Elvota

I thought I'd chime in a bit...

First off, what are you using to pull your codes? Any information you can see besides the code itself? Freeze frame data, when the code is occurring, etc. If you want, we can hook your truck up to my laptop interface sometime and see if any more clues show up.

PO136: That's a strange code to be getting since your installation of the bypass box should be feeding the correct parameters to the ECM. How do you mean you have it twice? Is it a code as well as a pending code? Do you still have the secondary O2 sensor connected, or did you eliminate it all together?

PO171: This is what I have from the FSM. When air fuel ratio feedback is stable after engine warming up, fuel trim is considerably in error on RICH side (2 trip detection logic). Possible causes: air induction system, injector blockage, mass air flow meter, engine coolant temp. sensor, fuel pressure, gas leakage on exhaust system, open or short in A/F sensor (bank 1 sensor 1) circuit, A/F sensor (bank 1 sensor 1), ECM.

I wonder what gas leakage on exhaust system could be? Meaning, I wonder if the ECM is reading that from the bad O2 or EVAP codes. I don't know if they are related, just throwing out ideas.

PO450: The vapor pressure sensor, VSV for canister closed valve (CCV) and VSV for pressure switching valve are used to detect abnormalities in the evaporative emission control system. The ECM decides whether there is an abnormality in the evaporative emission control system based on the vapor pressure sensor signal. DTC P0450 or P0451 is recorded by the ECM when the vapor pressure sensor malfunction.

If you didn't have the EVAP plugs in your harness, you need to break out your EWD for the 3.4 and pull new wires for the neglected ECM pins. If you look at the EVAP stuff on my thread, you'll see that you can use the old VSV's for some of the new 3.4 EVAP components, but you do need at least the primary sensor from the 3.4 stuff. I am 95% sure I have an extra 3.4 EVAP sensor, if you would like to at least try and plug it in your setup to check if PO450 goes away.

I don't think the motor will operate any differently with the EVAP installed or not, but the ECM will most likely throw a code. I think it depends somewhat on the year of your motor. Also CA editions seem to be more sensitive to such things.

I am not completely sure, but I think the EVAP not only helps eliminate excessive emissions but also allows the gas tank to breath, expel vapors. Seems like allowing the gas tank to regulate would be a good thing.

__________________

1990 4Runner | V6 3.4 | 5spd | 240 someoddthousand miles | SR5 | SAS | RLS | 35's | ARB | TJM | 217 to 1 | W8000

- four wheels | three sticks | two hands | one trail -

RobD

Good thing I never hooked up the check engine light, then!

And my gas tank expels vapors when I open the cap...seriously, though, I do have the EVAP canister but never got around to installing it. It runs fine without it. Lots of power, better mileage than the 3.0. Maybe I'll revisit it when the spring comes around.

__________________
1991 4Runner, 3.4 5VZFE swap, OME shocks/springs, 33" BFG All Terrain T/A KOs, Pioneer head unit, Infinity speakers, XM Satellite radio

screamer76

[quote=
I took the factory exhaust crossover pipe and chooped it up, and flipped it so that it comes out on the drivers side, had a total of about 2 hours into it, and $3.00. I took a ton of pictures and will do a write up on it if you all want one, I just didn't want to post pics until I knew that it fit, and we got that 3.4 set in place, and the pipe clears perfectly, and fits awesome.
:QUOTE]

please write this up! please please please! i'm going to be doing this swap in
a few weeks, and i am very impressed and interested in your solution. i don't
personally have a welder, or enough experience with welding to attempt this
myself. however, i talked to someone today who is willing to do it. he said he
could use as many pictures and information as possible. if these pics are
the only ones you have, we'll try to make do. i think it's a much better way
to go than a $300 crossover from ORS. so, i'm going to cut it up and
hopefully we can get it right the first time. any measurements or other help
you can give would be great. thanks-john

Jason4X4

I got a bunch more pics, I will get it done in the next couple days.

On a side note, I had to go rescue him last night on his way to Tucson the truck died, turns out the wiring that I ran by the exhaust had some reflective heat wrap on it, but it couldn't hold up to exhaust temps, and it burned through and melted a wire and shorted and popped the fuse. Atleast it was a simple find, and I got home at 1:15 this morning. I'll see if I can get pics when he gets back of where NOT to route the wires.

screamer76

hey, that would be great! i'm probably not even pulling the 3.4 out of the tacoma until next weekend and i want to make sure that i've got all my bases
covered before i start pulling the 3.0. so, no big rush. sorry to hear about last night. too bad it couldn't have happened a little closer to home, but at least it was an easy fix. looking forward to hearing from you again-john

Jason4X4

Got a 3.4 sticker made for the tail gate to replace the 3.0, If anyone is interedted, PM me, I got a couple extras.

Here is some Crappy pics..