Inlet Manifold

[pacmannewry 0]

Hi folks, a quick(ish) question: I have a 1.9 gti engine with a K&N filter set up. Since I've had the car, I have replaced the inlet manifold and recently I have noticed a strong smell of petrol in the cab combined with bad idling and a general random racing of the engine. I took it to the mechanic this morning and he noticed a screw hole on the manifold (on the top right hand side down where it bolts onto the engine) which when covered by his finger causes the engine to conk out. He speclkated that I may be msiing a vacuum pipe and I noticed a similar hole on the AFM also disused. Should there be a pipe connecting these two holes? Or is this hole just a mounting point for the oil filler cap? Does anyone have any picture of this side of the inlet pipe for comparison?

 

Cheers

 

Paddy

 

Update: arrowed in picture below.

 

 

http://imageshack.us/photo/my-images/52/img2206ml.jpg/

Edited May 7, 2011 by pacmannewry

[EdCherry 34 1 Cars]

Theres normally a bolt through the oil filler pot holding it on the inlet manifold. Somebody at some point has put a different bolt in and pushed a hole in the inlet. Just whack a bolt in there with a dowty seal or something to see if you can cure your problems.

[pacmannewry 0]

Theres normally a bolt through the oil filler pot holding it on the inlet manifold. Somebody at some point has put a different bolt in and pushed a hole in the inlet. Just whack a bolt in there with a dowty seal or something to see if you can cure your problems.

 

Thanks Ed - the mechanic has suggested putting a bolt in with a small drilled hole in it to let a small airflow in and out to see if it stabilises the idling.

[EdCherry 34 1 Cars]

Its meant to be sealed and not breathe at all otherwise its flowing unmetered air.

 

Doubt you will get it started with the bolt in if it dies when you plug the hole, probably overfuelling down to a duff coolant temp sensor above the SAD>

[pacmannewry 0]

Its meant to be sealed and not breathe at all otherwise its flowing unmetered air.

 

Doubt you will get it started with the bolt in if it dies when you plug the hole, probably overfuelling down to a duff coolant temp sensor above the SAD>

 

Thanks Ed - I'll investigate the coolant temp sensor then instead and seal the manifold as you suggest.

[GLPoomobile 958]

Thanks Ed - the mechanic has suggested putting a bolt in with a small drilled hole in it to let a small airflow in and out to see if it stabilises the idling.

 

I'd suggest finding a new mechanic, as the dude doesn't have a clue what he's on about!

 

The hole needs blocking, full stop. You shouldn't have any open holes in the inlet tract, as it sucks in unmetered air - for the engine to fuel accurately all air needs to go through the AFM, becuase that's what's metering the airflow. When you have any leaks after the AFM you are sucking in unmetered air and the mixture will lean, or your idle speed will increase and be unstable etc etc.

 

The fact that the engine is stalling when the hole is blocked suggests that someone has played about with the mxiture and idle speed adjustments to get it to run without relising that the air leak is the cuase of the problem. Block it up, then set everything up correctly (Haynes details how to do this) to get the correct idle speed and idle mixture.

[pacmannewry 0]

Thanks GL - Mechanic is a sound guy tbf but just not experienced with these cars. I'll advise him of what you guys have suggested and we'll see if we can make the correct adjustments to get it to run smoothly.

 

Cheers to you both.