MAP sensor waveform 5sfe. what it suppose to look like? digital or analogue MAP?

[gixer]

He probably doesn't have a vac pump, so easiest way to check it is to connect up volt meter to PIM(signal return) start engine and give it a few revs, you will work out really quickly if it's working or not

[oldcorollas]

don't need vac pump
a 25-100cc plastic syringe will be fine

[gixer]

don't need vac pump
a 25-100cc plastic syringe will be fine

you don't even need that just rev the engine, that'll change it's load

that's what we show the students, if they don't have a vac pump (or syringe....maybe if they were from Salisbury they would have a syringe )

[wilbo666]

A plastic syringe is good as one can connect a vac gauge and syringe with the use of a T piece off the MAP sensor and then move the syringe to a fixed point on the vac gauge. Easier than loading the engine up to get close to 0 vac...

I can also confirm that 5FSE is 0->5V output. No AC.

Are you sure you had the CRO in DC coupled (Not AC)? Are you sure your ground was good?



Cheers
Wilbo

[DrNick]

My brother and i hooked up our oscilloscope to the output and ground with the map sensor's original signal, and with my controllers output signal.

We found both to be a sine wave form, both oscillating positive and negative at a high frequency, with frequency decreasing and amplitude increasing with throttle

So if we have confirmed that the MAP sensor is outputting an analogue voltage then this means that your oscilloscope is picking up noise from other electrical components.

If it is affected by the throttle then its probably coming from the alternator. Perhaps the regulator on the alternator decreases its frequency as revs climb to keep the output the same. Just a guess, in any case it's not relevant to what you are trying to set up.

I suggest you follow the advice above and test the map sensor with the car turned off using a vacuum source.

[bajachris88]

Hi, we will get some pictures or a video in like a couple hrs. we will show ya the exact outputs.

I always thought it was analogue and not frequency type. the jaycar DAF controller does not work for frequency based signals.

The Vc is getting 5 volts max like it should when i get a multimeter between Vc (input) and E2 (ground). I am not using or monitoring PIM as that link to the 5sfe manual backs up the voltage difference between PIM and VC is around 3.9 to 13 volts and i neva saw it as an input, cause i was always told the map was a 5 volt range on the toyota. the E2 is the earth and i assumed it was the output.

When the car is running, even without the device connected (when the ecu is happy), the signal oscillations in both positive and negative sides of the x axis. It tripped me out cause it doesn't follow everythin i have seen or read for this motor.

Its a 1990 st184. original engine and factory ecu setup. From what i'm aware, and what it looks. I haven't got a digital multimeter, only an analogue, so it would average out the sine wave signal and it does to a point of around zero volts, cause it oscillations over the x axis both positive and negative. I have been monitoring the signal with both my oscilloscope on my laptop and my dick smith oscilloscope unit.

There are digital MAP sensors, i only found out about both digital and analogue ones earlier today via a few websites, in which it only mentioned ford, not toyota.

The map sensor signal was trialed while the engine was running, with the ecu liking the frequency ac style signal that we were getting on the oscillosope. We reved the engine, and the amplitude and frequency would increase with revs. As soon as i turned on my jaycar DAF controller we got a similar wave setup of lower frequency instead and the ecu had a spew.

I haven't tried it with a syringe yet. i could do that. Running the car should be no different though.

My map sensor is factory, only the 3 points as decribed in that diagram. and despite it having that graph, i'm getting oscillations between the output signal and earth terminal. And its not just bouncing around a +ve voltage, its fully oscillating about the horizontal x axis. (in both positive and negative)

But yea, as i said i will grab some photos/video's.

the oscilloscope was set to each mode, and it was the same result really. we will hook it up again tonight and have a look.

I could understand if the signal bounced a bit on the positive side of the graph on the oscilloscope cause the pressure is contantly going up and down cause valves are constantly opening and closing, creating vaccum and pressure at the same time, but rapidly.

But yea, i will get some pics/vids.

[bajachris88]

hmm is the output PIM?

that means the voltage range is between 13 and 3.9.
I chose to use VC and E2 as the vc was 5volt and i was informed the MAP sensor was 5 volt.

But Vc being the 5volt source, and even e2, its also shared with the thottle position sensor. (both terminals are used to the throttle position sensor.)

So does that mean i should be using PIM instead of Vc? meaning i am using a voltage range from 13 to 3.9 volt instead of 5?

[wilbo666]

hmm is the output PIM?

that means the voltage range is between 13 and 3.9.
I chose to use VC and E2 as the vc was 5volt and i was informed the MAP sensor was 5 volt.

But Vc being the 5volt source, and even e2, its also shared with the throttle position sensor. (both terminals are used to the throttle position sensor.)

So does that mean i should be using PIM instead of Vc? meaning i am using a voltage range from 13 to 3.9 volt instead of 5?

Yes PIM is the output from the MAP sensor.

I don't know where you are getting 13 to 3.9 volts from. This is wrong.

The PIM signal output from the map sensor is 0-5V. As shown on the docs oldrolla etc has found for you. I still don't know where your 13 came from, but it is wrong.

Vc is the 5V power to the Map sensor and also the TPS as you have discovered

PIM is the output from the Map sensor (0-5V)

E2 is Ground for the Map sensor (0V)


You will want your CRO DC coupled.

Cheers
Wilbo

[bajachris88]

You are a champion! i have been pickin my brain at this for a week, and was ready to sell the jaycar kit and kick myself. lol.

The link thats on page one leads to a manual for the 5sfe motor, and towards the end in teh electrical section it has the voltmeter testing/troubleshooting between the PIM and E2 terminals, saying that crazy voltage range.

You guys are awesome. i will give this ago.
Moral just shot above the roof.

The 5sge should be tuned nicely soon.

[wilbo666]

You are a champion! i have been pickin my brain at this for a week, and was ready to sell the jaycar kit and kick myself. lol.

The link thats on page one leads to a manual for the 5sfe motor, and towards the end in teh electrical section it has the voltmeter testing/troubleshooting between the PIM and E2 terminals, saying that crazy voltage range.

You guys are awesome. i will give this ago.
Moral just shot above the roof.

The 5sge should be tuned nicely soon.

The doc oldrolla links to mentions to apply 13kpPa of Vac, and it says the voltage drop the corresponds.

It doesn't say 13V anywhere

The graph is PIM vs pressure, and is very easy to read

Cheers
Wilbo

[bajachris88]

page 375 with the voltmeter on the pinout of the ecu had me confused.

[wilbo666]

There you go eh, pretty sure it is a misprint and should read 1.3V

Cheers
Wilbo