David_17
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| posted on 4/6/11 at 08:26 PM |
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Cat glowing red hot
Hi again guys.
Got another slightly worrying question just days before my IVA! 
Today i got my engine up to temp, after changing my fuel pump and heat wrapping the exhaust (after the cat just to the silencer, to cover my exhaust
clamps). Once the engine was warm, the cat was glowing red hot. I had to tweak the fuel settings slightly for the new pump, but the excessesive
exhaust temp seems odd.
My spark table seems ok compared to other peoples, and its the one that came with my base map.
Any ideas? As i need my emmisssions spot on for the test, and this can't be doing it any good!
Also, if i cut an aluminium plate to cover the burnt side panel, will this deflect the heat or retain it?
Hope someone can help. 
Cheers
Dave
[Edited on 4/6/11 by David_17]
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onenastyviper
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| posted on 4/6/11 at 08:42 PM |
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Do you have a lambda sensor fitted?
If I recall correctly, the CAT converts carbon monoxide into less harmful substances, you may be running very rich. Perhaps take it to a friendly
garage and ask for it to be put on their emissions analyser?
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David_17
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| posted on 4/6/11 at 08:43 PM |
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Sorry, forgot to mention, AFR is around 14.7 once i'd tweaked the settings.
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onenastyviper
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| posted on 4/6/11 at 08:50 PM |
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quote:
Originally posted by David_17
Sorry, forgot to mention, AFR is around 14.7 once i'd tweaked the settings.
Did it glow before or after tweaking?
Is the engine running smoothly?
Are you sure your AFR is correct?
(Sorry, lots of questions, I know)
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David_17
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| posted on 4/6/11 at 08:52 PM |
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I've been mapping (or trying) for a while, but my fuel pump got worse and worse. I changed it and all seemed well.
I'm sure the lambda's working fine.
All that's really changed is putting a little bit of heat wrap on after the cat.
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watsonpj
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| posted on 4/6/11 at 09:11 PM |
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Cats always run really hot its part of the conversion reaction, I had one on the fury for sva inside the bodywork and it got much hotter than the
exhaust does now. The problem with wrapping the exhaust, which they don't recommend on furys etc. for the risk of fire, is you are not allowing
the heat to dispate dowhstream of the cat which keeps the gas temperature high. The increase in gas temp is then making the tube hot and keeping the
upstream gas bulk temp high. I would say the best thing to do is remove the wrap and if you need to cover the exhaust extend the heat shield.
regards pete
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franky
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| posted on 4/6/11 at 09:24 PM |
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by wrapping before/after you've created a hot spot for the heat to escape from. I hope you've not done it any damage.
If you wrap the manifold the rest gets hotter. I'm not overly sold on the advantage it gives apart from a few deg less under bonnet temp
[Edited on 5/6/11 by franky]
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snapper
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| posted on 5/6/11 at 08:32 AM |
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Looking at a screen grab of a fuel map AFR runs mainly in the 12's & 13's you may be running a bit lean this can cause a lot of heat.
I eat to survive
I drink to forget
I breath to pi55 my ex wife off (and now my ex partner)
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David_17
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| posted on 5/6/11 at 08:48 AM |
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Thanks for all the replies.
@ Snapper, not quite sure what you mean 12 - 13 is rich?
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franky
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| posted on 5/6/11 at 08:53 AM |
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Have you tried it on the same map with the wrap off?
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flibble
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| posted on 5/6/11 at 09:05 AM |
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quote:
@ Snapper, not quite sure what you mean 12 - 13 is rich?
He means that during acceleration etc, afr often sits around 13 or or so, so if yours is 14.7 (fine at adle), then you may a bit lean.
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Andy S
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| posted on 5/6/11 at 09:37 AM |
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That looks a lean mixture thats still burning when the exhaust valve is open - richen the mixture or advance the timing.
Andrew
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Strontium Dog
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| posted on 5/6/11 at 11:33 AM |
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quote:
Originally posted by Andy S
That looks a lean mixture thats still burning when the exhaust valve is open - richen the mixture or advance the timing.
Andrew
That's what I think too! You are running too lean probably on acceleration or your spark is too retarded, or both!
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mookaloid
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| posted on 5/6/11 at 12:52 PM |
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does it run on when you switch the ignition off? if so its a sure sign that the ignition is too retarded.
for a non turbo exhaust to get that hot you have combustion happening in the exhaust system which makes it very hot. it is caused by the exhaust
valves opening before the combustion is finished, which is caused by the spark happening too late (retarded timing) this will also damage the exhaust
valves.
"That thing you're thinking - it wont be that."
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matt_gsxr
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| posted on 5/6/11 at 06:43 PM |
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Have you checked your TDC marks and the ignition timing with a strobe?
It might be that your table is correct but that the timing is offset.
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David_17
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| posted on 5/6/11 at 07:06 PM |
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Thanks for all the input guys, turned out to be a dodgey spark plug.
All good now.
Need to figure out accel enrichment next. 
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