Cleaning TVIS?

[widster]

Hi,

My mk1b has done 135k. I was told by someone that it is worth cleaning the TVIS system. Is it as simple as taking off the large rubber pipe going in, cleaning with carb cleaner and then putting it back on?

The car runs ok but i think after 20 years it could do with a clean up of the intake system but i don't want to do anything that could lead to problems.

Also, my car 'coughs' for about 10 seconds when cold before firing on all cylinders. I was told that it culd be the cold start injector but this is fine. I'm hoping a clean up may also help this problem.

Thanks for any help.

[un1eash]

To clean the TVIS properly you'll have to remove the inlet manifold to get at it. Aslong as you hear it kicking in and the cars running fine and you feel the pull around 4750rpm then i wouldnt think a clean is need.

I'm not convinced the cold start injector even does much, i ran my car for months with it disocnneted and it still started first time every time even in the very cold.

The coughing could just be abit of damp in the plugs or dizzy.

[JMR_AW11]

To clean the TVIS properly you'll have to remove the inlet manifold to get at it. Aslong as you hear it kicking in and the cars running fine and you feel the pull around 4750rpm then i wouldnt think a clean is need.

I'm not convinced the cold start injector even does much, i ran my car for months with it disocnneted and it still started first time every time even in the very cold.

The coughing could just be abit of damp in the plugs or dizzy.

The coughing could be the start of a headgasket failure.

Best to regularly check the coolant level and maybe have a sniff test done on the coolant by a garage with the gear to do this.

BTW a lot of the sudden 'pull' from the TVIS when it activates is from the ignition timing.

The ECU kicks in 3 degrees of timing advance at the same time the TVIS is activated. IMO this step in the timing was added for marketing reasons so people could 'feel' the TVIS kick in as well as hear it.

[widster]

Thanks for the replies. Not sure what thsi other person was saying then but i'm sure he was telling me worth cleaning somewhere on the inlet of the engine.

As for headgasket problems, i am a bit worried now. I don't use the car much but i have been running it this week. I checked the oil level yesterday and i thought i'd ckeck the coolant too although it doesn't usually need topping up. The coolant reservoir was empty!

Should i start saving now for a headgasket swap (although the engine feels fine with good pressure) or is it better to budget to change the whole engine for a 2nd hand one. What are the signs of impending headgasket failure?

Thanks

[JMR_AW11]

Thanks for the replies. Not sure what thsi other person was saying then but i'm sure he was telling me worth cleaning somewhere on the inlet of the engine.

As for headgasket problems, i am a bit worried now. I don't use the car much but i have been running it this week. I checked the oil level yesterday and i thought i'd ckeck the coolant too although it doesn't usually need topping up. The coolant reservoir was empty!

Should i start saving now for a headgasket swap (although the engine feels fine with good pressure) or is it better to budget to change the whole engine for a 2nd hand one. What are the signs of impending headgasket failure?

Thanks

It might not be the headgasket so don't panic yet...

However, here's a link to some stuff about headgasket failure.


http://www.waynesgarage.com/articles/hgaskets.htm


Fom what I have heard, the mk1 is prone to gasket failure at high mileages. The classic symptom of a tiny leak is a misfire during cold startup and gradual loss of coolant. If it gets worse then you see the classic milky gloop in the oil and the engine will be more prone to overheating etc.

You need to check the coolant level at the top of the system using the metal twist cap that sits on the highest part of the coolant pipe that crosses over the engine. Only do this when the engine is cooled down for safety reasons as the hot coolant can burst out under pressure.

The level in the plastic expansion tank doesn't really tell you much.

It's possible to drain out all the coolant and still have coolant in the expansion tank!

My blue mk1 had a mystery coolant loss and I though it was maybe the headgasket. It turned out to be a perished radiator hose that had lost its sealing at high temperature and pressure. It took ages to find it as it only leaked if I got the car really hot.

So yours could be similar and the misfire could be ignition related.

Good luck!

[monkeymax]

What gave away the headgasket on mine:






(Sorry I've not rotated it...)

Well, there were a few other signs too - an example of which was coolant all over the engine. When I pulled out spark plug number 4, I found it was also coated in coolant rather than oil...

[widster]

Thanks for the replies. I'll have a look out for the things you mention... and keep my fingers crossed!

[midenginedmaniac]

Cleaning the tvis is a long job. I reconditioned one as mine was faulty. Lots of bits to take off before you get it out. Mine was covered in poo but it made no difference to performance. Just got rid of the annoying squeal.

[widster]

Cleaning the tvis is a long job. I reconditioned one as mine was faulty. Lots of bits to take off before you get it out. Mine was covered in poo but it made no difference to performance. Just got rid of the annoying squeal.

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Cheers. Think i might leave well alone!

[widster]

Just reactivating this post as i have been out in my car and i have been advised that the TVIS may not be working on my car. I always thought it had been working since i had the car 4 years ago but it could be that it has never worked in this time.

I have been given some advice but would appreciate any other comments from anyone who has had the same problem.

Thanks
Widster

[un1eash]

Do you feel it pick up at around 4.5k? Also if you have an induction kit you should hear the change in engine tone.

[widster]

I went out in the car today with someone who's opinion i respect and who knows these cars. He told me that he doesn't feel that the T-VIS is working. I have to admit that there doesn't seem to be any discernible change at the 4.5k point. My car doesn't have an induction kit but it does have a mongoose exhaust, if this makes any difference. My engine doesn't like to rev too high, i.e. much past 7k ish, so this could also be a pointer that the T-VIS isn't working.

[un1eash]

Yeah System-G (garrick) knows a little about mr2's

Have you checked the movement of the valves and all vaccum pipes, especially the ones running to the vaccum chamber under the inlet?

[brin]

Hi all,

I've always wondered about the TVIS and how it should feel. I use to have a Citroen AX Gt with twin choke webber which pulled very strong when the second choke came in. I always expected that of the TVIS. My car runs perfect and pulls well but I too have never noticed any difference at any particular rev range.

[JMR_AW11]

A simple test would be to drive in 3rd gear on a dry clear road at a steady 3500rpm on light throttle and then rapidly go to full throttle.

The engine will labour its way through the TVIS opening point and you should hear a decent change in intake noise as it switches in.

(switches in at 4350rpm on a mk1a and 4650rpm on a mk1b)

You won't feel much of a kick though...


BTW there is a 400rpm changeover window so once the TVIS kicks in at 4650rpm on a mk1b it will stay in until you drop the revs below 4250rpm.

(figures for mk1a are 4350rpm and 3950rpm)

[widster]

Have you checked the movement of the valves and all vaccum pipes, especially the ones running to the vaccum chamber under the inlet?

I've not checked anything yet to be honest. I'm planning to take the TVIS apart bit by bit, take lots of pictures and bag everything up so i don't lose anything. I'll try to see if the butterfly valves are stuck. I will also try to make sure that the vacuum pipes are ok. I think you can also check that the actuator is working? Apart from that i have no clue. I have had a look in the MR2 repair manual that i have (the online version) but this seems to apply to US cars and i can't find any mention of TVIS. Did US cars have this?

My engine has done 135k and apart from normal servicing it has never been stripped down as far as i can tell so i'm hoping it's just due to a build up of grime and isn't too hard to sort out. Would be nice to hear the change in sound and for the engine to breathe a bit better at high revs although it appears that i have done 3 track days with it not working and i haven't missed it!

[widster]

A simple test would be to drive in 3rd gear on a dry clear road at a steady 3500rpm on light throttle and then rapidly go to full throttle.

The engine will labour its way through the TVIS opening point and you should hear a decent change in intake noise as it switches in.

(switches in at 4350rpm on a mk1a and 4650rpm on a mk1b)

You won't feel much of a kick though...


BTW there is a 400rpm changeover window so once the TVIS kicks in at 4650rpm on a mk1b it will stay in until you drop the revs below 4250rpm.

(figures for mk1a are 4350rpm and 3950rpm)

Thanks for that. I'll give it another try but i'm pretty sure that it isn't working.

[MartG]

When checking the vacuum lines from the actuator, don't forget to check that the VSV is plugged in too

[MartG]

T-VIS vacuum lines are at the right side of the diagram here http://opc.mr2oc.com/online_parts_catal ... 758393.gif - ignore all the emissiions crap though, that's only for the US market

[widster]

T-VIS vacuum lines are at the right side of the diagram here http://opc.mr2oc.com/online_parts_catal ... 758393.gif - ignore all the emissiions crap though, that's only for the US market

Thanks for the diagram, very useful.

Just out of interest, if any of my vacuum lines look like they need to be replaced, which i think they may do, does anyone know the best place to buy new ones? Cheers.