Terraclean by Ed China
Discussion
supermono said:
Of course catalysts don't store oxygen they allow the oxygen present to react with unburned hydrocarbons as the gases pass through
You're wrong. If there are partially burnt hydrocarbons in the exhaust, it implies there is no oxygen left, so how could the cat possibly oxidise anything?Three way cats work by storing excess oxygen during the weak cycle and then using it to oxidise the hydrocarbons during the rich cycle. This fits in very nicely with the way that narrow band oxygen sensors require a control scheme to oscillate either side of stoich.
Max_Torque said:
Piersman2 said:
I had an XJR which used to trigger the engine warning for inefficient cats every day or so
Piersman2 said:
After about 18 months I eventually replaced the cats with some sports ones thinking this would solve it
er, why?Your EMS flags up "inefficient" catalysts by measuring the oxygen storage capability of the catalysts. It does this by monitoring the post catalyst exhaust oxygen content verses the pre catalyst oxygen content, which is my modern cars have two sets of lambda sensors (pre and post cat)
I'd bet you £50 that to "fix" the issue, the garage just fitted some cheap(<£10) spacers to the rear sensor to move the tip of the rear lambda probe out of the exhaust stream and bingo, no MIL...........
ie:
More seriously though, the sports cats were fitted when the originals became so clogged up that it was impacting performance, it got so bad that acceleration above 4k revs was limited and I could no longer get above 100mph. Original replacements were £600 each, the sports I eventually managed to source were only £250 each.
Believe me I did a lot of research into the issue, and saw this 'fix' using a spacer on the rear lambda sensor being suggested for lots of different brand cars but there was obviously something wrong and I'd rather fix it properly than bodge round it.
Speaking to several Jag specialists at the time indicated this was not isolated to just my car, they wereall aware of other Jags or Range Rovers exhibiting the same problem.
No one had sussed out the answer by that time, about 2 years ago. Maybe someone has by now?
Mr2Mike said:
supermono said:
Of course catalysts don't store oxygen they allow the oxygen present to react with unburned hydrocarbons as the gases pass through
You're wrong. If there are partially burnt hydrocarbons in the exhaust, it implies there is no oxygen left, so how could the cat possibly oxidise anything?Three way cats work by storing excess oxygen during the weak cycle and then using it to oxidise the hydrocarbons during the rich cycle. This fits in very nicely with the way that narrow band oxygen sensors require a control scheme to oscillate either side of stoich.
ProTec do a similar cleaning system to Terraclean if you can find people that have it, there are two types of method, one adds to the airstream and one substitutes fuel as Terraclean does, the first is useful for EGR valves and throttle housings, inlet tracts etc.
I have a sensor extender which works brilliantly, actually two. One for the downstream sensor after a decat, and one for a wideband sensor upstream which is just to move it further from the heat as it couldn't be fitted far enough away and still before a cat. both are stainless angled ones for under a tenner each, perfect, not used to fix or conceal a problem though which isn't the best solution.
I have a sensor extender which works brilliantly, actually two. One for the downstream sensor after a decat, and one for a wideband sensor upstream which is just to move it further from the heat as it couldn't be fitted far enough away and still before a cat. both are stainless angled ones for under a tenner each, perfect, not used to fix or conceal a problem though which isn't the best solution.
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