: Intermittent MAP sensor issue?



ReagansRollsRoyce
07-05-07, 09:55 AM
'87 FWB

For the past two weeks, while driving on a longer trip on the highway, my CHECK ENGINE light has come on briefly, say for about a minute, then switched off.

When I got home, both times I checked the code it had stored, and it came up "34" which, looking on the code websites, is "MAP sensor too high"


Since this is intermittent should I be considering a MAP sensor replacement?

If so, is that an easy job?

The Ape Man
07-05-07, 02:19 PM
Maybe the MAP sensor connection is crapped up. IIRC they hook it up to pull a 5 volt reference voltage down towards ground with the sensor's resistance. A loose connection would cause a now and again failure. It's good to have spare stuff anyway so replacing it isn't a big deal.

carnut
07-06-07, 02:15 PM
Check the vacuum hose to it at both ends. Could be split or have moisture (condensation) in it. Also the vacuum port at the engine could be restricted with carbon. Check the electrical connector for looseness, backed out contact pins corrosion etc. MAP sensors are pretty fail safe sensors but they rely on good tight hoses and proper voltage. Codes do NOT tell you what to replace, they focus you to that specific system on the car. You still have to investigate and diagnose all items within that system.