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Another O2 question

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whiner

Member
Joined
Aug 30, 2009
Messages
84
I have installed a new Denso o2 sensor. Car does seem to idle better when hot. But I still have the o2 voltage on the scanmaster going from about 175-800 at idle. Any ideas? I could really use you help. TPS sensor is .42 when not running and .44 when running at idle. :confused:
 
I have installed a new Denso o2 sensor. Car does seem to idle better when hot. But I still have the o2 voltage on the scanmaster going from about 175-800 at idle. Any ideas? I could really use you help. TPS sensor is .42 when not running and .44 when running at idle. :confused:

if its a tt chip it should lock on around 800 ish at idle after warmed up. as for the .42 motor off and .44 running that is normal because the rush of air opens it up a little
 
I know the TPS sensor is set right. But what causes the fluctuation so much in the O2 sensor at idle? I take it this is not normal?
 
I have installed a new Denso o2 sensor. Car does seem to idle better when hot. But I still have the o2 voltage on the scanmaster going from about 175-800 at idle. Any ideas? I could really use you help. TPS sensor is .42 when not running and .44 when running at idle. :confused:

Are those readings in gear or out of gear?
 
In park after the engine is at operating temp.

I think the readings are normal if you are in park. I think the chip only goes in open loop idle if you are in drive. Put it in drive and see what the readings are.
 
I think the readings are normal if you are in park. I think the chip only goes in open loop idle if you are in drive. Put it in drive and see what the readings are.

it works in park as well as drive it changes when the tps is changed or when you press on the gas.
 
it works in park as well as drive it changes when the tps is changed or when you press on the gas.

QUIP'6' is technically correct. It is in open loop when the TPS is below .5V but the O2's do cycle if you are in P/N after you are warmed up even though the closed loop flag is not set. I just looked at some of my data logs and the O2's do cycle in P/N even though the Closed Loop flag is not set. I put the car in gear and the O2's stop cycling and hold around .820
 
My O2's are all over the place in park, neutral, or drive. I even tried different gas today and they still jump all over the place and now I even have a little knock. Also noticed the car idles anywhere from 750-850 in drive. Anys suggestions???
 
What are your MAF numbers at idle? Have you checked for any air leaks between the MAF and the throttle body? Check for vacuum leaks?
 
I will check the MAF #'s tomarrow. I did just check all the clamps and connections before I dove it earlier today.
Correct me if I am wrong, but won't the car barely run at all with a bad MAF?
I know how the new cars are with a bad MAF.
 
Just went and checked MAF reading at idle is 05. When I disconnect the MAF the idle does smooth out but stumbled when I give it a gas. I did not try to drive it.
Hopefully this will help.
 
Check to see if the car is staying in closed loop at idle. The knock retard decimal point on the Scanmaster will blink in open loop, and remain solid in closed loop.
With my chip, when fully warmed up, and you come to a stop, it should switch to open loop (blinking decimal point).
Eric
 
I've had a TT chip and a SM for 6 years...never knew what the blinking decimal point meant until now. Awesome!
 
What is your BLM at idle?
As long as it's idling ok, then the O2 number is not terribly important. "Usually" when idling in open loop, the O2 ends up somewhere above 700mv, but not always.
 
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