95.5-2004 Tacomas & 96-2002 4Runners 4th gen pickups and 3rd gen 4Runners

How well will a 5VZFE run with no O2 sensors?

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Old Aug 13, 2006 | 04:52 AM
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From: Oklahoma State
How well will a 5VZFE run with no O2 sensors?

I'm going to have to drive or tow my truck 5 miles to the shop making my exhaust system with no O2 sensors in place. So if I drive what can I expect it to run like?

It's a 2001 engine, ECU and auto tranny with supercharger and URD fuel kit (untuned). I mention the year because 2001 is suppost to have the slightly wider band A/F sensor in the front.

If I drive I will probably rig up a temporary exhaust from the crossover back through my old 3ZVE cat and muffler with some of that cheap flexable exhaust tubing they sell at the auto parts stores.
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Old Aug 13, 2006 | 06:59 AM
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Stumbly, CEL, but you'll be okay. Though if the holes for the sensors are there, then it'll be loud as well.
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Old Aug 13, 2006 | 07:07 AM
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yeah, plug the holes man! lol
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Old Aug 13, 2006 | 07:35 AM
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Originally Posted by midiwall
Stumbly, CEL, but you'll be okay. Though if the holes for the sensors are there, then it'll be loud as well.
Stumbly huh, how stumbly are we taking here? Like misfires or something?
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Old Aug 13, 2006 | 07:37 AM
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Yeah no holes, if I had the hole I'd just put the A/F sensor in and I wouldn't have this problem.
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Old Aug 13, 2006 | 07:42 AM
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Originally Posted by mt_goat
Stumbly huh, how stumbly are we taking here? Like misfires or something?
Nah, more like the ECU can't figure out how to set the fuel mixture so it may fall into a safe mode of running really rich, but it may take a bit of time (a couple of mikes of driving) for it figure out that the O2 sensor really isn't there. The 2001 will also be different than, say, my 96 since it's expecting a wideband up front.

Dunno for sure... The best thing to do is just try it. Fire it up and drive around the block. You won't "hurt" anything, and it sounds like it's your only recourse anway - short of renting a trailer and hauling it to the exhaust guy.
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Old Aug 13, 2006 | 08:41 AM
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Thanks Mark, yeah I do have the towing option (auto club) but I'd rather not do that, lol. It would go something like this, huh I need a tow, my whole exhaust system fell off in my driveway, dunno how it happened.
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Old Aug 13, 2006 | 02:43 PM
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It will run fine, just lots of gas The ecu will resort to using the maf and its internal mixtures to figure things out...but rich...
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Old Aug 14, 2006 | 07:38 AM
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Might wanna reset your ECU after you get your O2s replaced. Dunno if it would throw your short-term Air/Fuel mixture out of wack, but it wouldn't hurt?
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Old Aug 14, 2006 | 09:10 AM
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Originally Posted by OutdoorLiving
Might wanna reset your ECU after you get your O2s replaced. Dunno if it would throw your short-term Air/Fuel mixture out of wack, but it wouldn't hurt?
It's a good idea, practically a requirement. The ECU would eventually catch-up, but resetting it will make the process go quicker.

Last edited by midiwall; Aug 14, 2006 at 09:19 AM.
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Old Aug 14, 2006 | 09:18 AM
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From: Oklahoma State
Good point, thanks
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Old Aug 14, 2006 | 09:45 AM
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I drove mine open headers to the exahust shop about 10 min down the street.

no 02 hooked up. course it had a CEL, and was loud as hell, but for the most part drove fine.
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Old Aug 14, 2006 | 10:48 AM
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From: Oklahoma State
Oh wow, don't think I'll try that. I've heard it's not good to run open headers, something about warping a valve or something?

Thanks though, it's good to know it ran good.
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Old Aug 14, 2006 | 11:04 AM
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I am sure it will run fine with no O2 sensor (just rich), just reset the ECU by neg batt terminal method when you get back.
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Old Aug 14, 2006 | 08:21 PM
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open heads isnt good but open headers is fine...i did...LOUD
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Old Aug 15, 2006 | 04:14 AM
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Originally Posted by Weasy2k
open heads isnt good but open headers is fine...i did...LOUD
Yep, it's the open heads that mt_goat was talking about as having the ability to warp valves since they get very hot when running and can see massive temp gradients if left wide open to the air like that. Headers keep enough heat in there to prevent any possible warping, but they are VERY loud......sounds like a helicopter up close.
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Old Aug 15, 2006 | 05:03 AM
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Thanks for the clarification (open heads not open headers). I've got a cross-over in place with factory manifolds so sounds like that would be ok then?
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Old Aug 15, 2006 | 06:30 AM
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You should be ok to run the ORS crossover for the drive to the exhaust shop.

And ditto on the O2 sensors. I ran from the exhaust shop (30 miles) w/o the o2 sensors in place. It was a little louder but it ran and drove just fine.
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Old Aug 15, 2006 | 06:31 AM
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Originally Posted by mt_goat
Thanks for the clarification (open heads not open headers). I've got a cross-over in place with factory manifolds so sounds like that would be ok then?
Yep, you'll be fine then.
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Old Aug 21, 2015 | 05:43 PM
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I did a 5vzfe swap a while ago and only got it on the road now, the o2 sensor is in place but not connected.
it starts and runs (very rich) but it doesn't like to drive for very long; it seemed to drive ok for about 1k but then started to bog down when i opened the throttle; until it eventually wouldn't accelerate at all..... still idles and revs up in neutral though.

I was really hoping that hooking up the sensor would fix my problem but now i'm not so sure

Edit: Also the wire colour on the sensor don't match anything (two are black, one is white, and the last one is blue)
The wires from bank 1 sensor 1 are brown(E1), white\lavender(B+), pink\lavender(HT), and white(OX1)

Last edited by Seatbelts; Aug 21, 2015 at 06:36 PM.
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