When I touch the map sensor my car stalls

1. SlayeR L-plater Joined: Sep 2009 King's Lynn Posts: 48

   #1 7th October 2010, 12:11

   Okay so recently when i've been driving (in 2nd and 3rd gear usually) my car has been juddering a lot and I can smell a lot of unburnt petrol. I changed the spark plugs and cleaned the ICV, still doing it.
   
   This morning I put my hand on the map sensor and it started to stall, revs were going like crazy. Now is it the actual map sensor, or the connector + wires that plugs into the map sensor? Whichever one I touch causes the car to rev and the exhaust to misfire and stall.
   
   Thanks
2. burgerfeet Infrequent Poster Joined: Oct 2010 Bridgend Posts: 231 VTS 2002 - well the Mrs does

   #2 7th October 2010, 12:18

   Check that the rubber hose going to it is not split. This is a very common problem.
3. SlayeR L-plater Joined: Sep 2009 King's Lynn Posts: 48

   #3 7th October 2010, 12:34

   Quote:

   Originally Posted by burgerfeet Check that the rubber hose going to it is not split. This is a very common problem.

   Where abouts is this rubber hose?
   
   @Aidan: What should I look at on the coilpack exactly? And would the coilpack cause the map sensor to fail or something?
4. burgerfeet Infrequent Poster Joined: Oct 2010 Bridgend Posts: 231 VTS 2002 - well the Mrs does

   #4 7th October 2010, 12:39

   [QUOTE=SlayeR;4777352]Where abouts is this rubber hose?
   QUOTE]
   
   Which model of Saxo do you have?
5. SlayeR L-plater Joined: Sep 2009 King's Lynn Posts: 48

   #5 7th October 2010, 12:40

   [QUOTE=burgerfeet;4777367]

   Quote:

   Originally Posted by SlayeR Where abouts is this rubber hose? QUOTE] Which model of Saxo do you have?

   Saxo VTR 2001
6. burgerfeet Infrequent Poster Joined: Oct 2010 Bridgend Posts: 231 VTS 2002 - well the Mrs does

   #6 7th October 2010, 12:45

   Is your MAP sensor pushed straight into the ducting? If it is check that it is sealing properly. Are you touching or putting pressure on it? It sound like you are introducing air into the system when you apply pressure to it.
7. SlayeR L-plater Joined: Sep 2009 King's Lynn Posts: 48

   #7 7th October 2010, 12:50

   Quote:

   Originally Posted by burgerfeet Is your MAP sensor pushed straight into the ducting? If it is check that it is sealing properly. Are you touching or putting pressure on it? It sound like you are introducing air into the system when you apply pressure to it.

   If I touch the wires just slightly, the car will judder a lot and the exahsut will start misfiring and the revs will drop and go up and carry on until it finally stalls.
   
   If I touch the actual connector (which the wires go into) and thne it goes into the actual sensor, the same happens.
   
   If I touch the actual sensor, the same happens as well.
8. burgerfeet Infrequent Poster Joined: Oct 2010 Bridgend Posts: 231 VTS 2002 - well the Mrs does

   #8 7th October 2010, 13:00

   That is insane! From any electronic engineering angle it sounds like you are introducing stray capacitance into the circuit. I would be suspecting the sensor!
   
   Make sure that there is absoltuely no corrosion in any of the contacts and that the contacts in the connector naturally spring closed and have not gone weak.
   
   If you have a 3 pin connector you need to test that the earth (0V) is not missing. Between pins 1 & 2 you should have 5V. You should have approximately 1.4V from pin 3 when it is idling.
   
   To confirm the sensor you are into proper diagnostics unless you can borrow one for testing. This is a tricky one to diagnose across the internet.

   1 user thanked this post: SlayeR
9. SlayeR L-plater Joined: Sep 2009 King's Lynn Posts: 48

   #9 7th October 2010, 13:12

   Quote:

   Originally Posted by burgerfeet That is insane! From any electronic engineering angle it sounds like you are introducing stray capacitance into the circuit. I would be suspecting the sensor! Make sure that there is absoltuely no corrosion in any of the contacts and that the contacts in the connector naturally spring closed and have not gone weak. If you have a 3 pin connector you need to test that the earth (0V) is not missing. Between pins 1 & 2 you should have 5V. You should have approximately 1.4V from pin 3 when it is idling. To confirm the sensor you are into proper diagnostics unless you can borrow one for testing. This is a tricky one to diagnose across the internet.

   Well i've just ordered a new map sensor so hopefully this will fix the problem, I will keep you updated
10. SlayeR L-plater Joined: Sep 2009 King's Lynn Posts: 48

    #10 7th October 2010, 13:20

    Cant edit my post for some reason but I just unplugged the map sensor and started the car, was 100% fine. As SOON as I plugged it back in, it started doing it. So i'm certain I need a new map sensor, so when I get the new one in tommorow we'l lsee what happens.
11. burgerfeet Infrequent Poster Joined: Oct 2010 Bridgend Posts: 231 VTS 2002 - well the Mrs does

    #11 7th October 2010, 13:31

    Fingers crossed!

    1 user thanked this post: SlayeR
12. SlayeR L-plater Joined: Sep 2009 King's Lynn Posts: 48

    #12 9th October 2010, 02:26

    Put the new map sensor in today and boom problem fixed thanks everyone for the help <3