brokedown1

Hey guys, just joined a few days ago, I'm really hoping to get a problem solved. I hope someone here can help.

I have a 97 sr5 4runner with almost 200k on the clock. A few weeks ago I get the p0325 code for knock sensor bank 1. Changed that out with new sub-harness from Toyota, replaced valve cover gaskets, Intake gaskets and whatever else required for that job. Code comes back immediately, so I switched the wires for the two knock sensors, and the code changed to p0330, which indicates the code is being triggered by the same bank 1 sensor circuit. I have gone ahead and replaced the plugs, wires, coil pack boots, pcv, air filter, most of which needed to be done, and I'm trying to eliminate all of those. The code keeps coming back, so I was watching live data tonight, and just noticed that soon after start-up, the front o2 sensor starts cycling between .3 volts and .7 volts like most cars in closed loop, but the rear sensor is pegged at 1.245 volts for probably 2 minutes, after which it starts to come down, and eventually gets to about 0.04 volts and stays there, unless I go WOT, then it goes to 0.00 volts while at WOT.

This is the first time I have had any trouble codes with the truck. After doing some research on here I find out that the front o2 is actually a wideband, which is a 0-5 volt sensor. Is there any way that the previous owner/mechanic could have put the sensors in the wrong location? I suspect they will fit in the wrong hole, but I would think the connectors would be different. *edit* The connectors are the same. Now I have to wonder if they have been incorrectly switched up or replaced...

The other issue that I have felt for as long as I have owned the truck, is a slight surge on acceleration. I have not looked into it until now, but what is happening is a timing advance cut by the ecu. I watched that happen tonight, so I know it's happening, but don't know why. That's when I started thinking about the sensors.

If anyone has any experience or thoughts, I would greatly appreciate the help. I'm getting frustrated here.

TheDurk

Well on this point, the '97 has the regular O2 sensors. The wideband Air/Fuel sensors are only on the Cali. style two-cat system, which was introduced in 1999 on the Cali. cars and went Federal in 2001.

P0330 is NOT for the same bank as P0325. From the FSM:

http://tacoma.site40.net/4Runner_96-...e/cip0325p.pdf

Respectfully, I think you may be barking up the wrong tree.

brokedown1

Thanks for the reply. I'm not sure I communicated well enough what I did. I did switch the two wire going to the knock sensors (gray and black) per the fsm diag procedure, thats when the code changed. The wires were switched, but not the sensors that the wires were going to, hence the same sensor is throwing a code, but now it's on a different circuit, in relation to the ecu harness. I did pull the o2 sensors today and try to switch them in the exhaust pipe, but it won't work, because the harnesses are different lengths, so that rules out someone getting them mixed up in the wrong location. I'm still confused as to why the rear sensor could be reading over one volt at any time. Anyone have any thoughts about that? Thanks again. I also ordered new o2's today and will get them in asap, they are old and need replaced anyway, but I doubt that it will help. The next thing may be a used ecu, as I can get one for 100 bucks.

brokedown1

double post

hambob

If I understand correctly, when you switched the grey and black wires the code should have changed to the other bank if you where getting a knock on one side. Since the code stayed the same that would indicate a wiring issue.

just a thought, good luck

brokedown1

Yes and no. The code did change to p0330, from p0325, which indicates the issue stayed on the same bank (#1) as only the wires from the ecu were switched. The ecu "thinks" that bank 2 had the problem, but it did not, since the wire for bank 2 was actually connected to the bank 1 sensor, and the wire for bank 1 was connected to the bank 2 sensor.

Last night I added a can of seafoam to the fuel tank, on the way home the timing advance problem was noticably worse. Thinking that I may have had to much seafoam to fuel ratio, I filled the rest of the tank with premium fuel, but the problem still seemed to be there this morning. I am really starting to suspect a serious wiring issue, possibly an ecu going out.