o2 Sensor problems??!

[99Qx4GroundUp]

Hey guys,

Love the forums, you have been very helpful in helping me find what I need and the know how on how to execute the process, so first off, thanks!

My Qx4 has been giving me issue after issue since I purchased it in February (2015).

The truck has been overheating regularly since I got her. I replaced the heater hoses, when that didn't work I replaced the water pump (painful) and sealed her up well. Now she's bogged down and won't accelerate over 2200 RPMs unless I shift her to 1 or 2 (automatic transmission). A couple of days ago she wanted to not move at all and the accelerator didn't do a thing when depressed. I am in the process of replacing the timing belt when I can use a buddy's impact drill. But today I was taking off the air intake and noticed what looked (in my eyes) a o2 sensor just dangling in the back. The first thing I did was look at the sensors, all of them are in place and I have no check engine light on. I traced this wired to a harness directly behind the engine and it is plugged in, I have no visible or mental idea of where this sensor may go. I do not know how long it has been sitting there unplugged, but it bothers me that it isn't where it should go.

Any ideas on where it needs to be and could this be the culprit to all of my headaches?

Thanks


Javin.

[atraudes]

It certainly could be Could you take a photo and post it up? Folk's'll probably be able to recognize it immediately. To post a picture, just upload it to something like Imgur, and wrap the URL of an image in the img tags here. It's probably not actually an O2 sensor; if it was you'd have a significant exhaust leak!

As far as the overheating, if you don't have any bubbles in the system and your fluid's not grossly expired, your overheating problem is most likely due to the thermostat.

[99Qx4GroundUp]

Hey sorry for the super delayed reply, I've been reading up and learning by trial and error as I go. I have successfully installed the timing belt and had everything to 10 and 2 at TDC, I have the car running a whole lot better( can drive her around up to 50-60). It's not over heating anymore since I've replaced all the hoses. The overheating was coming from a hose behind the timing shroud and also underneath the air intake. But now I have her running, she is sluggish on accelerating after 30mph. I'm assuming it has something to do with air flow somewhere. I cleaned the MAF and when I unplug it while she is running the car dies so I'm "assuming" that its okay. I still don't know what to do about the O2 sensor that's still dangling behind the engine and I'm not quite sure how to post a photo just yet. Seems like a different language to me recently. There are four 02 sensors from what I understand... The fifth one I can't seem to put anywhere and any scimatics on the web don't show one even existing, could it be a spliced wire? I'll work on getting a photo up ASAP.

Thanks

[99Qx4GroundUp]

Hope this works

http://imgur.com/a/E4tll

[atraudes]

lol holy cow I'd trace the wires on the 4 installed O2 sensors back and make sure they're all plugged in. There was only ever 4, so my guess is one of your installed ones isn't plugged in at all, which could be leading to your acceleration problems. There will be one installed on either exhaust header, close to the engine, and one on either side of the exhaust pipes directly after the catalytic converters.

My bet is someone went to replace an O2 sensor and didn't complete the job, or like you said they spliced it in or something. If it is spliced in and all 4 are properly installed, I'd snip it off.

[99Qx4GroundUp]

Here's a link, all 4 are hooked up but I'm not sure their health or if they've been changed recently before I got the car. I have bad fuel economy, really bad and there is a rich gas smell when it's running.

http://imgur.com/a/uUfRC

The other photo is of the exhaust, there sounds to be a leak right there. I'm not sure what that'll do but was hoping you'd be able to tell me.

Thanks.

[atraudes]

Are their wires all plugged into the harness though? If you have the dangling one plugged into the harness, then one of the others isn't. In fact, based on your photo I'll say it's the driver's side upstream (on the header). If the computer is talking to the dangler instead of the one that's actually installed on the header, then it's never entering closed loop mode.

To elaborate a bit, when you first start the car it goes into something called open loop mode where the computer richens the fuel mixture to warm the engine up faster. When it reaches proper temperature and it gets a satisfactory reading from the O2 sensors, it goes into closed loop and leans the fuel mixture again. The upstream sensor not being hooked up would definitely explain the symptoms you're seeing.

[atraudes]

As for the exhaust leak, just bring it to an exhaust shop and they could probably stitch it up quickly and cheaply, though it's certainly not an emergency.

[99Qx4GroundUp]

I will double check the harnesses but I'm pretty sure that they are all secured properly... I'll link photos as well. I'm leaning towards the catalytic converters being backed up. I'm going to take them off tomorrow morning and take her around the block(hopefully not waking up the neighborhood). If it runs strong I know my problem. They aren't cheap but I have a couple of good salvage yards nearby that are honest. We shall see

[99Qx4GroundUp]

I couldn't get to the car today due to work. I'll update you tomorrow, does anyone on here have a "How-To" guide for replacing the catalytic converters on my car? I'm thinking that one or both are clogged and causing the lack of power. any thoughts?

Thanks,

Javin