Check engine diagnostics 1990

[where02190]

I cannot find anywhere that can diagnose my check engine light on my 90 with the 3vze v6 auto 4wd with 275k and still going strong.

This began after doing a tuneup. When I start it up it's out but as soon as I give it gas it comes on. It is definitely NOT the 02 sensor, it's recently been replaced and I checked the connection.

Add to this since the tuneup the mileage has dropped about 30% from 18 to 14 MPG on average. I did forget to plug in the electrical connection that goes in by the air filter when I finished and it ran but died until I figured that out.

I am positive all the vacuum lines got replaced correctly. It otherwise runs great, plenty of power, etc.

Thanks, and long live the 4runner!!!!

 

[20034RunnerV84x2]

Under the good of under the dash next to the driver side left leg.

 

[where02190]

I know where it is, what I cannot find is some place that can access it, no one has a diagnostic reader that old.

 

[DC runner]

You do not need a scanner for that vehcile. All of that era toyota's could be self diagnosed. I tell this to you, having done it, many times on my old 1990 4runner.

I no longer own that truck and I no longer own that repair manual. Pick up/borrow/find online directions.

It goes like this. You will be jumping 2 ports on the computer access board in the engine bay. When you do this, it will place the computer in access mode. You will go to the car, place the key in the ignition and turn the key JUST to ON, not start. Your check engine light will blink. A series of SHORT/LONG blinks.. This is the code.

Every pattern HAS a code it corresponds with and every HAYNES or Chiltons has a table for you to look it up.

They could do this, because the computers were much simpler. Modern cars have hundreds.. your truck.. 20.

Anyway. Google around and find the directions, but should take you 5 minutes.

 

[DC runner]

FOUND IT:

http://www.troublecodes.net/Toyota/


FOllow the top one, for 89-94. I swear this works. Done it MANY times.

 

[where02190]

OK so thanks for the info, I shorted as instructed and I think got a code 52, 5 blinks, followed by a pause, then 2 blinks, then a longer pause and the cycle repeats. This indicated the knock sensor.

What I can't seem to find is what it looks like or where it's located, or for that matter what it's official name is, as all the parts places I use have no clue what that is. Best i can find out is it's somewhere under the intake manifold plenum, which as we all know is a huge PITA.

She runs fine, although mileage since this happened (which was right after a tuneup) has decreased about 20%, so its worth fixing I guess.

Any further help is gratefully appreciated, long live our 4Runners!!!!!!

 

[SV_Dude]

Just a quick search on orielly auto parts website:
Import Direct 17-0745 - Knock Sensor | O'Reilly Auto Parts

They're expensive, but important!

 

[where02190]

Here's a much cheaper one than that, now that I know what the terminology is:

Ignition Knock Detonation Sensor Standard Ks95

I have gotten a bunch of parts from aptopartsshop.com and all have been top notch, with fast delivery and great service.

However since it appears you have to basically tear the top end of the engine off to replace, and since this occurred directly after a tuneup that required removing the plenum to change the PCV valve, my guess is there's a loose or broken off wire someplace. I'm going to have my mechanic check for that first before I go tearing into replacing it.

Thanks!!!