seth151

Well people im going out of my head :*( fitted new cat today and still that sound remains :*(
every one is telling me im crazy and they cant hear nothing.
The noise is not that loud(put ur ear down near the under front side of the car and can hear it) but it is defintly there.the garage told me today after fitting the cat and scratching there head "that must be what sound rotarys make" again im not convinced.
It sounds like its coming from manifold but that asure me theres no leaks there.
on the up side idle seems near on perfect seafoamed twice lol and grounding kit and a good all round clean up seem to have done the trick.
JUST THIS BLOODY NOISE LOL
please help , any ideas would be great.

So to sum up general performance of the car is good. just a little judder every now and then at idle (with A/C off) and the "lawnmower" like sound comin from the front under side of the car(under drivers feet area)

seth151

oh and tried the ecu and fuel trims reset.both reset ok but did not change anything.

Oh and somone tell me more about this "knock sensor" plz . thanks in advance

Speed_8

do any of you guys know` if our oxygen sensor in the rx8s is a wide band o2 sensor ????

Brettus

iTrader: (2)

How about you post a sound clip or video .

seth151

on route as we talk m8 :P just trying to get on my pc from my girlfriends bloody iphone

Polak Graphics

It sounds like its coming out of the engine and then being muffled by the exhaust.


Compression check the engine yet?

Also, that doesn't look like a stock cat?

seth151

cel came on because just unplugged maf while car was running few mins before the video.

[youtube]p7T8PQDHuB4[/youtube]

seth151

Hi no its not a stock cat,bought from ebay from cats 2 u.
you really think i have compression issues ? every thing seems to good to be a failing engine .... but i agree it is defo up near the manifold area,maybe a gasket?

seth151

obviously you have more experince then me :*( i just really dont wana have low compression lol , spent all my cash on the car and doing the things that i have done :*(

ASH8

If you are getting a shake, could be (more than likely) Engine Mount (s).

I was hearing two noises..
1.Could be VVVV Belt Idle Pulley.(intermittent high pitch)
2. The main one appears to be travelling down exhaust.

Side note, do you use pre-mix in fuel...you should.

seth151

Hi engine mounts were done 2 weeks ago with brand new ones from mazdas, the shaking is only very slight and dosent really bother me ( that much :P)
whats the vvvv belt idle pulley? and yes the other is defo exhaust / engine related
i dont use premix... how do i go about this? im uk as well , is it ok ?

dynamho

It sounds a little loud (perhaps it's just the way it was recorded) but doesn't sound alarming.
You might want to go to a local RX-8 meet or take a test drive at a dealer and compare sounds.

seth151

actually the shaking does bother me it just really isnt that bad . i had the same sort of shake on my old 330ci m sport and it was due to a bad crank case ventilation vavle . do rx8s have these?

seth151

Yes m8 i thoguht i sounded very loud in the video but infact its no were near that loud in real life , as u can tell wen i was in the car u can hardly hear it at all. i think thats my problem i have never actually herd a rx8 close in real life apart from this one.thanks for the input m8y

dynamho

Consensus seems to be to add about 4-6 oz of 2-cycle oil to a full tank of petrol.

ASH8

Small pulley front of engine that AC belt runs on.

Search for Pre-mix, it is two stroke oil you mix with Fuel, throw in 10 ounces (400-500 mils) per FULL tank at the moment and see if it helps.

You could have DRY Apex Seal, in other words No or little lubrication to Apex Seals as some or all of your 4 Oil Injectors are blocked...much depends on Service life and chance.

Just try the pre-mix first...then get back.

Polak Graphics

Since it isn't an OEM cat it might just not be good enough.

I'd do some research into what catalytic converter they used to make that in comparison to what they use in an OEM catalytic converter.

seth151

so i literatly get 10oz of good two stroke oil and put in my fuel tank and then fill with fuel? do i have to stop using my regualr oil? will this affect the car negativly at all? and how does it help the running of the car please?

can i check the oil injectors or unblock? or lube the seals a difrent way? or is this permnament damage? thanks

seth151

HHmmmm yes , tbh i didnt think of that :O i was 99% the cat was gona solve the problem as well

ASH8

Yes, and then Fill your Tank...

Does NOT change any engine oil use..

Oil Nozzles are more involved to test/fix..

Try this first, you should pre-mix anyway (slightly less than 10 Oz), just trying to get more in and you try it.

No wont hurt car..will improve.

seth151

Just been reading up on premix and decided i am gona try this tmorow.i have motocross bikes and i get the best 2 stroke oil they have in the motocross shop.. will this be ok for my 8?
should i add 6 or 10 oz to a full tank ?

seth151

just see ur post ash as i posted mine :P so just under 10 oz aye :D
what did this mean :p "just trying to get more in and you try it"

seth151

the annoying thing is im starting to fall in love with this car :P and i want her to blossom in to a beast :D
(without lawnmower sound affects :D )

ASH8

Pre-mix will lubricate your Apex Seals..try it then report back...simple.

If you want to know more SEARCH..

dynamho

I hope you don't mean to stop using your regular motor oil.

The 2-stroke oil (premix) supplements your regular oil in lubricating parts of the rotor.
The regular oil is added via the oil injectors, while the 2-cycle oil rides the fuel injectors.

Try what Ash8 recommends and dump about 10oz 2-cycle oil to your fuel tank, fill it up and see if that improves the noise situation.

I personally use 5oz premix every fill up but this is a diagnostic routine to see if the premix alleviates the noise issue, so 10oz is fine. You can choose to keep using 10oz or scale back later. There are no conclusive metrics that show which amount is best.

If you're worried about negative effects of premix, all I know is that the RX-7 guys have been doing this for a long time. There is some conjecture that it may clog up some fuel delivery components, but nothing is conclusive.

Ultimately though and IIRC, it appears to help lubricate the center portion of the apex seals.