Discussion
Here's the thing...
My Griff 500 has had it's pre-cats removed, but still has the main cat (I was advised to leave it there, if only because cars without one smell!). It's also had several significant modifications, including a P404 cam and bigger injectors (advised by Mark Adams, who set up the ECU after all the mods).
To date it has been running fine, but I have had a concern over the state of the main cat. When V8 Developments took off the front Y-piece of the exhaust a golf ball sized piece of the main cat fell out onto the floor... nasty and black.
Very recently (over the past couple of days) I have noticed some unexpected symptoms;
1. Seems a bit down on power.
2. Blows a bit of blue smoke when starting up.
3. Occasionally smells quite nasty!
4. Seems very hesitant below 2000 RMP, and does not like pulling away without riding the clutch (otherwise loads of transmission shunt).
Could it be that the cat has finally packed up? How can I find out? Would a buggered cat explain the symptoms above?
It it usual for a car to issue a puff or three (it's not bellowing) of blue smoke on start-up? I'm not convinced that the idle is quite right - Mark set it up when the engine was hot and we couldn't test cold starting - so it may just be over fuelled?
Advice much appreciated before I get the cheque book out again
My Griff 500 has had it's pre-cats removed, but still has the main cat (I was advised to leave it there, if only because cars without one smell!). It's also had several significant modifications, including a P404 cam and bigger injectors (advised by Mark Adams, who set up the ECU after all the mods).
To date it has been running fine, but I have had a concern over the state of the main cat. When V8 Developments took off the front Y-piece of the exhaust a golf ball sized piece of the main cat fell out onto the floor... nasty and black.
Very recently (over the past couple of days) I have noticed some unexpected symptoms;
1. Seems a bit down on power.
2. Blows a bit of blue smoke when starting up.
3. Occasionally smells quite nasty!
4. Seems very hesitant below 2000 RMP, and does not like pulling away without riding the clutch (otherwise loads of transmission shunt).
Could it be that the cat has finally packed up? How can I find out? Would a buggered cat explain the symptoms above?
It it usual for a car to issue a puff or three (it's not bellowing) of blue smoke on start-up? I'm not convinced that the idle is quite right - Mark set it up when the engine was hot and we couldn't test cold starting - so it may just be over fuelled?
Advice much appreciated before I get the cheque book out again
Marlon
Get the gas analyzer on it (as used by MOT testing stations). This will at least show how far gone the CAT is (or otherwise).
CAT's tend to die by collapsing in on themselves and blocking the pipe, so this could be your 'down on power' feeling.
Back to Scole or V8Developments me thinks?
If it's gone just take the thing out.
Richard
Get the gas analyzer on it (as used by MOT testing stations). This will at least show how far gone the CAT is (or otherwise).
CAT's tend to die by collapsing in on themselves and blocking the pipe, so this could be your 'down on power' feeling.
Back to Scole or V8Developments me thinks?
If it's gone just take the thing out.
Richard
Hello Simpo,
It's a difficult fragrance to describe, but a sulphurous odour is a significant part of it.
It's not there all the time, but on occasion I'll get a really big whiff of it, and accusing the girlfriend of making such a smell never goes down very well.
Doesn't your de-catted car smell?
It's a difficult fragrance to describe, but a sulphurous odour is a significant part of it.
It's not there all the time, but on occasion I'll get a really big whiff of it, and accusing the girlfriend of making such a smell never goes down very well.
Doesn't your de-catted car smell?
Marlon said:
Hello Simpo,
It's a difficult fragrance to describe, but a sulphurous odour is a significant part of it.
It's not there all the time, but on occasion I'll get a really big whiff of it, and accusing the girlfriend of making such a smell never goes down very well.
Doesn't your de-catted car smell?
I don't see why a decatted car should smell any worse than a precat one. Anyway, the idea is to leave any smell well behind (so that it can be enjoyed by cyclists who don't know what they're missing).
I think I have an exhaust leak from somewhere but that's another matter!
IMHO 
zumbruk said:
The sulphur is in the fuel. Catalysed cars oxidise it to sulphur dioxide, which gives that lovely eye-watering niff.
And SO2 (sulphur dioxide, not Bridgestones) dissolves in the moisture in your eyes, throat and lungs to make sulphurous acid. So in what form is the sulphur emitted as in non-cat cars?
Sorry to interrupt the science lesson!
Took the car out for a drive at lunch time and it's getting worse... power is slowly ebbing away from the poor old girl and she sounds like a very loud petrol lawnmower. Seriously, the exhaust note is getting louder and there's a defined beat to it...
Interestingly, there's also a noticeable 'whooshing' sound coming from the top of the engine - can't easily tell whether it's from the plenum or the heads, but I don't think I'll be driving it until a week on Monday - booked into Scole engineering for a diagnosis.
Having read a few articles on catalytic converters, it does seem likely that it's a factor in the problem; no pre-cats to protect the main cat until the exhaust gasses get up to temperature, bigger injectors squirting fuel everywhere, hotter cam producing... well... hotter gasses.
If it turns out that the cat has been buggered for a while and I just spent several hundred of my British pounds having bigger injectors fitted to compensate for it, I'll not be happy
However, I'm sure Mark Adams would have considered that that, so it's probably something far more serious
Any warm, cosy advice saying A) "It's probably nothing major", or B) "Everything will be fine once the main cat is out", or C) "Here's a few hundred quid to pay for it", would be welcome!
What a way to start the weekend...
Took the car out for a drive at lunch time and it's getting worse... power is slowly ebbing away from the poor old girl and she sounds like a very loud petrol lawnmower. Seriously, the exhaust note is getting louder and there's a defined beat to it...
Interestingly, there's also a noticeable 'whooshing' sound coming from the top of the engine - can't easily tell whether it's from the plenum or the heads, but I don't think I'll be driving it until a week on Monday - booked into Scole engineering for a diagnosis.
Having read a few articles on catalytic converters, it does seem likely that it's a factor in the problem; no pre-cats to protect the main cat until the exhaust gasses get up to temperature, bigger injectors squirting fuel everywhere, hotter cam producing... well... hotter gasses.
If it turns out that the cat has been buggered for a while and I just spent several hundred of my British pounds having bigger injectors fitted to compensate for it, I'll not be happy
However, I'm sure Mark Adams would have considered that that, so it's probably something far more serious
Any warm, cosy advice saying A) "It's probably nothing major", or B) "Everything will be fine once the main cat is out", or C) "Here's a few hundred quid to pay for it", would be welcome!
What a way to start the weekend...
Hmmm...
On further investigation...
Could it be that it isn't running on all 8 cylinders?
Oh yes - number 5 isn't connected!
I'm no mechanic (clearly), but I should be shot.
At least it was nothing major (or even approaching minor) and Simpo - I still have my cat intact!
Never overlook the bleedin' obvious!
In my defence, the cable did look like it was connected, but the shroud had pulled loose and the cable-tidy plastic thing was causing the connection to be broken every time the engine rocked from side to side.
Inexpensive to fix, but highly embarassing... and now I've told you... doh!
On further investigation...
Could it be that it isn't running on all 8 cylinders?
Oh yes - number 5 isn't connected!
I'm no mechanic (clearly), but I should be shot.
At least it was nothing major (or even approaching minor) and Simpo - I still have my cat intact!
Never overlook the bleedin' obvious!
In my defence, the cable did look like it was connected, but the shroud had pulled loose and the cable-tidy plastic thing was causing the connection to be broken every time the engine rocked from side to side.
Inexpensive to fix, but highly embarassing... and now I've told you... doh!
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