vacuum leak?

[gotham.r]

hey guys,

on the weekend I decided to clean out my plenum and throttle body as well as install the mace 25mm MI and 12mm PS. my car is a vx s1 v6 ecotec

had no problems with the install part, went quite smoothly but after I started the car it was running an alternating rough idle and making a hissing noise like there's a vacuum leak.. I've checked over the seals/gaskets with some soapy water and can't seem to find anything..

it seems to be running rich and churning through petrol like no tomorrow, a friend and even Steve told me that it can take a week for the car to reprogram the ecu but I'm not sure if this is correct?
any help is appreciated

[cander24]

Your symptoms and the fact you have a 'hissing' noise would suggest a vacuum leak. Have you also checked the vacuum lines to the throttle body and rear of the plenum?
Any pcm trimming/learning should happen fairly quickly.

[gotham.r]

yeah that's what I was thinking but I've checked over all the lines and the seals so I'm not sure what else to do other than redo it all..

[Deltak]

If it is a vacuum leak, soapy water doesn't help as the vacuum sucks it in!

What you need is, with the car idling, carelfully spray some WD40 or similar at suspect joints. The one thats leaking will cause the engine to race for a short time.

Hope this helps.

[gotham.r]

thought about that, was insure as it's flammable? but I'll give it a try, would it be worth looking for some high temp silicone and going around the edges?

[gotham.r]

found the leak then, would it be worth re-sealing the whole thing or is it possible to get some sort of high temp silicone and go around the edges?

[Brett_jjj]

Id be taking it apart and refitting the gaskets and spacer etc again properly as they shouldnt leak at all when correctly fitted, somethings not quite right there somewhere..

[gotham.r]

had another look over it again turns out one of the bolt holes In the plenum had cracked creating a massive hole for a vacuum leak.. so that was my problem, obtained a brand new plenum and throttle body and reassembled it all without the manifold spacer and is now running even better than before the problem so thanks for all your help