Full Version: dual cats on a 95?
I know that the 93-95 bodys only had one cat whereas the 96-02 had dual cats...however, I was wondering if you could put two on a 95, or would that mess up the computer in some way? I have a cutout now, but that just seems so unprofessional to me...
Actually I don't think you'd have the room to put 2 cats on a pre-1996 car. The 1996 to 2002 cars had a slight design change to accomodate the other cat. The cats on the 96-02 cars are in the engine bay tucked up on the drivers side and on the passenger side under the passenger side floorboard, which is why those year cars have the "hump" on the passenger side floorboard. It's to accomadate the cat on that side.
But really you don't need another cat. If you get a high flow cat for your car you'll be doing just as well as having two of them.
But really you don't need another cat. If you get a high flow cat for your car you'll be doing just as well as having two of them.
Both of mine are tucked up under the engine bay right after the manifolds. The hump contains the Y section. And BTW, I hate that hump. Makes the passenger side unbearable to ride in! I just want to take a hammer to it and beat it down!
QUOTE(SassySue09 @ Apr 9 2008, 08:44 PM) 
Actually I don't think you'd have the room to put 2 cats on a pre-1996 car. The 1996 to 2002 cars had a slight design change to accomodate the other cat. The cats on the 96-02 cars are in the engine bay tucked up on the drivers side and on the passenger side under the passenger side floorboard, which is why those year cars have the "hump" on the passenger side floorboard. It's to accomadate the cat on that side.
But really you don't need another cat. If you get a high flow cat for your car you'll be doing just as well as having two of them.
But really you don't need another cat. If you get a high flow cat for your car you'll be doing just as well as having two of them.
my car is a 95, and it definately has the hump...no doubt...having been under my car and my buddies (a 96) I havent noticed any difference in the layout around the cats...but then again, I wasnt looking for one either! I might just havat go with one highflow...is there a big difference between Magnaflow, Random Technology, and Catco?
If I am not mistaken they changed to two in the middle of the 95 models. Just like the OBDII on 95.5.
Matt
Matt
QUOTE(SiberianFirestorm @ Apr 10 2008, 09:59 PM)
If I am not mistaken they changed to two in the middle of the 95 models. Just like the OBDII on 95.5.
Matt
Matt
what is OBDII?
and I thought they didnt switch until the 96 model? Ive never read anything about switching halfway thru the year...but I do know mine only had one...
An ODBII is the type of connection underneath your steering wheel where emissions testers will plug an ODBII reader into your car to check to see if it is throwing any codes. For example, when your "check engine" lights comes on, you plug a little hand-held device (ODBII reader) into that little port under the steering column and that will diagnose your car. They did switch from ODBI to ODBII right in the middle of 1995. When i had my 95 formie, it was an ODBII. Also, the "new" 1995's had the steering wheel controls as well. If you've got those it is a pretty good indication that you've got the newer (95.5) formie.
And as for the question about cats...i hear that Random Tech is a very good and reliable brand. Go for their High-flow metallic cats...they have a good rep it seems
And as for the question about cats...i hear that Random Tech is a very good and reliable brand. Go for their High-flow metallic cats...they have a good rep it seems
In the middle of the 95 model year they changed from OBD1 to to the newer OBD2 computer, added a 2nd cat along with O2 sensors located after the cats. This is why if you get rid of the cats in a OBD2 car you have to have the rear O2 sensors tuned out or run O2 simulators to avoid throwing a code whereas on a OBD1 car you're good to go. At this time they also switched to the vented optispark.
If you have one cat, I would just run 1 highflow or put a straight pipe or cutout in it's place if you don't want one. I can't see the justification in switching to 2 cats.
If you have one cat, I would just run 1 highflow or put a straight pipe or cutout in it's place if you don't want one. I can't see the justification in switching to 2 cats.
QUOTE(Pyro97 @ Apr 11 2008, 09:27 AM)
In the middle of the 95 model year they changed from OBD1 to to the newer OBD2 computer, added a 2nd cat along with O2 sensors located after the cats. This is why if you get rid of the cats in a OBD2 car you have to have the rear O2 sensors tuned out or run O2 simulators to avoid throwing a code whereas on a OBD1 car you're good to go. At this time they also switched to the vented optispark.
If you have one cat, I would just run 1 highflow or put a straight pipe or cutout in it's place if you don't want one. I can't see the justification in switching to 2 cats.
If you have one cat, I would just run 1 highflow or put a straight pipe or cutout in it's place if you don't want one. I can't see the justification in switching to 2 cats.
my car has the buttons on the steering wheel, as well as an OBD II(i believe)...but Im pretty sure it only has one cat...
If I recall correctly, the cat under the pass. floor looks pretty much the same but there is another round one in the pipe directly beneath where the y-pipe bolts to the driver side exhaust manifold kinda hard to see.
also check the plug under the driver side dash. if it's rectangular it's OBD1, trapezoid then OBD2
also check the plug under the driver side dash. if it's rectangular it's OBD1, trapezoid then OBD2
QUOTE(MasterTomos @ Apr 11 2008, 01:48 PM)
my car has the buttons on the steering wheel, as well as an OBD II(i believe)...but Im pretty sure it only has one cat...
Yeah that sounds right. Mine was a 95 with ODBII and the steering wheel controls, but mine also only had one cat. They didn't put two cats on the car till 96.
Ok. A few things.
1. The vented Opti was 94.5 I think.
2. If you have 1 cat you have the OBD I computer, but may have the OBD II connector on the car.
3. I have the OBD I in my car and have the steering wheel controls.
4. On Board Diagnostics version I or II. This is the type of ECM (Engine Control Module) you have installed on your car. OBD I you can use a paper clip to short pins A and B (I think that is right) and read the flashes of the SES light, but you need a reader for the codes on OBD II. If you plan on doing any tuning on your car, you need to make sure which version you have before doing so.
5. A straight pipe will not make any more HP than a good quality High Flow Cat. All you will get is a lot more noise than needed.
Matt
1. The vented Opti was 94.5 I think.
2. If you have 1 cat you have the OBD I computer, but may have the OBD II connector on the car.
3. I have the OBD I in my car and have the steering wheel controls.
4. On Board Diagnostics version I or II. This is the type of ECM (Engine Control Module) you have installed on your car. OBD I you can use a paper clip to short pins A and B (I think that is right) and read the flashes of the SES light, but you need a reader for the codes on OBD II. If you plan on doing any tuning on your car, you need to make sure which version you have before doing so.
5. A straight pipe will not make any more HP than a good quality High Flow Cat. All you will get is a lot more noise than needed.
Matt
Ok here's some info for you:
1) 1993 and 1994 had the non-vented opti, 1995-1997 had the vented one. You can however, with certain changes, convert from a non-vented to a vented opti on the 1993 and 1994 models.
2) 1993-1995 only had 1 cat, dual cats started in 1996. The 2nd cat like Pyro said is in the engine bay tucked up in there. The closest I can describe it looking like is a small coffee can in shape.
3) ALL 1993-1995 F-bodies are OBD I no matter what connector was used under the dash.
4) In some of the last 1995 models they used the OBD II connector under the dash due to GM running out of the OBD I connectors and them not making any more of the OBD I connectors since with the 1996 model year they'd be going to OBD II on their cars.
5) On the 1993 and 1994 models you can use the "straight pin" technique to read any SES codes. However on the 1995 model year you can't do that due to the OBD II connector. You need a code reader that will read OBD I codes but you need to use an OBD II connector to get them to read correctly. And I can tell you that most places that do the "free" SES code reading don't have the correct code reader to read the 1995 codes.
6) OBD I read only the "basic" infomation that the computer needed. OBD II on the other hand gets more in depth with what the computer can read and also in telling you when something is wrong with your car. Oh and those two dealt with not only the engine but with the transmission as well. OBD I and OBD II SES codes are more or less totally different. Here's a link that shows both OBD I and OBD II engine and transmissions codes so you can see what I mean: http://shbox.com/1/Dtcs.htm Go to the bottom of that page and you can see where you can switch from OBD I to OBD II codes.
Also I know that the header/y-pipe are shaped different on the OBD I and the OBD II car cause of the single vs dual cat thing. I'll have to see if I can find some pics after I get home from work and post them up to show you the difference.
1) 1993 and 1994 had the non-vented opti, 1995-1997 had the vented one. You can however, with certain changes, convert from a non-vented to a vented opti on the 1993 and 1994 models.
2) 1993-1995 only had 1 cat, dual cats started in 1996. The 2nd cat like Pyro said is in the engine bay tucked up in there. The closest I can describe it looking like is a small coffee can in shape.
3) ALL 1993-1995 F-bodies are OBD I no matter what connector was used under the dash.
4) In some of the last 1995 models they used the OBD II connector under the dash due to GM running out of the OBD I connectors and them not making any more of the OBD I connectors since with the 1996 model year they'd be going to OBD II on their cars.
5) On the 1993 and 1994 models you can use the "straight pin" technique to read any SES codes. However on the 1995 model year you can't do that due to the OBD II connector. You need a code reader that will read OBD I codes but you need to use an OBD II connector to get them to read correctly. And I can tell you that most places that do the "free" SES code reading don't have the correct code reader to read the 1995 codes.
6) OBD I read only the "basic" infomation that the computer needed. OBD II on the other hand gets more in depth with what the computer can read and also in telling you when something is wrong with your car. Oh and those two dealt with not only the engine but with the transmission as well. OBD I and OBD II SES codes are more or less totally different. Here's a link that shows both OBD I and OBD II engine and transmissions codes so you can see what I mean: http://shbox.com/1/Dtcs.htm Go to the bottom of that page and you can see where you can switch from OBD I to OBD II codes.
Also I know that the header/y-pipe are shaped different on the OBD I and the OBD II car cause of the single vs dual cat thing. I'll have to see if I can find some pics after I get home from work and post them up to show you the difference.
Hmm well i definitely never knew about #'s 3 and 4!! Nobody ever told me that my ODBII connector had an ODB I computer on the other end haha! I learn something new every day here!!! Every little bit makes me THAT much more towards an expert on these cars!! 
QUOTE(SassySue09 @ Apr 13 2008, 11:53 AM)
Ok here's some info for you:
1) 1993 and 1994 had the non-vented opti, 1995-1997 had the vented one. You can however, with certain changes, convert from a non-vented to a vented opti on the 1993 and 1994 models.
2) 1993-1995 only had 1 cat, dual cats started in 1996. The 2nd cat like Pyro said is in the engine bay tucked up in there. The closest I can describe it looking like is a small coffee can in shape.
3) ALL 1993-1995 F-bodies are OBD I no matter what connector was used under the dash.
4) In some of the last 1995 models they used the OBD II connector under the dash due to GM running out of the OBD I connectors and them not making any more of the OBD I connectors since with the 1996 model year they'd be going to OBD II on their cars.
5) On the 1993 and 1994 models you can use the "straight pin" technique to read any SES codes. However on the 1995 model year you can't do that due to the OBD II connector. You need a code reader that will read OBD I codes but you need to use an OBD II connector to get them to read correctly. And I can tell you that most places that do the "free" SES code reading don't have the correct code reader to read the 1995 codes.
6) OBD I read only the "basic" infomation that the computer needed. OBD II on the other hand gets more in depth with what the computer can read and also in telling you when something is wrong with your car. Oh and those two dealt with not only the engine but with the transmission as well. OBD I and OBD II SES codes are more or less totally different. Here's a link that shows both OBD I and OBD II engine and transmissions codes so you can see what I mean: http://shbox.com/1/Dtcs.htm Go to the bottom of that page and you can see where you can switch from OBD I to OBD II codes.
Also I know that the header/y-pipe are shaped different on the OBD I and the OBD II car cause of the single vs dual cat thing. I'll have to see if I can find some pics after I get home from work and post them up to show you the difference.
1) 1993 and 1994 had the non-vented opti, 1995-1997 had the vented one. You can however, with certain changes, convert from a non-vented to a vented opti on the 1993 and 1994 models.
2) 1993-1995 only had 1 cat, dual cats started in 1996. The 2nd cat like Pyro said is in the engine bay tucked up in there. The closest I can describe it looking like is a small coffee can in shape.
3) ALL 1993-1995 F-bodies are OBD I no matter what connector was used under the dash.
4) In some of the last 1995 models they used the OBD II connector under the dash due to GM running out of the OBD I connectors and them not making any more of the OBD I connectors since with the 1996 model year they'd be going to OBD II on their cars.
5) On the 1993 and 1994 models you can use the "straight pin" technique to read any SES codes. However on the 1995 model year you can't do that due to the OBD II connector. You need a code reader that will read OBD I codes but you need to use an OBD II connector to get them to read correctly. And I can tell you that most places that do the "free" SES code reading don't have the correct code reader to read the 1995 codes.
6) OBD I read only the "basic" infomation that the computer needed. OBD II on the other hand gets more in depth with what the computer can read and also in telling you when something is wrong with your car. Oh and those two dealt with not only the engine but with the transmission as well. OBD I and OBD II SES codes are more or less totally different. Here's a link that shows both OBD I and OBD II engine and transmissions codes so you can see what I mean: http://shbox.com/1/Dtcs.htm Go to the bottom of that page and you can see where you can switch from OBD I to OBD II codes.
Also I know that the header/y-pipe are shaped different on the OBD I and the OBD II car cause of the single vs dual cat thing. I'll have to see if I can find some pics after I get home from work and post them up to show you the difference.
always there to set us all straight
Nah, not setting you all straight at all. 
I just wanted to make sure that the correct information was passed along.
Oh and on #4 I should have clarified that in 1996 ALL of their cars went to OBD II, not just the F-bodies. Also on #5, part of the 1995 year cars, the ones with the OBD I connector usually can be read with the "straight pin". It's only the ones in 1995 that had the OBD II connector where that technique couldn't be used.
I just wanted to make sure that the correct information was passed along. Oh and on #4 I should have clarified that in 1996 ALL of their cars went to OBD II, not just the F-bodies. Also on #5, part of the 1995 year cars, the ones with the OBD I connector usually can be read with the "straight pin". It's only the ones in 1995 that had the OBD II connector where that technique couldn't be used.
And I thought that some 95's had the OBD II computer. sheesh...
Matt
Matt
Learned something new from "Sue's book of useless facts" huh Matt? 
Can't i just get a pdf copy of this book so I do not miss them again? LOL
Matt
Matt
You can but only if you can figure out a way to PDF my brain since it's all in there.
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