Thread: TD5 MAP sensor...how high will it read?

The 100kpa reading occurs when the MAP output exceeds the voltage that corresponds to the maximum pressure it can accurately sense.

It's basically a sign the engine has detected over boost and is limiting.

The Td5 MAP sensor should read up to 250kpa, but that is the raw output. There are several manipulations done on the voltage reading to including compensation for sensor supply variations from 5V, so it's possible for the ECU display above 250kpa.



The MAP fitted to the Td5 is specified to read 20kpa at P1 and 250kpa at P2

Cheers
Paul

The 100kpa reading occurs when the MAP output exceeds the voltage that corresponds to the maximum pressure it can accurately sense.

It's basically a sign the engine has detected over boost and is limiting.

Cheers
Paul

Thanks Offtrack!

This vehicle is running a boost box etc but I just wasn't sure if the MAP sensor was faulty or not. Looks like it's all good.

Originally Posted by D110V8D

Thanks Offtrack!

This vehicle is running a boost box etc but I just wasn't sure if the MAP sensor was faulty or not. Looks like it's all good.

With a boostbox fitted the Nanocom reads the 'limited signal' and not the actual boost as I understand it.
That information was supplied to me from TD5alive or as they are now known Alive Tuning
This is how the ECU is tricked into not overboosting and cutting the fuel.

In order to measure actual boost you will need an independent boost gauge.
the 280kpa you are reading includes 100kpa ambient so actually 180kpa of boost which should be the 'limited' signal' generated by the boostbox and not actual boost however the boost limit on the TD5 is around 230kpa (total) so either the boostbox is not working or some other failsafe is coming into play?

Paul (Offtrack) or someone else may be able to elaborate further.

Cheers,
Paul.

The boost box should be reducing the voltage level from the MAP so the ECU doesn't hit the point where it limits. Is it possible to adjust the boost box?

As far as I can tell there is no adjustment of the boost box.

My reading of 280kpa is a little vague (my fault) as I was driving and keeping one eye on the nanocom and the other on the road. I didn't bother recording the data and then looking at it on the PC.

I noticed it getting up above 250-260kpa, but it rises quite quickly at full noise and by the time I got my next glance at it, it was reading a flat 100kpa.

Anyway my concern was that because the MAP sensor was topping out and reading 100kpa, I thought perhaps it's not working to full capacity so I thought I would ask the question, as all my searching online came up with nothing about it's range.

I realise I will need a dedicated boost gauge on the car but was really just going over everything and making sure everything was operating as it should after a long 6 weeks of repairs and upgrades. The car runs around 25-26psi boost, which is a fair bit beyond what a normal TD5 would be running from what I understand and as I mentioned I was curious to see if the MAP would keep up.

You will find the Nanocom pressure readings surprisingly irrelevant.
I use to live by it but when I put a mechanical gauge on it I found it to be quite inaccurate .

Originally Posted by djam1

You will find the Nanocom pressure readings surprisingly irrelevant.
I use to live by it but when I put a mechanical gauge on it I found it to be quite inaccurate .

A boost gauge might be useful for a direct reading of boost pressures when you are running a boost box but that doesn't make the pressure readings the Nanocom is displaying irrelevant.

The ECU sets fuelling on the basis of what the sensors are reporting not what the aftermarket boost gauge is telling you. It doesn't make the slightest bit of difference how inaccurate you might think those sensors are, the engine still calculates boost as MAP less AAP, and will still limit when the input exceeds a set value.

cheers
Paul