TR air metering device and idleing problems

Problem #1:
While performing balancing procedures for the right (1-6 cyl) and left (7-12 cyl) to establish the proper idleing RPM, I have noticed that depressing the pan of the right air metering device (even all the way) did not stall the engine, while depressing the left one - did.
What kind of a "symptom" is this?

Do I have to change the whole air metering device or it's electrical part only?

Problem #2:
The vaccum in the right plenum is 3 times stronger than in the left. I can not identify where is the leak, so far. There is a tube comming out of the left plenum and going down to connect with a black round device protruding from the engine below the left distributor.
What is this lilne and device? It looks like that is why the left plenum is loosing vaccum.

Can somebody advise me how to resolve these 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

 

Thanks for the advice. I will check the vaccum system all over again.

Still, what might be the problem with the left hand side air metering device?

 

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?

 

Steve, the engine is F113A040, 5.0L, *23159* (see attached photos).

The forse required to depres each pan was not really different, but now I think that it felt that the one having this problem (the right one) was somewhat easier to depress... There was not resistance in the movement of the plate in or out...

...and the vaccum differences in plenums now drive me nutts...

I really need your expert advice.
Thanks.

Juri Gelovani
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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 )?

 

You are ablsolutely right (as usual): it appears that before I got the car (now in Houston, TX) bunch of "mechanics" in Florida had tweeked it so at least it does not stall while ideleing... The ideling crews were set very unevenly... but several month earlier, when cleaning those air intakes, I did the same test: depressing either the right plate (1-6 cyl) or the left plate (7-12 cyl) had a profound effect and each stalled the engine. At that time everything seemed to work at least, although the engine never ran well and I did not feel the real Ferrari acceleration and power, when compared to my budy's 1987 Testarossa...

That is why now I also had to set those small ideling screws quite unevenly (those that have a spring and a rotation-limiting plasgic sleeve and there is a long pin sticking over it, limiting the rotation). The left screw (7-12 cyl) I had to screw in almost the half-way, while the right side only a quater of the way. The left large brown screw had to be unscrewed about 4 turns, while the right big brown screw had to be kept completely screwed in to limit the ideleing at about 1200-1400. If I tried to lower the RMP with the big screws, it would result in rather significant shaking and rumbling of the motor. That is why I instinctively started to test the air metering devices by pushing down those plates one by one and found this weird symptom... Of course, when the throttle push rods are disconnected from their levers and I open only the right throttle - then the motor revs up and runs on the 1-6 cylinder bank, which tells me that at least there is enough fuel pressure to sustain higher RPM, or is it?

Initially, I thought that this may be due to a leak in the vaccum system and, therefore, measured the vaccum levels in both plenums at the same time (as described in the Ferrari manual) using two identical vaccum gages (high resolution gages, by the way).

Then, not having enough experience with the KE-Jetronic system, I decided to seek for explanations to these weird problems at this forum.

Of course, I will have to put new vaccum lines throughout the car, but now I am concerned more about the air/fuel metering system function on the right side...

To answer CARGUY's specific question - yes, pressing upon the left plate (7-12 cyl) does stall the engine, while depressing the right plate (1-6 cyl) does not.

Your further advice will be greately appreciated.

 

Thank you for explanations and suggestions - I will check for the holes and other sites for potential vaccum leaks.

As for your last question, pressind onto the LEFT plate (7-12 cyl) does stall the engine, while pressing on the rigt plate (1-6 cyl) does not.

 

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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Steven, thank you very much for suggestions, I will perform those tests you recommended and report on results, which I will get most likely over the weekend...
Juri Gelovani.

 

Steven, I had some time today before going to sleep to perform several tests you recommended:

1) Spark is present on both sides and all spark plugs (I had recently rewired the whole ignition system: new coils, new Transpo modules, new wires tested for resistance while screwing in those pins inside the distributor cap, new park plug extenders, new spark pugs + dielectric grease in each connection).

2) Measured vacuum in both plenums simultaneously while disconnecting all tubes and plugging the outlet of that larger tube going down to the brake system. The measurements now are: the Right Plenum (1-6 cyl) = 37 cm Hg; the Left Plenum (7-12 cyl) = 26 cm Hg.

3) Checked the relay/fuse box white linear connectors - all OK, including those that I had to preventively "upgrade" to a more reliable contact. Checked all fuses - OK. Just in case, installed a new pair of fuel pump relays (the Tyco brand).

4) Measured the voltage on the red wire contact of the Thermoswitch while engine running as you indicated in your instruction, which was higher = 14.23 V (!?). See the attached photo.

5) Removing the LEFT Fuel Pump fuse (number 5, when counting from the right side) resulted in a drop in RPM to about 700, whereas removing the RIGHT Fuel Pump Fuse (number 6, when counting from the right side) resulted in a complete stall of the engine !!!

Had not checked yet the overload relay (with a 10 Amps fuse) in the KE-Jetronic box behind the ECUs.

Looking forward to your additional instructions.
Juri Gelovani
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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.

 

Steven,

Thank you for evaluation of results of those tests you suggested. Your analysis is very reassuring. However, I still don’t understand why there was no response from the motor (no change in fuel delivery to the right bank (1-6 cyl) when depressing that air metering device plate ???

What is your opinion regarding the following:

1) Could it be a faulty Control Plunger in the center of the air/fuel metering device ? (part number 7 on the attached diagram). It is in the center of fuel distributor device shown in the attached picture upside down with that plunger sticking out from the center. Could it be a stuck plunger which does not react to the plate depression ?
or
2) Could it be a faulty electro-hydraulic fuel pressure regulator (Primary pressure regulator indicated as number 1 on that scheme)? Apparently, original settings of that fuel pressure regulator device may change over the years due to the loss of rigidity of energy-absorbing plate (membrane) inside the device... I had read about this for Merc/Benz KE-Jetronic system somewhere before...
or
3) Could it be a faulty fuel pressure regulator? (a picture is attached to make sure that we are talking about one and the same device).

Your insightful comments will be greatly appreciated.

Juri.
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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).

 

If I understand the "mixture adjustment screw hole" terminology correctly, then those holes in my car engine are shown in the attached pictures. Also attached - pictures of air bypass screws (if my terms are right...). I hope this answers your question, because I am not sure - looks to me that those holes are closed.
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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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To set throttle plate adjusters, so that the throttle plates are open about 0.003" - means unscrewing small adjuster screws with springs under those the big "Air Bypass" screws, right? (more like on the right side)?
Please confirm this.
Thanks.
JG

 

Well, I had cleaned both FDs by spraying inside the air metering device several times (almost 20) air mass sensor cleaner. After about 15-16 times, motor would not start... I panicked a little, but then thought that this maybe a good sign - something changed in fuel flow... I turned those air bypass small screws with springs all the way out and those large brown bypass air flow screws in. The motor would not start at all... Then, I started screwing in those small screws in 1 turn (360*) at a time on both sides. At about half-way, the engine started and ran at about 650 rpm. At that time already, depressing the right plate of the air-metering device STALLED the engine !!! Hurray!!! Both sides worked !!!

Then, I continued turning those small screws on both sides eaqually untill about 800 rpm (took about 2 full turns!?). At that time, I started tuning with large bypass scrrews and after 1-1/2 (right) and 2-1/4 turns on the left got the motor to run at 1150-1200 RPM without struggling and shaking to much. Depressing either plate stalls the engine!
I would probably never know what was the reason, but looks like it was some dirt or gunk in the FD system !!!

Attached are pics of those plates while engine running at about 1200 RPM (see that gap).
Next project will be to change all hoses and tubes to high grade temperature and pressure resistant kevlar reinforced silicone. I found a good suppler http://www.pegasusautoracing.com)

Thank you all for comments and suggestions !!!
Juri Gelovani.
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Hi Guys,

Here is a YouTube link for you to hear how my Testarossa motor runs after cleaning the air-metering and FD and making adjustments for idleing RPM:

http://www.youtube.com/watch?v=o5DAda1J7BI

Your opinions will be greately appreciated, as usual.
Juri Gelovani

 

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?