i have a 87 century 4 cyl that has been sitting a while because of a bad fuel injector. i recently changed the injector, drained the gas and replaced the fuel filter on it and can get it to run at idle just fine. once i pull it out of park it dies. there is a small circuit or relay with 4 or five prongs attatched to the side of the air filter housing. i cant get the car to idle if it is plugged in. i have googled and tried to find out what this is but haven't had any luck.

what is this controlling when i have it plugged in?

Do you know how to post a picture?

I think what you are describing is the IAC valve.....does it look like this?



or like this? This is the MAP sensor, has vac line to it....

ya looks like the map sensor. three prongs with a vac line on the bottom. does this have something to do with it dying when plugged in? i would think it would be the opposite and it would die if i disconnect it

and with the car idling for 15-20 minutes or so will this cause a seal to bust allowing oil in the radiator? because the coolant was clean before we ran it with this unplugged. don't know if this had something to do with the coolant getting dirty or the fact that it sat for a while and then got hot idling

possible the map sensor could have been the issue to begin with? it died on us while my son was driving it and wasn't getting fuel. so i just assumed after troubleshooting the injector it just needed to be replaced. it would get fuel up to the injector, tested the connector with a noid light and it got power but no fuel was passing through the injector. thats why i replaced it

If the engine does not have a MAF sensor (probably the case here), the MAP (or Manifold Absolute Pressure) sensor is one of the primary measurements for the computer to calculate how much air is being ingested, and in turn, how much fuel to apply.

Nothing of this caliber should cause or allow oil to get in to the coolant however. That would likely be caused by an overheat causing a failure (head, head gasket, etc), or possibly a transmission oil cooler failure. If you are getting uninvited oil, try and track the source by seeing what fluid is being lost, or if it continues.