Pre-cat Elimination
Thread Starter
Burning Brakes
Joined: Nov 2003
Posts: 1,234
Likes: 5
From: Herriman UT
Pre-cat Elimination
I'm considering installing long-tube headers on my '86 including the front Y-pipe which will eliminate the pre-cats. What problems may I expect to encounter when being tested for emmissions? This is a Utah car.
Le Mans Master
Joined: Aug 2000
Posts: 5,192
Likes: 1
From: Airport Cruise-in 1 Veteran Airport Cruise-in 2 Veteran
Cruise-In II Veteran
Re: Pre-cat Elimination (geezel)
I have a Hotcam w/ LT's connected to my stock front y w/ the pre-cats hacked off going back to a hi flow cat. I'm going to take the emission test this Saturday, I'll let you know how it goes. :thumbs:
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: Pre-cat Elimination (geezel)
I have ported stock shortie headers, a 2 1/2" SS front Y, RT hi-flow cat and TPIS custom FlowMaster cat-back and pass emissions easily even in winter while running a 160 deg stat.
So long as your O2 sensor gets hot enough for the ECM to go closed loop you should easily pass the sniffer (I assume they don't do a visual check).
After you install the FL headers, use the ECM's diagnostic mode described on my site (link in sig. below) to assure the ECM is going into closed loop. If not, install a heated O2 sensor. You might perform this check before installing the headers to assure your O2 sensor and coolant temp sensor are both now ok.
So long as your O2 sensor gets hot enough for the ECM to go closed loop you should easily pass the sniffer (I assume they don't do a visual check).
After you install the FL headers, use the ECM's diagnostic mode described on my site (link in sig. below) to assure the ECM is going into closed loop. If not, install a heated O2 sensor. You might perform this check before installing the headers to assure your O2 sensor and coolant temp sensor are both now ok.
Le Mans Master
Joined: Aug 2000
Posts: 5,192
Likes: 1
From: Airport Cruise-in 1 Veteran Airport Cruise-in 2 Veteran
Cruise-In II Veteran
Re: Pre-cat Elimination (geezel)
I PASSED! :hurray: :hurray: :hurray:
Just barely though. The HC standard is 1.492 and I put out 1.491. :eek:
The CO standard is 57.371 and i got 31.061 for that. :thumbs:
The CO2 is N/A in Illinois but it was still documented and I put out 1024.8 grams of that.
I'm glad that's over with. :yesnod:
Just barely though. The HC standard is 1.492 and I put out 1.491. :eek:
The CO standard is 57.371 and i got 31.061 for that. :thumbs:
The CO2 is N/A in Illinois but it was still documented and I put out 1024.8 grams of that.
I'm glad that's over with. :yesnod:
