Check engine light is on. Says something like "MAP sensor too high" replaced MAP sensor, didnt clear code, didnt fix problem. Any ideas?

DoubtingAnterior,

The condition which caused the MAP sensor output voltage to be too high probably still exists. That is normally a vacuum leak, whether external or internal. It could also be related to the TPS, but since your '91 has a non-adjustable TPS, that's not likely the case.

Remember that Manifold Absolute Pressure is the OPPOSITE of vacuum. A relatively high absolute pressure is the same as insufficient vacuum. The sensor can only report what it sees.

Typical causes are external vacuum leaks, such as gasketed joints, control hoses, PCV hose, a leaking power brake booster, loose throttle body, etc. There can also be internal vacuum leaks caused by a leaking EGR valve, leaking EVAP purge solenoid valve, leaking intake gaskets into the lifter valley, or an incorrect PCV valve (I've had that happen more than once on a TBI).

It would help to get an actual idle vacuum reading with a separate vacuum gauge to verify what the MAP sensor is reading.

so I follow the pcv up the rubber hose and see a crack in the rubber hose next to the base of the TBI. I go to remove the hose and find that the metal tube connected to the tbi is all clogged with brown carbon deposits. I assume that I should try and scrape all that crap out?

Wouldn't this create more vacuum not less? I was looking for a leak and I found a clog...

ugh...


So I cleaned out all that crap from the pcv intake to the tbi. Went to autozone and bought a new hose, replaced it. Removed negative battery cable to reset engine codes, waited a minute, replaced it. Started car... check engine light came back on :banghead: . On top of that, car stalled at stoplight on the way home :frown: