Hi All, just joined this group. I have a 1985 Toyota motor-home with a 22re and auto transmission. When I bought it not much had been done to it maintenance wise:the plugs, wires,cap and rotor hadn't been changes since 1998. I recently changed out the O2 sensor,had 107K miles on it. I did it to hopefully help gas mileage and it was over 100k. The truck runs great. I get about 16.5 mpg on the highway. No problems, no hesitation, no stalling, etc. But since I changed the O2 sensor, after reaching operating temperature the check engine light comes on while cruising. I lift my foot off the gas, put it right back on and the light goes out in 4 seconds. Drove 1400 miles and it did this all the way. Oh, and no codes get stored. After doing much research on the web, I decided to test the TPS. I'm a former auto mechanic and I know how to use a VOM. But when I do the 4 part OHM check on the TPS, it's in spec on the first check but Infinite ohms on all the rest. YET, the vehicle runs fine. I'm not one to throw parts at a problem. Plus I'm retired and can't afford to do that. I know I could leave it with the CEL but it is annoying, and it tells me something isn't reading quite right. Anyways, any Ideas? TPS sensors are not cheap. And if it fails all the tests except one, why does the truck run like a top? I would appreciate any ideas.

 

Don’t bother setting the TPS with a voltmeter using the FSM. It’s not fun, easy, or terribly accurate. I’ve posted how to do it with a timing light here before. It’s the way we did it bitd at the dealer.

What brand O2 sensor did you get? If it’s anything other than Denso I recommend putting the old one back in.

edit: what brand of sparkplugs, cap/rotor/wire set did you get, too?

 

Thanks for the reply jimkola. I bought a Denso. I try to go OEM whenever I can, just not through the dealer. Worked at a dealership once, know the racket. I'll look your procedure up and try it. If that doesn't solve it, I'm gonna try and run some tests on the O2 sensor, per the service manual and take some voltage readings off it while it's running. This is weird,cause it runs great but as stated above, when cruising the CEL comes on. No codes, then goes out after a quick letup on the throttle. I might let it come on and let it stay on for an hour of driving and see if it stores a code. Ahhh, technology, ain't it grand.

 

Okay,
my 85' 4X does the exact same thing, but will store an O2 (5) sensor code.
I have tried everything.
New Denso (and NTK) O2 sensors, adjusted new Denso TPS via FSM procedures, fuel pressure within spec (even ran with regulator vacuum hose disconnected to always have full pump pressure), swapped AFM, replaced coolant temp sensor, flushed out my injectors and finally, as a last resort, got a refurbished ECU .....now I have a spare.
The truck runs great, gets great gas mileage for being on 35s w/5.29 gears.
However, I can also detect faint "pinging" under light throttle (no knock sensor code).
It's driving me crazy and I'm at my witt's end!
Note: This is a fresh motor, completely gone through by a reputable shop (overheated the old one due to a bad fan clutch) the only difference is, my old motor had an Engnbldr 261 crawler cam and never had these issues!
You know, I never checked the plugs....could they have put the wrong ones in?
Hans

• I

 

ND or NGK regular resistor plugs work best and hold up quite well. I saw quite a few Champion plugs in Toyotas where the porcelain cracked. Bosch plugs did poorly, too. They looked ok upon inspection, but just didn’t perform well.

You might try resetting the TPS using the timing light method I’ve referenced in the past.

in the mid 80’s there were a few 22R# where pinging was an issue. Higher octane gas did help. Toyota did address it in a TSB, with the only cure bing to retard the timing a degree or two.

 

Just checked them, they're the correct Denso W16EXR-U plugs.
Not familiar with this method....link to it?
Thanks,
Hans

 

https://www.yotatech.com/forums/f116...oubles-314045/

go to this thread and scroll down a bit

 

Okay,
Just read through that.
I have a dial back to zero timing light, would that complicate things?
I'll have to think about that.
I'll figure it out, thanks.
Hans

 

I found the CEL coming on while cruising... was a simple fix.
I adjusted the AFM a couple of clicks
Don't remember which way rrr
But if you go the wrong way the light will stay on, if you go the other way then it will go off. It's just running a little rich or lean and that's why it goes out when you lift the throttle.
I'm pretty sure it's running rich when this happens... So I'd make my adjustment to the lean side.
be sure to mark where is set before adjustment so you'll know where you started.

 

Was just thinking about that, but the color of my plugs are extremely clean, thinking it might be lean.
"Pinging" could point to that as well.
Hans

 

sorry I have done this a few times but it's been a while and I'm old enough I've forgotten more than I know. Lol
So. It must be too lean when the CEL comes on like that.... you'll just have to go a few clicks richer. If you Google AFM ADJUSTMENT there are some very good videos on how to.
PLUS it doesn't cost anything!!

 

Can't go wrong with the OEM plugs in any vehicle. Been using nothing but Denso W16EXR-U plugs since bought truck new in 1986. Never an issue, smooth idle, and great gas mileage.

 

If the Air Flow Meter has not been messed with before, leave it alone. Its adjustment is set from the factory to match the program in the ECM and should not need to be adjusted.

 

Doesn't hurt a thing to adjust the AFM.

 

I dunno. The odds of an issue from an unmolested airflow meter are pretty low. You run a pretty significant risk of creating some new symptoms to add to you existing ones.

 

Well,
I've tried just about everything else, can't hurt and....it is almost 38yrs old!
I wonder if an obstructed exhaust/muffler could cause this?
A few years back my cat disintegrated and I'm not sure if the muffler shop that replaced it fished all the pieces out before installing the new cat.
I dunno, grasping at straws at this point!
Hans

 

well, mark your AFM make an adjustment, if it's not making it better, put it back to the factory setting, it's not a big deal.
I've read where some have moved several clicks to get the desired ratio... I've moved mine at least 4 clicks.