Loud SSSHHHH sound on gear shift

[white1.8]

Hi

Ever since i got my car this has been happening, when i rev up close to redline then shift there is a loud sound much like a blow off valve and i have no idea why this is happening or if it could be detrimental if anyone has any ideas what this is i would much appreciate it. My car is a naturally aspirated 94 model with exhaust and a pod filter thats the only things that were different to stock when i got it, it also happens when the air con i on or off

Cheers Matt

[Boags]

My guess was going to be air-con. My car sounds like that with the a/c on.

No idea other than that. Didn't get a turbo by accident did you?

[Steampunk]

a leak in the idle bypass system?
Log a run and see what MegaLogviewer say.
Come out for a run tonight and we'll check it out. See the "MX5 events" section.

[Okibi]

A leak in the EGR ?

[@ndrew]

Congrat's you've bought a turbo car

[Caffeine]

Worn synchros?

[white1.8]

I wish it were a turbo, I've wrapped the exhaust from headers back to the diff and sadly no turbo,
I was under the impression that there was no EGR on the aus models.
I’m pretty sure its engine rather than gearbox, I think the intake pipe thing is loose on the throttle, it could have something to do with that, there is a hissing sound coming from there and it stops when I apply pressure to it.

Now there is a loud clicking sound coming from the top of the engine (so I haven’t had chance to test anything else like revving when not in gear). The clicking it didn’t happen on the way there but did on the way home about half hr later, the timing belt is due from replacement, is this a typical thing or has something drastic happened?
Thanks for all the help so far

Cheers Matt

[Steampunk]

so was I right?, or was I right?

[white1.8]

Its looking very much like you were right, ill check by using my arc intake thats got silicone conectors and hose clamps and see if it still happenes.

Still dont know what this clicking issue is though

[Tezzax5]

How old are your plugs & leads?

Hairline cracks in the ceramic part of the plug can lead to shorting out of the plug.....clicking sound from top of the engine.

I had the exact same sound....plugs and leads fixed mine...Hopefully yours will be an easy fix as well....

[white1.8]

I unplugged them and had a look then re plugged them in and now theres no ticking, so it must have been a loose conection, i also checked my timing and it was out by about 2 degrees

[white1.8]

I fitted my ARC intake with the silicone adapter things and now the ssshhh sound is even louder
the start bypas thing (i think) is very firmly fitted even though there is no hose clamps, and the ventalation hose is attached with hose clamps, ill try revving in neutral and then closing the throttle and see if that still makes the noise.

[white1.8]

i hope not, its been happening for 10 months, looks like ill be spending some money on maintainance soon.

[nick viner]

What is an EGR?

[mx52nv]

What is an EGR?

Exhaust Gas Return

Memory fails me as to when this was first implemented in MX5s but I think it started in the first NB8s ... can anyone please confirm this?