Guys, I've doen a bunch of reading and searching on here about what this could be. My truck is an 86 4runner. It runs and idles great for the first 5 minutes until it warms up and then the CEL comes on and it feels like a my "power switch" was turned off. It feels like I loose a ton of power. Sometimes it will do it while my foot is in it and the whole truck will lurch and slow down. It's really annoying. This is the weird part...it really started doing it about a week ago right after I put my new 4:88 gears in. I don't know if the 2 are related or if the gears just amplify the problem. I don't really see how they could be related. After searching, I'm thinking it might be the TPS. Does anybody have any thoughts? Thanks!

 

What's the CEL code? Do you know to check for that?

http://www.off-road.com/toyota/tech/codes/index.html

 

Thanks, I should have mentioned that. Last time I checked it was the knock sensor and the TPS. I'll check again tonight and see if it's throwing something new.

 

The KS code could be a result of the TPS. I'd check the TPS first. Unplug it and see if that makes a difference.

 

dido^^^^^^^^^^^^^^^^^^^^^^^^

 

OK, it's throwing a 5 and a 12. I know the TPS is the 12 but I'm not sure what the 5 is.

Do I just unplug the TPS and drive it...or should I check something else first?

 

I mean knock sensor...not TPS

Looks like code 5 means O2 sensor. Are the ones at Advanced or autozone any good...or is there a good cheap place to order online?

 

vibator^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^



Just because you're getting a code 5 doesn't mean your O2 sensor is bad. It just means there's an error on that circuit. The sensor could be bad, yes, but it could the wire or just that the sensor is detecting a lean or rich condition. In other words, doing it's job.

Yes...unplug the TPS and see if the condition improves at all....no power loss. The knock sensor maybe working and detecting spark knock and thereby killing the power. If the TPS is the cause, unplugging it may temporarily stop the problem. First reset the ECU (unhook the battery for 5min) and then run the test. Ignore codes for the moment......unless the KS code comes back.

Reportest thouest resulteststhsths!

 

I would be looking at your TPS for sure. Could also be your AFM sticking.

 

Well, I unkooked the TPS last night and it ran worse. As soon as I hit the gas it would upshift twice real fast. The CEl immediately came on. I guess it's not th TPS? Any other suggestions?

 

Okay. That does usually mean the TPS is still good. Try testing the AFM. Run a search on that. "AFM testing". Also, look for a thread started by me on testing. I've done one that's not covered in the factory service manual.

 

Code 12 for '86 is: "Knock control sensor signal has not reached judgement level in succession." Either the knock sensor wiring, sensor and/or the ECU are faulting. Make sure the sensor is plugged in (maybe you accidentally pulled it loose working on the gears?) and that the wire is not cracked or deteriorating and is continuous (using a multimeter) to the ECU.
Code 5 for '86 is: "Open or shorted oxygen sensor circuit or prolonged lean or rich condition." Make sure the wire(s) is/are not shorting out somewhere and that the wire(s) is/are firmly inserted in the plug and continuous to the ECU. I'm doing the "(s)" and "is/are" because I don't know if you have the heated O2 sensor, which has more wires to the sensor.

What I can imagine is happening is that once the engine warms up, it begins using the O2 sensor to adjust your fuel mixture and given the sensor circuit is failing for some reason, the ECU cannot get the proper mixture set. Considering you say that it is an intermittent problem leads me to believe there may be a problem in the O2 wiring. Check it very good, particularly around the transmission.

The KS problem may or may not be related to the O2 problem depending on which direction the O2 sensor problem is failing- lean or rich.

And the lower gears will amplify any engine power problem.

 

The '86 has a single wire, non-heated O2 sensor. I'd spent over a year here and there troubleshooting a code 5...even started a thread on it.....eventually finding the fault in the AFM.....which I started yet another thread on.

It's hard to tell on a code 5 which direction the fuel mix is leading because the earlier gen's do not throw a code 25 or 26 like later ones do. Atleast, my '86 never did. A good indicator, though, is if the exhaust smells more strongly of fuel with accompanying soot in the tailpipe.....or even black smoke. Mine did not smoke, but smelled strongly. Then again, sometimes it would run lean indicated by a slight ping under heavy load. The varying mix I suspect was due the nature of how the AFM operates when malfunctioning as it did.

BTW, I'm not saying your problem is the AFM. I'm merely suggesting it's a possibility. My truck lurched a bit because of it. Usually on deceleration, though.

 

Mine smells strongly of fuel. In fact if I start it in the morning, and let it run a minute or 2, I have a big black wet circle about 6" in diameter right at the exit of the tailpipe on my driveway. I'm pretty sure it's unburned gasoline.

Where is the AFM and what should I do to test it? I'm not sure if I even knoe what it stands for...but I'll do a search right now.

Thanks for all the good advice guys. Hopefully I'll get this solved soon.

 

AFM where, what and how:
- http://www.4crawler.com/4x4/CheapTricks/AFM/index.shtml

 

Replace your knock sensor. I had the same exact problem amd the knock sensor was it. The 22re knock sensor is known for going bad. I spent $170 on mine amd wasn't sure if it was the problem but it was exactly it. It's an easy fix too. Just screw it in the side of the block and attach the wire

 

Did you look at the time/date stamp on the thread before you replied? This discussion is over 4 years' old.

 

Ya I saw after I posted hahah. Sorry I couldn't get to u at the time

 

Uhh... get to me?
It wasn't me with the problem, but thanks all the same.

 

Oh sorry I just thought it was u bc u replied about it being 4 years ago :p