dumb CEL query

Also, I NEVER replace a MAF without also changing the air filter(s). Did you change yours at the same time?
This doesn't happen all the time but a handful of times I have run into a problem where a new MAF won't/can't self adapt because of dirty air filters. Even only "slightly" dirty as well.
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Old, original MAF/"New" MAF
ABSLT TPS 18% / 13.7%
RPM 2058 / 1072
Calc Load 15.6/11.3%
MAP 38(KPA)/29(KPA)
Coolant 96 F (not warmed up completely)/129 F
ST FTRM1 0.0%/0.0%
LT FTRM1 0.0%/0.0%
33mph
Fuel sys1 open (does this mean fuel cap open/defective?)/Open
Don't know if this is relevant, but looking at the MAF plug noticed it has 5 female recepticles, only 4 have metal contacts, MAF has 5 male pins. Does this mean anything? Here's photos...Thx
Last edited by ulmapache; Nov 27, 2011 at 10:27 PM. Reason: add more info/photos
Old, original MAF/"New" MAF
ABSLT TPS 18% / 13.7%
RPM 2058 / 1072
Calc Load 15.6/11.3%
MAP 38(KPA#/29#KPA#
Coolant 96 F #not warmed up completely#/129 F
ST FTRM1 0.0%/0.0%
LT FTRM1 0.0%/0.0%
33mph
Fuel sys1 open #does this mean fuel cap open/defective?)/Open
DTC code p2228
New air/fuel filter, spark plugs, coil ignition units, no vacuum leaks
Any ideas on which sensor to go after?

The freeze frame tells us nothing. Just gives
Throttle position
RPM
Load
Manifold pressure, coolant temp, speed etc.
"Fuel sys1 open" means the engine is not fully warmed up & the injection system is still running "open loop" i.e with enriched mixture & ignoring O2 sensor input.
You might have to get this car onto a Star to find why the aneroid "barometric sensing" is haywire.
I do not know the M271 as well as the bigger engines. The 4 cyl models use a different injection system. I just want to check the post above that the aneroid sensor is integral with the MAF. On older models it was not & used to get full of dust & cease to operate properly. Cleaning generally fixed it.

The aneroid/barometric pressure sensor is separate to the MAF on the M271 & thus is suspect. Clean or replace sensor 80 in the diagram. As you can see it's been updated a few times.

80 A 004 153 33 28 SENDER UNIT
ALTITUDE SENSOR
Replaced_By: A 005 153 72 28 001
80 A 005 153 72 28 PRESSURE SENSOR
ALTITUDE SENSOR
B18 001
80 A 004 153 33 28 SENDER UNIT
PRESSURE SENSOR INTAKE PIPE
B28
Replaced_By: A 005 153 72 28 001
80 A 005 153 72 28 PRESSURE SENSOR
PRESSURE SENSOR INTAKE PIPE
B28 001
Good luck
Last edited by Glyn M Ruck; Nov 30, 2011 at 06:04 PM.

I swear I'm going to donate this thing to a heavy weapons shoot in Bald Knob KY.....so long as I get the first shot with the biggest gun....
Again, thanks for all the help, I'll get to the bottom of this eventually.....



