Tuning for Supercharged Lexus V8

3uzfeTaco2006 · Newbie Joined: Sep 29, 2007 Posts: 1

I have a 2006 Tacoma I have swapped a Lexus GS430 3UZ-FE 4.3L VVTi V8 with electronic throttle, direct ignition and a Aisin A650E 5-speed automatic. The engine is currently equipped with an SRT (Swift Racing Technology) Intake Kit w/ Piggyback ECU that appears to remap the MAF output based on TPS & IAT. The current setup runs well with no problems.

I plan to install an Eaton supercharger from a TRD Tundra 4.7L V8 SC Kit, I think it's an M90. This is the "version 2" kit with the electronically controlled boost & two fuel injectors. I have worked out the mechanical connections of this unit to the 4.3L V8 which differs slightly from a 4.7L, however I cannot use the supplied TRD Piggyback ecu because the control systems of the two engines are substantially different, including a different redline, compression ratio and transmission (4 sp vs 5 sp). For this reason I am seeking an aftermarket piggyback ECU to do the following:

1. Control the supercharger bypass solenoid to modulate boost.

2. Control the extra injectors to maintain sufficient fueling under boost and utilize the "intercooling effect" afforded by these injectors location at the compressor outlet.

3. Remap the MAF similar to the SRT piggyback so it can be removed.

4. Modify stock fueling to maximize power (relates to #3 above) and account for the extra fueling provided by #2.

5. Retard ignition timing sufficiently to prevent detonation.

As far as I can see, the XFC can handle #'s 1-4. My concern is with #5: I assume this has to be done indirectly by "lying" to the stock ECU about engine load (MAF) and IAT (intake air temp) to get it to retard the timing, is this correct? How much timing retard can be achieved with this method? Is there (or will there) be an option to directly control the ignition retard by intercepting and delaying the ignition pulses from the stock ECU (there are 8 of them on this motor)?

Also, how will remapping the MAF affect the transmission controls, specifically Line pressure? Since line pressure is a function of LOAD on most OE ECUs and LOAD is calculated from MAF, won't changing the MAF affect shifting?

Finally, do you see any problems with using the XFC in this application? Any suggestions or hints? Any other customers you know of using an XFC on a Toyota/Lexus VVTi V8?

Thanks!

Russ · PCS Employee Joined: May 12, 2004 Posts: 286

Timing control by altering the MAF or IAT would probably not work that well. You need to retard the timing by either intercepting the crank and cam signals or by intercepting the coil signals. Our XFC does not have any ignition control at this time.

Changing the MAF will only have a small effect on the line pressure. Once you get over a certain amount of air flow through the MAF the line pressure is set to the max.

The only problem I see with attempting to use the XFC for your application is timing retard. Due to the VVTi, your best bet would be to find a system that can intercept the coil signals. If you intercept the CAM and Crank signals it will alter the VVTi timing.

Russ