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87geeinn
05-27-2006, 08:02 PM
With the motor up to operating temp, under moderate to heavy acceleration and subsequent deceleration, my o2s on the Scanmaster will read several numbers but they all are less than 099. For example, Scamaster will show, 032, 078, 025, and sometimes 000 for several seconds, etc. and once I let off the throttle and coast or come to a stop the o2s switch back to what you would normally see at cruise or idle (i.e.-random numbers jumping around from 000-999). What is the 02 sensor doing and/or what is the ECM thinking while this is occuring? New factory GM o2 sensor BTW.

kenmosher
05-28-2006, 10:10 AM
It could be several things:

Faulty sensor
Sensor cooling off
Exhaust leak
Bad ground to O2 (via the pipe)
Chip calibration

87geeinn
05-28-2006, 11:33 AM
*This thread needs moving, but I'm trying to be coherent*

Ok, so in layman's terms, what is the ECM changing when it is recieving those numbers?

The reason I asked is I have a intermittent studdering problem under very light throttle/coasting/deceleration while the aforementioned conditions are occuring. Now that temps down here in FL are 90+ I've noticed that the studdering hangs around longer, hence the other post dealing with "PE vs. coolant temps." It almost feels as though fuel is being dumped into the cylinder minus the backfire. Kind of like the injectors are still pumping away even though the throttle has been decreased. :idea:

The 02 ground is on the back of the passenger head right? If so, I've checked this and it seems secure, plus the sensor is new. I'm leaning toward something in the chip as I don't recall this happening with the 30# injectors i had before moving to 009s.

kenmosher
05-29-2006, 09:19 AM
The O2 sensor readings are just the feedback part of the strategy and used as correction factors.

Basically, the ECM has a series of 3D tables that the code (strategies) use to calculate fuel and spark. These tables use sensor inputs to calculate the indexes for looking up values in the tables ... these sensor inputs are mass air flow, O2 sensor, knock sensor, crank sensor, cam sensor, etc.

The strategies are the "logic" that uses these inputs and the look up tables to determine what the engine needs/wants and drive actuators (injectors, coils, IAC, etc.).

Thinks like Acceleration Enrichment are strategies that involve adjustments to to "logic" (in this case, it acts like a carb pump shot) that deal with transitional conditions or Power Enrichment (to deal with load conditions).

Specifically, in your case, usually the coolant temp is used in every strategy as a factor, not specifically in PE.

Basically, I think the idea of a hanging injector, weak MAF, or chip cal might be where you need to be looking.

The O2 grounds through the exhaust pipe, BTW.

87geeinn
05-31-2006, 09:58 PM
Complicated, but I get a rough idea of what your saying. Given the fact, I have been working with Eric @ TT on tweaking my car, I'm leaning toward my stock replacement MAF sensor. The injectors are new 009s, the Delco 02 sensor is new, etc. I think I'm a good candidate for going to the LS1 + Translator given the reputation of those stock replacement MAF sensors even though my MAF "appears" to work properly on the Scanmaster.

onefastcar
06-02-2006, 09:43 PM
I went to a trans + and it was noticeably better at idle, i like the tunability that i have with it also, wouldn't be a bad move in my opinion oh and BTW i live in florida and it was 96 today, still suprises me that my rad temps don't go much over 173 with air on to.:thumbsup: