datalogging open loop.

[GTP091]

Im certainly not a pro with TunerPRO.  Was taking a look at the datalog last night just for shits and giggles.  After getting to temp TunerPRO showed the ECM was still in open loop with a status of the cat 'not ready' ? After a bit more time I shut the car off, disconnected the ALDL, reconnected, started a new session, restarted the car (it was to temp) and it went into closed loop right away.  Not sure if this is an issue with TunerPRO, this was just an anomaly or if my car is getting grumpy.  Nothing was amiss other than this, all values seemed to be good.  The O2 sensor has always made me wonder if it's bad.   The only sensor that hasn't been replaced is the O2 sensor. I have a new Bosch o2 sensor but couldn't budge the original so let it alone, will change when I pull the engine for 5speed swap.  The o2 sensor value was around 320-450 of whatever that value means.

 

Any comments on this?

[55trucker]

 edit

[55trucker]

  The o2 sensor value was around 320-450 of whatever that value means.

 

Any comments on this?

That reading is more than likely in millivolts, if reading an OBD1 scanner the reading would display as between .1 -.9 volts or 100-900 millivolts.

 

A reading that is stuck near 450 millivolts (.45v) would indicate a failed sensor.

[Imp558]

An o2 should read in volts and periods, I'm not sure what a front o2 should be but a rear is .9v at 3.3 seconds at 50% duty cycly. I make rear o2 sims.

[GTP091]

It's certainly OBD1 and the reading during warm up hovered very close to mid 300 but then wnet higher as it warmed.  I'll run it again tonight and note the readings more closely.  It would make sense if the o2 sensor is failed as the car seems to run richer than it should.  Its such a bitch to get at.  I wish I could just change it easily.

[55trucker]

When the engine is still not up to temp so as to allow the fuel system to go *closed loop* the ECM will not be looking for a signal from the o2. I've not had the scanner on my engine for some time, I believe that the temp has to reach 140F before the ECM commands *closed loop*.

 

at the time I replaced the o2 on my engine I had to pull the airbox & remove the exhaust crossover to make adequate room to get my arm down in there.

 

Are you noticing a *stumble* at highway speeds that feels as tho the torque converter is continually locking/unlocking & the throttle pedal when held steady doesn't produce a smooth steady rpm?.

[GTP091]

No stumble at high way speeds.  It revs higher than I think it should when cold but is idling exactly where the ECM says it should in the datalog. The engine seem to run to rich and 'spits' out the exhaust when cold, seems like an ignition miss but I've rebuilt the ignition system so I highly doubt its that side.  The service manual says the o2 sensor is one thing to check but if it doesn't use the o2 data when cold it must be something else going on?  I believe the ECM uses the coolant temp sensor for fuel metering when in open loop.  Ive not replaced that sensor but the data log info shows its fine.  I've replaced all the other sensor culprits it mentions; Other than cleaning/replacing injectors so that might be it which is on the list for the winter 5 speed swap.

[Imp558]

The TCC can be disabled by gently putting your other foot on the brakes, just enough to turn the lights on. You should check fuel pressure and watch where it goes after the engine is shut down. A leaky injector will bleed pressure off and there will be gas in the oil. That's a great way to wash a bearing and destroy an engine.