coloradotom

OK, got an 89 22RE in my 4x4 5 speed truck.

About 1 month ago, CEL came on and I pulled the code, 21. I got under there and saw that the wires to my O2 sensor had gotten too close to the exhaust because one of the clips broke. So I fixed the melted wire problem and reset the computer and all was well.

I was on a long trip with a good load on the truck. After about 100 miles the CEL comes on. I figure it must be that something I did with the wires failed and it's the same problem, since I had just rectified it. Since I was out of town, I just did a visual, couldn't see anything wrong with my wiring fix so I ignored the light.

Today I had a chance to pull codes.

25 AIR/FUEL RATIO LEAN INDICATOR--LEAN SIGNAL SENT TO ECU FROM O2 SENSOR

26 AIR/FUEL RATIO RICH INDICATOR

41 THROTTLE POSITION SENSOR SIGNAL--OPEN OR SHORT IN TPS SIGNAL

So, my first guess is that it's just the TPS. That the TPS is sending garbage and the other codes come up because of that?

If it make any difference, exhaust has no cat. Any ideas?

coloradotom

Posted this on the Saturday of a 3-day weekend, hoping that's the only reason no reply...

So I'm assuming that the TPS code is a red herring. I'm assuming that it's getting both rich and lean signals because the O2 sensor has sheet the bed and is either sending nothing or random garbage.

I have been wanting to replace it since even before my CEL went on, but it looks like a bit of a project to get the old one out without destroying something.

Here is a crude cell-phone pic I took of the sensor. The bolts look like blobs of nothing useful, but the threads on the studs seem intact and not really rusted. Perhaps they are stainless?



Do you folks think there's a way to replace that bad boy without destroying the mounting hardware? Cut this junk out of the exhaust and weld in a new one?

Edit: do TPSs fail very often? Doesn't seem like a part that would be under much stress. Not sitting in a hot exhaust stream like an O2 sensor...

TIA for any input.

metalhed

PB blaster The bolts are super rusty and use a box end wrench. On the 94 I own it was touchy trying not to break the O2 sensor bolts. I used Sparkplugs.com to buy a new Denso sensor.
take your time and spray and wait

as far as the codes-- not much help here. see if a new sensor clears them up

Yot@_bruce

I recently dealt with the same issue on my '88 runner...codes 25 & 26. Replaced O2 sensor with OEM with the same results. Turns out the flange on the exhaust pipe had a pinhole leak from all the rust allowing outside air in, O2 saw the extra air thus throwing the code 25.

My guess is the ECU then overcompensated causing the code 26. I ended up replacing the downpipe over a year ago and have not had either code come back. Not the cheapest fix but the runner deserves it

coloradotom

I just yesterday ordered a new downpipe. It's going to be expensive, but my estimate shows me paying for it in gas savings in a year or less. Having more range out of a tank of gas will be a fairly valuable thing too.

Couple weeks ago I drove about 220 miles on a tank of gas, half a trip with the truck with nothing in it but me and then a return trip with a very light trailer and dirt bike. The overall fuel mileage for that trip was 14 MPG. It was mountain driving, and a little bit of trailer drag, but I think that was pretty ridiculous.

I'll have it fixed sometime late next week. I'll report about what happens after there's a working sensor (I'm convinced mine has failed, it's really old, like maybe even original equipment. 235K miles.) If there's a leak that would be a bonus, but I doubt that in my case.

coloradotom

Picked up my truck with new downpipe and Denso O2 Sensor. Haven't had a chance to run a whole tank, but it sounds different and feels more smooth. CE light staying off.

Looking forward to better mileage.

Gevo

I had nothing to help with on this, but I read any 'new to me' problems that I can for my own future reference. So, thanks for posting up on the results, many just vanish.

coloradotom

I think for most of the folks on yotatech my question was pretty much a routine. I really tried to search the forum, but I rarely have much luck getting specific info doing that. So even if the question and answer are redundant, perhaps it will pop up in somebody else's search down the road.

What I'm pleased about so far is that even though my truck was throwing codes for O2 sensor and "41 THROTTLE POSITION SENSOR SIGNAL--OPEN OR SHORT IN TPS SIGNAL", replacing the sensor seems to be keeping the computer happy. I had a concern that once the O2 sensor was replaced I'd be bouncing back to deal with the TPS. And then what?

Now I want to see how the fuel mileage is...

Terrys87

iTrader: (1)

I just found your thread. Glad you mentioned what fixed your codes. Don't always hear back from others that have similar problems. Someone will eventually benefit from your experience.

coloradotom

Meh. The fuggin' light came back on.

I took a 120 mile round trip on the highway Wednesday. Incidentally, my errand was to a city above 10,000 feet elevation, but I doubt that's a factor. The light was off the whole time and the truck was running great.

Last night I headed out for the town 30 miles north of me. Once the truck hit the open highway, probably just about the moment that the motor had become fully warm, the friggin' light came back on.

Just pulled the codes, 25 and 26. Looks like it's going to be time to go buy a voltmeter to see if there's a problem in the wiring harness. Or what. I'll follow what I saw in this yotatech post:

https://www.yotatech.com/50800857-post17.html

coloradotom

Didn't get a volt meter yet, but crawled under to just check out the wiring to see if there was anything obvious. Found several wires had been spliced in when the wire got too close to the exhaust some time and burned. It was way too long anyway, so I chose to cut out the splices and rejoin the wires with one set of splices only. Pics:



Connector end after cutting it off, several splices underneath the electrician's tape.



The piece as it comes off the harness. Several splices.



Trimmed back to just the base wires, stripped, carefully spliced.



Taped up. Going to get some insulated heat shield tape for the final job.

Haven't driven it yet, finished this up over beers last night. Will reset computer and take it for a drive soon. Will report.

coloradotom

First run yesterday afternoon after my wiring cleanup. Pulled EFI fuse for a while to reset CEL, but when I started the truck it was on. I figured there was a chance I hadn't properly reset the computer, but was leaning more toward the theory that the wires weren't my problem.

Drive out of town, engine comes up to operating temp, dink! Light goes out. Couple thirty mile drives and she's still off. Running extra smooth!