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MAP Sensor talk
Topic Started: Oct 18 2013, 03:45 PM (564 Views)
rjmockster
New Member
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Hey guys, on Map sensors, do they go bad very often? Basically what's going on with my car is a few weeks ago, I got an engine light, car started running kinda funny and going through more gas from the ECU going into a closed loop. I had 2 consistent codes, 14 for ECT sensor circuit, and 31 for pressure sensor circuit (MAP sensor). So I ordered a new ECT sensor and that got rid of that code but I still had code 31. I ordered a used MAP sensor off of ebay, put it in and it seems to run a little better at idle but I get the 31 code back as soon as I hit the throttle. Prior to getting the MAP sensor I ohm's checked the 3 wires going from the MAP sensor plug to the plug on the ECU and had perfect continuity. So right now I guess I'm just kinda scratching my head wondering if it was a good idea to get a used MAP sensor. Do you guys think at this point it might be a good idea to get a brand new MAP sensor and try it or does this sound more like an ECU issue? Thanks in advance :beer
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Memphis metro


These map sensors seem to rarely fail. Did you check the vaccum line and port? Was the number on the replacement map sensor the same as the one you had? Done a tuneup on the car lately? Does the temp gauge reading read normal when the engine is at normal operating temperature?
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rjmockster
New Member
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I would think the same thing about a Map sensor, but my lines are good and vacuum is tight. The sensor I got is the same part # (looks like straight off of another car just like mine) but it does have another number that is different which I'm thinking serial number. I just rebuilt the engine about a year and a half ago, it has about 50000 miles on it (the car itself has 310, 000 miles on it). I've kept up with oil changes every 6000 miles and still no leaks. I did (while troubleshooting this issue) pull the throttle body off and cleaned it up real good although it was'nt all that bad to begin with. I've also verified that the throttle position sensor is giving a 1 volt signal to the ecu with the .14" gap there at the throttle stop screw. I guess when payday gets here I'll go ahead and spend the $65 at the part store and get a brand new MAP sensor if nothing else to at least know that I've eliminated the sensor itself as a probable cause. I have noticed though in this forum section there seem to be alot of folks with the same problem as I have but I dont see any of them posting about what actually solved the issue, so when I do finally get this worked out and my car going right again I'll make sure to post it here and hopefully it'll help people out as this has seemed to be quite a tricky problem to figure out so far. ^o)
Edited by rjmockster, Oct 18 2013, 07:31 PM.
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clarkdw


My 94 upgraded emissions hatch had a MAP sensor go bad. The only way I could keep the car running was to dance on the throttle. I had to keep tapping it rapidly, otherwise it just quit running. I replaced the MAP sensor with a used one from a 95. The actual part for the 94 upgraded emissions is very, very expensive so I thought it was worth it to try the used one.

My feeling is that they do not go bad very often and the likelihood of paying out as much in used ones before I got a good one than it would have cost for a new one was pretty slim.

I scored on the first used one I got and it has been working for a year and a half since.

My problem was more than just the sensor though and in the end i had to reset the throttle stop screw that the previous owner had moved and the TPS which I moved. Getting the throttle plate position correct was a big step in geting the idle perfected. The TPS setting got rid of some cycling.

There is a 94 Factory service manual in the manuals section of the forum. Go to section 6E for upgraded emissions and find your DTC code 31. There is a great troubleshooting section in it. As long as you look at the upgraded emissions part of the 94 manual it is identical to your controls and will work fine.
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rjmockster
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Hey thanks Clark I'll look at the manual and see what I can get out of it :cheers
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