Check Engine Light And Lean Code After Replacing Exhaust

[Erudite]

After fitting the original exhaust the check engine lights come on and it's throwing out the following codes:



Any ideas as to why?


If I didn't tighten the nuts where the the cat meets the back box enough, could this cause air to be sucked in an throw a cel even though it's past the O2 sensor?

When I did the exhaust swap I just swapped over the back box (cat and manifold remained the same). I'm wondering if it's more likely to be an issue with the back box (very old and rusted) or if it's more likely that I damaged the cat flex pipes when removing the back box



Background info

I've had an annoying metallic reverberating noise for around a year now and it's been driving me mad trying to track it down.

I've posted about it before but the gist of it is:

-sheet metal/metallic sound reverberating at around 2500 rpm when the engine is hot (up to temperature and driving)
-very quickly goes after pulling up to the side of the road. Seems to be rapidly affected by changing temperature.
-if you pull up and slam the door you can hear metal on metal squeaking (short sharp squeak).
-present with and without cat heat shield

Current Situation

All of this had lead to me removing the tte exhaust under the assumption that it may be a loose baffle/something in the exhaust with the issue being closely connected to the temp of the engine.

I've shaken the exhaust around after removal and I can't hear anything loose or moving around in there.

My plan is to fit the original exhaust to confirm 100% if this is the problem.

Gaskets

Does the cat to back box gasket look like it needs replacing? It's pretty rock hard (not sure if that's how it's supposed to be).




Also, if it was a loose baffle, would I definitely hear it when shaking the exhaust around? I don't mind fitting the original exhaust to make certain but the rubber hangers are a real pig to get off.

[Gaz mr-s]

That gasket looks ok to me. They're pretty robust.

A rattle at 2500rpm is very often the heatshield around the exhaust. The holes that the bolts pass through break up & they buzz.  Sometimes fixed by a large jubilee clamp around it.

[Erudite]

That gasket looks ok to me. They're pretty robust.

A rattle at 2500rpm is very often the heatshield around the exhaust. The holes that the bolts pass through break up & they buzz.  Sometimes fixed by a large jubilee clamp around it.

Unfortunately it persists with a decat pipe without heat Shields and the original cat with the heat shield.

I'll have a look if any other heat shields are loose in there now I've got the exhaust off.

[Carolyn]

Background info

I've had an annoying metallic reverberating noise for around a year now and it's been driving me mad trying to track it down.

I've posted about it before but the gist of it is:

-sheet metal/metallic sound reverberating at around 2500 rpm when the engine is hot (up to temperature and driving)
-very quickly goes after pulling up to the side of the road. Seems to be rapidly affected by changing temperature.
-if you pull up and slam the door you can hear metal on metal squeaking (short sharp squeak).
-present with and without cat heat shield

Current Situation

All of this had lead to me removing the tte exhaust under the assumption that it may be a loose baffle/something in the exhaust with the issue being closely connected to the temp of the engine.

I've shaken the exhaust around after removal and I can't hear anything loose or moving around in there.

My plan is to fit the original exhaust to confirm 100% if this is the problem.

Gaskets

Does the cat to back box gasket look like it needs replacing? It's pretty rock hard (not sure if that's how it's supposed to be).




Also, if it was a loose baffle, would I definitely hear it when shaking the exhaust around? I don't mind fitting the original exhaust to make certain but the rubber hangers are a real pig to get off.
 

I tend to cut the hangers off and put new ones on (bog standard item from the local parts shop). A spot of washing-up liquid makes it a breeze.

[Erudite]

Background info

I've had an annoying metallic reverberating noise for around a year now and it's been driving me mad trying to track it down.

I've posted about it before but the gist of it is:

-sheet metal/metallic sound reverberating at around 2500 rpm when the engine is hot (up to temperature and driving)
-very quickly goes after pulling up to the side of the road. Seems to be rapidly affected by changing temperature.
-if you pull up and slam the door you can hear metal on metal squeaking (short sharp squeak).
-present with and without cat heat shield

Current Situation

All of this had lead to me removing the tte exhaust under the assumption that it may be a loose baffle/something in the exhaust with the issue being closely connected to the temp of the engine.

I've shaken the exhaust around after removal and I can't hear anything loose or moving around in there.

My plan is to fit the original exhaust to confirm 100% if this is the problem.

Gaskets

Does the cat to back box gasket look like it needs replacing? It's pretty rock hard (not sure if that's how it's supposed to be).




Also, if it was a loose baffle, would I definitely hear it when shaking the exhaust around? I don't mind fitting the original exhaust to make certain but the rubber hangers are a real pig to get off.
 

I tend to cut the hangers off and put new ones on (bog standard item from the local parts shop). A spot of washing-up liquid makes it a breeze.

Thanks, I will do just this when I fit the tte back on. When I was half way through pulling off the old ones I did think that it may be easier just to buy new ones but I was too committed at that stage.

[Frank Rabbets]

I use silicone sealer on 2nd hand gaskets. Even ones on the exhaust. You would not think the sealer would stand high temps but it does. It's used on gas fire assembly amongst other uses.

[Erudite]

Just to update, I fitted the original exhaust and the metallic noise has gone so there must be some metal loose in the third party exhaust that's rubbing when it gets hot and expands.

I do have another issue though. Since having the original cat fitted around mot time, the car makes a noise like an air-cooled VW when accelerating. Could it be a loose heat shield reverberating or is it most likely a leak on the cat?

[Carolyn]

You could use the 'flappy tissue' method to find any leaks.  A bit of tissue taped to a screwdriver - start the engine - hold it all around the joints and, if it's leaking, you'll see it flap.

No flapping = loose heat shield (which is highly possible).

[Erudite]

After fitting the original exhaust the check engine lights come on and it's throwing out the following codes:



Any ideas as to why?

[Carolyn]

Looks like a very leaky exhaust to me.

[Erudite]

If I didn't tighten the nuts where the the cat meets the back box enough, could this cause air to be sucked in an throw a cel even though it's past the O2 sensor?

When I did the exhaust swap I just swapped over the back box (cat and manifold remained the same). I'm wondering if it's more likely to be an issue with the back box (very old and rusted) or if it's more likely that I damaged the cat flex pipes when removing the back box.

[Carolyn]

I'm sure otherswill come along with help. 

to me, 'Bank 2' means a sensor in the manifold is reading that.

So upstream of that, which would be manifold/head gasket.

Otherwise an injector not keeping up?

@jonbil ??

[Dev]

What kind of manifold do you have?
If its the original does it still have the pre cats in them?

When you get a 02 code for one bank and not the other it can present with broken precat material first before it gets worse. 

[Erudite]

Thankfully it's an aftermarket one.

I took it out today, checked the fuel trims and O2 voltage and I think it all looks ok?



I'm wondering/hoping that it may have just been an anomaly. The light hasn't come back on yet.

[jonbill]

I think the VW noise and the 'too lean' codes are related. manifold not sealed at the head or down pipe, letting sound out and air in.

[Erudite]

I think the VW noise and the 'too lean' codes are related. manifold not sealed at the head or down pipe, letting sound out and air in.

Thanks jonbill, my first suspicion is the manifold to downpipe seal:

[shnazzle]

I wouldn't say that B2 reading is OK tbh.
It seems to be reading max rich.
0.76 /out of a max or about 0.9v contradicts the lean code.
What is making the car think it's running lean enough to trigger that?
Something else at play?
B2 o2 sensor knackered?

[Carolyn]

I think the VW noise and the 'too lean' codes are related. manifold not sealed at the head or down pipe, letting sound out and air in.

Thanks jonbill, my first suspicion is the manifold to downpipe seal:

That looks like exhaust paste in there?  Not a great idea - it will get into the cat.

Ideally it should be sealed with just the OEM crush rings.

[Erudite]

I think the VW noise and the 'too lean' codes are related. manifold not sealed at the head or down pipe, letting sound out and air in.

Thanks jonbill, my first suspicion is the manifold to downpipe seal:

That looks like exhaust paste in there?  Not a great idea - it will get into the cat.

Ideally it should be sealed with just the OEM crush rings.

Yeah, I took it in for an mot and had the guy fit the cat back on. I wasn't too happy with the work he did to be honest which is partly why I'm trying to do stuff myself now.

Thanks for the heads up on the paste, I didn't know it could get into the cat. Are the crush rings available online? Is the paste a job to remove?

[Carolyn]

It will come off with a wire brush, once it's on the bench.

Crush rings from Toyota, or TCB (our affiliate supplier).

[Erudite]

Finally got around to opening up the silencer and found the cause of the rattle.

[Dev]

It must be satisfying to actually see it.