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Uprev: Params to log to determine P0171 P0172 cause?

Old Aug 21, 2012 | 08:56 AM
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Default Uprev: Params to log to determine P0171 P0172 cause?

RIght now I am using my Proefi to control fuel/timing, but letting the stock ECU control the cam phasing.

I have Uprev Tuner. Its an 2003 with all narrowband O2 sensors. I cannot get my H02S to go "ready", but there are no codes indicating an issue. (which could be either the up or downstream O2 sensors...)

I am getting the P017x codes (Fuel injection system too lean or too rich) which in turns, shuts off the cam phasing. I need to determine where the stock ECU switches from open to closed loop and if these codes can still be thrown during open loop. Also need to see logs of the situation that causes the CEL to be triggered.
***explains why every p017x thread ppl complain of poor gas mileage and stuttering***

Which params in Uprev should I be logging to determine if my O2 sensors or my MAF is not right?

I have not changed any of the stock ECU fueling params. My target AFR maps look about the same as what I am trying to have the Proefi target.

I figure if its a MAF problem, I should be able to tune it out with Uprev Tuner.

I figure if its a O2 sensor problem, there must be a way to see % compensations or something and again tune it out with Uprev tuner

I cant wrap my head around how the stock ECU/Maf setup even works at all considering it should be maxxing the MAF voltage almost immediately. But thats how the car has been tuned for a couple years now and teh cam phasing works when I dont have that code(s).

Any uprev guru's with suggestions?

Last edited by str8dum1; Aug 22, 2012 at 06:20 AM.
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Old Aug 22, 2012 | 06:17 AM
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so, easier question maybe,

here is a quick log of my NB O2 sensors during a short pull. The upstream sensors follow pretty close, but the downstream ones seem way off. Wouldnt you expect them to overlay? I dont know what narrow band traces should look like though

My Proefi widebands overlay just fine

Attached Thumbnails Uprev: Params to log to determine P0171 P0172 cause?-nb-02-sensor-cipher-08-22-12.jpg  

Last edited by str8dum1; Aug 22, 2012 at 06:19 AM.
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Old Aug 22, 2012 | 08:09 AM
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I thought by definition that a narrowband was only meant to provide two states, stoich or not?
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Old Aug 29, 2012 | 10:05 AM
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I see you have a pretty big difference between upper and lower sensors, whatever is causing that could be part of the issue leading to your codes. Unless you have cats the upper and lower sensors should be reading the same...

(FYI, those codes are usually the result of closed loop corrections maxing out).

Last edited by djamps; Aug 29, 2012 at 10:30 AM.
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