thook

This morn on me way into the job, my '86 began to rise in temp at the gauge. The thermo is fairly new, but the ECT sensor (not the sending unit) is original. It began acting up a few years ago, but I cleaned it up and it's worked fine...up until now, I think. I say that because the CEL came on over a week ago (code 5...O2 sensor) and I replaced the sensor (the O2). The light came back on briefly the next day, but went away for a little while until a couple days ago. So, the way I figure it is that it's running rich (fuel smell before it gets good and warm) and it's probably related to the ECT. It looks like the cooling system could use renewing, as well. But, since I'm going to try and clean up the ECT again to see if that does the trick I figured I'd get a new one as a standby just in case. Toyota wants $65.90 and O'Reilly (if it is indeed the correct part...Borg Warner) wants $27. It's obvious which one would be more affordable, but I was wondering if I went with the Borg Warner if I was going to run into any problems. Now, has anyone bought one of these BW's before? How did it work for you?

BTW, I would go with the OEM, but the $$$$..hmmm

longhungsilver

Ive never used the brand you speak of....I know you don't want to hear it but...for sensors oem is the only way to go...

thook

Yes, yes...I know. But, when one only has so much money at any given point, then one makes compromises just to keep the vehicle running. Besides, I'm not even sure my original one needs replacing, yet. Thank you for the reply, though.

If I do wind up having to use the B-W part, I'll be sure to report how it works. I'm using a Bosch O2 sensor right now, and so far so good. The runner has much more pep than it did. Plus, my mileage is up to 20 mi/gal from 18. Can't argue much with that. Although, I guess we'll see how long the part lasts...ha!

longhungsilver

awsome.. were u gettin a CEL on the 02 sensor or u just replaced it cause it was old?

4runnerx3

what do you mean by ECT sensor?

thook

Yup....code 5....O2 sensor signal.

ECT is....(drum roll please)....engine coolant temperature.....sensor.



Verdict is still not in, yet. The CEL has not come back on since and the truck has not tried overheat again. It was a little low on coolant, but not nearly enough to cause an overheat. I had the coolant vacuum flushed and recycled a year ago this month, so it's not due for service until another year.....according to the little sticker the thoughtful mechanic left on the engine compartment to remind me. Pulled the ECT (the original one) and it's as clean as a whistle. Put it back in.(The BW sensor doesn't even have the correct style harness, anyway...pffft!). Then, I topped the coolant off and so far everything seems okay. Now, I'm just perplexed. My only guess is the thermo is just getting a little sticky, even though it's not but a few months old. I don't know. It's still running a bit rich, and I could do some testing on the few suspect components, but for now I'll just have to watch it I suppose. Hmmmm...

longhungsilver

hmm 02 is new and ect seems fine and your running rich? hows the timing? what else could cause the engine to run rich?

thook

Well, I've not actually tested the ECT with a multimeter, yet, so it still could be a factor. And I haven't inspected the cold start injector for leakage, either. That could be one thing, also. The timing I've not checked, but it really does seem to be just fine. Honestly, I've been too busy with driving to start really diggin into the issue. But, I've a stretch of lovely weather and I'll be home all week with little to no driving. So, I can track down in earnest....only after I've done some work on my wife's runner, of course. Needs some TLC, too.

I'll post what I find. Thanks for asking.

OH! I just though of something. The valves are due for adjustment. Do you think that could be a factor?

4runnerx3

Well you had me confused. Never heard it called ECT, only thing ECT is electronic controlled transmission. This is what I call them, so does the Factory Manual.

thook

Consider us both confused....a little.
http://personal.utulsa.edu/~nathan-b...40engineco.pdf
It's even what the dealership calls it.

thook

Okay, turns out there was air in the coolant system screwing with the thermostat and causing the almost overheat.

The running rich....well, the valves still need adjusting and I suspect the timing chain has slack in it, according to what a mechanic was telling me when I described the symptoms. Lots of racket on start up and at idle sometimes. Plus, the idle is sometimes slightly high. Too much to take care of, so I haven't gotten at it all. Maybe next week I'll know more.

Thanks all.

beaker

any new news about these issues your having? I also am experiencing bad air purging problems in my water line. I eventually had to drill 2 holes in my therm to allow the water to flow. However i am still having high temp problems on warm days. It is also running extremely rich and wont pass emissions. I have replaced my o2 and checked for vacume leaks. I pulled my intake off and cleaned it, lubed the airflow meter door flap thing, (i'm sure some nerd will correct me on that term) and checked all ignition parts.

My next line of attack will be the ECT sensor, injectors, and fuel filter. If anyone else has something to add to this diag please feel free. Oh, it also has been trippin a code 25. Yes that is the lean code, but my emissions test came back very rich. I can supply the test numbers if anyone would like.

94' 3vze

thook

Nope, not yet. I have to wait and get my other runner back in commission so's I have back up in case something unexpected turns up and I need transportation. Sucks living 26 miles outside of town and no way to get there.

Sounds like you're on the right track. Have you look at all your coolant lines for leaks? Everything tight enough when you put the plenum back on...yadda, yadda?

Interesting...lean code, but you're running rich. ??? Leaky cold start injector???

1990 LJ78 Prado

The sensors correct name is THW sensor. It sends the coolant temp to the ECU. And is not to be confused with the sender for the guage in your dash.

Regards

thook

I'm aware of that...thanks.


I did a google and all I could turn up for TWH is Tennessee Walking Horse. What does it stand for in your book.....whatever book that is? That abbrev. is nowhere in any Toyota/Haynes manual I've ever seen for my vehicle.

ECT is what Toyota calls it per FSM. Some other manufacturers may call their equivalent something else. Heck, it may called something else by Toyota for a different engine...I don't know. But, whenever I asked for the part ECT is how it was identified.....for my vehicle. I suppose it doesn't matter, though. The part is what it is and does what it does.

thook

Drilling a small hole in the thermo finally took care of the fluctuation in the temp guage.

The code 5 turned out to be a bad AFM......the measuring plate track.

BTW, THW is thermal water sensor. But, in the manual as I've seen, this abbreviation only refers to the circuit from the coolant sensor to the ECU. IOW, it's the THW circuit

thook

Oops........double post.