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Discussion Starter #1
So a few weeks back I installed the TRD Supercharger high boost kit for my 1999 2.4 for a little pep in the daily. It's been N/A for a few years and super reliable. (before that I was turbod)

I am having issues with the way it runs. It hesitates really bad in transient, low RPM conditions when going into boost (spikes lean). It's also going way rich (like 10:1 AFR) when I hammer it and go into open loop and make boost.

So basically it seems like in close loop boost it's lean, in open loop boost it's rich.

I have the 5th injector kit, with the Split second FTC1. I have a patch harness also from URD I am using to splice in the FTC. I would assume if it was not wired correctly it would not run. I also have a wideband, and a fuel pressure gauge. I have the fuel pressure regulator referencing boost so it rises with boost, and it does so (rises to about 52 psi in boost).

I removed my cat some years ago because I had suspected it was clogging. Due to that, I receive P0420. I have longtubes, and a full stainless 2.5" exhaust I tig welded myself.

Summary of build:

Walbro 255
W58
Detroit trutrac posi
2rz sc with 8 psi pulley
long tubes and 2.5" exhaust with cat removed
stock airbox

I contacted LCE and they are trying to tell me I need an o2 sim for the rear o2 sensor. I find this hard to believe because from my years of knowledge and reading these forums the ECU does not use this sensor as a feedback to fueling and does not enable any processes based on the output of this sensor, just illuminates a CEL.

I have double checked wiring, vacuum leaks, exhaust leaks and no issue. Truck idles super smooth and runs great, holds 14.7 AFR in cruise and idle....can anyone lend a hand? I am getting a USB to serial adapter so I can start checking the tune in the FTC1 to make sure it is correct.
 

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Mambeau / Admin
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Did LCE give you any explanation for what an O2 sim at the rear sensor was supposed to do / fix / accomplish?
 

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Discussion Starter #3
Did LCE give you any explanation for what an O2 sim at the rear sensor was supposed to do / fix / accomplish?
this was our exchange:

LCE - "Devin, You mention that you have the stock o2 sensors, do you still have both of them installed in the factory locations? I am guessing you used a test pipe to replace the catalytic converter ? If that is the case then the first place to start will be an O2 simulator for the rear cat, as the stock o2 can definitely be causing problems with the cat not being in place and trying to rely on the stock Ecu to provide proper readings so the system can adjust accordingly."

me - "Yes a test pipe, and stock o2 sensors.

I thought the rear sensor only was there to detect of the cat was functioning correctly? I didn't think it actually enabled any processes and affected the tune. Thanks!"

LCE - "Devin, the rear o2 is the one that reports to the ecu, so it can definitely cause you some issues if its not getting proper readings.
Have a great day
Wes"

No further info as of yet. I have a feeling a sensor sim wouldn't impact the tune that much if at all..
 

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Mambeau / Admin
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The problem is that the FSM never explains what the ECM might do in response to an O2 sensor problem that's been detected. Toyota never provided documentation on the internal logic of the ECM itself.

For example ... A code P0125 is thrown in response to "Insufficient Coolant Temp. for
Closed Loop Fuel Control", and the front 02 sensor (Bank 1 Sensor 1) is one of the possible causes. Does this mean the ECM responds by preventing entry into closed loop? The documentation gives no clue, so it's anybody's guess.

My theory is that LCE might indeed know something about the mysteries of ECM responses to sensor-related faults, but I can't prove their advice is sound. :shrug:
 

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Discussion Starter #5
I got my USB to serial adapter today and read the tune on the Split Second FTC1. It was way off. It was apparently for a 6 cylinder and was making no additional injector or timing adjustments until 10.5 psi of boost.

I flashed the 2rz/3rz map from LCE engineering and it runs better, but needs tweaking.
 

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Mambeau / Admin
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I got my USB to serial adapter today and read the tune on the Split Second FTC1. It was way off. It was apparently for a 6 cylinder and was making no additional injector or timing adjustments until 10.5 psi of boost.
:jawdrop:

Yeah - that would explain it ... :evil: :doah: :rolleyes:

Glad to hear you're making progress ... :waytogo:
 

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at least you didnt blow your motor prior to finding this out.

what a bummer, they sent the unit with the wrong flash.
 

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Discussion Starter #8
yeah....haha

it's still going way rich at WOT, but not as immediate. I may need to tweak the tune, and pull down the 5th injector values for that part of the map.

Does anyone have any solutions to OBD2 scan tools that can also data log an external sensor like a wideband? I can't find anything.
 

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About the second O2, its function is only to confirm the proper working of the cat. The second O2 has nothing to do about the actual reading of air/fuel. The air/fuel ajustment is the job of the first O2 sensor.

That being said, if you have removed your cat or someting on the exaust system that impacts the cat and you have a MIL related to O2#2, there is a lot of chance that will change injection parameters to switch in safe mode. Not because of the sensor but because of the presence of MIL.

Usually safe mode means more rich. If you installed a test pipe of some sort and you are not driving with a check engine related to the O2#2 you shouldn't have problem with that. If you have a check engine related, it may modify injection parameters. As I said, not because of the actual reading or the sensor but because of the reaction of the ECU related with the engire trouble code.

I'm a certified mechanic and I work in a VW dealer, I deal with those things everyday.

Hope it helps.
 

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Dick removing the rear O2 sensor does not put my 2002 into limp mode. Removal of the front one definitely does thought. As you said the rear just checks for proper cat function. Removing the rear may put other vehicles in limp mode but it didn't for mine.
 

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Mambeau / Admin
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Just for the record ...

There *is* an ECM fail-safe response relating to the Heated O2 Sensor (Bank 1, Sensor 2), but I don't think it adds any additional complications to the OP's situation.

If the ECM detects an anomaly with the heater circuit for the sensor, it should throw a P0141 code and shut off the heater circuit. This circuit shutoff remains in effect until the ignition is shut off.

This would mean the ECM is controlling things without accurate readings from the rear sensor. That situation is already in effect by having removed the sensor. This is why I said it doesn't add any complications or additional possible causes for the reported issues.
 

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Dick removing the rear O2 sensor does not put my 2002 into limp mode. Removal of the front one definitely does thought. As you said the rear just checks for proper cat function. Removing the rear may put other vehicles in limp mode but it didn't for mine.
Yeah might be the case then. What was being said about ECU reaction to MIL related to O2#2 is a change in injection time to richen the blend to avoid damage caused to cat caused by a potential too high temp.

But if your experience doesn't confirm that I would say there is nothing best than real life measurement.

Sorry for the misinformation.
 

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There probably won't be any difference if you clear the CEL. You are going rice for some other reason.
 

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I got my USB to serial adapter today and read the tune on the Split Second FTC1. It was way off. It was apparently for a 6 cylinder and was making no additional injector or timing adjustments until 10.5 psi of boost.

I flashed the 2rz/3rz map from LCE engineering and it runs better, but needs tweaking.
LCE says they don’t have a tune to send me for my high boost 3RZ 8 Port Setup - which blows my mind...

Do you still have a copy:reference you could send me?

Mine runs terrible with the FTC hooked up until boost, I had to disconnect the boost reference hose just to make it tolerable under 3500 rpm.
 

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You said "I had to disconnect the boost reference hose just to make it tolerable under 3500 rpm."
My 3rz is a 2002 and the fuel pressure regulator is not supposed to ever get a vacuum signal like it is in most cars. I think most Tacoma engines are set up that way. The fpr only gets atmospheric pressure then it gets boost pressure when in boost. Make sure you hook your fpr to the correct port. If I pull the hose off my fpr at idle there is no change in fuel delivery pressure.
 

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You said "I had to disconnect the boost reference hose just to make it tolerable under 3500 rpm."
My 3rz is a 2002 and the fuel pressure regulator is not supposed to ever get a vacuum signal like it is in most cars. I think most Tacoma engines are set up that way. The fpr only gets atmospheric pressure then it gets boost pressure when in boost. Make sure you hook your fpr to the correct port. If I pull the hose off my fpr at idle there is no change in fuel delivery pressure.
I have to disconnect the vaccuum line to the FTC or it runs terrible. The FPR is hooked up proper.
 

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