What can be up with my o2 sensor

[cecil bass]

When i test from the ECM do i just test for ohms? Should car be running or test with car off?

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[earlbrown]

The car can't run with the ECM unplugged. If you want to make sure the wire from the 02 to the ECM is intact do this.... Ground the 02 wire under the hood (and easy way is to cut a pigtail off of an old 02). Then probe the 02 wire at the ECM with a VOM set to 'ohms'. If the wire (I believe it's purple, but make sure) shows a direct short to gound I.E. '0 ohms', the the wire is intact. Then get someone to watch the meter while you wiggle the underhood wiring and see if the reading goes open and fluctuates. With you setup I don't think that's your case, but hey, you're already there

Personally I'm guessing your chip has you idling on open loop, your 02 gets lazy and quits talking. Running the heated sensor complicates things since they have a track record of not coding when they go bad.


Or just hook up the scanmaster and watch the CC screen when it acts up.

 

[cecil bass]

How much should the CC # go up at a time?

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[earlbrown]

It jumps a few digits at a time when it's working. When it's working well it jumps quite a few.

The CC measurement tells you how many times it's ran the A/V back and forth across 14.7:1 in a 1.4sec timespan. I haven't paid enough attention to mine to see if the powerloggers faster update changes that variable though.

 

[cecil bass]

Ok i hooked up my scanmaster w/ the 2.2 upgrade the CC is go to a number and just sits there for any where from 30 secs to a few mins. I unpluged the O2 sensor from the harness and im not getting any trouble codes is this normal?

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[earlbrown]

If the engine is warm and in closed loop you should be seeing the CC go up to 255 then start over.

I wonder if it didn't throw a code because it was in open loop and not looking at the 02? That would be a question for Eric.

 

[cecil bass]

Is he on this forum too?

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[Pronto]

He makes Turbo Tweak chips.
http://www.turbotweak.com/forum/forum.php
Join the forum and post away...

 

[TurboTdr3.8]

-Open loop idle for smoothness, idle BLM still has learning capability (not locked to 128). from the Turbotweak site

 

[cecil bass]

so this mean the O2 sensor is fouled out? or is something else "out".

 

[Pronto]

I always check the cc while driving. You can see easily if it's cycling or not. If it's slow or stuck I replace it.

 

[Emiliano Lago]

x2

 

[cecil bass]

I reset the ecm and drove the car around so it can learn... now it runs a little better but it runs better with the o2 sensor unplugged with the o2's 395-400 when I plug the o2 sensor it jumps to 700 - 800 for a few seconds then they just fall to 000 ???? The CC go up by 2 every 5 to 10 secs ....... any suggestions ?

 

[cecil bass]

the temp here was finally above 0 so I was able to install a new single wire sensor and took the heated one off. The car runs better at least it doesn't surge as much at idle, but the voltage for the o2 sensor keeps falling. Im not sure what to do from here. im attaching a log file so hopefully someone might be able to catch something. ohh by the way when I unplug the sensor im not getting a trouble code..... is this normal? I thought the check engine should come on if the car is running and the o2 sensor is unplugged
Thanks in advance for any help

 

[earlbrown]

Did we ever establish if you had a cracked header?

and, yes, the engine should code when you unplug the 02 sensor. It should throw a soft code, but I've never tried it to make sure.

I guess there's a chance if you have an 'open loop at idle' chip, it won't care as long as you're only idling. A chip burner should be able to answer that question.

 

[cecil bass]

no I don't know if I have a cracked header or not how can I tell? I have a TT chip 5.7 how can I tell if its open loop idle or not ?

 

[cecil bass]

my cross counts are going up rapidly when the car is driving thou. don't know if that has to do with anything ......

 

[Eric Stage I]

It looks like the O2 is working in the log since it gets richer when you stab the throttle. You will not get a code if you unplug the O2 with a TT chip.

However, you have a MAF code 34, which means the reading is way too low, or its not reading the MAF at all. So I would dig into that.