cat delete??

**speedyWS6** · 06-04-2010, 01:29 PM

Hi Guys...,

I put a wanted ad on for a pair of SLP cats to go in my system which is SLP right the way from front to back because my drivers side cat is clanking and rattling and appears to be on it's way out.

But..... after talking to a few people they seriously suggested "just" deleting the cats and replacing with the relevant pipework!

Hopefully somebody can give me a definitive here, as this appeals both thru cost and ease ( i am in the UK and would have to mess around getting them shipped over). any gas testing is not an issue as our yearly inspection is "get roundable"

Simply put... is this a simple option and will i be thwarted with loads of codes being thrown up and will it cause any sort of poor running which will need tuning out???... or will it be an easy option to achieve with the minimum of fuss???!!!

The car is a 2000 TA WS6 with SLP LT's...Y...and a loudmouth 2. And before anybody quips...i bought the car with these items as i know you guys always holler about SLP, but there it is!!

Please get back to me soon as it is my DD and thanks in advance!

Trev....

**35th-ANV-SS** · 06-04-2010, 01:35 PM

I don't know about emissions in the UK, however, if all you have is an OBDII plug in and NO physical inspection, you can remove your cats without harm.

If you do remove them, you will need to a) get O2 simulators for the 2 rear O2's which monitor your cats or b) get your 2 rear O2's sensors tuned out by a hand held program or tuner.

Until you remove the O2 with a tuner or install simulators, you will get SES codes since the O2's are trying to monitor whether the cats are working properly and you won't have cats.

**speedyWS6** · 06-04-2010, 01:45 PM

Wow...

Lovely and quick...thanks!!

Now... just to elaborate, when you say "no harm"...do you mean the engine will run absolutely fine as it is at the moment and just be "happy" with no cats (codes aside)

I do have a Diablosport Predator which also came with the car...if i read the instructions...will this delete the codes satisfactorily??

Also...i have a mechanic bud who has the OBII gizmo....what precisely is he able to do/achieve with this ??!!

Thanks again for the help and just keep typing if you think you can help further!!

Thanks

Trev....

)

**35th-ANV-SS** · 06-04-2010, 01:49 PM

Engine will be fine. Car will run fine. You just need to have the O2's tuned out. I am not sure if the Diablo has that capability or not.

By OBDII, I was referring to what the emissions place uses to check your emissions.

**Smittro** · 06-04-2010, 01:55 PM

35th is exactly right.. You may actually see a slight gain in power. No harm to anything @ all.. In fact your motor will like not having the added restriction from the cats in the exhaust..

It will throw a code and a SES light but nothing more.. The light and code can be tuned out also with no ill effects in performance.. You may even see a slight gain in kilometers per litre...

**speedyWS6** · 06-04-2010, 01:57 PM

Ok 35th...

Thanks for the update and to elaborate some more... where would i get O2 simulators from and would the installation of these elimimate any codes due to all of this?? Hopefully they would eliminate the codes, but also thanks for assuring me that the car will run as it is right now... which is absolute fine and strong! It only has 44K on it and is a real pampered example of the marque!

Thanks again...and as before...the more info and help the better as i am real new to LS1's and codes and all of that!

Thanks a lot

Trev...

**35th-ANV-SS** · 06-04-2010, 02:01 PM

Honestly, don't get the simulators...just get them tuned out.

**Smittro** · 06-04-2010, 02:06 PM

Originally Posted by 35th-ANV-SS

Honestly, don't get the simulators...just get them tuned out.

This guy is on it huh? o2 sims sometimes do not always work to keep the SES light from returning.. As 35th stated tunning them out is best...

**speedyWS6** · 06-04-2010, 02:07 PM

Tuned out it is then....

I have a shop an hours drive away which purports to be a tuning shop and does all of the things such as dyno tuning,engine mapping etc and is an American car specialist so i reckon a phone call in the morning!

Thanks guys...but keep the thoughts coming if you can add anything!

Thanks

Trev...

**Smittro** · 06-04-2010, 02:16 PM

Well since you're new to the scene, I'll throw this out there just incase..

Tunning out the SES light for the cats will not eliminate the abillity for the SES light to warn you of other issues.. Rear 02 tune out just eliminates the rear 02's catalyst efficiency detection and the SES light for those codes nothing more..

**35th-ANV-SS** · 06-04-2010, 02:17 PM

Just be sure that for emissions that you don't have to have cats. If they do a visual check, you will be screwed. If they do a visual you can always just gut your cats and make it appear that they are still there....but you still need your O2's tuned out either way

**Glue Maker** · 06-04-2010, 04:41 PM

the only side effect is an added fuel smell but its not bad, i dont have cats on anything lol

**speedyWS6** · 06-04-2010, 10:17 PM

Smittro..,

Thanks for adding your thoughts on the codes and how this is specific to rear O2 codes.

Now.... as i have a predator (bought in '06 i believe) by the previous owner, will this unit be able to tune out the codes for the rear sensors ( i would look but the predator is 10 miles away stored at work as of this writing!)

A bit of a look around the diablosport forums suggested that a unit of my vintage may be able to turn off the codes but a newer version (not sure from which date) has this facility removed/disabled??!

Any thoughts on this will be much appreciated! ( as always)

And Glue maker...... if an added fuel smell may be a side effect.... hopefully just the smell..... or do you mean it will be running rich, as previous responses have suggested that the motor will still run fine with no ill effects!?

Look forward to hearing back!!

Trev....

)

**Glue Maker** · 06-05-2010, 06:36 AM

the motor will run the same the only thing the rear o2's do is sence to make sure the cats are burning any gasses that the motor did not so with the cats gone you will smell those gasses not a big deal i just though you should no

**Smittro** · 06-05-2010, 07:10 AM

Originally Posted by speedyWS6

Smittro..,

Thanks for adding your thoughts on the codes and how this is specific to rear O2 codes.

Now.... as i have a predator (bought in '06 i believe) by the previous owner, will this unit be able to tune out the codes for the rear sensors ( i would look but the predator is 10 miles away stored at work as of this writing!)

A bit of a look around the diablosport forums suggested that a unit of my vintage may be able to turn off the codes but a newer version (not sure from which date) has this facility removed/disabled??!

Any thoughts on this will be much appreciated! ( as always)

And Glue maker...... if an added fuel smell may be a side effect.... hopefully just the smell..... or do you mean it will be running rich, as previous responses have suggested that the motor will still run fine with no ill effects!?

Look forward to hearing back!!

Trev....

)

No problem.. Sounds like you have the same kinds of testing as we do here.. Some areas are more strict than others.. Here in the state (PA) I live if you're yearly mileage is under 5000 miles per year you can get an exemption sticker.. Which means they don't even bother smog testing.. Other areas don't test @ all such as rual areas but the law does state that the smog equipment has too be @ least visiable.. So we can get away with gutted cats.. My engine did'nt come with a factory air pump so they don't even open the hood..

**BillieJean99** · 06-05-2010, 06:33 PM

Now, I love my LS1 and F-Body, but I'll admit that I am clueless when it comes to how things work. I'm thinking of taking the cats off of my 1999 Pontiac T/A, bone stock. I'm not sure what all this code and tune talk is...can you elaborate for me? You may have already elaborated but I'm just too stupid to realize

**mxlplx71** · 06-05-2010, 06:48 PM

the code is a trouble code from the sensors reading as the cats inopperable or too much air, the tune is a computer hooked up to the engine computer to shut some things off change settings otherwise reprogram the cars computer.

**35th-ANV-SS** · 06-05-2010, 06:49 PM

Originally Posted by BillieJean99

Now, I love my LS1 and F-Body, but I'll admit that I am clueless when it comes to how things work. I'm thinking of taking the cats off of my 1999 Pontiac T/A, bone stock. I'm not sure what all this code and tune talk is...can you elaborate for me? You may have already elaborated but I'm just too stupid to realize

This is very basic...

Your car has 4 O2 sensors. The front 2 O2 sensors which are mounted in the exhaust monitor how much unburned oxygen is in your exhaust as it exits. By monitoring this oxygen level, the O2 sensor determined what your A/F ratio is. It then sends a signal back to the PCM to tell it to add more fuel or less fuel based on whether your car is running lean or running rich. When your O2 fails, it can no longer tell the PCM how much fuel to add, so your PCM guesses and as a result, your car can run like shit.

The rear O2 sensors, the ones we are talking about, monitor the catalytic converters to make sure they are doing their job..they have no bearing on how your car runs or performs.

The signal that all sensors use is voltage. It ranges from say 0.2V to 0.9V. If the voltage is low, this means the O2 sensor has detected that your car is running lean (not enough fuel) and when the voltage is high (too much fuel). When the PCM gets this voltage reading signal, it then knows how to adjust the fuel to compensate.

When you "tune" out the O2 sensors, what you are doing basically is fooling the PCM. You set the voltage to read a constant. Therefore, your PCM "thinks" that the converters are doing their job when in reality they are not even there.

I hope I got that right lol.

**speedyWS6** · 06-06-2010, 12:37 AM

35th-ANV-SS...,

A VERY well worded explanation of the whole scenario!

After all of your help/suggestions i have the car booked in on a dyno on the 26th June. This is not to go ooh,ahh at the figures produced

but to have the codes removed if any fire up, and to "tweak" things if there is any need to, after the cat removal. The guy there also says it's possible that it will not throw any codes after the cat removal but i am unconvinced on that one.

Already have an order in for some S/S tubing and once delivered i will cut to length and get busy with fabrication and with the spanners!

As i am unable to get the car in the air right now for a good look, i am guessing that one end of my replacement tube (or indeed the cat) would be flared (evenly expanded) slightly to go over 3" tubing (from the L/Ts) and the other end (onto the Y) would be straight, to fit into into the Y ?!

Any sort of confirmation of the last paragraph would be great

As always..... thanks a bunch for all of the help!!!

Trev

**BillieJean99** · 06-07-2010, 12:47 AM

Originally Posted by 35th-ANV-SS

This is very basic...

Your car has 4 O2 sensors. The front 2 O2 sensors which are mounted in the exhaust monitor how much unburned oxygen is in your exhaust as it exits. By monitoring this oxygen level, the O2 sensor determined what your A/F ratio is. It then sends a signal back to the PCM to tell it to add more fuel or less fuel based on whether your car is running lean or running rich. When your O2 fails, it can no longer tell the PCM how much fuel to add, so your PCM guesses and as a result, your car can run like shit.

The rear O2 sensors, the ones we are talking about, monitor the catalytic converters to make sure they are doing their job..they have no bearing on how your car runs or performs.

The signal that all sensors use is voltage. It ranges from say 0.2V to 0.9V. If the voltage is low, this means the O2 sensor has detected that your car is running lean (not enough fuel) and when the voltage is high (too much fuel). When the PCM gets this voltage reading signal, it then knows how to adjust the fuel to compensate.

When you "tune" out the O2 sensors, what you are doing basically is fooling the PCM. You set the voltage to read a constant. Therefore, your PCM "thinks" that the converters are doing their job when in reality they are not even there.

I hope I got that right lol.

Ahh, that you very much 35th! It made perfect sense to me, helps alot. And BTW, badass Camaro man!