O2 Simulator Resistor Sizes & Install Tip
Thread Starter
Burning Brakes
Joined: Jan 2002
Posts: 885
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From: The Woodlands Texas
O2 Simulator Resistor Sizes & Install Tip
Okay, I keep fouling my O2 sensors where my precats used to go (installed a set of SLP long tube headers) - retained the main cats and all 4 O2 sensors. Results in "check engine" light coming on all the time.
I read a thread a long time ago on the size and installation method (which prongs on the plug head to attch the resistor ends to, etc) for installing a set of Radio Shack resistors to simulate the O2's.
Does anyone know the answers to this item? Would appreciate the help.
I read a thread a long time ago on the size and installation method (which prongs on the plug head to attch the resistor ends to, etc) for installing a set of Radio Shack resistors to simulate the O2's.
Does anyone know the answers to this item? Would appreciate the help.
Drifting
Joined: Jul 2000
Posts: 1,818
Likes: 3
From: SoCal
Re: O2 Simulator Resistor Sizes & Install Tip (jeanlucpicard)
You can't just stick resistors into the plug to simulate O2 sensors. That isn't how they work.
Are you trying to just bias the signal from the front o2's a bit, or what? The rear o2's have nothing to do with the A/F ratio. I don't think I understand what you are trying to do.
Jon
http://www.ls1howto.com
Are you trying to just bias the signal from the front o2's a bit, or what? The rear o2's have nothing to do with the A/F ratio. I don't think I understand what you are trying to do.
Jon
http://www.ls1howto.com
Thread Starter
Burning Brakes
Joined: Jan 2002
Posts: 885
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From: The Woodlands Texas
Re: O2 Simulator Resistor Sizes & Install Tip (jmX)
My O2 sensors at the precats are fouling constantly due to the removal of the precatalytic converters - necessary when I installed my headers - resulting in a rich fuel mix combined with higher tempertatures, etc being seen at the O2 pickup point. There is an aftermarket O2 sim kit that sells for around $150 that simulates the O2 input so you can remove the actual sensor - and eliminate the fouling problem. The kit simply plugs into the existing O2 plug under the car.
I want to "simulate" my front pair of O2 sensors so I can do away with the constant check engine light hassle. There have been a few folks on the CF who have done this $150 mod using a set of $5 Radio Shack resistors and connecting the ends to the O2 plug terminals in lieu of purchasing the more expensive prebuilt "plug-n-play" kit. I am seeking info on that approach.
I want to "simulate" my front pair of O2 sensors so I can do away with the constant check engine light hassle. There have been a few folks on the CF who have done this $150 mod using a set of $5 Radio Shack resistors and connecting the ends to the O2 plug terminals in lieu of purchasing the more expensive prebuilt "plug-n-play" kit. I am seeking info on that approach.
Thread Starter
Burning Brakes
Joined: Jan 2002
Posts: 885
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From: The Woodlands Texas
Re: O2 Simulator Resistor Sizes & Install Tip (c5chris)
c5chris:
No, the CAGS is related to a 6-speed's required 1st to 4th shift function which I defeated 3 days after I purchased my vette. My question relates to the 4 oxygen sensors on the exhaust system. I want to bypass / simulate out of the system my 2 "front" precat O2 sensors. See my reponse to another CF member and that may help communicate what I am looking for.
Thanks.
No, the CAGS is related to a 6-speed's required 1st to 4th shift function which I defeated 3 days after I purchased my vette. My question relates to the 4 oxygen sensors on the exhaust system. I want to bypass / simulate out of the system my 2 "front" precat O2 sensors. See my reponse to another CF member and that may help communicate what I am looking for.
Thanks.
Melting Slicks
Joined: May 2000
Posts: 2,974
Likes: 5
From: CenTex Texas
Re: O2 Simulator Resistor Sizes & Install Tip (jeanlucpicard)
I've never heard of anyone that sells FRONT O2 sims ( before the carts), only REAR O2 sims (after the cats). But if someone does then it's news to me. :lurk:
Racer
Joined: Sep 2002
Posts: 332
Likes: 0
From: Austin Tx
Re: O2 Simulator Resistor Sizes & Install Tip (jeanlucpicard)
You cannot do any of the things you are talking about.
1.) Your front 02's are there for the PCM to read how the engine is running. It definitely needs those, you cannot bypass them with a resistor or your car will run like crap (if it runs at all).
2.) You cannot bypass a rear 02 sensor with a resistor. You need 02 simulators. The rear 02 sensors check for the presence of cats and the PCM needs to see a fluctuating signal, which is not possible with resistors.
You need to reinstall/plug back in your fron 02 sensors and buy 02 simulators for the rear.
1.) Your front 02's are there for the PCM to read how the engine is running. It definitely needs those, you cannot bypass them with a resistor or your car will run like crap (if it runs at all).
2.) You cannot bypass a rear 02 sensor with a resistor. You need 02 simulators. The rear 02 sensors check for the presence of cats and the PCM needs to see a fluctuating signal, which is not possible with resistors.
You need to reinstall/plug back in your fron 02 sensors and buy 02 simulators for the rear.
Drifting
Joined: Jul 2000
Posts: 1,818
Likes: 3
From: SoCal
Re: O2 Simulator Resistor Sizes & Install Tip (jeanlucpicard)
My O2 sensors at the precats are fouling constantly due to the removal of the precatalytic converters - necessary when I installed my headers - resulting in a rich fuel mix combined with higher tempertatures, etc being seen at the O2 pickup point. There is an aftermarket O2 sim kit that sells for around $150 that simulates the O2 input so you can remove the actual sensor - and eliminate the fouling problem. The kit simply plugs into the existing O2 plug under the car.
I want to "simulate" my front pair of O2 sensors so I can do away with the constant check engine light hassle. There have been a few folks on the CF who have done this $150 mod using a set of $5 Radio Shack resistors and connecting the ends to the O2 plug terminals in lieu of purchasing the more expensive prebuilt "plug-n-play" kit. I am seeking info on that approach.
I want to "simulate" my front pair of O2 sensors so I can do away with the constant check engine light hassle. There have been a few folks on the CF who have done this $150 mod using a set of $5 Radio Shack resistors and connecting the ends to the O2 plug terminals in lieu of purchasing the more expensive prebuilt "plug-n-play" kit. I am seeking info on that approach.
1) You can NOT make O2 simms with just a couple of resistors, period.
2) You can not run o2 simms on your front o2 sensors. That would be practically like running a maf simulator, or simulating some other ESSENTIAL sensor. The rear o2 sensors are the only ones you should run sims on.
Jon
http://www.ls1howto.com
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Racer
Joined: Jul 2001
Posts: 386
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From: Round Rock, Texas, USA
Re: O2 Simulator Resistor Sizes & Install Tip (jeanlucpicard)
The real question is "Why are they fouled?" There are lots of people running LT's without fouled O2 sensors. I have fouled mine before for two reasons: 1) mild (very minor) tear the head gasket allowing coolant into combsution & out to exhaust. 2) running a big cam (106 lsa) having idle & partial throttle way too rich.
What are you other mods? Have you done any tuning? Have you scanned to see if you are running rich? Do you have LS1 Edit?
What are you other mods? Have you done any tuning? Have you scanned to see if you are running rich? Do you have LS1 Edit?
Thread Starter
Burning Brakes
Joined: Jan 2002
Posts: 885
Likes: 0
From: The Woodlands Texas
Re: O2 Simulator Resistor Sizes & Install Tip (TXNC5)
Yes, I am running rich. Have known I was since I installed the headers. Scantool indicates it's my 2 "front" O2 sensors, not the rear 2, that are failing. I can pull them, clean them, reinsert, clear the code and be just fine for about 1 day. Then we're back to square 1.
No, I do not have a blown head gasket, leaking head gasket or excessive oil consumption. The fouling is sooty and is rich fuel mix deposits. If I swap the leads from the front O2 sensors to the rear O2 sensors (leave the rear 2 installed) and sim out the front O2 sensors I'm thinking I'll get out of this aggravation loop. As long as the car sees a set of O2 sensors the PCM can regulate the fuel mix as needed.
Guess I'll but the O2 sims from Xtreme and make the mod. By the way, the O2 sensors fouled again - today. 1 day after I last cleaned and reset.
Any thoughts?
Later
No, I do not have a blown head gasket, leaking head gasket or excessive oil consumption. The fouling is sooty and is rich fuel mix deposits. If I swap the leads from the front O2 sensors to the rear O2 sensors (leave the rear 2 installed) and sim out the front O2 sensors I'm thinking I'll get out of this aggravation loop. As long as the car sees a set of O2 sensors the PCM can regulate the fuel mix as needed.
Guess I'll but the O2 sims from Xtreme and make the mod. By the way, the O2 sensors fouled again - today. 1 day after I last cleaned and reset.
Any thoughts?
Later
Drifting
Joined: Jul 2000
Posts: 1,818
Likes: 3
From: SoCal
Re: O2 Simulator Resistor Sizes & Install Tip (jeanlucpicard)
Well, I *really* wouldn't do what you are planning on doing.
The front o2 sensors are supposed to be up close to the engine because they need to be hot. If you try to make the PCM read off the rears, it may not be accurate enough.
In addition, o2 simms will not fit the front wiring harness on a C5, only the rear 02 wiring harness...so you're going to have to cut and splice wires if you wanna do that.
It sounds like to me that you have a tuning issue if the car is really dumping so much fuel that it fouls the o2's.
Jon
http://www.ls1howto.com
The front o2 sensors are supposed to be up close to the engine because they need to be hot. If you try to make the PCM read off the rears, it may not be accurate enough.
In addition, o2 simms will not fit the front wiring harness on a C5, only the rear 02 wiring harness...so you're going to have to cut and splice wires if you wanna do that.
It sounds like to me that you have a tuning issue if the car is really dumping so much fuel that it fouls the o2's.
Jon
http://www.ls1howto.com
Racer
Joined: Jul 2001
Posts: 386
Likes: 0
From: Round Rock, Texas, USA
Re: O2 Simulator Resistor Sizes & Install Tip (jeanlucpicard)
Let us know if that works. I would think that it might lead to other problems. The front O2's are used for closed loop processing. Like jmx said, they need to be hot and close to the engine. The rear O2's are used for the OBD-II diagnostics.
If you actually lengthen the wires to read from the rears O2's, you may still get error codes from inadequate switching. Or, even worse the PCM will start making adjustments based on the readings from those O2's and possibly make the car run even richer (assuming the rear O2's indicate a lean condition). I don't usually trace the rear O2's when scanning because of the non-impact to performance. After cleaning your front ones, you should scan your car and compare the front & rear O2 values. I would be interested in seeing that data, or I'll try scanning my car to see the different values.
I hope you solve your problem. BTW, if the car is actually running rich you might also check: fuel pressure (too high), inaccurate IAT, bad MAF signal.
If you actually lengthen the wires to read from the rears O2's, you may still get error codes from inadequate switching. Or, even worse the PCM will start making adjustments based on the readings from those O2's and possibly make the car run even richer (assuming the rear O2's indicate a lean condition). I don't usually trace the rear O2's when scanning because of the non-impact to performance. After cleaning your front ones, you should scan your car and compare the front & rear O2 values. I would be interested in seeing that data, or I'll try scanning my car to see the different values.
I hope you solve your problem. BTW, if the car is actually running rich you might also check: fuel pressure (too high), inaccurate IAT, bad MAF signal.
Drifting
Joined: Apr 2001
Posts: 1,763
Likes: 24
From: Austin TX
Re: O2 Simulator Resistor Sizes & Install Tip (TXNC5)
If you are running rich like that at part throttle then you may have pegged your Ltrims. If not, then you have bad sensors that no amount of cleaning is going to fix.
You shouldnt be running that rich, using O2 simms on the front is fixing the symptom and not the problem.
Eric
You shouldnt be running that rich, using O2 simms on the front is fixing the symptom and not the problem.
Eric
Thread Starter
Burning Brakes
Joined: Jan 2002
Posts: 885
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From: The Woodlands Texas
Re: O2 Simulator Resistor Sizes & Install Tip (66ImpalaLT1)
Dealership replaced all 4 of my O2 sensors Tuesday under warranty (I have a nice dealer). They fouled again. The dealer advised what I already knew - running too rich to keep the sensors clean enough for the PCM. I'm probably going to have to do an LS1 Edit on a dyno to lean the car out properly.
Burning Brakes
Joined: Feb 2003
Posts: 871
Likes: 0
Re: O2 Simulator Resistor Sizes & Install Tip (jeanlucpicard)
What Jon and the others have already said... jus to recap for other people wondering this..
You cannot fool the PCM with a resistor for an O2.. The PCM is looking for an active switching of the voltage level (representative of the A/F in mv), which will set off a code if not present. You also would not want to read off your rear O2's as this is not an accurate measurement of A/F at that location, rather, is used in comparison of the front O2's to satisfy emissions (a standard OBD-II test).
Sounds like you definitely have some tuning issues. Throwing any other codes? Got ATAP you can borrow? Sucking in oil by the quart through your PCV by any chance? :lol:
You cannot fool the PCM with a resistor for an O2.. The PCM is looking for an active switching of the voltage level (representative of the A/F in mv), which will set off a code if not present. You also would not want to read off your rear O2's as this is not an accurate measurement of A/F at that location, rather, is used in comparison of the front O2's to satisfy emissions (a standard OBD-II test).
Sounds like you definitely have some tuning issues. Throwing any other codes? Got ATAP you can borrow? Sucking in oil by the quart through your PCV by any chance? :lol:
Le Mans Master
Joined: Dec 1999
Posts: 8,540
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From: And on the fifth day, subpoenas were served to Obama senior staff
Re: O2 Simulator Resistor Sizes & Install Tip
You have to fix the rich condition. Using sims for the front sensors is not a good idea. Rear O2 sensors (post cat) do not act like the front sensors, so the simulator would be useless. Hooking to the rears is also useless for the same reason.
I would say that you have a leak in the new headers causing excess O2 to enter the system just before the O2 sensor, which would make it read lean (and the PCM whould then cause it to run rich). However the possibility of this occuring on both sides is a little far fetched.
I would check for bad O2 sensor ground, perhaps disturbed in the installation. It is something of this nature I'll bet.
Need to get a scanner on that car and find out what happened. This is a failure or leak not just a tuning issue.
Good Luck
Pete
I would say that you have a leak in the new headers causing excess O2 to enter the system just before the O2 sensor, which would make it read lean (and the PCM whould then cause it to run rich). However the possibility of this occuring on both sides is a little far fetched.
I would check for bad O2 sensor ground, perhaps disturbed in the installation. It is something of this nature I'll bet.
Need to get a scanner on that car and find out what happened. This is a failure or leak not just a tuning issue.
Good Luck
Pete
