3.5bar MAP Sensor Signal

[playn07]

I am in the middle of tuning a car with a 1050 box and 3.5bar map sensor, but I cannot get a good signal from the sensor. The sensor signal should look like a parabola, instead it is jagged and inconsistent. The boost gauge shows steady boost being held. Is it possible that there is some sort of electrical distortion from another electrical component? How can I remedy this?

[playn07]

I have heard of people using "map bombs" in the pressure line to remedy this. Also using hose with high pressure ratings. Any thoughts?

[SB]

Define 'inconsistent.'  Are you zoomed in so closely that a +/-1%  fluctuation appears large?

There will be actual engine load variations due to the location of the sensor, remember that the valves are opening and closing... airflow is not perfectly smooth like a vacuum cleaner. In addition, engine bays are an electrically noisy environment, it may be helpful to use twisted and shielded wire (ask someone who is familiar with wiring and electronics).

If you are using an EMS there is an option (MAP Filter) that can be used to filter the MAP signal that has been measured. Adding a restrictor in the vacuum line between the sensor and the intake manifold may help mechanically dampen whatever pulsations might actually exist. It's likely the boost gauge has some dampening or filtering built into it.

[playn07]

The tricky part is that the map sensor signal is perfect out of boost, but ounce in boost it will do something like the following (target boost = 10.5psi): -10, 0, 3, 7, 11, 10.7, 10.5, 10.5, 10.5, 7.2, 10.5, 10.5, 5.7, 10.5.... It will continue to do this through the rev band. I cannot figure out for the life of me what it could be. My boost gauge is reference to the same point and it reads steady yet the map sensor does not. 

[playn07]

If I add another ground source to the map sensor referenced from somewhere away from the motor would this eliminate the possiblity of rpm dependent engine noise? Another solution I was thinking about was using the 5v output from the TPS sensor.

[specialed]

How do you currently have the MAP sensor wired in? Where is the sensor mounted to the manifold/pressure source? Is it hard mounted (directly) or do you have it mounted elsewhere with a vacuum line running to the source?

[playn07]

How do you currently have the MAP sensor wired in? Where is the sensor mounted to the manifold/pressure source? Is it hard mounted (directly) or do you have it mounted elsewhere with a vacuum line running to the source?

The map sensor is currently wired in to the corresponding pin inputs/outputs on the AEM. The sensor is getting a pressure signal from the manifold via a hard vacuum line. The sensor itself is not hard mounted anywhere it is support by a zip tie attached to a bracket.

[specialed]

Do you have a log showing the "MAP Volts" parameter jumping around like what you describe? Also post up your calibration if possible.

Just to confirm, this is an AEM 3.5 Bar MAP sensor?