1uz4runner

Ok, so have a 1994 4runner and the engine went bad. Blah, blah we all know about the V6 engines. Anyways I removed the boat anchor and replaced it with a 1994 LS400 engine. I mated it to the original Toyota 5 speed tranny with a new bell housing. I took the truck to Toyota only swaps for the wiring portion of the job as wiring is not my specialty. I am more the mechanical side of things. I have the front 02 sensors and only one rear cat. I have not installed the rear 02 sensor yet.

So I got the rig back and they said that the IACV must be stuck from sitting for so long as the rig idles great with the hose plugged going into the intake housing, but the idle searches when released and you can hear the whine of the air going past the open idle valve. They checked the codes and it had a code 21, 24, 28, 31, 71.

I was expecting an error of 27, 29 since the rear 02's were not present yet. But they have not showed up.

The ecu is not the original from this car the motor came from. I ordered a used ecu form another member on a forum that has built several of these same style of rigs.

I got the runner home and plugged the idle air control hose and adjusted the thottle nut and this thing works perfect. Idles great, sounds good. I took it out for a ride and put about 20 miles on it. Didn't miss a beat.

I am in the process of fixing the things that caused the CEL light. I pulled the ground cable from the battery and wanted to reset everything. That didn't help, so I pulled the EFI fuse and checked the codes again.

This time I came up with a code 21, 28, 71. The issues with the AFM seem to have gone away at least for now. I have an extra AFM if I need it. So I replaced the 02 sensors, and cleaned out the IACV, still have codes for the 02's and the IACV still isn't working, I even ordered another IACV and it still does the same thing. Wondering idle up and down. I pulled the plug to the IACV and checked for voltage on all 6 pins. I got nothing from any of them. I am confused as to why I don't have any power going to the IACV from the ECU. I thought that it should go directly from the IACV to the ECU?

So after all this rambling. Sorry trying to give you all some back ground information so you know what I have done. I just want to check and see if I have a bad ecu since I am not seeing any voltage at the IACV.

I need to know where the wires from the IACV go? If anybody has any answers as to why the front 02 sensors are not working either?

ECU# 89661-50142
34P 22P 16P 28P

I pulled the covers and opened up the boards to look at the caps, all appear to be in good shape. I don't have any leaking and no domed caps on anything.

Thanks for the help.

rrgone

Interesting swap. This site has helped me several times with schematics:
http://search.ebscohost.com/login.aspx?authtype=url,uid
User ID - tech; password - tech
Scroll down and click Auto Repair Reference Center

Good luck.

mikes7ke

iTrader: (1)

This might sound silly but did you check for vacuum leaks?

Yotarip

My first sugestion would be to go to your nearest junkyard and get the oem plastic intake tube assembly.


I think the setup you have there may be part of the problem. Is the IACV plumbed directly into the MAF housing? That may not be a good idea. It's way to close to the meter. May thow off air mass readings.

1uz4runner

Thanks for the helps guys. I appriciate all the responses.

rrgone- Very helpful for pin outs. I appriciate the link.

mikes7ke- I have looked for vacuum leaks. All the vaccum lines look good. Funny thing is that I would think that vacuum leak would cause it to run bad all the time. But it runs great if I pinch off the IACV hose. It is definetly the IACV that isn't moving to the closed position.

yotarip- I had one of those intakes and I still had the problem. I moved it to the current location so I could put an extra battery in that spot it opens up so I can run an ARB fridge and winching system. I did remove the plug in the side of the AFM and install a barb and put the hose there when I moved it. It didn't seem to make any difference. I also have the PS vacuum line running to the AFM as well. If everybody thinks that I absolutely have to have the stock tube back I am happy to do so, just let me know what you all think.

I will check the pin out on the ecu and see if I have any readings for voltage going to the iacv and the 02's as well. At this point I am hoping its just an ECU that the problem. Easy fix by just replaceing the unit and not having a wiring problem.

Anybody else have idea's please feel free to chime in.

python

iTrader: (4)

awesome work! its my opinion u now have one of the most reliable motors on the planet in ur 4 runner..good job!

1uz4runner

Thanks for the compliments guys.

Ok so problem solved. Used the link that rrgone listed. That is exactly what I needed to fix this problem, my hats off and a big thanks.

I have learned that you should never pay somebody to do what you can do for your self, even if you must put something on the back burner for a while until you get the time to complete it.


The shop that did the wiring said they wired everything up and all was good to go but the IACV was just sticky. Well after cleaning the unit and then finally replacing the unit. I determined that they never actually supplied a power wire to the IACV unit. Low and behold I sourced an ignition on 12 volt source and inserted the power supply thru the factory harness.

All is well now. The IACV is responding correctly, my throttle and idle are spot on, my CEL light is out now and the ECU is picking up the 02 sensors. Amazing what one power wire in the right spot can do to solve problems. The response and acceloration is even better now.

So very happy.

This engine is what Toyota should have installed into these rigs back in the 90's when they came from the factory. My MPG's are so much better then when I had the dog of a V6 too. More power, better acceloration, better towing. Win, Win. So they can't use EPA as a reason for not doing it to begine with either....