GrandPrix34 Posted December 2, 2003 Report Share Posted December 2, 2003 thats wat another specialized GM mechanic said after he ran some kind of TECH computer through the car...the MAP sensor reads lower than normal vacuum, which is an indication of bad timing.... is this true? or should i just go buy the MAP sensor and call it a day? j/k... nah for reals, would bad timing cauz unstable MAP readings? Quote Link to comment Share on other sites More sharing options...
quaddriver Posted December 2, 2003 Report Share Posted December 2, 2003 thats wat another specialized GM mechanic said after he ran some kind of TECH computer through the car...the MAP sensor reads lower than normal vacuum, which is an indication of bad timing.... is this true? or should i just go buy the MAP sensor and call it a day? j/k... nah for reals, would bad timing cauz unstable MAP readings? Well hold on a second...all the MAP does is compare outside baro to the manifold and give a voltage based on the differential. A scan tool will only give the indicated voltage and it can be compared to a chart that says 'for a perfect MAP, this voltage = this vacuum', and when a MAP fails, they fail 99.99% low voltage as the diaphragm rots. If you think your vacuum is off, use use a simple vacuum gauge. otherwise, swap over the map (clips onto the mounting bracket, has a vacuum connection and an electrical connection) Quote Link to comment Share on other sites More sharing options...
gmrulz4u Posted December 2, 2003 Report Share Posted December 2, 2003 Exactly what "quaddriver" said! What right-in-the-head mechanic uses a MAP Sensors voltage to determine the amount of vacuum an engine is producing!!!?? It takes 3 seconds to hook-up an actual VACUUM GAUGE and SEE what the engine vacuum actually is, which is measured in inches of mercury(hg). Quote Link to comment Share on other sites More sharing options...
GrandPrix34 Posted December 2, 2003 Author Report Share Posted December 2, 2003 you guys rock! thanks for the input I had the question by the way...when the MAP sensor fails, wouldn't it produce a SES light? It wasnt really a scan tool, it was those long scan computers that you swap different circuit boards depending on the car/year/etc. Red and black computer scan tool...??? So would a failed MAP sensor actually produce strong vibrations throughout the engine? And on the vacuum gauge, how do you test vaccum? Connect it to the TB wit engine running, and were do i compare the vacuum reading to DESIRED level or normal level Quote Link to comment Share on other sites More sharing options...
gmrulz4u Posted December 2, 2003 Report Share Posted December 2, 2003 A failed MAP Sensor will produce an SES light 99% of the time! You can verify this yourself by simply disconnecting the MAP Sensor's vacuum hose connection, then look at your dash, the SES light should, and probably will, be ON. As for using the Vacuum Gauge, here's a few nice links that explain using one in good detail: http://batauto.com/articles/vacuum.shtml http://www.centuryperformance.com/vacuum.asp http://autorepair.about.com/library/weekly/aa112401a.htm I originally bought(and still use) a portable Vacuum Gauge for like $20 from Canadian Tire. I liked the whole idea of it SO much that I bought an AutoMeter Vacuum Guage for $80 and have it permanetly installed where my ash tray was!!! Quote Link to comment Share on other sites More sharing options...
quaddriver Posted December 3, 2003 Report Share Posted December 3, 2003 you guys rock! thanks for the input I had the question by the way...when the MAP sensor fails, wouldn't it produce a SES light? It wasnt really a scan tool, it was those long scan computers that you swap different circuit boards depending on the car/year/etc. Red and black computer scan tool...??? So would a failed MAP sensor actually produce strong vibrations throughout the engine? And on the vacuum gauge, how do you test vaccum? Connect it to the TB wit engine running, and were do i compare the vacuum reading to DESIRED level or normal level Sounds like the mech used an older snap-on and the boards were 'personality keys' (if only they worked on women) There is an allowable range of output voltage...eventually when it gets to low you will get a code for the map being out of range and a fixed set of values will be used based on Baro, TPS and MAF (if equipped) Quote Link to comment Share on other sites More sharing options...
GrandPrix34 Posted December 3, 2003 Author Report Share Posted December 3, 2003 my question is will a MAP sensor cauz vibrations/undesired motor operation? Quote Link to comment Share on other sites More sharing options...
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