I've been getting an SES light every couple of days for code 34 lately. I know it has to do with the MAP sensor, but I'm not sure what to look for to correct it. Basically my MAP reading is 3.2 when I get the SES light. But I've been keeping an eye on it since it happened the first time and it stays at about 12, then I'll be driving and I'll get the light, check my MAP reading and it is down around 3. Then it will go back up to 12 or so. I'm thinking that maybe the sensor is bad. I know the MAP should be about a third of what the Barometer is, and the BAR is generally 28-30, so with my cam my MAP should be about 12. It just seems to drop every couple of days and throw the code and SES light, then it goes back to normal. Any ideas? I don't want to just start swapping parts, or throw a new sensor at it if I don't have to.
Thanks!

 

I got the SES light again and the MAP reading was 3.2, and it didn't move at idle, and only went up a bit when I gave it gas. I've checked for vacuum leaks and couldn't find any. I was thinking that if I had a major vacuum leak that could cause the SES light that it would be there all the time not just once in a while.

 

Well it just happened again when I drove it, and I'm stumped.

 

ttt

 

Check the wiring harness connector to the MAP sensor. These things get brittle and start to fall apart. I had a problem with erratic MAP readings and it was due to the connector coming apart.

If the wiring is OK, check for the correct voltage from the PCM (+5V) to the connector. If that is OK, it may be the sensor itself. Rob/Shoebox's site has the wiring info and diagrams that will tell you which wire is ground, +5V and "signal".

 

I had this problem, and eventually the sensor stopped working and had to be replaced.