Engine air leak causing uneven idle - but from where?

[trublustu]

There shouldn`t be a `hissing` and that could very well be your issue.
Mind out that the fan doesn`t kick in while you are sticking your arms down there with the engine running.
That`d sting some...

 

[Frank]

There seems to be a loud hissing noise coming from somewhere. I guess if I can locate the leak, and seal it with my finger, the hissing might dissapear, to indicate I've found the leak.

These leaks are pretty easy to find. Good diagnosis technique will save you all this 'change it and see' stuff, because you know exactly what you are fixing.

I had this on a Citroen, the 'official' car smoke test costs a lot, but you can make your own in minutes, well, in under an hour anyway. Mine was an old biscuit tin and old vacuum cleaner tube - plus the magic ingredient which cost £1. http://www.diy.com/departments/rothenberger-90230-smoke-pellet/257117_BQ.prd" onclick="window.open(this.href);return false; (you waste one pellet getting the tin/tube position right and working out that you don't need whole pellets when using this on a car! )

You just put the smoking end of the tube near where you think the leak is and watch the smoke. Where the leak is you'll see the smoke being sucked in. Took 5 minutes to find when I did it.

 

[Bobby4Puma]

B are u still on here? Mate i have the same issue and its driving me nuts... Wild E tried to help me but i couldnt find the problem i have a feeling this is caused by a leak somewhere but i couldnt find it...u didnt say if u fixed your problem and how u fixed it

 

[red]

Maybe try sending B a message? They were active in September, so there's hope.

 

[Bobby4Puma]

Thanks Red...i have the same issue and its driving me nuts...i tried looking for leaks with the brake cleaner and i find none

 

[Poolo81]

It can be broken inlet manifold gasket.

 

[Bobby4Puma]

Bruv i think its the bloody VSS its causing a lot of problems...i checked for leaks everywhere...i bought a VSS aftermarket it worked fine for a short while then its causing problems again...i think i will get a genuine ford one so i wont bother...theese sensors are so poor if they are not genuine ford

 

[idolguy]

Did you check the "Rubber Grommet/Blanking Plug" that CherryVimto mentioned?

Air Blanking Plug 1

• YOG
• Feb 3, 2011

Air Blanking Plug 2

• YOG
• Feb 3, 2011

This turns out to have been the problem plaguing my 1998 Puma. Discovered completely by accident by my niece’s partner when cleaning the throttle body. I came here to confirm this was the issue. It’s been repaired using a rubber hose with a screw in the end. Garage I took it to completely missed this twice and it’s been like this for nearly a year now. I honestly thought it was the ‘end of days‘ for my car, which I have had since 2002. Runs like a new car now. Thank you for confirming this hose connector just needs blanking off. Not sure where I would obtain a replacement blanking plug, but the current fix appears to be working well.