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86-95 Trucks & 4Runners 2nd/3rd gen pickups, and 1st/2nd gen 4Runners with IFS

O2 sensor

Old 03-09-2010, 05:27 PM
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O2 sensor

Ok, I've been reading old posts for about an hour now and can't seem to find the answer. I have been tracking down an idle problem (just like everyone else) for quite awhile now.

I came across a post mentioning a problem with the O2 sensor. I replaced mine with a Denso unit from sparkplugs.com when i rebuilt my motor. Tonight I tested the resistance and got 9 ohms, this is out of spec according to the FSM. FSM says to replace the sensor. I have no check engine light. Mileage is about 17 mpg. My timing is way advanced just to get it to run smoother.

What troubles would a higher resistance O2 sensor cause? Would it cause a rich or lean condition? Since I don't have a check engine light is it still ok? I'm running out of things to check. This truck used to be kind of a hobby but it's starting to wear me down. Any help would be great.

Thanks,
Jason
Old 03-09-2010, 05:36 PM
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If you didn't notice a problem after you installed the new O2 sensor then I wouldn't worry about it.

What is your idle problem that you are trying to solve?

Fink
Old 03-09-2010, 06:08 PM
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The O2 sensor was installed during the rebuild about 35,000kms ago. I had a couple problems during re-assembly that might have damaged it. I got a gas line crossed with a vacuum line and it sucked the intake full of gas and down the exhaust. The FSM says it should read 6.8 ohms max. I'm reading 9 ohms. Basically I'm just grasping at straws.

The engine idles rough. Not loping or anything, just shakes alot. Which shakes the whole truck. My timing is advanced but I can still get it to idle at 800+ or -.

This weekend I pulled the plenum and replaced that gasket. I pulled the throttle body and replaced that gasket as well. I adjusted the TPS to within spec and installed new plugs (gapped) and Toyota plug wires. I also timed it and adjusted the idle. My problem is still there.

My next ideas were the O2 sensor and maybe something wrong with my cooling system. I know that effects idle as well. when i turn my heat on I can hear rushing coolant. there is never any puddle on the ground or in the truck so I don't think it's leaking. I've bled it with the truck on ramps while it runs. My heater turned on and squeezing the hoses while it circulates.

The truck runs great as soon as you touch the gas. Lots of power (for a 3.0) while driving. Thanks for the help.



Jason
Old 03-09-2010, 11:15 PM
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If you hear the bubbles in the heater core, you got air in there. I used to hear it untill I replaced my rad and burped it good (used my jack on my slanted driveway to get the front end really high).
Old 03-10-2010, 09:48 AM
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If it specs out of range then replace it.
Old 03-10-2010, 09:31 PM
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Hey Jay did I give you the old O2 sensor from before the rebuild? I can't quite remember. If so did you ever get the nuts undone and off the pipe? What does it read?? If you still have it maybe i could just swap it in to see what happens with the engine. Sucks though...this one should barely be broken in.

Jason
Old 03-11-2010, 07:14 AM
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You sure you don't have a vacum leak?
Old 03-11-2010, 07:48 PM
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I am pretty sure there is no vacuum leak. That's why last weekend I pulled the plenum and installed a new gasket, as well as throttle body gasket. All vacuum lines are new. I've used propane to check for leaks, and had no luck. I have plans for an ISR mod just to make sure the intake isn't leaking. The plastic gets pretty brittle.

Any help appreciated

Jason
Old 03-11-2010, 09:15 PM
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Nope, I didnt get your old one.

I do have my brand new NTK sensor, wonder if it would work with the 93?
Old 03-11-2010, 10:22 PM
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Well that's another thing to drive me nuts. I went through my big box of left over stuff and didn't see it. I'll have to tear through everything again. Unless
I tossed it because I couldnt get the nuts off.

I re-timed my truck the other day. She is tmed right to the edge of the little plastic piece
with the timing marks. There's no numbers there but I guestimate
it's about 19*. It's a little harder to start but she has noticably more
pickup when driving.
Old 03-12-2010, 02:55 PM
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I need to time my truck and 4runner.. guess I should fix the truck first heheh
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