1JZ > 2JZ Map Sensor Upgrade Myth Burried.

[JZA70 R]

After my last attempt at exposing this myth I had some people come forward and announce possible flaws in my testing. The flaws were based around the fact i was testing the map sensors not only using my power fc as the voltage monitor but also the pressure monitor. It was indeed possible the powerfc could affect readings and results. And to some degree it did.

Well now im back with concrete results that show the factory 1JZ map sensor from a JZA70 is in fact exactly the same as a factory 2JZ map sensor from a JDM JZA80. The only turbo charged JZ powered vehicle i could fathom using a map sensor that is not relevant to this testing is perhaps VVTI xJZ vehicles. However this does not bother me since 99% of map sensors people are upgrading to in an effort to raise boost cut's or lean out fuel mixtures are from either a non VVTI JZA80 or a non VVTI Aristo.

In short this is how I conducted my testing.

I used 5.0v from a computer power supply to power the map sensor. (Both the power rail direct from the PSU & power from a USB cable give 4.99 - 5.00v constant so I used the USB 5v for convienience.

I used a 40 PSI racing tyre pressure gauge for measuring positive pressures. (i chose this because of the huge dial face that give a eye accurate reading as close as 1 PSI.)

I used an everyday digital multimeter to measure the output voltage of the map sensors.

And i used a 99c plastic syringe from my local chemist to charge the map sensors.

This basic equipment gave me the foundation i needed to eliminate any possibilities of false readings. Isolating the map sensors, pressures and voltages from the ecu and the car was what i needed to do.

Anyway I thought the next most important thing to do was take photos, so here they are. (They also contain the voltage output comparions between the 2 map sensors.)

http://www.jza70r.com/external/forum...ting%20002.jpg
http://www.jza70r.com/external/forum...ting%20003.jpg
http://www.jza70r.com/external/forum...ting%20005.jpg
http://www.jza70r.com/external/forum...ting%20006.jpg

To conclude, the differences between testing on the car and testing independantly showed the following.

Both map sensors actually stop producing voltage at a bee's dick away from 18 PSI. (17.9X PSI & 4.91 Volts) according to the pressure gauge i used. The powerfc read to the same voltage but showed 16.5 PSI as the maximum pressure however personally from what i know about the powerfc i believe the analogue pressure gauge would stand correct.

That's it. So next time you read of someone upgrading their 1J map sensor to a 2J map sensor *cough* soarer central *cough* you can politely tell them that they will be wasting their time.

Thanks.

-Todd.

[mrshin]

While it hardly constitutes anything scientific, I can at least say that on a mates car, which uses a JZZ30 ECU, and a JZA80 MAP sensor (because these were the parts I had at the time!), it still runs bulk rich, and has no trouble hitting the boost cut. Jaycar DFA and a little driving around with the wideband made a genuine difference, unlike any other part number theories.

[chris davey]

Great work Todd. The "upgrade" actually came from supraforums US AFAIK. Silly Americans

You must spread some Reputation around before giving it to JZA70 R again.


You will get some soon

[MR 1JZ]

Great work Todd. The "upgrade" actually came from supraforums US AFAIK. Silly Americans

surprised?

lol

nice work todd...and a good bit of info...

[Endless]

F**king good work Todd!

Much respect goes out to putting americans to shame.

[The Witzl]

I think this is about the 20th seppo "fact" that has been disproven on Toymods. Well done!!

[Norbie]

Great work, it's nice to see internet rumours defeated by actual testing.

The only turbo charged JZ powered vehicle i could fathom using a map sensor that is not relevant to this testing is perhaps VVTI xJZ vehicles.

VVTi 1JZ/2JZ's use a MAF sensor so that explanation doesn't work.

[MR 1JZ]

dont they still run a secondary map sensor norbie?

like teh 1G?

[VeeP]

is it possible that the US 2j setups use a different map sensor?

[JZA70 R]

As far as im concerned, yes its possible since i havent looked into that. Like i said no one has even tried using one (as an upgrade) so no need to prove invisible people wrong. However for research's sake if you want to send me one ill test it. Chances are it wont even plug into the loom. (2JZ is a direct plug in replacement)

While im at it ill test a JZZ30 sensor and even the JZA70 boost gauge sensor (it looks just like the map sensor)

[chris davey]

I thought the USDM non vvti 2jz was MAF like the newer vvti engines. Not sure if they have a map sensor for something else but I am 99% sure the US guys speak of getting a "standalone" to get rid of the MAF.

[The Witzl]

the US guys talk some shit out their bums sometimes

usually the secondary MAP sensors used for the instrument cluster boost gauges and the like are usually not quite as linear or high resolution as your normal MAP sensor, and so cant normally be used as a replacement for a primary MAP sensor - or so i've heard from Mr Kellam anyway.

[ReQuieM]

I don't spose you checked the voltage output under vaccum conditions? Interested to see the range...

[Norbie]

usually the secondary MAP sensors used for the instrument cluster boost gauges and the like are usually not quite as linear or high resolution as your normal MAP sensor, and so cant normally be used as a replacement for a primary MAP sensor - or so i've heard from Mr Kellam anyway.

What he said, I think it's also used for boost cut. Actual engine load is determined by the MAF sensor though.

[JZA70 R]

I don't spose you checked the voltage output under vaccum conditions? Interested to see the range...

No I didn't since its totally irrelavent to the issue at hand.

But if you would like i can test vacuum for you... are you hoping negative pressure voltages varie between the two, so perhaps you can use a 2JZ map sensor to increase offboost performance? because thats about the only result you would get from that outcome. Thats IF the voltage difference favours the 2JZ sensor. theres a 50/50 chance it could be the other way around and decrease offboost performance.

If you think that a difference in vacuum voltages could give an effect with postive pressures you would be very mistaken.