Hello , 2006 Red MR2 , Pre-cats and preventative Rust treatment

[carspath]

Hi All ,

I'd like to say Hello to all of you as i've just bought myself a red 2006 MR2 with a black cloth interior .

Its done 57,000 miles in teh hands of its 2 previous owners and has a full Toyota Main Dealer service history .

I've used this Forum's Search function re ''pre-cat problems '' , but would be grateful for teh forum member's more up-to-date  opinions about the following issues :


1) I understand that the face-lift cars had quite extensive engine improvements to reduce the likelihood of bore -ovalisation and pre-cat issues , BUT is it true that 2005&2006 had further engine modifications and improvements carried out by Toyota ?

2) At the moment my car is not consuming any oil at all , but I understand that by the time it does the pre-cat issue would already have caused irreparable damage .
So I am wondering if I should be de-catting the car now .
Is it worth doing in a 2006 cars .
This forum's poll seems to indicate that all teh affected cars were pre-cat cars except for 1 2002 car and 2 2003 cars .
So do you have any idea what % of 2005 and 2006 cars are susceptible to the pre=cat issue ?

3) This forum suggests that many members are removing the existing cat matrix , and then reusing the original manifold ( but with new gaskets) .
(a) Is it better to do this than getting a new aftermarket manifold without pre-cats ?
Some members are suggesting that some after-market manifolds do not align up properly
( b) How many new gaskets are needed , and where can I get reliable proper gaskets from ?
Some members appear to have had problems with replacement after market gaskets .
(c) I would prefer to re-use my original manifold after it has been de-catted , so as to save on buying a brand-new after-market manifold , but is this a false economy .?
How difficult is it for an experienced mechanic ( ie not me !! ) to completely remove the original catalyst matrix without leaving residue behind that might then bet sucked back into the engine ?
(d) This forum mentions the CHE manifold in the early posts , but not recently
Which replacement aftermarket manifold would you recommend , how much does it cost , and where can i buy this particular manifold please ?
(e) OR have you re-used your original manifold after the de-catting without problems ?


4) Some members have had their CEL coem on after de-pre-catting , others have not .
How likely are the CELs to come on after de-pre-catting a206 MR2 


4) Any recommendations for garages experienced in decatting MR2-precats in the Dorset area please ?

5) Any recommendations for rust-proofing the underside of an MR2 -- what product do you use ?
Any garages close to Dorset that you would recommend ?

A number of MR2 experts have suggested that I simply leave my 2006 car as it is as removing teh pre-cats in these very late cars is very unlikely to be necessary .
Do you agree ?
Would you de-pre-cat a 2006 car ?
Having the CEL come on after de-pre-catting would be a big incentive for me NOT to touch the manifolds , and to take my luck and leave the existing pre-cats as they are . Would you do the same or would you carry on with the de-pre-catting anyway  ?

Thank-you for taking the tiem to read this , and thank-you also for amy advice

Best wishes

Carspath

[Zxrob]

Hello and welcome

Fair few questions there and you probably get a fair few different replies, me personally

Mine is a FL 2004 so in theory should be ok however, I removed the pre-cat material, reused the standard manifold and have never had an issue with any sensors or lights using the standard cat and exhaust, I have a TTE exhaust on now and that is fine, I did have the ELM light on one point but that was when I was running a decat system

Quite a few put on aftermarket headers, personal choice really

Rob

[JohnGee]

Welcome aboard.

I had the pre-cats taken out of my 2006 Roadster shortly after I bought it, certainly can't do any harm now. Opinions will vary, judgement call for you at the end of the day. I don't recall any warning lights coming on after the pre-cats were removed - perhaps I was lucky.

I got a stainless decat manifold from EBay for something like £130.

Enjoy the ride.
 

[fawtytoo]

I have the original manifold and precats in my 2002 PFL 65k miles. All checked and ok.

[Joesson]

Hello and welcome.
I have had my 2002 car for ten years. The first job I did was to remove the precats , as was the general consensus then and replace the OE manifold which was contentious, with new OE Toyota gaskets.
One sensor then needed to be replaced. I now understand that they do not like to be disturbed.
So, Catch 22! You have to remove the top two sensors to check the condition of the precat material!
Today, my understanding is that regular / frequent oil changes are the key to avoiding the sticking piston rings that it is believed is the cause of the bore wear and resultant oil consumption and damage to the precats.
Your car has been regularly serviced by MrT and therefore could be OK on that basis.
You have a late model, therefore your car could be OK on that basis.
You mention a big incentive NOT to touch the manifold would be a CEL light coming on. In my experience and reading on here, that is not uncommon after removing and replacing them.
NB, again my understanding , is that changing the exhaust manifold could be considered to be a performance modification .
For what it's worth I would likely do exactly what I did previously if I were to start again.

As for rust removal/ protection, the main area for any concern/ inspection is the rear cross member.  I like the Bilt Hamber range of products.

As for recommending garages, anywhere, my experience with Mr T means that they are off my list and I service and maintain my 2 myself. However, if you do not have that enthusiasm an independent family type organisation is often better value than a chrome and glass main dealer.

[Carolyn]

Wow big post!  But it comes down to year of car and pre-cats.

You've done your research, but did you notice how old much of the information is?

Any well maintained roadster should be fine with the pre-cats left in.  I've seen year y2000 cars that were well looked after with very high miles, that still have intact pre-cats.  And I've seen y2006 cars that weren't well maintained that were terrible smoky oil burners.

The pre-cats can get destroyed by unburnt oil that gets past the piston rings.  It's a problem that can affect about 95% of all the roadsters that were produced!

It's all down to changing the oil.

Firstly, the Toyota recommended intervals are rubbish.  Oil is cheap, compared to engines, so many and frequent oil changes are your best buddy.  Every 3,000 miles or once a year (whichever comes first) is ideal.

Forget what the journalists have to say.  They just repeat the most repeated myth and make it 'fact'.

Don't get carried away with what year it is. Service history and maintenance are the key.

If your engine doesn't use oil and the pre-cats look good when you remove the O2 sensors and have a look, then just look after the little bugger properly and it will be fine.

If the pre-cats have been knocked out, you will be left with a less than ideal pair of empty cans masquerading as an exhaust manifold.

The modern budget alternative is to install a 'Toyosports' manifold, if you can get one. They are made in batches and tend to sell out pretty quick.  There are other equivalents out there, but they do vary in quality,  I've seen acceptable ones and others with such shoddy fitting and welding as to be downright bad.

If dosh is no problem, then the 'Zero' manifold is the dog's. But it is £600 as opposed to £140 (ish).

I always wrap them with good quality titanium wrapping.  I know there are those who insist it might make the manifold crack at some point.  The man who makes the Zeros has no problem with wrapping and the Toyosports ones might crack after five years or so (not always) , but they're so cheap, who cares?

With either manifold, it's easiest to do the wrapping on the bench before it's installed.

Please don't have your car sprayed with any kind of gunk to prevent rust.  You wouldn't do that to an old Ferrari or Lagonda, so why do it to an MR2?  I've had cars on the lift that had water sitting behind the 'underseal'.  The last one took two miserable days to get it all off and deal with the rust.

I like to get the car up on a lift and remove rust with a rotary wire brush and then treat with a good rust treatment like Bilt Hamber, and then use zinc primer and a couple of top coats of a paint the roughly matches the rest of the underside.  After that, I get the car up once year and deal with any corrosion which pops up.  There won't be much.

It is worth paying special attention to the rear subframe, which can rot from the inside out (just above where the exhaust passes underneath).  So it needs to be inspected.  I like to seal the open top corners (to stop wet and salt getting in) and remove some of the small rubber bungs and treat the inside to some sort of treatment/coating, such as Waxyoil, but there ore other ones as well..

It sounds as though you've got a lovely little car that has fallen into good hands.

Enjoy!

[Ardent]

Hello and welcome.
You have found the best place to be fir solid info and care.

My 2p. (Which only mirrors above posts)
Low milage. Not burning oil now.
Previously well maintained.

Regardless of history service it now.
I would put the pre cat thoughts on the back burner. Leave well alone. Do them last if at all.

Service now. Any good quality 5/30 synth will do.
Closely inspect sub frame.
What state, age, condition, brand, pressures are the tyres?
Suspension refresh?
Maf clean.
Inspect and clear the drains.
All take precedence over pre cats.

[Petrus]

1) I understand that the face-lift cars had quite extensive engine improvements

They had not.

2) At the moment my car is not consuming any oil at all , but I understand that by the time it does the pre-cat issue would already have caused irreparable damage .
So I am wondering if I should be de-catting the car now .

Don´t worry about the pre-cats.
Them causing damage is basically myth.

If they are gutted, the exhaust works worse as Carolyn observes.

4) Some members have had their CEL coem on after de-pre-catting , others have not .
How likely are the CELs to come on after de-pre-catting a206 MR2 

The CEL will come on after removing the maín cat. You will need a distance piece for the O2 sensor to avoid that but without cat you will not pass MoT.

Bottom line is: Just change oil regularly and enjoy your car!!!

[fawtytoo]

@Petrus I believe, in the UK, removing the precats doesn't fail an MOT.

[Call the midlife!]

@Petrus I believe, in the UK, removing the precats doesn't fail an MOT.

It doesn't usually but he's talking about the "main cat"...

[carspath]

Zxrob , John Gee , fawtytoo , Joesson , Carolyn , Ardent , Petrus , Call the midlife ,

WOW , SIMPLY WOW .

Thank-you for all your replies and the huge amount of experience and wisdom contained within -- I am hugely grateful and will take on board your advice .
It is interesting that there is so much agreement between all your replies , which makes things much easier for me .

I am really enjoying my Mk3 .

It seemed pretty much up to the mark when I bought it , but its suspension geometry ( and tyre pressures ) were clearly out .
So within a week I took it up to ''Wheels-in-Motion '' in Chesham ( a 200 mile round trip from where I live , but they had done some good work for me previously ) , and Joe there went about his magic and the car now drives beautifully and goes where you point it at .

I'm currently on OEM recommended Bridgestones and am running at the factory recommended 26 and 32 psi .
Are you doing the same ?

I've come to this MR2 after 18 years with my beloved Mk1 MX5 ( sadly rust got to her after 147,000 delightful miles ) , and Ive been pleasantly surprised that despite my rose-tinted view of the Mazda , the MR2 stands up well as a replacement .

I've had to alter my driving style a little -- I've found that specific bends need to be taken 1 gear lower with the MR2 compared with the MX5 .
And you feel the MR2 pivoting directly below you more

Its also much , much better on petrol -- esp if you like zipping up to the red line on the odometer .... which is great when you have to pay-up at the Tesco cashiers .

Although the MR2 redlines 400 rpm above the 6500 at which my MX5 did , I feel that the MR2 feels less eager to zing through the rev-counter .
But that just might be me as I've got used to a certain exhaust noise and certain vibrations while working up the rev range in the MX5 , and the noises and vibrations are different with the MR2 .

Hopefully with more experience , I'll be able to better exploit my MR2 capabilities ..... and to start with I'll try cornering one gear lower than I've been doing thus far .

Thank-you all once again for all your help

Take care and Best wishes

Carspath

[Ardent]

Yep.
We are the best. Just saying.

Wheels in motion. Excellent. They dialed in their b road setting. Never been happier.

Re tyres.
If you are on original Bridgestones they must be quite old now. The re04's have not been available for a few years now. Certainly 1 size was dropped if not both.

That will need looking into. Tyres make a world of difference on a 2. Pressure wise. Bang on.

Glad to hear you are enjoying it.

[cptspaulding]

I've not driven an MX5 so can't comment on the zing. However the performance curve I would imagine is similar, you really have to have these cooking at >4500rpm to feel it working (it really doesn't mind). I've always found it more than adequate for slinging around the B-roads (getting a wee bit wet for that right now).

I'm another who despairs when reading about the pre-cat myth. Seems top have been perpetrated a number of years ago & folks are quick to take it as gospel without further research (a bit like using a mobile phone in a petrol station I guess). As @Carolyn says, have a look at the top of the pre-cats with the O2 sensors out. Should be & probably will be a perfect flat honeycomb in front of you.

Welcome & enjoy

[Dev]

What is the pre-cat myth.

I know several cars that had pre-cat failures. One I personally witnessed that consumed no oil or had other issues and just like that they disintegrated and damaged the engine. When sampling the oil from the dipstick I observed white chalky material that could have been some of the matrix sucked up.   
 Some of these cars were nearly brand new with less than 30k miles of ownership. Toyota replaced the engines under warranty or they rebuilt them and in addition to this they replace the pre-cats and main cat. The later cars after 2003 did not have these issues however over the years there were a few that was reported.  There are many that did not suffer pre-cat failure well into the engines life but it does mean that this kind of failure did not exist and it is believed that those that replaced or gutted the pre-cats as advised probably lessen the numbers of incidences over the years and that is probably how history has been rewritten to call it a myth.
 Our car is not the only car that had pre-cat problems. Nissan also had cars with pre-cats that did the same thing.
  Those are the facts of ownership that occurred when the car was still being sold and now it is a myth which is very interesting. Back then some owners were not interested in joining a car forum but they did to seek advise as their first post after they suffered pre-cat issues which they documented the entire process.

 If by myth will all cars will suffer pre-cat failure then yes but it is not a myth that is is a potential failure point that is unexpected and can occur quickly with immediate damage to the engine even if caught early.

[carolineasb]

@Carolyn so glad that you have said about underseal!! My hubby (as you know a mechanic) cringes when he hears of people undersealing their 15-20 year old cars and, therefore, sealing in corrosion that will eat away unseen. We've been here before with undersealing many years ago and it stopped and like any other fashion it has come round again in a cycle.

[minimike]

Hey, late to the thread but🤷‍♂️
I bought a red 2006 with 32 k on it in July. It's my fourth MR2, my first was a brand new one in 2001!
This is what I did-
1. Service! Full service kit from Toyota for less than £40, can't go wrong.
2. Full detail, clean the drains and strip the brakes. Paint the callipers too.
3. Set up the hand brake.
4. Four new tyres.
5. Guy the pre-cats. Reuse manifold, reuse gasket, no issues.Check the engine number, there is a list somewhere. Yours  should be the latest engine piston design which should mean it won't be anywhere near as likely to burn oil. Pre cats best off in the bin IMO, nothing to worry about from there.
6. Replace the headlights for brand new. Not cheap but worth it IMO.
7. New fog light, eBay £20.

I have it booked in this year for a full underbody rust treatment and protection at a classic car company, there was nearly a years waiting list!

Enjoy the car. Mike.