Stays in open loop, DTC, o2 readings
06-01-2005, 01:16 PM
#1
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Join Date: Aug 2004
Location: Augusta, Georgia
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Stays in open loop, DTC, o2 readings
Ran Datamaster for the first time today and I need some opinions. I'm getting Malf 29 (EAS Electrical Fault) and my SES light comes on intermittantly. The car is staying in open loop and one O2 reads 900's while the other stays at about 450 mv. If someone could take a look at the file and give me some feedback I'd really appreciate it.
Datamaster .uni file:
http://briefcase.yahoo.com/lperkins30909
(must have yahoo id)
Datamaster .uni file:
http://briefcase.yahoo.com/lperkins30909
(must have yahoo id)
06-01-2005, 01:49 PM
#2
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Location: Jacksonville,fla
Posts: 1,983
Re: Stays in open loop, DTC, o2 readings
First off, if one o is bad and the other one is good, your pcm willl not go into closed loop. You need to replace the 02 sensor, it wont hurt your car by any means but you will get crappy gas mileage and your pcm will not know what kind a/f ratio to look for being that it wont be reading the o2's.
Im not sure about the eas ses coe your pulling, I'll let some else comment about that one as Ive never dealt with that one before.
Im not sure about the eas ses coe your pulling, I'll let some else comment about that one as Ive never dealt with that one before.
06-01-2005, 02:44 PM
#3
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Re: Stays in open loop, DTC, o2 readings
So the one reading a constant 450 mv is bad and the one jumping around in the 900's is good, right? Does that reading mean its not heating up/dead? I assume "0" mv reading would indicate a wiring problem?
I read that Malf 29 has something to do with the air pump. Would the air pump cause a o2 sensor to go bad if its not functioning?
I read that Malf 29 has something to do with the air pump. Would the air pump cause a o2 sensor to go bad if its not functioning?
06-01-2005, 02:53 PM
#4
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Re: Stays in open loop, DTC, o2 readings
DTC 29 means the fuse is blown to the AIR pump power supply. Replace the fuse. If it continues to blow (the AIR pump rusts and siezes up), you can unplug the harness connector, then put a good fuse in the circuit to eliminate the code and SES. A faulty AIR pump won't hurt the sensor. In theory the AIR is there to help the cats heat up faster.
The PCM supplies 450mV to the sensor. If the sensor is 1) cold, or 2) deceased, the PCM simply "sees" and reports its own 450mV signal.
When you start the engine cold, both sensors should read about 450mV. As they heat up, the signal should start to drop gradually, all the way to 00X mV's. Then, the PCM will go into closed loop and the sensors should start to swing between 0XX-9XX mV about 10 times per second. They change so fast, you can't capture all the data on a scan log, unless you can get the scan time per frame down to 1/10th second.
The PCM supplies 450mV to the sensor. If the sensor is 1) cold, or 2) deceased, the PCM simply "sees" and reports its own 450mV signal.
When you start the engine cold, both sensors should read about 450mV. As they heat up, the signal should start to drop gradually, all the way to 00X mV's. Then, the PCM will go into closed loop and the sensors should start to swing between 0XX-9XX mV about 10 times per second. They change so fast, you can't capture all the data on a scan log, unless you can get the scan time per frame down to 1/10th second.
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