high map readings at idle

[scott0999]

91 beretta 3.1 auto

I have a laptop with ALDL cables and tunerpro so I can datalog it

the MAP is showing 55kpa at idle, so its dumping 2x as much fuel it needs and running like crap.

heres what I've done sofar:

looked at all the vacuum lines - no cracks
ohm'd the injectors, all were between 12-12.2
cleaned the plenum and installed new gasket
cleaned the TB and installed new gasket
completely disassembled EGR/cleaned new gasket
changed the PCV valve
replaced the O2 sensor (old one broke in 3 pieces)
tried a different IAC (IAC counts seem lower now)
tried the ECM from my Z24
tried the ECM and memcal from Z24
replaced the map connector
tried a different vacuum source for the MAP
plugged the EVAP and cruise, hvac, vacuum ball lines
tried different MAP of course
and ya I disconnected the battery...

[IsaacHayes]

Can you measure the manifold vacuum to verify? With a gauge of course.

[geoffinbc]

Do the map values change when you step on the throttle?

Also if you have a hand held vacuum pump you can apply vacuum to the map and verify the map readings with the mechanical gauge on the pump.

[scott0999]

if I disonnect the vacuum line it goes up to 95kpa if that helps

[geoffinbc]

Ok well that means the ECM is reading the MAP sensor. But you still need to verify with a gauge. I don't know how hard it will be to find a vacuum gauge in kilopascals though.

However looking at the results your are not far off from the norm. The MAP sensor has a range from 0 to 1 bar. 1 bar=100 KPA so at WOT or the map exposed to atmosphere you should read 100KPA you are getting 95 I would say that is spot on if you are anywhere above sea level. At idle you are getting 55kpa which is roughly 1/2 atmosphere which seems to also be ok. The vacuum an engine will pull depends on a lot of different things. Maybe the map is correct and its running poorly because of something else.

[85_Olds_Ciera]

91 beretta 3.1 auto
the MAP is showing 55kpa at idle, so its dumping 2x as much fuel it needs and running like crap.

Coolant Temp Sending Unit - What is vehicle's temperature when running?

[MidnightriderZ24]

i was going to say temp sensor, or a intake gasket leak.. u try a fuel pressure test? could be a bad fpr..

[scott0999]

i got it fixed, the lim gasket was blown

[85_Olds_Ciera]

i got it fixed, the lim gasket was blown

Good to hear....now what is a "lim gasket?"

[TazMan]

Good to hear....now what is a "lim gasket?"

LIM = Lower Intake Manifold

[85_Olds_Ciera]

LIM = Lower Intake Manifold

Oh...then if you buy a $2.00 can of Starting Ether...and spray here, spray there while engine is idling, then you don't have to do this below, right?

looked at all the vacuum lines - no cracks
ohm'd the injectors, all were between 12-12.2
cleaned the plenum and installed new gasket
cleaned the TB and installed new gasket
completely disassembled EGR/cleaned new gasket
changed the PCV valve
replaced the O2 sensor (old one broke in 3 pieces)
tried a different IAC (IAC counts seem lower now)
tried the ECM from my Z24
tried the ECM and memcal from Z24
replaced the map connector
tried a different vacuum source for the MAP
plugged the EVAP and cruise, hvac, vacuum ball lines
tried different MAP of course
and ya I disconnected the battery...

[Superdave]

I don't think that would have helped since the LIM gasket isn't really accessable other than with a curved straw and removed valve cover.. but who wants to spray ether into the crankcase?.. dosen't sound like fun to me

[85_Olds_Ciera]

...LIM gasket isn't really accessable other than with a curved straw and removed valve cover.

You mean you could spay ether down individual push rods, while motor is running?

On SBC, hydralic lifters can be adjusted via removing valve covers, and letting motor run. It makes a mess...but it has been done this way years ago.

On my 2.8 motor today, I sprayed around and found EGR's "push-rod" is not completely sealed, and around top-intake cover is not completely sealed on one side.