Hi All
I am new to this forum, as well as the world of distributorless ignition, so there's lots of reading going on and my head is starting to hurt a little.
I am installing MJLJ V4 in my 1986 Landrover 90 3.9 V8. I'll be mostly running LPG, so will be making use of the switchable maps.
I have all the major bits n bobs installed now and have begun testing various parts, although I have yet to run the engine, even just on EDIS.
I have powered the MJLJ and it's connected to my laptop via serial port, all communicating fine.
On looking through all the config pages, one thing I cannot fathom out is why the load gauge reads in reverse. I have my MAP sensor connected to a spare port on the Rover's Hotwire plenum. I have disconnected this from the engine for diagnosis and have simply sucked on the pipe to check the readings. With the engine off it reads 102 KPa, if I suck on the pipe it heads anti-clockwise towards the zero mark. My first thought was that I had fitted the MAP sensor upside down, but that's not possible to do and still have it fit the aluminium case correctly. Is there a setting in the config to reverse the MAP reading? If not, what else could it be?
Thanks
Michael
MAP load sensor reading in reverse
Moderators: JeffC, rdoherty, stieg, brentp
Hi,
Don't quote me on this but :
102KPA is the current air pressure. 102 KPa is equal to 1020 Milibars. This is roughly the average Uk airpressure at the mo. Acutally it's 1013, but close enough.
If you suck on the tube the airpressure will fall and so will the reading. Vice versa if you blow down the tube.
The air passing along the throttle speeds up as it moves into the engine. This fast airflow reduces the airpressure (Some physics thingy) the MAP sensor reads this pressure drop therefore increasing or decreasing the advance as required.
I would link the theory for you but it's all aircraft based. Basiccally an aircrafts airspeed is given by measuring the drop in pressure as the air passes across a small hole in the aircrafts skin. While it's a little more complicated then this the basics are the same.
To summise, expect a drop in pressure as you rev the engine (more airflow = lower pressure)
Don't quote me on this but :
102KPA is the current air pressure. 102 KPa is equal to 1020 Milibars. This is roughly the average Uk airpressure at the mo. Acutally it's 1013, but close enough.
If you suck on the tube the airpressure will fall and so will the reading. Vice versa if you blow down the tube.
The air passing along the throttle speeds up as it moves into the engine. This fast airflow reduces the airpressure (Some physics thingy) the MAP sensor reads this pressure drop therefore increasing or decreasing the advance as required.
I would link the theory for you but it's all aircraft based. Basiccally an aircrafts airspeed is given by measuring the drop in pressure as the air passes across a small hole in the aircrafts skin. While it's a little more complicated then this the basics are the same.
To summise, expect a drop in pressure as you rev the engine (more airflow = lower pressure)