MAP SENSOR QUESTION ???
 

Am I correct in thinking that the 1st facelift Classics i.e. 1997MY>on are fitted with an uprated 1.7bar MAP sensor, compared to the earlier 1.2bar item?

Hi,

I have a Jan 98 (prob made late 97) phase 1.5 and it cuts out at 1.2 bar if thats any help? Not sure if it can be adjusted.

Hmmn. Perhaps it's the phase 2 1999-2000MY models then :wonder:...

I think the MY97/8 MAP sensor can read up to 1.8 bar, its just the ECU that doesn't let you get that far...

Cheers, thought that was the case. I'm just trying to identify the correct one in case I get an Apexi Power FC and wish to run more than 1.2bar :thumb:...

If you're thinking of using the MY97 sensor on a MY93-6 then it kind of works, but the PFC sees a lower value for boost

Ah, how would you get round that then? Dial in more target boost :wonder:...

The map sensor from a post97 car can be fitted to a pre96 car but the ECU needs remapping/rescaling to work with it.
The voltage returned from the later map sensor will be lower compared to the earlier sensor.
This is likley to confuse the OE ECU and cause overboost, boost fluctuations or even Code 45 Map Sensor fault.

I have never run a car for more then a few minutes on an OE ECU map with the later Map sensor, before remapping/rescaling the ECU. So the above is theory based on the voltages recieved and how the ECU controls the WGD.


As Jay says it can be used with an Apexi, but the Apexi will report a lower boost level on the display compared to actual boost generated (also due to the lower voltage output from the sensor).

I have heard though that the post97 map sensor does not work all that well with the Pre96 Apexi and is a little un-stable. So the Apexi Boost pack or AVCR is the way to go.

Cheers Scott. Would the Delco 3bar MAP sensor be any better in this regard?

The Apexi is expecting a certain Voltage Vs Boost level. So the Delco will have the same issues as the Post97 Sensor

IIRC the easiest way forward with Pre96 Apexi to get beyond 1.1bar is to turn the boost control off and fit some sort of external mechanical or electronic boost controller.

Gotcha. Do either of those boost controllers work in harmony with the Power FC - or is it a bit of 'bodge' cheat way of doing it?

People with a bit of cash normally plumb in an Apexi AVCR.
It adds another £200+ to the costs.

Those with short arms and deep pockets go for a Dawes/MBC for £35..

Ah, the famous Dawe's device - how does this differ from a 'dodgey' bleed valve?

not alot.
rather then bleeding air away from the actuator, it holds the air via a ball and spring.
then releases the air to the actuator at the pessure defined by the tightness of the spring.

So, in effect, doing the same thing, right? Isn't this bad practice re. fuelling?

If you wanted to go this route, isn't it simpler (and at no expense) to screw in (or is it out?) the actuator arm a little - to effectively increase the spring rate, so that more boost pressure is required to overcome it and cause it to open?

I think the Dawes allows quicker spool up than an MBC??

I have one on mine set to the same boost as oem, it has increased my low end torque and boost starts about 1600rpm, in full boost by 2500....

PS I only have one as i havent got the cash for an AVCR lol

Manual Boost Controller i assume, i.e. bleed valve....

As i understand it, the bleed valve always bleeds air, the dawes only does when it reaches the preset pressure....

anything that controls the boost that isn't electronic is an MBC (Mechanical Boost Controller).

Yes tightening the actuator has a similar effect (the old fashioned way of doing things). But the ECU will try to compensate for this if using ECU boost control and you will still run into the same issue of fuel cut and the mesurement limit of the map sensor.

A Fuel cut defender will solve the problem of fuel cut and the map sensor limit, but you need to be sure your ignition timing and fueling in the ECU are mapped for the extra boost.