Over Heating - Complicated

greaseandmetal · Jul 26, 2013

I'm running with my TPS disconnected, haven't got around to checking out the wiring as the TPS tested ok by itself.

Anyhow having the TPS disconnected makes the computer run closed-loop mode, relying solely on the O2 sensor. Engine has been running hot and over heating. Checked thermostat, fluid, pump, radiator, all fine.

So my theory is that the O2 sensor is faulty causing the engine to run lean. Is this nonsense? Maybe theres another reason it could be overheating, like EEC doesn't adjust timing or something. Any ideas folks? If it is my O2 sensor I'd like to know now so I can go spend the arm and leg for a new one. Kinda tight on arms and legs right now.

HAPPY+RANGER+GUY · Jul 26, 2013

video

This video may give you some directions to look.
https://www.youtube.com/watch?v=hUzOTnsWImI

I don't think any lean condition is your problem.

adsm08 · Jul 26, 2013

Lean running will make it run hot, but running rich, which it may do in open loop will cool it off too.

Pull a few plugs out, at least one per side, and look at them. If they are a whitish tan color then you are in fact running lean. Post pics if you aren't sure of how to read a plug. Normal can look a lot like lean to the untrained eye.

HAPPY+RANGER+GUY · Jul 26, 2013

O2 sensor

greaseandmetal said:
So my theory is that the O2 sensor is faulty causing the engine to run lean.

I would expect it to run rich if the O2 Sensor was bad and likely in the open loop.

greaseandmetal · Jul 27, 2013

Thanks

Thanks for the info guys.

I'm still suspicious of my O2 sensor as it is very old, but after reading about how they function I see now, HAPPY-RANGER-GUY, that a defective O2 sensor would not be producing enough voltage consequently reporting a lean condition, increasing fuel delivery, which would not overheat the vehicle.

As for the overheating, I retested my TPS with just an ohm-meter rather than the complicated signal voltage check. I discovered that the ohms which read high at closed throttle and low at open throttle jumped off the charts as I moved the throttle just a little bit and all through the movement, randomly going open circuit. So I replaced it, resolving the stumbling and allowing it back into open loop. Which according to adsm08 will help. A thought on that, it's a manual trans, so when I come off the throttle it doesn't stop fuel delivery if my TPS is disconnected.

Also at least 1/3 of the surface area of my A/C radiator had fins totally bent over. So I straightened those out, which I would have just ignored if not for having watched the video you posted a link to.

Results are I drove it 8 miles 3 times in 92 degree weather today and the temp needle only went as high as maybe 60%. Sounds like a fixed problem.

HAPPY+RANGER+GUY · Jul 27, 2013

Closed and Open

greaseandmetal said:
So I replaced it, resolving the stumbling and allowing it back into open loop.

Closed loop is the desired mode of operation, not open loop. When the computer is happy with good inputs from sensors and such....it uses those inputs in a closed loop operation with feedbacks provided and adjustments to make air fuel mixture nearly perfect.
You may be confusing the terms or I'm just misunderstanding your communications perhaps.

HAPPY+RANGER+GUY · Jul 27, 2013

cross those fingers!

greaseandmetal said:
Results are I drove it 8 miles 3 times in 92 degree weather today and the temp needle only went as high as maybe 60%. Sounds like a fixed problem.

I hope your overheat is gone. There are a lot of a factors that can come into play here and certainly the problem can come and go randomly at times. Did you pull plugs and get a good assessment on them?

Good luck and be sure to give us an update down the road here.

greaseandmetal · Sep 24, 2013

Update

So it's down the road and here's that update you requested.

I'm ashamed to admit I still have not pulled any plugs to look at them... I should really put that on my to-do list.

It did over heat again. So I flushed the cooling system and found at least 5 cups worth of silt in the radiation. It wasn't slimy, it was more like sand and dark brown/red like rust. I did this 1-hour prior to pulling a trailer with all my furniture on it in 97 degree weather. Temp gauge moved up and down a bit at first which I understand is normal then stabilized right in the friggin middle. Obviously the garbage in the system was the problem. What was it the video you posted a link to kept saying, something like: Don't overlook the basics/obvious stuff?

Over Heating - Complicated

greaseandmetal

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