If i can space the O2 sensors out of the exhaust path, will that get rid of my CEL for no Cats?
02-07-2005, 05:17 PM
#2
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I read a thread about that on the WRX forums recently...
Seemed to delay the onset of the DTC/CEL in some cases but did not prevent it. I have no confirmation, but expect our cars would be the same.
-Dave Pramanik
-Dave Pramanik
02-07-2005, 05:23 PM
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The spacers have been brought up here before... with no one really offering an opinion.
I would agree with DAP though. It's just a matter of time.
However, the spacers plus a MIL eliminator might work a little better than either of them solo.
However, the spacers plus a MIL eliminator might work a little better than either of them solo.
02-07-2005, 05:31 PM
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I don't buy the MIL eliminator idea for our cars.
All those do is cap the upper and lower voltage limits by a certain amount. The ECU looks for more than just the absolute voltage difference, I think, so those are unlikely to be successful either.
Most likely what each of those things will do (particularly if used together) is provide the ECU with a signal that it can tell is invalid and thus you'll get a different DTC (implausible signal or something like that).
The only sure solution IMO is a programming one a la APR testpipe code.
-Dave Pramanik
Most likely what each of those things will do (particularly if used together) is provide the ECU with a signal that it can tell is invalid and thus you'll get a different DTC (implausible signal or something like that).
The only sure solution IMO is a programming one a la APR testpipe code.
-Dave Pramanik
02-07-2005, 05:33 PM
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are we 100% sure that the secondary O2's are ONLY used for emissions?
I thought there was some talk a while back about the possiblity of them being used in for minor afr adjustments in conjunction with the primary O2's.
02-07-2005, 05:34 PM
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Some of the A4 guys are doing this.
Digit@lex in particular threw these in after he threw a CEL light following a HFC install in his T28 A4. I forget how long it's been, but I think it's been over six months now, and no CEL has returned.
02-07-2005, 05:35 PM
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O2 sensors have to reach a certain temp before they work. Somehow the ecu knows/guesses this temp
or, at least, it waits for them to go "rich" before it starts using them. Since exhaust is a lot cooler after the cats, it takes the downstreams longer to reach operating temp. So what I'm saying is, even if it worked and the ecu never even looked at them, it would never complete the "catalyst monitor" test and would never pass an emission inspection even if the CEL stayed off.
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02-07-2005, 05:36 PM
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I might just be old fashioned/missing the point/dense, but............
Why don't you just run it with the damn cats installed??? Good high-flow cats are not going to make THAT much of a difference.
02-07-2005, 05:44 PM
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Bentley says they are used but numerous sources disagree...
including tuners who have looked at the code. FWIW, I have a wideband sensor in place of one of my secondary sensor with no ill effects. Fuel trims still adjust as necessary based on data from the primaries.
I'm convinced that the Bentley is wrong and the rear sensors have no effect on fueling, FWIW.
-Dave Pramanik
I'm convinced that the Bentley is wrong and the rear sensors have no effect on fueling, FWIW.
-Dave Pramanik
