eratic map reading

Hi all , i have a small problem that is bugging me , the map sensor reading on the car i am tuning {Ford RS200 replica} with a cozzie YB fitted , using a genuine Marrelli 3 bar sensor and Canems EMS is very eratic , ie difficult to hold in the center of a cell it jumps from the one below to the one above , thinking back to my bike carb tuning days my gauges have a damper screw to stop exactly this happening on the gauge, does anyone use a restrictor in their map line to the sensor to stabilize the readings.

cheers Keith

I've had YB cossie on the dyno last year, and haven't had a problem with erratic readings from the 3bar Magneti Marelli Sensor. Check the vaccuum line and also try to manually apply pressure to the sensor and see what readings you get.

I've had limited experience with the YB motor and certainly not for many years so I'm not able to say whether this is a common issue. I'd recommend looking at where the vacuum feed for the MAP sensor is coming from - If it's off one runner then you may expect to see some pulsation. Earthing issues for the ECU or the sensor may also show up the same problems.

Thanks for the input guys , this has got me scratching my head a bit , i swapped the map sensor today and still the same , with engine off and using a vacuum pump .. still the same . i think as Andre said its time to check the earths , i know all the ecu earths go direct to the battery , i will check the sensor earths tomorrow but i am sure they go to the battery as well.

Cheers Keith

The ECU earths go directly to the battery? usually they go to the engine