2003 Cavalier and the dreaded p0172 - FIXED!!!

Last week I began to have running rich problems with my Cavalier, after a week of research and the normal throw money at the problem I thought I would post here to see if anyone else has some ideas.

Things replaced:
o2 sensor
fuel pressure regulator
Injectors + wiring harness for the injectors

The return line is not plugged or blocked in anyway
A new fuel pump was installed 9,000 miles ago

Below is the Freeze Frame when it threw the p0172:

===========================================
Stored:
P0172 System Too Rich (Bank 1)

Pending:
P0172 System Too Rich (Bank 1)


DTC for which Freeze Frame was Stored P0172
Fuel System 1 Status Closed Loop
Fuel System 2 Status Not Supported
Calculated LOAD Value 95.69 %
Engine Coolant Temp 179.60 °F
Short Term Fuel Trim - Bank 1 -18.75 %
Long Term Fuel Trim - Bank 1 -7.03 %
Intake Manifold Absolute Pressure 23.03 inHg
Engine RPM 1753 rpm
Vehicle Speed Sensor 34.18 mph

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The question I have is what else would effect the car and cause it to run rich? I was going to replace the other sensors but I dont want to just keep buying parts untill it runs. I did find alot of useful info on this site and that information is what got me to the point im at now.The car runs a little better than it did but its still running too rich.. blows some black smoke when ya get on it. Any help is greatly appreciated.

Thanks!
Rusty

why the high calculated engine load reading at such a low rpm? Is the fuel pressure spec correct? is it bleeding off? is the egr functioning properly?

as well take a vaccum reading from the intake to verify that the exhaust isn't restrictted. Can you scope the map sensor?

Fuel pressure is good, This year ecotech has no egr. I will check the MAP tomorrow. Exhaust is ok no restrictions. No vaccum leaks that could be found I will try and get a reading at the intake tomorrow also. It is bleeding off the fuel via the return line.

Thanks!

so if the return line is plugged off then the rail holds pressure? it's not bleeding? the pressure isn't too high?

I finally fixed the issue! It ended up being the MAP sensor. 56.00 at the parts store I bought mine off Ebay for 19.99 + 6.00 Shipping.

Thanks to everyone for the help and I hope this post helps someone else that runs into this same issue.

Rusty

Kinda what I thought it'd be! the clue in your freeze frame is like I pointed out the calculated engine load at 96% while at such a low rpm! I had a caravan last week with the same fault code with a failled map sensor. The scan tool reading was 11 hg at idle when actual gauge reading was 22 hg.

congrats

Ya when you mentioned the high load I did some reasearch on it and thats why I replaced the MAP sensor what you said made sense. I would have resolved this alot sooner but I didnt buy the nice OBD2 reader untill after I replaced the common parts.

Thanks for all the help!

helo ¡

Jeff: I have a question: If the MAP sensor is working bad, why it didn´t appeared like a trouble code ??? Is these common ??

thank´s

specific sensor failure dtcs are pretty much just to tell you that the circuit it's involved in is failling! ie unpluuged, high, high resistance on signal, low etc, his map sensor circuit was fine but the sensor was nfg. These are the kind of cases that seperate real good techs from okay techs. Take away any code from the equation and leave only data and most guys can't see the forest for the trees!