WildCard22RE

Up front:
CEL came on last week, threw code 21 (Main Oxygen Sensor Signal). I reset the ECM and the CEL hasn't come back on. I have a 22RE with 257,xxx Kilometres.

Background:
In September I had the Cylinder Head off to replace my disintegrated Timing Chain Guides and leaky Timing Chain Cover (y'all heard that story before...)

Current Problems:
I have been having a noticeable lack of power since the job; particularly up to and around 2000 rpm it's really gutless. Anything more than about 1/4 throttle does little to effect the engine's performance, until around 3000 rpm, where it picks up again.

The Engine is also much more hesitant right off the line; I have to be much more careful with how much throttle/clutch I give 'er. This off-the-line issue has gotten slowly worse following the job.


My Idle has also been having trouble making up it's mind: sometimes it will warm up and sit at 800ish rpm, but others it will stay high, around 1000-1100 rpm. The Idle will change where it wants to sit throughout driving, but doesn't tend to go above 1100 rpm. Sometimes it will even drop to 700ish.
It also is not Idling as smoothly as it did before: quite a bit of low-frequency noise and vibration in the cab, but not alarmingly so.
(I replaced the Thermostat during the job, and the Water Tempurature stays steady after warming up)

Another thing I have noticed is hard to describe: when I am gently, smoothly accelerating, I can feel the engine lose and then regain power, just noticeably, about 2 times per second.


So: do any of these "symptoms" sound related to the Oxygen Sensor? How would a failing o2 sensor effect performance?

The Toyota 22RE diagnostics says Code 21 could mean I have a trouble ECM. Is this likely, considering any of the other problems my engine is having?

Do these problems ring any bells or raise any flags?


Sorry that this post is so long and all over the place!!! Thanks for your time reading this and any help you guys have to give!!!

scope103

code 21 is not "Main Oxygen Sensor Signal." It is " Open or short in heater circuit of heated oxygen sensor." http://personal.utulsa.edu/~nathan-b...85diagnosi.pdf (Okay, it's multiplexed with other signals, but this is the first and most likely one.) The connector sits in a hellish environment, and can be melted, torn, crushed. Visual inspection first, followed by a simple multimeter check. http://personal.utulsa.edu/~nathan-b...01heatedox.pdf .

Your other symptoms could be explained by ignition timing. Easy to check, and should be done first.

WildCard22RE

Thanks for the response scope.

Checked ignition timing, it's good.

I'm using the '93 factory manual that's a sticky at the top of this forum (86-95 Trucks & 4Runners) as I have a '93, and it says that code 21 is "Main Oxygen Sensor Signal." (The link isn't working anymore but I saved all of it).

Regardless, looks like the multimeter check is the next step.

Under the "Inspection of Feedback Voltage" there is a "Replace ECM" bubble. What situation is this referring to???
Also, in the manual I am using, the arrow points from "Check the number of times the voltmeter needle fluctuates in 10 seconds" up to "Replace ECM," but in the link you provided, scope, the arrow points the other way... more confusion...

jennygirl

I would check TPS, clean and check engine grounds, and alternator connections.

At night, do your headlights flicker/dim at all when it's doing the weird thing?

Just throwing out ideas

There is a great write up on the grounds here at yotatech. Google search "22re ground locations" and you'll find it

Terrys87

iTrader: (1)

You were asking about the ECM/computer, I have never had one of these to go bad unless it has been wet. They are really dependable from my experience. Would be the last part I would suspect.

I would check for vacuum leaks, leaks will cause all kinds of problems.

WildCard22RE

Thanks for the replies everyone.

Checked the Oxygen Sensor as per the Toyota manual (I have the page posted above), and things are within parameters... which is good cause the bolts holding the o2 sensor in are completely stripped from rusting...

Reset the ECM and sprayed some Contact Cleaner on the o2 sensor connector as well, so I'll see if that connection was what was throwing Code 21.

This leaves me back at square one re my 22RE's dropping performance, so I'll take your advice Terrys and look for vacuum leaks. And no, Jenny, I don't have any flickering issues.

I'm also gonna check my valves to see if I didn't tighten them down enough and they've adjusted themselves, as I adjusted them by myself for the first time myself a few months ago, and advance the timing as well.

To revisit one of the abnormalities I'm experiencing, when the truck is warming up, the Idle will suddenly drop significantly, then creep back up, repeating this a couple times before warming up and settling, incase this anecdote rings any bells.

Thanks for reading and considering!!!

thefishguy77

iTrader: (1)

Have you checked your tps?

jennygirl

I am quite confident that you might simply have some air in the coolant system which causes surging idle as the thermostat opens and closes. There might be air surrounding the sensor occasionally which throws it off... fast. I had very similar symptoms and burping it cleared most of them up.

Do a search and you will find plenty of info on how to do it. It's easy and practically free. Might as well try

Terrys87

iTrader: (1)

Agree with Jenny on the air pocket. Raise the front end as high as you can and let it idle with the radiator cap off to let trapped air escape from the radiator. I let the thermostat cycle 3 or 4 times.

Also check the dashpot, I have seen those cause issue. The spring assembly down to the little brown filter.

You don't say what year 22re you have. 87 and old the O2 sensor is in the manifold. Usually those nuts will come off. If it is in the exhaust pipe (88 and up), I just have an exhaust shop to install a new bung for the sensor. They are used to that as most are just to rusted up if you need to replace the sensor. In my areas it is a $25 job.

WildCard22RE

Thanks guys, I think you're on to something re the coolant system, gonna get my hands on one of them fancy spill-free funnels.

I advanced my timing to about 10 degrees. Wow, huge difference, power band restored. Is this going to be hard on the engine long-term? Where do you guys have your timing set?

Terrys, I have a '93 22RE. $25 sounds too good to be true, but I'll keep my fingers crossed for when I have to replace it. Where is the dashpot located?

Fishguy, I haven't checked my TPS, sounds like another good thing to do.

Thanks a lot for your help everyone!

thefishguy77

iTrader: (1)

Use caution in the about 10 degrees advance. Make sure you use a timing light.

WildCard22RE

I retarded the timing to 8 degrees, out of concern for engine wear.

Does anyone else have their 22REs Ignition Timing advanced past 5 degrees?

thefishguy77

iTrader: (1)

A lot of us have done it. I was urging caution with the statement about. If your using a light you should just use your best judgement.

Edit. Here is a google search with lots to read on
https://www.google.com/search?q=how+...&client=safari

mattbz2103

Hey all, first time posting, this thread seems to reflect an issue I am having.

I have a 1994 toyota pickup. CEL - error code 21 (heated oxygen sensor / wiring) - I have 2 Ho2s...

I checked resistance across the +B and HT (just like the PDF from this thread explained) for both the Ho2 BEFORE the Catalytic converter and AFTER.
- Resistance for the one BEFORE cat is 6.1 (I was told spec is 4.5 - 6.0 Ohms at 73*F OR )
- Resistance for the one AFTER cat is 13 (I am not sure what the spec is for this one.... Should BOTH resistances be the same?)
If yes, seems like the h20 sensor AFTER cat may be the issue? Can the heated oxygen sensor AFTER the cat cause the error 21?

Also any recommendations on next steps and a part number for replacement (if needed)?
First 5 of VIN: J**R* (think the J means Japan built, and i was told the R means CA emission requirements).