Tuning out all O2's
Tuning out all O2's I was told that instead of buying a corvette O2 sensor, that I could just tune them out. I already have rear O2 deletes. My question is this, if I tune out all the O2's will it effect power, drivability, or make it run rich or lean? If it is going to make the car run weird I don't want to do it. However, it would be nice not to deal with O2's anymore.
I was told that instead of buying a corvette O2 sensor, that I could just tune them out. I already have rear O2 deletes. My question is this, if I tune out all the O2's will it effect power, drivability, or make it run rich or lean? If it is going to make the car run weird I don't want to do it. However, it would be nice not to deal with O2's anymore.
You will need to get the car tuned to run open loop. I can't comment on any increase in power but when running open loop you can create a pseudo lean cruise setting to help on the gas mileage if its a concern.
You can also choose to run with the MAF or with out the MAF (SD tune) as they are not related.
You can also choose to run with the MAF or with out the MAF (SD tune) as they are not related.
While I can agree on the MAF and possibly the O2s, I can't see why you would remove the knock sensors. I know some tuners "desensitize" them but I would think you'd want some warning if you get knock say from a bad batch of gas.
I cannot agree with the IAT sensor comment, it is very well needed to get optimal timing, without it, your just compromising somewhere.
You are a little quick to disagree. Did it ever occur to you that purpose built race cars tend to run with the timing locked out? You might want to consider other applications (aside from yours) before making a blanket statement. Please notice I said "sometimes" on the IAT.....
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Verdad Gallardo 1. Noise interference from aftermarket bolt on parts.
2. The harmonic frequency of the rotating/reciprocating parts.
Both things will trigger false knock counts. Let's say the rockers are loud. Then you desensitize the pcm's response to the false knock. Many people consider any registered knock counts (after that) as true detonation. When in fact, it's just a resonance of the offending part. In this case the rocker arms.
Knock sensors are designed to send a signal when a certain frequency is reached. Changing any rotating/reciprocating part will alter the harmonic frequency of an engine. Thus changing the harmonic frequency of detonation. In turn, making the knock sensors useless.
For the record, You must have front o2's ONLY if the vehicle has catalytic converters.
My statement is still factual.
your still making a compromise with locked timing, for a race car, where consistancy is more important than optimal/safe power, it is an acceptable method of acheiving the desired goal.
Ryan
your still making a compromise with locked timing, for a race car, where consistancy is more important than optimal/safe power, it is an acceptable method of acheiving the desired goal.
Ryan
The timing is not locked out due to a compromise. That is what the engine likes/wants. The IAT is actually remove FOR consistancy, not to throw safety out the window for a few extra ponies...
FormerVendor
Joined: May 2006
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O2 sensors report rich, then the PCM pulls a little fuel or O2 sensors report lean, then the PCM adds a little fuel.
PCM uses data from the O2 sensors to establish both Short-term and Long-term fuel trims in an effort to maintain an injector pulsewidth that will create an A/F ratio being commanded. In Closed Loop operation with a stock PCM, this desired A/F ratio is 14.7:1 which creates the minimal amount of harmful emissions.I thought a lot of people ran front O2's for this purpose regardless of whether or not they were running cats. I could be mistaken though.
Last edited by ChrisS@sdpc; Feb 4, 2008 at 07:59 PM.
I was under the impression that the front O2 sensors monitored A/F ratios to provide feedback to the PCM for Closed Loop fueling.
I thought a lot of people ran front O2's for this purpose regardless of whether or not they were cats. I could be mistaken though.
O2 sensors report rich, then the PCM pulls a little fuel or O2 sensors report lean, then the PCM adds a little fuel.
PCM uses data from the O2 sensors to establish both Short-term and Long-term fuel trims in an effort to maintain an injector pulsewidth that will create an A/F ratio being commanded. In Closed Loop operation with a stock PCM, this desired A/F ratio is 14.7:1 which creates the minimal amount of harmful emissions.I thought a lot of people ran front O2's for this purpose regardless of whether or not they were cats. I could be mistaken though.
fronts are for stoich commanded AFR.
you delete them by disabling closed loop fueling.(open loop)
as far as disabling knock sensors, that is not necessary in most cases.
FormerVendor
Joined: May 2006
Posts: 187
Likes: 0
I was told that instead of buying a corvette O2 sensor, that I could just tune them out. I already have rear O2 deletes. My question is this, if I tune out all the O2's will it effect power, drivability, or make it run rich or lean? If it is going to make the car run weird I don't want to do it. However, it would be nice not to deal with O2's anymore.
Depending on where you live, you may need them for inspection purposes.
The biggest problem I have found (w/ CL operation) is camshaft reversion. This means AFR via wideband is skewed anywhere there is a large amount of overlap. Most of the time the problem lies at idle. Running CL with a big cam CAN result in a rich condition the wideband cannot sense.
..at any rate, vehicles do not run optimum at 14.7 . For example,light load/cruse situations at 15.5ish will net the best MPG. Depending on the cam, 16.0 might net the smoothest idle. You cannot do this type of programming in closed loop. Hope this answers any questions you might have....
FormerVendor
Joined: May 2006
Posts: 187
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You are right, a lot of people do run the front O2's to monitor and adjust AFR. Here is the deal. Stoichiometric is the AFR required for proper catalyst operation. That is why the factory O2's are designed to operate @ that exact AFR. Removing the front O2's while keeping the cats will change the average AFR from 14.7, regardless of how well the tune is. This will kill the cats. Higher than 14.7 will burn em up while lower than 14.7 will clog them.
The biggest problem I have found (w/ CL operation) is camshaft reversion. This means AFR via wideband is skewed anywhere there is a large amount of overlap. Most of the time the problem lies at idle. Running CL with a big cam CAN result in a rich condition the wideband cannot sense.
..at any rate, vehicles do not run optimum at 14.7 . For example,light load/cruse situations at 15.5ish will net the best MPG. Depending on the cam, 16.0 might net the smoothest idle. You cannot do this type of programming in closed loop. Hope this answers any questions you might have....
The biggest problem I have found (w/ CL operation) is camshaft reversion. This means AFR via wideband is skewed anywhere there is a large amount of overlap. Most of the time the problem lies at idle. Running CL with a big cam CAN result in a rich condition the wideband cannot sense.
..at any rate, vehicles do not run optimum at 14.7 . For example,light load/cruse situations at 15.5ish will net the best MPG. Depending on the cam, 16.0 might net the smoothest idle. You cannot do this type of programming in closed loop. Hope this answers any questions you might have....
I don't have any questions as it relates to the purpose of the front O2's. I've been around for a little while.
I think you might be confusing some people with your posts though.
I never said stoich was "optimal", but I did say that it produces the least amount of emissions. There is a lot of documentation out there regarding this.
BTW, a lot of research that is going on in the automotive industry involves cats. I spent about a week at MIT a year or so ago, and most of the tests in the lab involved cats. Generally speaking, other constituents in the exhaust stream are much more likely to kill the cats than a lean or rich condition. This is one of the main reasons that the composition of standard motor oil has changed in recent years, but that is an entirely different discussion. I was also under the impression that most 3-way catalytic converters worked better with slightly lean input. I could be mistaken though.
Not too many people on this board remove their front O2's and keep their cats. Most people willing to remove their front O2's don't care too much about the effects, probably do their own tuning, etc. i.e. they are fairly hard-core about it.
Now, there are quite a few people that have added exhaust systems in which they have removed their cats but keep their front O2's. Several of the sponsors sell off-road setups (wink wink).
The original question was "can I tune out my front O2's?" For most people here (95%+), this is not a realistic option for a whole list of reasons.
Of course, Ban1dit could simply go unplug his front O2's. I am willing to bet the outcome will be less than 'optimal'.
Last edited by ChrisS@sdpc; Feb 4, 2008 at 10:12 PM.
BTW, slow is absolutely right about locked out timing being a compromise. There is no such thing as a single timing value "that the motor likes" across all rpm and throttle values. The reason for this compromise generally involves eliminating excess moving parts and other variables in a race only motor.
FormerVendor
Joined: May 2006
Posts: 187
Likes: 0
If you run SD, the IAT is absolutely necessary, unless you plan to retune everyday (or several times a day). The ONLY way that isn't true is if you don't mind random AFR fluctuations with every temperature swing.
BTW, slow is absolutely right about locked out timing being a compromise. There is no such thing as a single timing value "that the motor likes" across all rpm and throttle values. The reason for this compromise generally involves eliminating excess moving parts and other variables in a race only motor.
BTW, slow is absolutely right about locked out timing being a compromise. There is no such thing as a single timing value "that the motor likes" across all rpm and throttle values. The reason for this compromise generally involves eliminating excess moving parts and other variables in a race only motor.
I don't have any questions as it relates to the purpose of the front O2's. I've been around for a little while.