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Discussion Starter · #1 ·
While taking apart my FI syste

While taking apart my FI system on the TR, I went TOO far!!!!!!!! I removed the plungers, on both units, thinking that the slotted screw holding the plunger was bottomed out. Well, it is not....it adjusts the plunger depth.

How far should the air flow sensor be pushed down, to where the back portion will start moving the plunger? I assume not much, if any.

Jeff: Can you check? Push the air flow sensor down and see if you can feel the touch of the plunger......you should be able to.

Thanks
 
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Discussion Starter · #2 ·
Henry,
This spec should be in


Henry,
This spec should be in the WSM...as the sensor plate height is usually set to either the top edge, or the bottom edge of the funnel. Hopefully, Jeff can send you a photo of his to clarify my ageing thoughts.

Regards,
David
 
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Discussion Starter · #3 ·
David: FYI: The resting posi

David: FYI: The resting position of the sensor plate is not set by the plunger. There must be a gap between the plunger tip, and the sensor plate lever.......this assures that the plunger will rest in it's most downward position, when the engine is off......so that no gas can "creap" into the FI manifold.

It appears that the resting position of the sensor plate is "fixed", and only adjusted downward by hitting a pin "with a hamnmer"!!!!!

Since I did not disturb this, I don't want to go that route.

If the gap is too large, then the sensor plate, and throttle, will have to open too much before contact with the plunger.

I may have to experiment.
 
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Discussion Starter · #4 ·
David: FYI: The resting posi

David: FYI: The resting position of the sensor plate is not set by the plunger. There must be a gap between the plunger tip, and the sensor plate lever.......this assures that the plunger will rest in it's most downward position, when the engine is off......so that no gas can "creap" into the FI manifold.

It appears that the resting position of the sensor plate is "fixed", and only adjusted downward by hitting a pin "with a hamnmer"!!!!!

Since I did not disturb this, I don't want to go that route.

If the gap is too large, then the sensor plate, and throttle, will have to open too much before contact with the plunger.

I may have to experiment.

Oh what fun it is working on a Ferrari!!!!!!!!!!
 
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Discussion Starter · #5 ·
Henryk: I posted a response t

Henryk: I posted a response to your FD question on the fchat "diesel oil" thread. The plate should be at the transitional "edge" or point where the entry portion and the concave "chamber" portion meet, just as it contacts the plunger. At least that's what it looked like using my eyeball. If this does not make sense just let me know.
 
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Discussion Starter · #6 ·
Henry,
I understand the dyman


Henry,
I understand the dymanics of the sensor plate height...I though the plunger was the adjustment pin you were referring to...

My mistake. Sorry for the confusion.

David
 
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Discussion Starter · #7 ·
Jeff: I say that in FChat....

Jeff: I say that in FChat.....I did post a response. Let's continue this in this forum.....OK?
 
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Discussion Starter · #8 ·
David: No problem.....I appre

David: No problem.....I appreciate your input. It was interesting to note that the sensor plate has nothing to do with the plunger adjustment. It is the "gap" that is important.

If I learn any more, I will be able to retire in TX, and work for JRV!!!!!! HAHAHA

BTW: There is no mention of this in the WSM......probably one of those things that we are not supposed to touch!!!!!!!
 
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Discussion Starter · #9 ·
Okay....does my observation ma

Okay....does my observation make sense? Not sure how to describe the situation clearly.
 
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Discussion Starter · #10 ·
Jeff: 3/16 sounds about right

Jeff: 3/16 sounds about right. After your "senses" come back (LOL), try this: Push VERY slowly downward on the sensor plate. You should be able to "feel" when it touches the plunger......again, NO reason to see this. I would like to know if it is still 3/16 inch.

Thanks.
 
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Discussion Starter · #11 ·
I'm not sure I'm follo

I'm not sure I'm following what this gap you are looking for is all about?

The sensor plate should have 2 positions, rest engine off, set with the plate hieght adjust stop pin (set with hammer as Henry notes)and idle position, engine running, set with 3mm idle mixture screw. This second position can only be determined engine running and fuel system pressurized.

When the system is pressurized the center piston will move to it's farthest position and is moved to the position that creates proper idle flow of fuel by the 3mm setting screw, which acts against the Fuel Pressure to manuely move the piston.

What am I missing?
 
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Discussion Starter · #12 ·
JRV: This is the gap between

JRV: This is the gap between the plunger and the "push arm" of the air flow meter, with the engine off. With no fuel pressure, it is a spring, above the plunger, that keeps it down so that it seats.....thus preventing fuel from entering the air flow meter.

The first position is where the sensor plate rests, in relation to the air tunnel wall, with the engine off.

The second position is where the plate rests, just as the plunger is being touched by the push arm, again, with the engine off.

These are positions pre-set by the factory when they built the FDs......without running the engine.

The first position is changed by "hit the pin with a hammer" technique. The second is changed by adjusting the "stop screw" that holds the plunger in the FD, and adjusts it's height.

Fine tuning of the second position is done by the air/fuel mixture screw, while the engine is idling.
 
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Discussion Starter · #13 ·
Jeff: Do you have your FD sep

Jeff: Do you have your FD seperated from the air flow meter?

If so, I would like to know the measurement (exact) between the rim of the barrel (where the plunger inserts), and the surface of the slotted nut that screws the plunger in place.

If anyone else has this measurement, I would appreciate it. If so, I would also need to know what year TR it is, and whether it is US or Euro version......mine is an 88.5 US version. There could be a difference due to models, etc.

I would keep these measurements for future use by other members.

Thanks.
 
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Discussion Starter · #14 ·
Jeff: If I understand you cor

Jeff: If I understand you correctly, the top of the sensor plate (furthest from the FD) and at rest, lies ABOVE the "ring"? The ring would refer to that narrowest portion of the air flow chamber. And, when you push on the plate, to touch the plunger, the top of the sensor plate lies EVEN with the ring. And, the distance from rest to the plunger is about 3/16 inch. Is this correct?
 
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Discussion Starter · #15 ·
Yes Henry...that is how I see

Yes Henry...that is how I see it. The air flow sensor plate is even with the narrowest "lip" just below the air flow entrance rim. I think I would place more emphasis on getting the contact to the plunger at the same instant as the sensor plate is aligned with the narrow lip, and consider the 3/16 gap as a secondary measurement.
 
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Discussion Starter · #16 ·
Jeff: I would tend to agree.

Jeff: I would tend to agree. At "zero" position, my plate lies ABOVE the ring line. The point where contact is made with the plunger, is called the "basic" position.

However, the WSM states that, at the zero position, "The upper edge of the sensor plate should be flush with the beginning of the cone at the point shown in fig. 28". The figure shows the top of the plate EVEN with the ring!!!!!

Also, the Probst Bosch service manual states: "....zero position of the plate should be even with the top of the vertical face - or cylinder - of the air-flow sensor that is furthest away from the FD." When touching the plunger, "...the plate should be at the bottom of the vertical face of the tunnel so you can see all of the cylinder, but none of the tunnel below." It also states that free travel from zero down to basic (where plunger contact is felt), must be 1-2 mm.

Can Ferrari and Bosch BOTH be wrong?????? Go figure.

This is the reason for my thread on air flow meter measurements.
 
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Discussion Starter · #17 ·
>>the Probst Bosch ser

>>the Probst Bosch service manual states: <<

You just answered the question I was going to ask, if you had the Bosch books. They are far more detailed and accurate imo. Here's my problem with understanding & answering most of these questions so far..."I LOANED OUT MY BOOKS" {
}

I'll see if I can get my Bosch books back later this week and study up on the relivant chapters. There are certian complicated procedures that I would always consult the books on to insure things are properly set up.

Regards, JRV
 
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