need code 44 lean exhaust help

Sep 10, 2005
got a code 44 lean exhaust, ecm seems to stay in open loop,integratr at 128,block learn 150,iac 38,spark advance 36,coolant 177,maf 6,02 crosscounts 0,any help? I was thinking of a vacuum leak, bad egr,coolant sensor,02 sensor? i do have noticed a small leak at the left exhaust mani...but i think i should start with the reason why the car is in open loop....what do u folks think?...
BLM @ 150 is trying to add fuel to the max, (lean condition, long term). Zero O2 crosscounts might be why it won't go into closed loop. IAC at 38 (idle I assume) is good indication of no vacuum leak @ idle. What's the idle RPM?
I'd like to see the O2 sensor readings: switching rich/lean or changing up and down from the .45 volt center point. You can tap in with a voltmeter to the single wire O2 sensor lead, positive lead to sensor and ground anywhere. When warm and running, you should see constant changing up and down from .45 volts. Actual rich condition above .45v and actual lean below .45v. Integrator above 128 is trying to add fuel short term and BLM above 128 is long term fuel addition.
I would check for clogged fuel filter by removing and blowing through it, you want NO restriction. Replace it if you have any doubts, $12.00. You will also need fuel pressure reading to properly diagnose, 42 psi, regulator vacuum line off is a good standard.


Trouble Code 44 indicates that the O2 sensor is showing a persistently high exhaust oxygen content (lean), despite the efforts of the ECM to increase injector on-time (thus increasing fuel delivered). Integrator and BLM numbers may indicate > 128 by a substantial margin.

The conditions for setting this code are:

no Code 33 or Code 34 (MAF Error) present, and
the O2 sensor voltage remains below 250 mVolts, and
the ECM is in Closed Loop control, and
the above conditions exist for more than 50 seconds.

Typical causes for this code include:

1) O2 sensor defective or lead shorted
2) Lean injectors (dirty or blocked)
3) Water in fuel
4) Exhaust leaks upstream of O2 sensor
5) Fuel pressure or volume too low
6) MAF sensor reading lower airflow than is actually present
7) Vacuum leaks
8) Incorrect or poorly calibrated PROM

Ya, puttin it simply, your indications point to a fairly serious vacuum leak or a pre turbo exhaust leak.
the exhaust leak before the turbo can cause this i see,i will address this first,do u think the 160 thermostat prevents the coolant sensor from reaching operating temps?..what does the car need to see to reach operating temps for the ecm to go into closed loop?...thanks
The 160 thermostat should not be an issue. Closed loop min. temp. is a lot lower than that.
all done, had left side header welded, runs like old times....had to find another header, mine was rotted at the flange with the 2 bolt nuts just barely hanging on...lasted 200,000 miles..can't complain...bad thing is the header has the spark plug shields missing....caddy's back on the road...