Man, do I need help....

I have had an engine light on for a while that reads 25 (engine lean). At first it was on a lot and would some times turn off. When the light would turn off it was like an instant fix to the problem, but then it would turn on and be crappy again. Now it stays on all the time and it seems to be getting worse. Here are the symptoms when the light is on:

~ It idols real rough and has low RPM idol but eases up when in N.
~ It has serious loss of power at any RPM.
~ Though it claims to be running lean, it smells very rich and recently it has strated smelling like straight gas.
~ Of coarse because of the oder my MPG is around 12 when it used to be around 17.

What has been done recently:

~ I have had the head gasket replaced, but not sure if they did any valve cleaning or adjustments and that shop is no longer open.
~ New O2 sensor installed, but it has never ran well since it was replaced.
~ Oil weight changes from 10w30 to 30 and then back to 10w30 which ended up making it lose about 1 quart per 750 miles. Now I am back at 30 and don't lose any oil. (BTW does anyone know if Castrol 30 has any detergent?)
~ I had a couple mechanics tell me compresion tests came back OK, but I have not tried it myself.

I have had some suggestions to fuel injectors and valves, but what stumps me is why does my engine think it is running lean? You could run a engine on my fumes it smells so much like gas. I have had the sulfur smell for about a year, but I am attributing that to an orginal mufler with 180,000 on it. I need my truck back soon and as I fear it is getting worse. I have time this weekend to poke and prod, but I have no idea where to begin.

Ted
1995 4x4 4Runner
V6 3.0L

Check the O2 sensor....it may be out.

I'm not extremely familiar with the '95 model, but I'd also look into investigating the AFM. However, from what you describe, I would check the O2 sensor first.

Anybody else have ideas?
Max

I could basicall just disconnect the O2 sensor and see if there is any change in the way it runs? I'm not realy sure how to check it any other way.

What brand o2 snsor did you use? If not OEM Toyota, go back, bend over, and pay the extra money for a real Toyota sensor.

If your computer thinks you are lean, but you are running rich, the o2 sensor is not sending the signal.




<<<WAIT A MINUTE>>> You said it runs fine, then pops the code, and runs crappy, right? Then it pops back to normal for a bit? YOU HAVE A LOOSE WIRE IN THE O2 CIRCUIT! The computer can't see the O2 signal, so it thinks lean, and dumps fuel in the engine. When the wire is just right, it leans back to normal.

Go start the truck, warm it up fully, and slowly move the O2 sensor wire around. If there are any changes in the way it runs, you need to check the wires in the circuit.

You are a brilliant man! I don't care what your Mama says about you. <img src="/forums/images/graemlins/butwiggle.gif" alt="" /> My sensor is new so I am going to check the wireing from the harness to the ECC. Any ideas where my ECC is, though?

They certainly did not do anything extra except replace the head gasket. You can count on that. It is very curious that after you replaced the O2 sensor, the runner runs rich/lean. Typically then a vehicle runs rich/lean I suspect the O2 sensor as the problem. You are blowing oil and the O2 sensor will get coated with soot, no doubt. However I do like DRTDEVLÆs suggestion. Blowin one quart/750 miles is trouble though. Good Luck.

Actually running thicker oil and then thinner oil will cause a lot of gunk to get cleared out and the end result is that you go through about a 1 quart every 1000 miles. Mine being 180,000 miles it is just a worse case scenario. Going back to straight 30 has stopped that problem, but now I am stuck using straight 30. I'm going to check the wiring right now. Thanks for the help guys!!!!

Second thought to my previous thread: when the engine is cold, on start-up, the ECU uses a default code, hence the O2 sensor is not really used until itÆs at operating temperature. Therefore if it runs funny as soon as it starts, then itÆs probably not the O2 sensor. At least thatÆs how other vehicles that I have owed, run <img src="/forums/images/graemlins/confused.gif" alt="" />

It got a little worse when it warmed up.

I found a gash in one of the wires. Patched that and all is good.

Damn, I am good.... <img src="/forums/images/graemlins/rolleyes.gif" alt="" />