blair1

Hey guys, benn searching the forums for a while now and have found great info and decided to sign up. So hello all. Any way just bought my first yota, a 1995.5 tacoma extended cab 4x4 sr5 with 195k miles. frame good, bed rusted out. overall good shape, 2500.00?? good? Anyway check engine light was on so checked code and said rear o2 sensor and knock sensor. well did the dreaded knock sensor and replaced both sensors when I was in there, drove about 200 miles now when i check the code it says both sensors are bad. Per the advice I found on the forums I also replaced the harness that goes to the knock sensor. Old sensors said "ND" on them so I bought the Denso replacements. What gives? Didnt replace the o2 sensor because i realized SOMEONE cut the cat out and welded the sesors in and im not sure what to do about that? Truck has a hesitation not a miss at about 3k rpm not sure if thats from the knock sensors, the o2 sensor, or lack of back pressure due to no cat. Plugs, wires, coils, are new. Any help would be appreciated. Sorry for such a long post.

matt92yota

pics?

blair1

Img_0461.jpg img_0458.jpg

gdutch

Welcome! My first guess on the hesitation would be a bad coil pack, but you said they're all new. What are the actual codes that it's throwing?

mt_goat

I think I'd start with cutting out the welded in O2 sensor in the front and replace it with OEM. You'll probably have to make or salvage a sensor bung. I can provide steps for making a bung if you want. EDIT: I just noticed its the rear sensor CEL now...hum....not sure what to do now.

Don't know what to tell you on the knock sensor problem, maybe a problem with the engine harness.

BTW it sounds like maybe you over paid for it.

blair1

i am def. interested in the steps to make the bung. I have looked everywhere and can't locate 1. Think the o2 sensor is causing the hesitation?

mt_goat

This is copied from my swap thread here: https://www.yotatech.com/forums/f160...45/index8.html

Getting ready to have a custom exhaust system built from the cross-over back. I couldn't find anyone that sells a Toyota O2 sensor bung to weld into the new exhaust piping. After talking to a friend that works at the local Toyota dealer about where to get one, he says why don't you just make one? I hadn't thought of that Jason, thanks for the idea. So here's how to make your own O2 sensor bung.
I started with a piece of 3/8 steel and marked the outline with a gasket and drilled and tapped some holes (8mm x 1.25):


I used some exhaust studs from the dealer that were left over when I was putting on the ORS cross-over.


Then I started cutting it out with a cutoff wheel on an angle grinder:

After using a grinder and beltsander to smooth it out:


Now that was one bung, but I need two for the 5VZ right. The first one took me about 2-3 hours to make so I decided to try cutting an old one out of my old 3.0 exhaust pipe and using it. That took about 2-3 hours too, counting replacing the old studs and smoothing it out with a grinder and beltsander too.

Here's the two side by side, the one I made from scratch will have to be welded in parallel to the pipe since it's not curved to the shape of the pipe:

mt_goat

What are the actual codes its throwing?

I'd probably check the continuity of the knock sensor wiring all the way to the ECU.

blair1

i will have to check the exact codes.

blake.nemitz

arent those ecus programmed to read a cat, if one isnt there is throws everything outta whack, especiall sensor #2,

Vantucky

I'd ask what specific codes are setting now, and in what order.

Then follow the FSM troubleshooting steps for each code in the order that they pop. Solve the issues relating to the first code before working on the second one.

Regarding the second O2 sensor causing the hesitation, I don't think it would cause that. AFAIK, the second O2 sensor just checks to make sure your CAT is working and is not used by the computer to adjust your fuel trims.

Here is a good article on O2 sensor issues for your truck: http://www.4x4wire.com/toyota/4Runner/tech/O2_Sensor/

Also assuming that your truck is throwing a P0420 code, which it will if you remove the CAT, and your back O2 sensor is working as it should, there is a writeup on how to fake the ECU into thinking that CAT is working. I don't have the link in front of me though, sorry.

mt_goat

Unfortunately I think he has the older OBDI, so diagnostics is going to be less sophisticated.

Vantucky

My bad, I missed that from earlier.

mt_goat

It wasn't mentioned earlier but I saw his other thread in the newbie section about a code 52, which is an old OBDI code. https://www.yotatech.com/forums/f120...sensor-230271/

drift_king

there is no such thing as an OBD1 tacoma, i have a 95.5 and theres a obd2 port under the dash right by the ebrake

mt_goat

So how did he get a code 52? Maybe during the switch from 1 to 2 there was some of both in the same year model. What is your actual build date?

blair1

I actually had to go out of town for a few days for work but when I get back I am going to get you guys the exact codes and what order they come in.

drift_king

mt goat, ive been told by a few ppl theres no such thing as an obd1 tacoma, i may be wrong and if i am i apologize, but i think maybe he got 52 by jumping the dealer tools? and my actual build date idk and the trucks at my dads house right now so i cant check, sorry

blair1

Ok, I got the exact codes and the order they came in. First code is po141, second is po325, and next is po330. Please help I can't figure this one out. I know the first code is for the o2 sensor an the next 2 are for knock sensor malfunction.

mt_goat

Well Drift King you were right its OBDII.

Here's the free online FSMs, find the codes under the diagnostics and it will show all the areas of possible causes for each code : http://www.ncttora.com/fsm/index.html

I'd recommend clearing all codes now and see what comes back first.

EDIT: Here's the 2002 FSM P0141 info: http://www.ncttora.com/fsm/1996/SIL/...fe/cip0141.pdf

P0325/330: http://www.ncttora.com/fsm/1996/SIL/...e/cip0325p.pdf

On the knock sensor codes, I mentioned earlier to check the knock sensor wiring continuity all the way to the ECU. You may have some broken wires.