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Supercharged 3RZ/FTC1-E tuning questions

1747 Views 1 Reply 2 Participants Last post by  [email protected]

OK, I'm back with a two 3RZ tuning questions.

Background: 1998 4Runner, 3RZ, TRD supercharger, 2.4" (~6psi) pulley, 330cc/min injectors, LCE header, URD/SplitSecond FTC1-E, 91 octane fuel (aka squirrel piss, Northern California blend). Currently making 180 rwhp on the dyno, but my AFR at WOT is in the 10.5:1 range, and I think that's too rich.

I have an Innovate Motorsports LC-1 wideband and an OBD Diagnostics BR3 laptop OBDII interface, so I can get plenty of data. What I'm looking for is some real world data from others with tuned supercharged or turbocharged 3RZs who have wideband O2s.

I have read Gadget's U-Tune guide, and in it he advises tuning for a WOT AFR of 12:1. Before I start pulling out more fuel, I have two general questions: for supercharged or turbocharged 3RZ motors with stock internals, is 12:1 a reasonable AFR for WOT street performance? What AFR are people running for part throttle cruising? I understand that in closed loop the ECU is going to try to correct the mixture back to what it wants, and my goal is to adjust the FTC1 to essentially neutralize the fuel trims, so my question for folks that have been able to do that successfully is what AFR are you seeing at part throttle cruise?


1 - 2 of 2 Posts
You are going to be working that engine pretty hard in a 4Runner. I would tune it to 11.0:1 AFR especially if you have your cat still installed.

If the ECU is in closed loop mode the fuel mix has to be 14.7:1 or your will get a check engine light. So, in cruise you should be seeing 14.7:1 AFR.

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