PreCat Removal
Thread Starter
Burning Brakes
Joined: Nov 2000
Posts: 1,040
Likes: 2
From: BowlingGreen KY
PreCat Removal
I have a 90 L98 with 148000 miles. I think I still have the original precats on the car. Can I just take them off and weld in some straight pipe? Will this set off any codes or cause any engine problems? If anybody has done this I'd like to hear your opinions. And will it make the car louder? Thanks.
[Modified by KYVette90, 3:14 PM 9/4/2001]
[Modified by KYVette90, 3:14 PM 9/4/2001]
Drifting
Joined: Mar 1999
Posts: 1,931
Likes: 1
From: Norcross GA
Re: PreCat Removal (KYVette90)
Louder Yes
Codes No
Pass emissions Yes
Look out for the smog police. If they really know their stuff, they will flag the no pre-cats thing. Most just look for a cat.
Codes No
Pass emissions Yes
Look out for the smog police. If they really know their stuff, they will flag the no pre-cats thing. Most just look for a cat.
Safety Car
Joined: Jun 2000
Posts: 4,870
Likes: 25
From: Long Island, NY
Re: PreCat Removal (KYVette90)
You can also purchase a Ypipe that replaces your current precat ypipe. This way you just ubolt your's and install the new one.
You will still pass emissions and it is not that much louder.
Vic
You will still pass emissions and it is not that much louder.
Vic
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: PreCat Removal (KYVette90)
This would be a good time to replace the front Y-pipe with a 2 1/2" mandrel bent (no pre-cats) and go to a Random Tech 3-stage hi-flow cat, all emissions legal in 49 states. And yes you can just replace the pre-cats with straight pipe as an option.
As you reduce air flow restrictions it will get louder but you can control that with mufflers. Check my sig for results of this mod plus hi-flow cat-back.
As you reduce air flow restrictions it will get louder but you can control that with mufflers. Check my sig for results of this mod plus hi-flow cat-back.
Thread Starter
Burning Brakes
Joined: Nov 2000
Posts: 1,040
Likes: 2
From: BowlingGreen KY
Re: PreCat Removal (65Z01)
Thanks alot guys. I'm going to take them off this weekend. I hope it gets louder. I have two brand new flowmasters and I want them to sound a bit meaner. :reddevil
Le Mans Master
Joined: Dec 1999
Posts: 8,540
Likes: 1
From: And on the fifth day, subpoenas were served to Obama senior staff
Re: PreCat Removal (KYVette90)
It's very possible with your mileage that the pre-cats are just chunks of moon rock looking things at this point. I would cut them open when you take them off and see. If they are shot, probably also ejected tons of junk into your main cat which could also cause problems / restrictions. My pup-cats killed my main cat at about 68,000 miles.
Good Luck with the project!
Pete
Good Luck with the project!
Pete
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
Re: PreCat Removal (PeteL)
Beware of the dreaded Code 32. Altering the exhaust backpressure on 90 or 91 cars can result in an unsolvable EGR error code. You may need a new chip to shut it off. :eek:
Instructor
Joined: Jun 2001
Posts: 116
Likes: 0
From: Ft. Worth TX
Re: PreCat Removal (KYVette90)
I gutted completely gutted my main cat and my pre-cats gutted themselves. IT took about 2 weeks of normal driving to get it all out. Now is sounds and runs like a bat out of hell...
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Burning Brakes
Joined: Aug 2000
Posts: 1,052
Likes: 0
From: Warrenville IL
Re: PreCat Removal (KYVette90)
I am not that familiar with the exhaust setup on the 90 but here is a suggestion if you are concerned with emissions. What I did with my 92 Camaro (3" exhaust & single cat) was took it to an exhaust shop and had them make me a straight pipe to replace the cat. They welded the correct flange on one end with a aircraft T-clamp on the other. I ran the car with the straight pipe and kept my high flow cat for emissions. What you need to do is find a performance exhaust shop, typically most places won't do it unless you know someone. They will also not install the pipe on the car you'll have to do that yourself.
I could definetly feel the difference with the straight pipe and the car was quite a bit louder.
The car had a TPI 355 (7730 ecm) I didn't have any problems with codes or anything.
I could definetly feel the difference with the straight pipe and the car was quite a bit louder.
The car had a TPI 355 (7730 ecm) I didn't have any problems with codes or anything.
Original Founding Member!
Joined: Jul 1999
Posts: 9,037
Likes: 88
From: Granby, MA
Cruise-In 1, 3, 9. 10 & 11 Veteran
Re: PreCat Removal (KYVette90)
yeh KYVVette90 PLEASE let me know especially....(an email would be great!) I want to do this to my 1990 vette.....so Iam really paying attention on how it works for you.....
loudness....codes....etc...
thanks a lot bud
jeff :cool:
loudness....codes....etc...
thanks a lot bud
jeff :cool:
Team Owner
Joined: Aug 2000
Posts: 42,935
Likes: 20
From: Sydney, Australia
CI 6-7-8-9-10 Veteran
St. Jude Donor '07-'08-'09-'10-'11-'12-'13-'14-'15-'16-‘17, '22
Re: PreCat Removal (KYVette90)
Another thing that hasn't been covered here is that in hot weather it will take a longer for the interior & motor to heat up in traffic because you don't have those two metal cans heating up the firewall/engine compartment area.
Unless I am mistaken, the precats were put there to satisfy the cold start portion of federal emissions testing. The main cat should keep you emissions legal during testing (ignoring the visual test aspect, if applicable).
With regard to noise, the tone of the exhaust note improves but there is not much of an increase in volume.
I get the check engine light coming on fairly often, mainly after cruising at constant speeds for a while.
My car sounds better, runs cooler, the underbonnet temps are lower and the car goes harder. :yesnod:
Unless I am mistaken, the precats were put there to satisfy the cold start portion of federal emissions testing. The main cat should keep you emissions legal during testing (ignoring the visual test aspect, if applicable).
With regard to noise, the tone of the exhaust note improves but there is not much of an increase in volume.
I get the check engine light coming on fairly often, mainly after cruising at constant speeds for a while.
My car sounds better, runs cooler, the underbonnet temps are lower and the car goes harder. :yesnod:
Burning Brakes
Joined: Nov 2000
Posts: 1,012
Likes: 1
From: Bowie MD
Re: PreCat Removal (KYVette90)
My precats were removed and I put a Random Cat main on. I guess, I didn't get any codes, because I had a Custom Chip put in at the same time? Yes Eklers has a replacement pipe that does away with precats. The change in mufflers is what is going to change the noise level. I went tooo far with the Eklers Targa style stainless muffler elims. TOO loud for me, and an annoying resonance at 2000 to 2200 rpms where I cruise at on the beltway. Just my 2 cents worth. Looking for a quieter muffler, maybe power effects.
Original Founding Member!
Joined: Jul 1999
Posts: 9,037
Likes: 88
From: Granby, MA
Cruise-In 1, 3, 9. 10 & 11 Veteran
Re: PreCat Removal (65Z01)
so...hmmmmm....how do you effectively remove the pre-cats and not set off any codes...or that dreaded CHECK ENGINE SOON light?....
need help
need help
