Lazy 02 Sensors? Time to Replace?

[06300CSRT8]

Car runs decent but I am finally spending some more time on the idling and cruising, still have a decent amount of surging and wild fuel trims. Never believe I am have seen 02 voltages like this, nearly zero out. What do you guys think? This is a pump gas tune, 426ci stroker, pretty big cam, long tubes with no cats. Log attached is in park, then a short reverse, then slow cruise for just a mile or so. Also in the middle there is a free rev in neutral, you can see how it cant hold a steady rpm at all.

3.0 Suite Michels300CSRT8 TCM Rev1 PCM Meth 9.hpt3.0 Tune TCM Rev1 PCM Meth 9 Slow Cruising.hpl

[06300CSRT8]

Bump, anyone able to weigh in?

[RonSSnova]

Look in the fueling section under open & closed loop.
See if you have O2 airflow delay over on the left of the screen under closed loop enable.

If you have these, the tables change the timing of the NB O2 sensors. Helps a lot with surging etc caused by headers.

Multiply by 2-300%.

If you have them anyway....

[06300CSRT8]

Nope, not in our cal

[RonSSnova]

They have added it for us on a case by case basis. But you need to make the change in Diablo first, then read the file and send to support.

[Mep_q8]

Re-scale the throttle airflow voltage to show you a higher resolution at idle, that should do the trick for a smoother idle. I once tried putting values in the 0V with really bad results.

[06300CSRT8]

Re-scale the throttle airflow voltage to show you a higher resolution at idle, that should do the trick for a smoother idle. I once tried putting values in the 0V with really bad results.

I will give this a shot, which specific table? The actual throttle body airflow table or the Desired Throttle large and small? My current throttle body table is attached, you think I should add more than the 0.10 increments it has?

TB Airflow.JPG

[Mep_q8]

No the Throttle Body Airfow

Under: Engine - General - Throttle Body Airflow

[06300CSRT8]

Ah yes, thought that's what you meant. So add some more rescaling...how do I know based on the log if the values need to actually be changed?

My tune has a value in the 0V spot, been that way since a few tuners ago. What "bad" results did you actually see?

TB Airflow.JPG

[06300CSRT8]

I took an older log and made a quick histo of TPS voltage vs Total Airflow and these were the averages, should I be putting in these values into my TB Airflow table? Quite a bit diferent than whats in there now, but I assume its right and this is the real airflow coming in.

Histo TB Airflow.JPG

[06300CSRT8]

Just keeping this discussion updated, in factory form the throttle body airflow and the desired throttle small and large tables are 100% inverses of each other. I am assume if I do not want to have the PC correlating my commanded pedal position vs airflow table, these other two tables should be lined up to the new throttle body airflow table?

Otherwise, I would think I push the pedal to 0.30 volts, computer knows that means I want 126 lb/hr of airflow, goes to the throttle body airflow table, finds 126 and now sees that as .20 volts. SO I will be left with a log that shows 0.20 TPS voltage and 126lb/hr.

TB and Desired Airflows Small and Large.JPG

[Mep_q8]

Yeah this table is a little tricky, it's the maximum airflow the ecu should be seeing at these voltages. If you were facing a surging idle, I would decrease these values just to stop with the extra airflow creating the surge.

Interesting it was there from the factory. From what I've seen the 0V is normally set at 0. The results I had was a really jumpy idle that wouldn't settle down. I set the 0v back to 0 and increased the resolution to get more control. I've adjusted yours, by no means will it work, but get you in the ball park.

Take a look at the difference in voltage settings on the row tables. In the scanner above I couldn't seem to find TB Votage, but from experience I've seen idle to hang around 0.20-0.27 V. If you're getting a surging idle, then the values set between the 0.2V and 0.3V are too far apart. Breaking them down you should get more control.

[Mep_q8]

Just keeping this discussion updated, in factory form the throttle body airflow and the desired throttle small and large tables are 100% inverses of each other. I am assume if I do not want to have the PC correlating my commanded pedal position vs airflow table, these other two tables should be lined up to the new throttle body airflow table?

Otherwise, I would think I push the pedal to 0.30 volts, computer knows that means I want 126 lb/hr of airflow, goes to the throttle body airflow table, finds 126 and now sees that as .20 volts. SO I will be left with a log that shows 0.20 TPS voltage and 126lb/hr.

Attachment 57882

I haven't played around with the large throttle and small throttle tables yet. But that makes sense, the way I'm doing it is limiting the airflow factor to get idle to be tame.

[06300CSRT8]

Yeah this table is a little tricky, it's the maximum airflow the ecu should be seeing at these voltages. If you were facing a surging idle, I would decrease these values just to stop with the extra airflow creating the surge.

Interesting it was there from the factory. From what I've seen the 0V is normally set at 0. The results I had was a really jumpy idle that wouldn't settle down. I set the 0v back to 0 and increased the resolution to get more control. I've adjusted yours, by no means will it work, but get you in the ball park.

Take a look at the difference in voltage settings on the row tables. In the scanner above I couldn't seem to find TB Votage, but from experience I've seen idle to hang around 0.20-0.27 V. If you're getting a surging idle, then the values set between the 0.2V and 0.3V are too far apart. Breaking them down you should get more control.

Going to try this. FYI I am getting PID response on whats called "Throttle Position Sensor" [electric Potential]

[06300CSRT8]

This has been very helpful, I took a few more logs I had stored and ran them through my new histogram and what I am seeing is a little confusing. In most of my logs, the lb/hr that recorded was higher than my TB table. Sometimes only by a few lb/hr but most of the time at least 5-10lb/hr higher in the idle rpm areas. Should I be raising up my TB airflows? I am running a 90MM Arrington cast TB.

[06300CSRT8]

Sooo....didn't work haha.

I went out to do some VE tuning last night. I turned off my O2 sensors and also rescaled my TB airflow table. Same values as before just added more rows in the lower TPS voltages. I also zero'd out the 0 mark. Well surges way more this way. I tried in subsequent tunes to lower the values in the idle area by 5%, then 10% and it actually seemed to get worse. For some reason the TB wants to move around a lot more. I put my original TB airflow table back in, still in SD mode and was much smoother.

3.0 Suite Michels300CSRT8 TCM Rev1 PCM VE Mode 1.hpt
3.0 Tune TCM Rev1 PCM SD 1.hpl

[06300CSRT8]

The difference in the 02 mv from bank 1 to bank 2 also troubles me a bit, my wideband is installed in bank 1. When my WB is reading almost dead nuts 14.7 AFR the 02 sensor is reporting 200mv, and in general my B1 sensor seems really low mv and response compared to B2.

[06300CSRT8]

Alright I actually kind of see whats going on now if I look at the dips in rpms. The way my tune behaves I never see it use timing to bring idle speed back UP once it falls below desired, it only uses the TB. Idle spark correction is opposite, meaning a positive idle spark correction = reduction in idle timing. So the tune is setup to run my part throttle timing, allows it to pull back timing if idle goes ABOVE desired rpm but isn't allowed to go above my part throttle table as idle rpms drop, if you look even when my idle dips to 600rpms the spark advance stays pegged at my commanded 14*. instead it resorts to using the throttle body to open up and bring the rpms back up. When it does so, seems like it is TOO SLOW to react, it opens up too slowly so I get a dip in rpms, the TB opens up, RPMs shoot back up slightly above desired idle rpms, then it pulls some timing, then starts to dip again, opens the throttle body....the cycle continues.

Guess I have to play some more to get this to smooth out.

[Mep_q8]

Leme get back home tmrw and I'll dig into it if you still need some help.

[06300CSRT8]

Leme get back home tmrw and I'll dig into it if you still need some help.

Thanks I have a feeling I am going to. I need to understand better the torque airflow tables, as well. I know this is also part of the puzzle.