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cfc1 last won the day on November 3 2010

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    2005 MR2 Roadster... 2006 CTS Compressor
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  1. Whilst the MR2 Roadster has very few flaws as either a fun cheap sports car or as a precision tool to hit the track with, there is one thing that we as a Club feel every owner should be aware of, and that is the pre-catalytic converters (or pre-cats for short). There have been a huge amount of questions on here since the forum began regarding these, and this thread is here to hopefully answer any and all questions that have cropped up about the pre-cats, as well as dispel some myths about them. *Please note: The Club neither encourages nor advocates the interference with emissions equipment on any motor vehicle, and we take no responsibility for any action taken by any person as a result of reading this article. All text and pictures here are for information purposes only.* What is a pre-cat? To put it quite simply, the pre-cats sit before the main catalytic converter in the exhaust system and help to keep the harmful emissions as low as possible for a short period after you start the car up. Of course, there is slightly more to it than that… The main catalytic converter in the Mk3 works best at converting the harmful compounds contained within the exhaust gas at high temperatures: However, since the engine takes a while to heat up to it's optimum running temperature, there is a time when a great deal of harmful emissions are allowed to simply pass straight through the cat and are dispersed into the air. Toyota obviously wanted to keep these emissions to an absolute minimum to enable the car to be classed as a ULEV (Ultra Low Emissions Vehicle) to allow the Mk3 to be sold in California (they have practically the most stringent rules on car emissions anywhere in the world there!), so between the engine and main cat they placed two pre-cats contained within the main manifold itself. The manifold itself looks like this: The four headers run into the two chambers containing the pre-cats, and then they're passed onto the main cat to let it do its job. The pre-cats are made from a ceramic material, which whilst excellent at absorbing the noxious gasses at low temperatures, is also highly brittle… Why are we worried about them? As stated above, the pre-cats themselves are not the strongest material known to man, and they have been known to break down and enter the engine, causing serious damage to the internals. When this sort of damage has occurred, you are almost certainly looking at needing a new engine. Woah, wait a minute! How can the pre-cat get back into the engine: Surely the exhaust flow pushes it all out? True to a certain extent, but here's the clever bit… The 1ZZ-FE engine (Toyota's designation for the engine inside the MR2 Roadster) is a very clever piece of kit, and arguably its main party piece is the VVTi, or Variable Valve Timing Intelligent. This increases engine response all over the rev range by altering the timing of the cams, allowing for differing amounts of valve overlap in order to give great low-down torque as well as good top-end power. The 1ZZ also uses it's VVT to perform EGR (Exhaust Gas Recirculation) functions without the aid of a specific valve like other cars. Under certain operating conditions (usually steady cruise) the cams are timed to scavenge some exhaust gas back into the cylinders, as a way of reducing the high hydrocarbon emissions that modern petrol engines generate at certain times. Unfortunately, when you combine this with some very sharp ceramic pre-cat particles, you can imagine what happens: The pre-cats start breaking down, and get dropped into the main cat which then causes excessive pressure, leading to oil blow-by in the engine. When the VVTi kicks in, the pre-cats are sucked back in and scratch and score the cylinder walls, leading to more oil passing by the piston rings and being burnt off without you even realising it. No oil in an engine leads to massive failure as every moving part grinds against metal, and in short you end up with a practically useless engine. When this happens the situation is compounded by the fact that hot oil is now allowed to drip directly onto the pre-cats and break them down even quicker, which in turn allows large chunks to block the main cat even more, which then stops any smaller pre-cat material escaping at all and sucks even more back into the engine to cause even more damage… A vicious circle of the very worst kind. Some common symptoms of pre-cat failure are extreme oil loss, very noticeable lack of power all the way through the rev range, and horrible noises coming from your engine bay. Essentially, if you've got any of these problems and they are directly related to pre-cat loss, then it's too late. Even the oil warning light won't save you here, as by the time it comes on there's almost zero oil left in the engine anyway. For more information on how an engine works in general, please click here for a link to HowStuffWorks.com But I've read elsewhere that the pre-cats themselves are fine, it the piston rings which are the weakness… This is where we come across a real conundrum, and a question to which no-one has a definitive answer. It's true that on very early MK3s there was a known problem with the piston rings themselves on a 1ZZ, and Toyota issued a technical document to the dealers around the world stating as such. They also changed the design of the piston rings for the facelift version of the Roadster, which became available in 2003. Now whether it's a case of the piston rings failing, oil dripping onto the pre-cats and breaking them up, or the pre-cats self destructing and taking the piston rings with them, we just don't know. All we do know for certain is that whilst you can't take the piston rings out of the engine, you can remove the pre-cats from the manifold. No pre-cats = Nothing to get sucked back into the engine. Okay, so the pre-cats are obviously a bad thing, but what can I do about it? Is there any way to tell if they're okay on my car? There is only one sure way of telling, and that it to remove the entire manifold and check both the top and bottoms of the pre-cats for any signs of damage. This is the only 100% way. I'm not very mechanically minded, so is there another way? Even if it's not 100%? Yup, and this is the way 99% of people do it (myself included). It's very simple, and requires nothing more than a 22mm O2 sensor removal socket (Available from here for one, but you can get them at many other places as well, this is just an example), a can of PlusGas or similar penetrating oil (WD40 will do at a push, but it's a lot easier with the PlusGas), and a torch. The picture above shows the heatshield which covers the manifold itself, and is how your car looks when you open the engine bay. Coming out of either side of the heatshield are the O2 sensors, which need to be removed to see the pre-cats from the top only. 1. Get the engine nice and warm first, it'll make this job a lot easier! 2. Spray the PlusGas liberally onto the joint where the O2 sensor meets the manifold. Leave for 10 minutes, then spray it again. You cannot use enough of this stuff, trust me! Don't worry about the steam coming off; it's not doing anything any harm. 3. Being very careful not to burn yourself on the heat shield, use the O2 socket to remove the sensors, Unplug them first from the plastic clip (it's a simple push-tab-and-release connection), and make sure you turn them anti-clockwise. If you have an older vehicle, you may find that these are very stubborn, but do persevere and don't be afraid to give it a little elbow-grease! 4. Pull the sensor out of the socket and place carefully on the floor, away from your feet. You don't really want to tread on it now you've done the hard part, do you?! 5. Take the torch and shine it into the holes. You're looking for a completely solid honeycomb matrix with no cracks or large holes in it, like this: 6. When you've finished checking (and hopefully found that they're still intact), simply screw the O2 sensor back in and nip it up with the socket. Oh, and you may want to plug it back in too. My pre-cats look fine! I'm safe! *dances* Not quite: They're still very fragile, and remember you can't see the bottom of the matrix from that angle either. All this means is that your engine is still fine and you're not in any immediate danger of the pre-cats failing. Oh, okay. So what's the next step then? The only 100% sure way to protect your engine is total removal of the pre-cats from the manifold. This isn't a particularly hard job, but it is more involved than simply removing the sensors. CONTINUED IN THE POST BELOW
  2. Steve

    Happy Birthday cfc1!

  3. Hints and tips are.... http://www.toyotaownersclub.com/forums/index.php?showtopic=65122 The forum for the problem discussed here can be found... http://www.toyotaownersclub.com/forums/index.php?showtopic=61112
  4. No.. they can still be twitchy in the wet.. it comes from being mid engined and rear wheel drive, but thats where the fun is, it's so easy to drive them if you know your limits. The 2003+ models came with bigger and wider rear wheels and some extra bracing to make the car handle slightly better than the older model, but there is still plenty of room for improovement and plenty of aftermarket options to choose from, everything from anti-roll bars to chassis braces. The most important aspect of the handling is the tyres, keep all four corners the same make and model (tread pattern) and maintain the staggered set up with wider tyres on the rear, failure to do this will seriously impare the handling charasteristics of thye car.. Ss far as improoving the handling goes, the same changes can be made to both pre facelift models and post facelift models, so don't let that be a factor in chooseing a car. The biggest and, argueably,most important change to the post facelift car was the change in the piston ring design, the newer designed engine is less likely to suffer from oval bore syndrome.. or more commonly refered to as pre-cat failure (which is in actual fact a symptom of oval bores), so if you can get a good facelift car all the better.
  5. This gets really annoying... 1. Mod bashing... again, it's why I got sick of this forum and stopped posting so much. 2. What has this topic got to do with the Toyota Hybrid/Prius? This sort of topic should be in general discussions, but no.. no-one uses it, instead they post on their own marque forum even although it is completely irrelevant to the section. If the members of this club used the forums the way they were designed to be we could find that meets would be better attended as we might just get to know other members from other parts of the forum.. but thats just too much to ask.. isn't it. So instead of having a go at the moderators.. use the forums properly and make it easier for them... just a suggestion.
  6. Les.... I'm sorry mate but I do not understand why you would expect any input from member who did not attend. If they were not part of the event why would they be part of this thread Sorry Steve I should read paragraph 3 more often. ;) I foolishly thought that if there was ANY reaction to what a Toyota Owners Club meet (Yes it was a Toc meet) can be like, there might be some enthusiasm from members wanting to partake in something similar and give encouragement to organisers of any future events but sadly this is not so.......as expected. Steve.. this is in no way aimed at you personally, so please don't read it as such. Input from members who did not attend.... would be nice to get opinions on whether or not it would be worthwhile organising the event fot TOC members next year. Reaction to what a TOC meet is like... so far we have absolutely nothing worth bothering about, except for a couple of posts. In days gone by this thread would be on page 4 by now with people ooohing and ahhhing and saying what a fantasticx time they had or saying they wish they could have went. The only thing the members of TOC have on meets is apathy, 100% apathy, no-one can be bothered organise a meet, if they do.. no-one can be bothered to attend. This club used to be full of friendly people who you could meet up with regularly, now... for me anyway.. it's full of faceless usernames with no interest in anything meets related, it's no wonder Les has said this was the last event he will organise for TOC. People will think I'm a hypocrite for posting this as I didn't attend this event and they would be right, but a 682 mile round trip and only one day off at the weekend makes my excuse reasonably understanding, there are people on here who couldn't care less about it even if it was 20 miles away. In my defence I will say I done a 568 mile round trip for a BBQ (which I was late for, but still got fed and some liquid refreshments... oh!, and I only got 4 hours notice that I could attend) I have recently wondered why I even bother coming here anymore, or why I am indeed still a moderator (think that hat should be passed to someone else) I have lost interest in this forum because I hardly know anyone on it (see above.. faceless usernames) and thats because the members on it have no interest in meets, they won't even post their opinion on a few photo's or a video for god's sake... it's time the members here debated whether or not they actually need a meets section anymore.. because it's surely the least used section here?
  7. No hiding from anyone eh! lol
  8. Fizz... nothing has changed, it's just that perfunctoriness has grown Still... good to see you stopping by .
  9. Why a metal bucket?.. did someone break your plastic one last year? I will be attending this year, but like Hou I don't know who with. I have already had a couple of offers from elsewhere and both.. no offence to the company on TOC which is always fantastic.. are more appealing at the moment. Should I not be on a TOC stand I will most certainly spend time getting bladdered with friends who will be
  10. Hi, I saw the Pillar Pod on the MRS, any indication where I can get one from. It's a right-hand one like the one in the photo. Thanks

  11. Sassenach is a word used chiefly by the Scots to designate an Englishman. It derives from the Scottish Gealic Sasunnach meaning, originally, "saxon", from the Latin "saxones"; it was also formerly applied by Highlanders to (non-Gaelic-speaking) Lowlanders. As employed by Scots or Scottish English-speakers today it is usually used in jest, as a (friendly) term of abuse. Not racist at all.. merely the use of an adjective which points out (Dsignates ;) ), in this particular use of the word... an English person in a crowd of non English people. The diiference between racism and (friendly) banter ;)... oh!.. and I could write better lol.
  12. What we want to know is... What type of event would you go to? What would you want to do at a regional meet? ..and of course... Why don't you go to any meets that may get organised or talked about? We could post up a regional meet, get 20 odd names saying they will go and when you arrive there are 3 people who bothered to show up... we want to know why so we can improove things and get people together, the more often it happens the more you get to know other members, before you know it youre going to regular meets (aswell well as shoows and events) and thouroughly enjoying yourselves. Where is the Scotlands meets???? I've been to more meets with another club in 2 years than I've been to in the 6 years or so I've been a member here.... so something isn't right.
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