Greetings Mudders!! 93 4runner..

[O'Shell]

So my friend has a 93 4runner 3.0 V6 EFI auto trans. She is convinced that I can fix it for her, but I am a FJ40 guy I have no clue when it comes to computers. So here is the problem. At idle, slow, 15 and 35mph it sort of "misses" or "hesitates" and she reports a power loss in general. She had moved to Cali and had it tuned to sea level, then she moved back here to 7000'. This problem started and she took it to a shop to have the oil changed and a tune up. They told her her fuel filter was really dirty and replaced it. And of course a few days after she got it back it started doing the same thing. I read up on it and the FSM suggesters the fuel pump control circuit. But I do not have a computer to plug it in to. Is there a way to check this without the computer? Am I even barking up the right tree? Any help would be appreciated as she is going to leave it with me for the day tomorrow.

 

[Hilux]

God I love OBD-1....


Not saying I know, or can help... But can't you stick an Ohm meter in "Fp" or the appropriate terminal and see if it's in spec?

Or take the circuit out and test its resistance or connection?

 

[2ndGenToyotaFan]

Just have the truck tell you what's wrong with it:

Off-Road.Com - Toyota Tech - Diagnostic Trouble Codes

 

[4rnr]

If the CEL is on, yeah check the code.

For a completly different angle...

It kinda sounds like it could be an o2 sensor, or a wet o2 sensor connector. when she feels a "lack of power" tell her to go to full throttle, if once she reaches wide open throttle the truck sudenly surges ahead at the 3.0L's version of warp speed. Id take a look at the o2 sensor. Or if it seems to happen more on wet days...

 

[O'Shell]

Alright so I used the paper clip and got two codes. First code is 1-4 igniter circuit, and the second is 5-2 knock sensor. I went ahead on the first because well it seems to fit more... I used the multi-tester on the igniter it checked out ok, same with the dizy, I did throw a new cap on it because the contacts were pretty crusty. Plug wires checked out ok. I did not feel like going at the plugs and I bet you know why. At a loss I threw a timing light on it and it was off. Set the timing and it was running ok and the sun was setting. I gave it back to her and told her to text me as soon as it started acting up again. Well sure enough about a week later it would not start. I went out and spent alot of cold windy hours just trying to get it started. Only thing I was adjusting was the dizy. Finally it started but very rough and a big cloud of white smoke. It stayed rough and Smokey for a few minutes then leveled out a bit. My timing light took a poop on me so I was only able to adjust it by ear just to get it home. I just went over now to check the plugs as they were the last thing the FSM suggested. They were all in good condition less #4 that was in so tight I broke it in half getting it out and the clip to one of the plug wires on the dizy. Now she is going to get a new plug and a timing light for me. But I am still at a loss as to what is the main problem. It would seem that the computer is self adjusting due to its sensors being out of whack. But what else in the igniter circuit would blink that code? And where the heck is the knock sensor? Dammed things cost $200 at Toyota and $150 at Autozone. If I knew where it was I could at least check the wire. I know not much about it. But I did read it has to do with knocking cylinders (duh) I do not however understand what it would tell the computer to adjust or if it is the culprit. Other than that I am at a loss. She does not have the money to give another rip-off artist mechanic. And I have alot of time on my hands. Plus I like doing good. I also love learning this stuff. I have done more to my fj40 than I ever dreamed I could and that's %100 because of the good people here at MUD!!

 

[KLF]

There's a lot less "computer" stuff on those trucks than you think. The engine ECU is pretty easy to diagnose, as you found out.

The knock sensor is on top of the engine, UNDER the intake. Yes, the intake has to come off to get to it. Here's a great picture of it, right in the center of the engine (stolen from another thread):

Now, there is a TSB out on the wiring harness for the knock sensor for that engine, apparently the harness can fail and cause issues. Not sure if this is your problem but it's worth investigating. Call your closest dealer with the VIN, have them pull up the TSB, see if there is any record of it being done on that truck. They may say they've never heard of it (likely, they stopped making that engine 15 years ago), just insist that they look, be persistent. If they find the TSB and it has not been done, they *might* fix it for free.

Also check to see if the head gaskets have been replaced under the SSC.

 

[pappy]

So here is the problem. At idle, slow, 15 and 35mph it sort of "misses" or "hesitates" and she reports a power loss in general.

My first reaction after reading this was a dead spot on the Throttle Position Sensor. But that would not be consistent with the other problems. A failed Ox sensor might cause the other issues, but that should have showed up when you checked the trouble codes.

Also, make sure the connection at the Air Flow Meter is tight, and there are no cracks on the rubber connections from the air box to the throttle body.