Pre cats Question

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Nov 10, 2003 | 10:48 PM

darkred91

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Joined: Mar 2003

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From: Navarre fl

Pre cats Question

Will cutting off the pre cats make your car run lean if so whats the cure...THANKS.
91 L98

[Modified by darkred91, 3:49 AM 11/11/2003]

Nov 10, 2003 | 11:06 PM

bogus

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From: San Pedro CA

Re: Pre cats Question (darkred91)

I have never heard that... the precats are designed to light off faster, so they can get lower emissions sooner.

Nov 11, 2003 | 12:37 AM

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From: Phila., PA burbs

Re: Pre cats Question (darkred91)

I replaced my front y-pipe about a year ago with a 2.5" SS unit w/out precats and have had no problems. The only consequence was quicker ETs :yesnod:

Nov 11, 2003 | 01:03 AM

The Dingo

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From: Sydney, Australia

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St. Jude Donor '07-'08-'09-'10-'11-'12-'13-'14-'15-'16-‘17, '22

Re: Pre cats Question (TA)

Don't worry about running lean without precats. Your ECM is smart enough to make sure things run as they should with a basic mod like that.

Nov 11, 2003 | 01:54 AM

65Z01

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From: SE NY

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Re: Pre cats Question (darkred91)

The ECM will get the A/F correct at part throttle in closed loop; in open loop it should run a little leaner due to more air flow.

People have said that our stock L98 run a little rich at WOT so a little leaner should not matter.

You can use an AFPR to tune fuel flow at WOT for best power using a dyno or trap speed data.