Check Engine light...Code 21.

[lispeej]

1989 Toyota pickup 22re 2.4 cyl 2wd. 5spd.
Check engine light code 21.
I know this code pertains to the O2 sensor before the cat. But to make long story short,..

My spark plug#1hole seems like it's cross threaded. It sits in there tight, but I feel and believe it needs and should go in just a bit deeper (as compared to the other three). The PO didn't tell me about this issue.
When idling, it idles okay,,,but once the engine warms up after a few miles of driving, then it seems like I have a hard time trying to accelerate (Unless if I floor it) then it's kinda okay.

I've been driving this way for about 10k miles now. I'm actually getting kinda use to it, but would like to see if I can fix the issue or not.
Others have recommended me to clean/replace the TPS, but it looks hard to get to.



question#1. Would/can a spark plug not seated properly all the way in cause a code 21?

question#2. Would anyone recommend chasing the threads with a tap&Die kit, if all else fails, use "heli-core"? (spelling???)

Question#3 Replace the O2 sensor and don't worry about spark plug#1 because that isn't relevant?

I looked into the O2 sensor, and it'll run me about $114 from CDan. As mentioned, I'd have to get a california emmissions O2.

Give my your 2cents worth.
Thanks.

-Pheng

 

[KLF]

I'm a little rusty on the entire EFI system wiring, but I don't believe it's smart enough to detect if one of the plugs isn't firing properly or not. Now, what COULD be happening is if that plug isn't firing, then unburnt fuel will get tossed out the exhaust and this could possibly foul the O2 sensor.

Have you pulled the plug out to see what it looks like? Looked at the threads in the head?

 

[lispeej]

Have you pulled the plug out to see what it looks like? Looked at the threads in the head?

I have looked at the previous spark plug, it didn't look too bad. I haven't looked at the one I put in when I first bought the truck.
I will take the plug out this weekend and look at the threads on the plug and the head. I really don't want to spend $114 on the new O2 sensor and find out it's not that.
So, you're thinking my O2 could still be good and just be gettting a faulty reading from the unused fuel?

I just remembered...
Sometimes if I don't give it enough gas, it seems to misfire and make a popping noise(Like when switching gears too soon, or starting from a stop sign in 2nd gear). It's not as bad as it sounds.

 

[KLF]

Well, like I say, I'm kinda rusty on this stuff, but I believe the O2 sensor (assuming it's still working properly) will see all the extra fuel and adjust the injectors to try to get the Air/Fuel ratio corrected. I'm really not sure what the ECU does if it can't get it down no matter what it tries.

I would start with the simple cheap stuff first, fix the suspect plug, maybe even try some new wires. There is a diagnostic procedure in the FSM that you can test the O2 sensor.

 

[WristPin]

the poppin and snappin could be over advanced timing. which would cause it to run rich, which would jack your o2.

 

[2ndGenToyotaFan]

I'd check the timing, and check the TPS.