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Thread: Map sensor question??

  1. #1
    UN4TOLDVRSS is offline un4toldvrss
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    Default Map sensor question??

    Hi Guys,
    A mechanic i was having a chat with recently said that the MAP sensor hose has to be a certain length, otherwise thecar performance will be affected. Does anyone know how long it should be?

  2. #2
    Chirpstr's Avatar
    Chirpstr is offline A new project attack
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    Enough so that it sits flush on each end. (not stretched) Should be roughly 30cm.

  3. #3
    KiWi1's Avatar
    KiWi1 is offline 11.00@126 Miss dat ****
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    I copied and pasted this, as i roughly know, but factual is better than half factual LOL

    MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR. The MAP sensor is mounted on or connected to the intake manifold to monitor intake vacuum. It changes voltage or frequency as manifold pressure changes. The computer uses this information to measure engine load so ignition timing can be advanced and retarded as needed. It performs essentially the same job as the vacuum advance diaphragm on an old fashioned mechanical distributor.

    On engines with a "speed density" type of fuel injection, the MAP sensor also helps the PCM estimate airflow. Problems here may cause an intermittent check engine light (light comes on when accelerating or when the engine is under load), hesitation when accelerating, elevated emissions and poor engine performance. The engine will run with a bad MAP sensor, but it will run poorly. Some PCMs can substitute "estimated data" for a missing or out of range MAP signal, but engine performance will be drastically reduced.

    MAP Sensor Strategies: Some MAP sensor problems are not the fault of the sensor itself. If the vacuum hose that connects the MAP sensor to the intake manifold is loose, leaking or plugged, the sensor cannot produce an accurate signal. Also, if there is a problem within the engine itself that causes intake vacuum to be lower than normal (such as a vacuum leak, EGR valve that is stuck open or leaky PCV hose), the MAP sensor's readings may be lower than normal.

    Hope that helps bro. Also........

    Same to the effect of running your MAF too close to the TB. Especially with an OTR on a LS1, running the MAF.

    Its also not wise to have your IT sensor too close to anything hot. (best left where it is)

    Simon

  4. #4
    UN4TOLDVRSS is offline un4toldvrss
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    So to long will send the wrong or inappropriate signals to the pcm?? Think the hose on mine is a fair bit longer than 30cm

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    KiWi1's Avatar
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    Find a mate, or the likes, with the same car, and compare....

    Or someone on here should take a picture of there car and show you?

    Simon

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    shouldnt matter. ive run all different lengths of hose for my map sensor on my supercharged v6. didnt seem to make a difference.

    1995 Manual HSV Clubsport
    Wade Cam :: 9.2:1 CR :: Pacemaker headers :: Twin 2.5" Exhaust :: VT Brakes
    1991 Supercharged VN Berlina
    9 PSI SC14 Intercooled :: Genie headers :: Twin cats :: HM Twin 2.25 exhaust :: 3.45:1 LSD





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