((Po505 code)) I have tried everything I know. Please some help.

Hello. First time looking for help in a forum. I basically hit a wall with this problem.
I have been fighting this po505 code for few months now.
Checked for air leaks multiple times. Smoke test few times.
I did had 2 leaks that I fixed . But did not remove code.
Removed and clean throlle body and iac valve.
Didn't fixed.
Replaced iac valve 2 times.
Didn't fixed.
Flushed antifreeze cus someone told me bubbles might caused the codes. Sounded weird but I tried any ways.
Did not fixed.
Then... I replaced the pcv and I was super exited because the code went away and car was driving awesome.
For one day everything's was great. I was super happy.
But next day I turn the car and boom! Freaking po505 again there.
I replaced the pcv again since they so cheap. But nothing.
Checked for air leaks again with smoke test and not leaks.
Checked wired and connections, they look good.
Tested the iac valve with multimeter and with a 12 v battery.
Works fine.
Tested the tps and is fine.
Tested maf and also fine.
What else can I do ?????

 

Odd, I waited twenty years before changing the PCV valve.

 

Well. Is probably been that long for me too.
Weird thing is that . It temporarily fixed the problem.
Why code came back ?

 

System RPM incorrect. Valve resistance cold: 17-25 OHMs. Did you replace with Denso part?
Leaks? Ya any leaks on the intake bellows anywhere and it throws stuff off usually it dies.

 

Thank you for this info. I will run this tests in the iac valve. I haven't done this tests.
I'll need to get couple of tools to be able to do it.
But I'm determined to fix this code.

But why yoi think changing pcv fixed the issue for 24 hours?

 

I know after 20 years, my vacuum hoses were hard as a rock and I replaced them all. I would go through and replace all hoses.

If after testing the IAC...and you verify wiring to the ECU is good, you may want to consider a new ECU.

Here is a thread and full tear down with some testing tips: I would NOT sand blast like the guy did but just use Throttle Body Cleaner and compressed air to blow out any dirt.

 

Any update Harold?

 

I have been driving like this. I haven't got time to run that particular test on iacv. So is still dealing with this problem.
I replaced almost all the hoses so I don't think is any issues with that either.

Now the symptoms I have is:
Car at idle speed is hesitating and acting oit.
It did stall once and only once when I was reversing.

Also the must annoying symptom is that car reache a speed according to the preasure at gas pedal and when it reaches that speed instead of maintaining it, it drop back. I can actually feel.a lil bump like feel.
So I have to press pedal again to be able to maintain speed in highway.
And obviously the stupi po505 code still there and not going any where.
I just hope is iac and not yhe computer.

The test I ran on iac showed that it was good. But I want to do that other test. But to be honest I don't feel alot of hope with that.

But ill do it.

 

I wonder if your TPS is going bad too?

Did you use a Toyota or a Denso IAC? There are huge issues with sensors from non OEM sources (even big box stores no longer carry parts that work reliably).

 

I also tested the tps and passed the test.
And not. I didn't got a toyota or Denson iac valve.
I tested the one that I had with a 12 v battery and open perfectly.

 

Did you test the TPS through its whole range?

The problem with a TPS sensor is that it wears in spots. Typically it wears above the idle because that's where the car is driven 99% of the time. The TPS is at idle when the car is stopped (obviously) but also sits a little above the idle position while cruising. Eventually after 25 years, that spot has been worn out while the rest of the TPS is working fine.

So yeah, if you have issues at IDLE plus at CRUISING...I'm starting to think "worn TPS". This was the issue with my car. I was getting surging at idle and a hesitation when starting to accelerate. For me, the TPS was not available and I needed a new Throttle Body which fixed the issue. My throttle body also has NO IAC. 2001-2002 4runners are special in that way.

Your IAC has 3 wires I believe. I am not sure if just testing if it opens is enough to verify it's good. As it opens, one of the other wires may need to return a correct signal back to the ECU. I don't know...I haven't needed to play with an IAC and I don't have a wiring diagram for your year to make any more of a guess. I would hope that if you got it from at least a big box parts store, that it would at least work for a bit. But the parts business seems to be a race to the bottom, and there is just garbage sold everywhere now.

 

Really appreciate yoir time, tips and knowledge.
Let me ask u something.
Because I'm under the impression that a bad tps would cause the code po505

I belive a bad tps triggers a different code.

 

Did you replace the IAC Valve with a factory OEM IAC Valve ???

 

Yeah, not sure.

An outright bad TPS will throw a different code. Mine didn't throw a code for years until it just got REALLY bad and threw a code that, while I don't remember exactly what it was, it was an IAC code. Which I found funny because there is no IAC on my rig.

You may be chasing two issues.

 

Ok wow. Haha crazy huh.

 

And not I didn't replaced the iac valve with a oem iac

 

Hello so. I finally replaced the iacv for a autozone part. 280 dollars.
The car does drive different (better) but I notice 2 things:
Idleling a lil high
And
I still reading same code.

I just replaced a day ego.
My question is.
Does the code sometimes takes a while to go away?
I deleted the code with the scanner right after replacing the part but canlme right back when I turned on the car.

I heard someone told me that the computer takes a while to adjust? Is this true ?

 

code should not come back right away.

The ECU will take a day or so to try and relearn and drop the idle down but it shouldn't show a code right away.

It seems like you have an ECU or wiring problem.

Check all body and engine grounds.

 

How can I go about checking all the grounds? Can yoi guide me the right way?

 

You need to get a factory wiring schematic to know where the locations are. I don't have one for that year.

 

Thank you. I'll do that. Just curious. Approximately how many ground a vehicle from this year could have ?

 

Now that you mentioned that. I also been noticing flickering dashboard lights , interior lights and headlights. Basically all lights in car been flickering. And is not the alternator.
I gues it could be a ground wire that is loose right ?

So yoi say I can search for a diagram for all the ground points and then I can make sure is connected well.

 

Yes, it absolutely might be a bad ground wire. Since it's all the lights that are flickering, I would guess that it's one of the main grounds. Probably, not a certainty, but in my mind probably, the one from the battery negative to the body. I would pull and clean both ends of the cable that goes from, as I said, the battery negative terminal to the body metal. Pull it off the battery, and scrub the terminal with a brass bristled wire brush. Until it's bright and shiny. Then do the same to the end of the wire. Then follow the wire to where it connects to the body metal, pull it off, and wire brush it until IT is clean and shiny. Both the wire's terminal, and the area on the body metal where it bolts on. Clean and shiny. No paint, no dirt, grease, corrosion, nothing but nice, clean, dry metal.

Now do the same for the battery's positive terminal.

Take your multimeter, and connect it to both ends of the wire, on the lowest ohms scale it has. Flex the wire around, especially the end connectors, and watch the meter for a flickering of the ohms reading. Hopefully, it won't. If it does, either replace the wire entirely, or re-do the end connector(s). Then bolt it back on, and see what the lights are doing. Again, make sure where the wires connect to ANYthing, is clean.

A little dab of silicon dielectric grease, available at any auto parts store, is a fantastic preventative for corrosion, invasion of grease, or oil, and so forth. A small amount, either on the wire's end connector(s), or what they bolt to, is all it takes. A small amount, injected into plugs or connectors is a very good idea also. Any plug or connector you take apart, do that to. Just a small dab of the stuff is all that is needed. That includes plug wires, the coil wires, etc. ANY electric connection benefits from the presence of silicon dielectric grease.
None is required on fuses, but ensuring their metal prongs are clean and shiney is a good thing. If they appear corroded, either replacing them, or wire brushing them until they are clean again, is needed.

Does this help at all? Don't forget the ground points behind the kick panels on either side of the passenger compartment.
Good luck!
Pat☺

 

It does help !! Tha k you so much for the time and knowledge.

So I did this.
I checked the battery voltage. 12.8
Then with a multimeter I tested the ground on the car frame and also on the engine and the voltage was the same (12.8)
I did this test with the car on as well.
Voltage was in this case about (14.9)
So appears to me that the car is well grounded according to this test.
What do you think ?

And... man so I replaced that iacv (new one from autozone)
Now car is Idleling at 1000 rpm and code still coming up.
Any ideas?
No air leaks anywhere . I checked

 

Hello everyone. So I did another smoke test and there's is smoke coming oit from around yhe spark plug boots. From 2 of them only.
You can see in the picture. It's not coming out from where yhe spark plug screws in. Is coming out from the top. Between that gap yoi can see there at the top.of the whole.

What is this and how to fix?
I would think that's my air leak right there.

 

Sounds like you have a bad wire at the connector on the wire harness that connects to the connector of the IAC. Did you happen to use the wires to pull on when disconnecting the cable from the IAC? I accidentally pulled a wire out of the TPS connector when trying to disconnect it. Try inspecting the interface of where the pins attach to the wire of all 3 IAC pins of the connector on the wire harness. This would explain no change after replacing the IAC. Or your ECM is bad but that is worst case. Wiring diagram in the Haynes Repair Manual for Taco, 4Runner & T100 that covers 96-99 4Runner is on page 12-27. IAC connector is at the bottom center of the page. Can use a multimeter to measure continuity between the pins of the IAC connector of the harness to the ECM connector of the harness in the cab.

In your April23rd post with the photo of the spark plug tube, the smoke is leaking through the circular gasket that seals the valve cover to the spark plug tube. Those gaskets get hard/brittle and shrink after +20 years, so I could see how the smoke would get through. This isn't going to cause a significant vacuum leak. It would be a ton of work to replace all the valve cover gaskets for little improvement.

Got Timmy in your life? His videos are helpful if you want to replace allllll those valve cover gaskets. https://www.youtube.com/watch?v=N5fAXAuGozI&list=PLPMpPriBUyJBswzxy00gJpFg55Zk2fZmq&index=15

 

Omg guys! I still dealing with this stupid code.
Is been a long time and because the car still drives I just kept putting it off.

Now I have a battery lights that comes in and off.
Alternator and battery are good and past the test 2 times.

Car idles high and now I'm noticing surges when driving at around 25 to 40 mph.
Speeds go a little up and down.
If I give it some Gass it stabilize.

I honestly don't know ow what else to do.
Oh the belts look fine as well.

Someone one told me about a problem with the piping ? Idk

I'm so frustrated

 

You said you have blinking lights? A ground wire? I had an auto zone alternator that would flash the lights, all the interior lights and exterior lights at all times, on another vehicle, not a four runner.

It tested good at auto zone of course, I pulled it off and got another one from them and it's worked fine ever since. Of course they told me it was a ground wire.

Lesson learned on any rebuilt junk alternator.
Don't take any flashing lights being a ground for granted, now it could be, but did the lights flash before the new alternator was put on? Oh yeah I searched for two weeks for a faulty ground