[Z06] No Cats SIMS lean condition on nitrous
Thread Starter
Former Vendor
Joined: Aug 2001
Posts: 1,756
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From: Atlanta GA
No Cats SIMS lean condition on nitrous
I took the beast to the dyno the other day with no cats and I put in the SIMS this time and got 375.9 RWHP at 365RWT. The car still runs rich on the motor 12.2 on the wideband but the kicker is with the Nitrous on. When I nailed the 100 shot the fuel mixture went lean as hell with the SIMS 14.5 with the nitrous on I thought the engine was done. I jetted up the fuel two stages and cam out at 11.9 fuel to rich:mad: . But the car made 470RWHP the same as before so I will lean it up some more and take it back. I just wanted to share that is you are running no cats and SIMS and use nitrous be careful because it makes it LEAN on the nitrous. I think with the back o2’s not reading mixture that is the problem.
:cheers:
:cheers:
Melting Slicks
Joined: Feb 2000
Posts: 2,109
Likes: 73
From: ATLANTA/HOUSTON
Re: No Cats SIMS lean condition on nitrous (opticZ06)
I don't have any cats either & have the simms, I haven't had ANY lean issues, Thank God. You can run Rich MANY times, but you'll only run Lean ONCE!! :crazy:
Race Director
Joined: Jan 2001
Posts: 11,183
Likes: 85
From: Castle Rock CO
St. Jude Donor '15
Re: No Cats SIMS lean condition on nitrous (opticZ06)
The information in the GM "helms" manual for the 2001s(info not specific to LS1 vs LS6, though) and the 1998 LS1s states that rear O2s have very little effect on the overall delivery of fuel to the motor. If the rear O2s are starting to show a lean or rich condition, they can get the PCM to add or subtract a very small amount of fuel in the overall view. I don't think the rear O2s being non-functional has anything to do with the overall lean. I have been involved with 4 LS1 vehicles on nitrous and have seen each respond differently. All 4 did require a fuel jet size change, though. Most where slightly lean.
Todd
Todd
