "Air-Bypass" adjustment screws:
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Glad to hear that you've got it running better, and your adjustments are certainly much, much closer to where the should be -- but you're mistaken about any cleaning product introduced past the airflow pan as having an effect on the fuel distributor. The air (+ cleaner) that enters past the pan does not flow thru the fuel distributor.

Are you also saying that the vacuum levels in each bank are now equal at warm idle?