Engine Not Running Well, Noisy Exhaust And O2 Sensor Issues

[Erudite]

Since having the cat fitted back on for the mot (coming from a decat pipe) there has been a fluttering noise when accelerating.

For a long time I thought it was the heat shield on the cat as it was loose and reverberating.

At first I got a CEL and a lean code:



I cleared this and it hasn't come back since.

Yesterday I went out for a drive and took some o2 sensor and fuel trim readings.

This is what I came back with:

At Idle:





Accelerating:





Constant Speed:



Overnight I removed the ECU (25A) fuse and upon re fitting it and taking it out for a drive, the bank 2 O2 sensor was stuck on high voltage at idle, bank 2 was lean and bank 1 was rich. These were the readings I was getting back:





I've since taken the car on a 3 hour drive and the problem has become a lot worse. I had to take the roof down as fumes from the engine in the cabin were pretty strong.

The exhaust is now a heck of a lot louder (and not in a good way), performance also seemed a bit choppy towards the end of the trip (slight lack of throttle response and otherwise just not seeming 100%). The o2 sensor readings had also gone completely haywire on both sensors:



Post drive I've gone to have another look and the CEL has come on and is throwing out the following codes:

============1==============
P0136
Raw code: 0136
ECU: 10
Status: Confirmed
OBDII: Heated oxygen sensor (HO2S) 2, bank 1 - circuit malfunction
Toyota: Oxygen Sensor Bank 1 Sensor 2 Malfunction

============2==============
P0153
Raw code: 0153
ECU: 10
Status: Pending
OBDII: Heated oxygen sensor (HO2S) 1, bank 2 - slow response
Toyota: Oxygen Sensor Bank 2 Sensor 1 Circuit Slow Response

============3==============
P0150
Raw code: 0150
ECU: 10
Status: Pending
OBDII: Heated oxygen sensor (HO2S) 1, bank 2 - circuit malfunction
Toyota: Oxygen Sensor Bank 2 Sensor 1 Circuit Malfunction

============4==============
P0136
Raw code: 0136
ECU: 10
Status: Pending
OBDII: Heated oxygen sensor (HO2S) 2, bank 1 - circuit malfunction
Toyota: Oxygen Sensor Bank 1 Sensor 2 Malfunction


============1==============
P0136
Raw code: 0136
ECU: 10
Status: Confirmed
OBDII: Heated oxygen sensor (HO2S) 2, bank 1 - circuit malfunction
Toyota: Oxygen Sensor Bank 1 Sensor 2 Malfunction

============2==============
P0153
Raw code: 0153
ECU: 10
Status: Pending
OBDII: Heated oxygen sensor (HO2S) 1, bank 2 - slow response
Toyota: Oxygen Sensor Bank 2 Sensor 1 Circuit Slow Response

============3==============
P0150
Raw code: 0150
ECU: 10
Status: Pending
OBDII: Heated oxygen sensor (HO2S) 1, bank 2 - circuit malfunction
Toyota: Oxygen Sensor Bank 2 Sensor 1 Circuit Malfunction

============4==============
P0136
Raw code: 0136
ECU: 10
Status: Pending
OBDII: Heated oxygen sensor (HO2S) 2, bank 1 - circuit malfunction
Toyota: Oxygen Sensor Bank 1 Sensor 2 Malfunction

============5==============
P0136
Raw code: 0136
ECU: 10
Status: Confirmed
OBDII: Heated oxygen sensor (HO2S) 2, bank 1 - circuit malfunction
Toyota: Oxygen Sensor Bank 1 Sensor 2 Malfunction


I've looked around the exhaust and can't find any obvious signs of a leak. This was the only location (exhaust paste pending removal)  where there was slight movement in the tissue on stick, even then it was hard to tell if it was just the air causing the movement. I also looked around the manifold seal and couldn't see any signs of movement there.

https://imgur.com/a/64N2Ywg

This is a reading from an old post I made here on the B1 O2 sensor last year when the decat pipe was on and by the looks of things it didn't look 100% then?



Any suggestions on where to start?

[potge]

The fact that one goes really flat would tend to imply or a really bad leak or something bad in the sensor or its wiring.
I would check for leaks in the exhaust. There should be something quite obvious I reckon.
Also, since is quite an evil coincidence, is there any chance that during installation something went really bad with cat, any other exhaust component or that the sensors/wiring took any abuse?

You can check on steady state rpm the sensors. From memory, the manual described that with steady 2500-3000 rpm (with a fully warmed car) the precat O2 sensors voltage should oscillate around 0.5V. And you can also check their resistance.

[Erudite]

The fact that one goes really flat would tend to imply or a really bad leak or something bad in the sensor or its wiring.
I would check for leaks in the exhaust. There should be something quite obvious I reckon.
Also, since is quite an evil coincidence, is there any chance that during installation something went really bad with cat, any other exhaust component or that the sensors/wiring took any abuse?

You can check on steady state rpm the sensors. From memory, the manual described that with steady 2500-3000 rpm (with a fully warmed car) the precat O2 sensors voltage should oscillate around 0.5V. And you can also check their resistance.

Ok thanks, any tips on where to look for the leak given the symptoms? I think I may be able to hear the leak but it's very hard to track down the source of the noise I can hear when the engine is running. I'll have another look around the engine tomorrow with the tissue stick.

I didn't fit the cat myself, the cat was the original one that came with the car. When I bought the car the decat pipe was fitted (there were no apparent issues with the car when this was fitted). So it could be that there are issues with the cat.

The only other thing that springs to mind (possibly related to the P0136 code?) is that the post cat sensor that was fitted when the cat went in was a third party budget one.

[potge]

Thinking out loud, any connection or gasket point would be the first guesses. So after the precat and before the exhaust.

About the sensor your are right. But having absolute 0 (as I think it was) seems more like wiring or indeed a faulty sensor.
Thus, check the wiring and the sensor after the cat. Someone posted euro car parts had a good discount on denso post cat 02 sensors, so it might be a good timing.
If it gets (or is still zero) ask someone to wiggle it and see if you get any reading. You can also swap with a precat one, though length will be an issue, but there are some ways to trick it so you can check if is wiring issue.

[frogger]

The area of the 3-amigo's (bottom of manifold where the 2 pipes join the flexi pipes of the cat section) is prone to leaking after reassembly - as are the flexi's themselves.

And both are hard/impossible to 'see'.

But quite easy to detect - if you lightly dampen your fingers (spit will do!) and carefully hold them at different points until you feel the leak puffing air at your fingers.

Needs to be done with the engine on, so try not to burn your fingers!

A leak here will cause all manner of O2 sensor codes on the post-cat sensor.

........ But if all the sensors are playing up, could be a leak further up, such as at the head-manifold joint.

[Erudite]

The area of the 3-amigo's (bottom of manifold where the 2 pipes join the flexi pipes of the cat section) is prone to leaking after reassembly - as are the flexi's themselves.

And both are hard/impossible to 'see'.

But quite easy to detect - if you lightly dampen your fingers (spit will do!) and carefully hold them at different points until you feel the leak puffing air at your fingers.

Needs to be done with the engine on, so try not to burn your fingers!

A leak here will cause all manner of O2 sensor codes on the post-cat sensor.

........ But if all the sensors are playing up, could be a leak further up, such as at the head-manifold joint.

Thanks for your reply. I'm pretty sure there is a leak so I'll have a closer look tomorrow. I'll try not to burn my hands! I'm not the most careful at times and did burn myself not too long ago when looking around the exhaust.

I'm also wondering if part of the reason for the voltage/circuitry related error codes may be a duff battery. I've not been using the car very frequently and have been having to jump start it. I did think that something was just draining it but now I'm wondering if the battery is part of the problem. It's not an old battery but is a lion one which I've heard aren't the most reliable. I'm going to get it to get it tested tomorrow.

[Carolyn]

The area of the 3-amigo's (bottom of manifold where the 2 pipes join the flexi pipes of the cat section) is prone to leaking after reassembly - as are the flexi's themselves.

And both are hard/impossible to 'see'.

But quite easy to detect - if you lightly dampen your fingers (spit will do!) and carefully hold them at different points until you feel the leak puffing air at your fingers.

Needs to be done with the engine on, so try not to burn your fingers!

A leak here will cause all manner of O2 sensor codes on the post-cat sensor.

........ But if all the sensors are playing up, could be a leak further up, such as at the head-manifold joint.

Thanks for your reply. I'm pretty sure there is a leak so I'll have a closer look tomorrow. I'll try not to burn my hands! I'm not the most careful at times and did burn myself not too long ago when looking around the exhaust.

I'm also wondering if part of the reason for the voltage/circuitry related error codes may be a duff battery. I've not been using the car very frequently and have been having to jump start it. I did think that something was just draining it but now I'm wondering if the battery is part of the problem. It's not an old battery but is a lion one which I've heard aren't the most reliable. I'm going to get it to get it tested tomorrow.

Tape a piece of tissue to the end of a suitable screwdriver and pass that around all joints.  When it flaps, you've found a leak.

[Erudite]

I've had the battery disconnected for the past couple of days as I'm away from home without a jump starter.

Started up again this morning (no issues there) and the readings looked slightly better:





I'm starting to think that it could be a failing alternator?? I've put my ear to that area of the car and it does sound slightly rough/gravelly. The spot that the alternator is in is difficult to get at, is it best to test it across the battery terminals?

@Dev I read a post where you said to test the diode pack in the regulator to see how much AC voltage is leaking through to see if an alternator is going intermittent. Does this require removal of the alternator?

I tried the tissue again today and also stuck my hand in there and although I didn't do too thorough a check, the main place I could feel a movement of air was coming from the direction marked on the photo below low down on the engine block.

[Dev]

 You can take the reading at the battery while the car is running although they say to take it at the alternator but its not necessary.  Just switch the multimeter to measure AC volts and check the allowable limit. If one or more diodes are shot it will be obvious. 

[Dev]

I gave your first post a good read.

This is what I would do.

1. Check all of your grounds
2. Check to make sure your battery connections are tight and no corrosion around the terminals.
3. At idle carefully spray some induction cleaner around the vacuum hoses, throttle body and intake manifold. If the engine rpms rise you have a leak that is causing the lean code due to unmetered air. 

 I hope that helps.

[Erudite]

I gave your first post a good read.

This is what I would do.

1. Check all of your grounds
2. Check to make sure your battery connections are tight and no corrosion around the terminals.
3. At idle carefully spray some induction cleaner around the vacuum hoses, throttle body and intake manifold. If the engine rpms rise you have a leak that is causing the lean code due to unmetered air. 

 I hope that helps.

Thank you Dev. I will try everything you suggested.

Would the induction cleaner test be the same if the car was running rich (sorry if this is a dumb question)?

I went to a garage here today and he tested the voltage on the battery which showed at 14v. I will get a multimeter when I get home and check the allowable limit to rule out the alternator being a potential issue.

[Dev]

I gave your first post a good read.

This is what I would do.

1. Check all of your grounds
2. Check to make sure your battery connections are tight and no corrosion around the terminals.
3. At idle carefully spray some induction cleaner around the vacuum hoses, throttle body and intake manifold. If the engine rpms rise you have a leak that is causing the lean code due to unmetered air. 

 I hope that helps.

Thank you Dev. I will try everything you suggested.

Would the induction cleaner test be the same if the car was running rich (sorry if this is a dumb question)?

I went to a garage here today and he tested the voltage on the battery which showed at 14v. I will get a multimeter when I get home and check the allowable limit to rule out the alternator being a potential issue.

The suggestions I gave are just a process of elimination. It could be something else entirely and it is always better to diagnose from easiest to hardest.
 Not a dumb question and you are right, by using intake cleaner and spraying it on these components (if they are cracked and taking in air) it will in effect richen the mixture and raise the idle. Intake cleaner is much safer than spraying with fuel LOL. 
  This is to check for any vacuum leaks along the closed intake path. If  the idle raises then you can lightly spray each vacuum line or intake joint to isolate exactly where it is leaking.

That fluttering sound could very well be a bad connection of your exhaust manifold at either end and since that is what was changed it is a potential problem but generally a leaking gasket doesn't always throw a code, it just leaks. What I would do is re-install your de-cat pipe and see if the noise goes away as well as the codes.
  Good luck.

[Erudite]

I gave your first post a good read.

This is what I would do.

1. Check all of your grounds
2. Check to make sure your battery connections are tight and no corrosion around the terminals.
3. At idle carefully spray some induction cleaner around the vacuum hoses, throttle body and intake manifold. If the engine rpms rise you have a leak that is causing the lean code due to unmetered air. 

 I hope that helps.

Thank you Dev. I will try everything you suggested.

Would the induction cleaner test be the same if the car was running rich (sorry if this is a dumb question)?

I went to a garage here today and he tested the voltage on the battery which showed at 14v. I will get a multimeter when I get home and check the allowable limit to rule out the alternator being a potential issue.

The suggestions I gave are just a process of elimination. It could be something else entirely and it is always better to diagnose from easiest to hardest.
 Not a dumb question and you are right, by using intake cleaner and spraying it on these components (if they are cracked and taking in air) it will in effect richen the mixture and raise the idle. Intake cleaner is much safer than spraying with fuel LOL. 
  This is to check for any vacuum leaks along the closed intake path. If  the idle raises then you can lightly spray each vacuum line or intake joint to isolate exactly where it is leaking.

That fluttering sound could very well be a bad connection of your exhaust manifold at either end and since that is what was changed it is a potential problem but generally a leaking gasket doesn't always throw a code, it just leaks. What I would do is re-install your de-cat pipe and see if the noise goes away as well as the codes.
  Good luck.

Thanks Dev, all makes sense and sounds a good way forward. 

I will try the old pipe as all this has happened since the cat was fitted. I've also been meaning to remove the cat to get rid of the exhaust paste that was put on there (as flagged up by Carolyn).

I'll update once I've carried out the work and run through your suggestions. Thanks again for the help

[krazysteve]

The fact that one goes really flat would tend to imply or a really bad leak or something bad in the sensor or its wiring.
I would check for leaks in the exhaust. There should be something quite obvious I reckon.
Also, since is quite an evil coincidence, is there any chance that during installation something went really bad with cat, any other exhaust component or that the sensors/wiring took any abuse?

You can check on steady state rpm the sensors. From memory, the manual described that with steady 2500-3000 rpm (with a fully warmed car) the precat O2 sensors voltage should oscillate around 0.5V. And you can also check their resistance.

Ok thanks, any tips on where to look for the leak given the symptoms? I think I may be able to hear the leak but it's very hard to track down the source of the noise I can hear when the engine is running. I'll have another look around the engine tomorrow with the tissue stick.

I didn't fit the cat myself, the cat was the original one that came with the car. When I bought the car the decat pipe was fitted (there were no apparent issues with the car when this was fitted). So it could be that there are issues with the cat.

The only other thing that springs to mind (possibly related to the P0136 code?) is that the post cat sensor that was fitted when the cat went in was a third party budget one.

start from a cold engine, use a bit of tissue around all exhaust joints, watch your fingers lol. 

[Carolyn]

I suspect the crush ring gaskets, which are the only way to reliably seal the manifold to cat joint, aren't in place (seeing as there's exhaust paste in there). If that's the case - it will leak, sooner or later, usually 'sooner'.

Best to get OEM ones installed. I'm happy with a lot of aftermarket stuff, but crush rings are best in original form.

The cat needs to come off, the sealing surfaces thoroughly wire-brushed and then re-installed with the crush rings and a decent 'donut' gasket in the cat-to-silencer joint.

I'm not saying that you might not have another issue too (hopefully not) but this job definitely has to be done.

[Erudite]

I suspect the crush ring gaskets, which are the only way to reliably seal the manifold to cat joint, aren't in place (seeing as there's exhaust paste in there). If that's the case - it will leak, sooner or later, usually 'sooner'.

Best to get OEM ones installed. I'm happy with a lot of aftermarket stuff, but crush rings are best in original form.

The cat needs to come off, the sealing surfaces thoroughly wire-brushed and then re-installed with the crush rings and a decent 'donut' gasket in the cat-to-silencer joint.

I'm not saying that you might not have another issue too (hopefully not) but this job definitely has to be done.

Yep I suspect you're right regarding the crush rings.

I've started to take it apart today and found that the flexi pipe has a hole in it.

I'm thinking the best thing is to buy a new cat from ebay and buy the new crush rings from my local Toyota garage?

I see with the cats on ebay that there's a fitting kit. Will I need this if I still have all the fittings from the original cat?

Also, is a torque wrench necessary when fitting the replacement cat?

[Carolyn]

"I'm thinking the best thing is to buy a new cat from ebay and buy the new crush rings from my local Toyota garage?"
Yep theCats2U one is fine. It you have a convenient dealer, they're not usually too badly priced.  Our affiliate, TCB Performance parts has them.

"I see with the cats on ebay that there's a fitting kit. Will I need this if I still have all the fittings from the original cat?"  Very often the bolts and springs are fairly badly corroded, so the kit is not a bad idea, except that the crush gaskets that come with the kit ain't too great! 

You don't need a torque wrench, do everything good and tight and re-check when you've put a few miles on it.

[Ardent]

Good n tight will be plenty.

Cat to box 43nm.
Cat to manifold the 3 amigoes 62nm.

[Erudite]

Finally got around to ordering the crush rings, just want to make sure I've ordered the right part before fitting?:

[Ardent]

Look right to me.
If I was ordering crush rings. That's what I would expect to turn up.

[Zxrob]

 Hmmm, every crush ring I have fitted be it to a bike or car has had either a round or oval section, not saying they are not correct and wont work but they look shape wise like a ring that's been crushed

Rob

[shnazzle]

Hmmm, every crush ring I have fitted be it to a bike or car has had either a round or oval section, not saying they are not correct and wont work but they look shape wise like a ring that's been crushed

Rob

Nope they're flat in the 2. Know what you mean though

[Zxrob]

Hmmm, every crush ring I have fitted be it to a bike or car has had either a round or oval section, not saying they are not correct and wont work but they look shape wise like a ring that's been crushed

Rob

Nope they're flat in the 2. Know what you mean though

Ah, is that the std Toyota part then, hmm, I just refitted mine with an aftermarket one, round in section, thats what I'm used too

Rob

[Erudite]

Thanks guys. One thing I've overlooked is that the old cat to back box gasket has fused to the cat.

Is it best to get an oem replacement or do the third party ebay options work ok? If oem is the route to go down, does anyone have a part number?

[Carolyn]

The non OEM ones work fine.