Advice for stripped threads upstream oxygen sensor exhaust manifold

I went to O'Reilly's and Autozone today, where the loaner tap and die kit at O'Reilly doesn't come close to the M18x1.5 needed here but they do sell the M14x1.25 thread chaser for those smaller spark plugs:

I bought from Autozone this M18x1.5 thread chaser and will get the kid to work with me in a couple of hours before nightfall and report back.

I understand that a used exhaust manifold is problematic.

Worse, it appears that the catalytic converter is integral with the exhaust manifold on this vehicle, so, getting a "used" cat is problematic to start with.

They are not even allowed to sell you a used converter - at least not here.

Thanks for that advice based on your experience, since I have zero experience with these things.

I saw that kit at O'Reilly's which I photographed on their counter.

The sort of good news is that the thread chaser bottomed out entirely by hand, without any strength required whatsoever, but the sort of bad news is that it didn't clean up much as a result:

Still, at least that "jb weld" or "epoxy" or whatever it was, seems to be cleaned out.

The thread chaser really didn't clean up the threads as much as it pushed out the jb-weld-expoxy-whatever stuff from the valleys.

This is California, so, if there's anywhere on earth that you're not allowed to do something, it's gonna be in California for sure.

So that knocks out a used exhaust manifold from the equation.

BTW, I think I figured out WHY the ham-fisted person cross-threaded the old oxygen sensor.

The radiator upper hose is in the way of a straight shot, so I gently removed the upper radiator hose (which was rather loose with a hose clamp).

Then I was able to get a perfectly straight shot on the thread chaser:

Hi Clare, You've always been right, over the years, on everything!

I will always strive to take your advice, as you have the experience I lack.

I did clean out the threads late this afternoon just before nightfall:

After removing the upper radiator hose to get a straight shot and hand threading the oxygen sensor thread chaser a few times up and down into the hole, I hand tightened the new oxygen sensor (which came with a crush gasket like spark plugs do) into the threaded bung.

When it met a slight resistance, I used the crows foot, still by hand:

Then, when it bottomed, I gently applied leverage ever so slightly:

I figured it would be better loose than too tight, as I didn't want to risk the threads, but I did snug it down with, oh, about 20 foot pounds in the last 1/8 turn or so. Then I transferred the old metal bracket to the new oxygen sensor:

And I buttoned back up the heat shield & routed the oxygen sensor wiring:

Hi Clare, I had the teen run a short test (the car isn't street insured and the kid doesn't yet have his license so I had the kid test it on a bunch of private roads at 10 mph (if that) where it's legal to drive at least on private property - where all the neighbors have been prior warned).

There was some smoke around the exhaust manifold where we were working, and the car stalled a few times when it just about warmed up (so I presume the choke went off), but I am hoping that the mist of oily smoke is just the oil that got on the manifold when we removed the old lambda sensor.

Of course, the amber "Service Engine Soon" light was lit the whole time:

I cleared the SES light such that the SRS is the only remaining warning:

There are a few other anomalies I noticed, but the main question is how to test if the oxygen sensor is in tight enough.

What did you want it to do? A "thread chaser" is supposed to clean foreign material out of the thread. If the threads are not badly deformed, it will NOT remove metal.

You now have a pretty fail percentage of a thread - - -

First of all - it has NO CHOKE. The computer may have to "relearn" with the new sensor. Any finger prionts or penetrating oil etc on the manifold will make it smoke. Let it cool down and start it again. If it smokes a lot less, or not al all, you are good.

As for "tight enough" - if you could get 120 foot lbs out of it it's tight enough. Only takes about 10 to squash the washer.

I believe the torque spec is 33 ft lbs on a Mitsu. Many others are spec'd as finger tight (no movement) plus 1/4 turn - about 18-25 ft lbs.

Thanks Clare.

To answer your question of "what did you think was gonna happen?", I pretty much was hoping it would "feel" like I was tapping new threads, as I've tapped things before.

But it just felt loose.

Still, it tightened the last 1/8th of a turn, so, if that's enough of a "bite", then I'm happy.

I don't know how to *test* if the lambda sensor is leaking, but there's no sound coming out of it (of course, the engine is loud so the sound would have to be huge like it was when we moved the car a bit with the sensor out).

Thanks for that choke advice. It must have "some" mechanism of increasing the fuel-to-air to achieve the 14:1 stoichemotry when cold, so that's kind of sort of what I meant by choke.

Basically, it stalls at low speed (which is all we've been able to do) whenever it's transitioning from warm on the gauge (about 10 minutes or so of low-speed driving). It did this *before* the oxygen sensor, so it's unrelated to the sensor.

The OBDII tester gives us a 800 rpm reading at idle. Dunno how to increase the idle speed yet, as this car isn't mine (mine is a bimmer which is a drive by wire mechanism).

Thanks for that advice Clare, where you have always been spot on in accuracy. I'm gonna assume it's tight enough since I did get a good last

If that's the case, then I think the torque is fine.

The funny thing is I wonder why the mechanic who screwed it up didn't just do what I just did. What did he gain by jb welding it (or whatever that gray hard metal-like paste was)?

Right. The error message you got about the sensor was ALSO unrelated to the sensor. The error message says the output of the sensor is out of range. It's out of range because the engine is running way too rich or way too lean.

You don't. You find the vacuum leak or the bad idle control valve or whatever it is that is causing the mixture to be all wrong, and then your idle speed will stabilize and you will be able to accelerate again.

--scott

He didn't have to replace the sensor he screwed up. He "salvaged" it and didn't have to tell the customer he screwed up - or it was A DIY job and he figured he wasn't going to spend money on "another s***ty sensor" that likely wouldn't fit either - - - - - -

Always blame the part - don't take the blame for your mistakes - - -

Or mabee it's not - - -

Or the sensor is bad - or the ground return (if used) is bad - a hundred and one things can turn on the CEL - and that code

What code was it displaying?????

That is possible - definitely check for leaks - but now at least he knows if the light comes on again he DOES have a problem. The sensor definitely needed to be fixed, either way.

Need to check the block learn readings etc to know for sure , but too rich or too lean should give rich or lean codes, not out of range codes. Out of range means voltage higher or lower than normal operating range, and generally static - not clocking. Too lean means violtage higher than optimum - too rich means voltage too low .

Too lean would generally be a P0171, or P0174. Too rich would be P0172 or P0175.

A bad sensor would generallly be a P0130 to P0170 - but other problems can cause these codes as well.

That makes sense (from his standpoint).

The old sensor didn't look at that old, so, maybe it was his attempt to fix the code. Dunno.

I just think it was a crappy job that I'd be embarrassed to do if it were me.

I'm glad you pointed to the chaser - as - I think - it did the trick (cross my fingers).

Unfortunately I don't remember the code. But it was related to the oxygen sensor, but I should have written it down. P0133 perhaps? I don't remember though. So I apologize not to be able to provide that fact to you.

The good news is that a new code, if it pops up, will tell me something since the sensor is new (and they don't last forever).

I agree. The 800 is fine as an idle speed. But it does stall. So, there's something wrong when it transitions from cold to warm. Dunno what yet. A cost-effective smoke machine is something I've always wanted ...

(I built one, but it sucks.)

As I recall, there were no misfire codes and no lean condition codes. Just the O2 code (might have been a cat code, I wish I remembered it.)

Yup. None of those. Since I own a bimmer that is almost two decades old, I know all about lean condition codes.

This code was cat or sensor specific. But let's see if it comes back.

Yup. Chasing codes is always fun. Not.

Understood. The error is just an error in the input, output, or power of the sensor.

Always wanted to buy a good smoke tester at a good price that a home mechanic can make an argument for on cost/benefit analysis.

There is also a code for the O2 sensor heater. That's the common failure on the BMW here. They don't work unless they are hot, so to get it working faster with a cold engine the sensors have heaters.

I've seen stories of people using disco smoke machines that you can buy on ebay.

Maybe it will be back soon. How old did that previous sensor look? Possible that there is another problem and it's not the sensor,so some hack changed it recently. Did anyone check out this car before buying it to make sure it wasn't a lost cause?

If it was P0133 it means slow response - definitely a bad sensoe