1KZT, mechanical injection and MAP sensors

[monsterer]

Hi there,

Another technical question i'm afriad!

So I have a 1KZT with the mechanical diesel injection system. I assume that because its mechanical, its just connected directly to the engine rotational speed by some kind of gearing system.

This indicates (to me, at least ) that the amount of fuel injected does not relate to boost pressure. So, why do i have a MAP sensor still?

Cheers, Paul.

edit: this really should have gone in the technical section, can a mod move it for me? Thanks!

[BUSHWHACKER]

The MAP sensor can be used to directly measure the BAP (barometric absolute pressure).




BAP = MAP (When either of the following conditions are true.)

When the engine is not turning.
When operating at wide open throttle, (WOT) (nearly equal to the barometric pressure)

Once the BAP is known, the MAP sensor can be used to calculate intake manifold vacuum.




BAP - MAP = Manifold Vacuum
or
BAP = MAP + Manifold Vacuum
or
MAP = BAP - Manifold Vacuum

When the engine is running, the difference between the BAP and the MAP is known as intake manifold vacuum. The ECU learns the BAP just before cranking the engine, i.e., when MAP equals BAP.

As atmospheric pressure decreases with increasing altitude, vacuum must also decrease to maintain the same MAP in order to maintain the same torque output. This is accomplished by opening the engine's throttle more as altitude increases. However, the BAP learned at the beginning of the trip becomes obsolete as altitude changes.

Sometimes an engine control system will use both a BAP sensor and a MAP sensor to continuously maintain an accurate barometer and manifold vacuum. However, neither vacuum nor barometer are necessary for fuel determination, although they are helpful for other engine functions. The critical information is the air's density in the intake manifold, and the speed of the engine, i.e., the speed-density method.

The BAP sensor is often located within the ECU, and the MAP sensor is usually located near the intake manifold.


All clear now?

Let the sensors do the thinking, you just enjoy the ride!

[monsterer]

Hmm, thanks for the info, maybe i didn't word my question right. I'll come at it from a different angle:

On a forced induction petrol engine, you need to know the amount of air entering the engine in order to inject the correct amount of fuel. This is done with a MAP sensor and an AIT sensor to measure the temperature (on a more modern engine, a MAF sensor is used, but anyway).

Now, because i have a mechanical injection system on my 1KZT, I assume the ECU cannot control the amount of diesel entering the engine, so i'm wondering why does it need a MAP sensor at all?

Cheers, Paul.

[BUSHWHACKER]

I thought I just explained it!!!!
Basically to maintain vacuum pressure for the brakes and A.D.D. system.

I think you're thinking of a MAF (mass air flow) sensor, which measures the amount of air flow entering the intake manifold, and adjusts the fuel delivery to suit to ensure optimum efficiency.

[marky]

Blinded With SCIENCE

[TonyN]

Blinded With SCIENCE

Blinded by B/S!

[marky]

[NiftyNev]

Blinded by B/S!

I want some of whatever Vince is drinking or

Nev

[NiftyNev]

So, why do i have a MAP sensor still?

Are you sure. Where is it located? Have you got a pic?

Nev

[monsterer]

I thought I just explained it!!!!
Basically to maintain vacuum pressure for the brakes and A.D.D. system.

I think you're thinking of a MAF (mass air flow) sensor, which measures the amount of air flow entering the intake manifold, and adjusts the fuel delivery to suit to ensure optimum efficiency.

Okey... right, sorry - I thought you were just giving me a definition of what a MAP sensor did.

A MAP sensor and AIT (Air Intake Temperature) sensors were used (in petrol applications at least) before MAF sensors were common place for the same purpose; i.e. to work out the volume of air entering the engine.

So, all definitions and terminology asside, lets get down to brass tacks:

The 1KZT engine has no boost related control over the amount of diesel injected?

Cheers, Paul.

[monsterer]

Are you sure. Where is it located? Have you got a pic?

Nev

I'm starting to wonder if it was actually a different sensor that i saw. Its just under the silver bit of repair tape on the intake pipe - you can just the yellow label on it in this picture.

Cheers, Paul.

[TonyN]

The 1KZT engine has no boost related control over the amount of diesel injected?

Cheers, Paul.

I'd doubt it. All the tech info I have is for the 1KZ/TE, so can't help you much.

[TonyN]

I'm starting to wonder if it was actually a different sensor that i saw. Its just under the silver bit of repair tape on the intake pipe - you can just the yellow label on it in this picture.

Cheers, Paul.

Thats the turbo boost pressure sensor.

[NiftyNev]

The 1KZT engine has no boost related control over the amount of diesel injected?

They would if there is a boost compensator on the pump. Is there???

Nev

[NiftyNev]

Thats the turbo boost pressure sensor.

Correct.

Nev