Hey guys,

 

Ok so my mechanic thinks that my bad idle is due to an airleak... When you listen to the engine there is an extreme sucking/hissing sound coming from the front passenger side down below as if it was a hose or something.. Do you know what this could be? It is right deep down behind the headlight. I can't exactly pinpoint it but he seems to think that may create a rough or unstable idle and may be the "misfire" on idle I have been noticing..

 

best, William.

most likely one of the intercooler hoses if its under the headlight.

remove the plastic cover from under that corner and check the hoses.

Thanks Dave, I'll check that out!! Is it bad to drive it if it is the intercooler hose as I am on my way to London tonight (90 miles)

Ask him to leak test the induction system. It's most likely the inter cooler loop. But there is other stuff down there.

front left/passenger side ... there are quit a few vac lines ...

 

Main one is Turbo Actuator line feed .. tucked under the Large inner boost pipe

then there is 3 smaller ones between the large boost pipes

 

2 are for the carbon canister

1 is for the Recirc valve or dump valve

Thanks a lot guys! Could any of those be associated with inconsitent idle?

Any vac leak can make the idle erratic

Hello guys!

 

OK so I unplugged the MAF and it sat at a touch over 1k perfectly without any hesitation or rough idle / misfire!

 

What would this mean?.. does this suggest the vac leak is the root cause or is it an issue with my MAF?...

 

Best, William.

you said previously that there was a vac leak (or a hissing) have you done a vac test yet?

 

I wouldn't go making assumptions until you're ruled out all the problems.

 

find the vac leak if there is one and try again...

 

if you buy a MAF now you may be spending money you didn't need to.

The mechanic is coming over next week to do some testing on the Vac system, I was just bored and wanted to rule out the coilpacks being the culprit!... Which I think that does seeing as they were firing smooth as anything without the maf meanign it is probably not an electrical issue, but instead a vac leak issue etc causing incorrect/inconsistent fuel/air mixing.

good thinking...

 

http://stadzport.com/FSM/EFEC_Engine_Fuel_Emissions_Control.pdf

 

will help diagnose the MAF page 113 & 174

Great thanks buddy!

I also ripped this from the erratic idle thread...

 

 

MAS:

Mass Airflow Sensor (pic 6) tells the ECU how much air is enteringthe engine which in turn gives the information about how much fuel needsto be supplied.

 

Check the MAS by looking through it to see if the hot-wire is damaged or clogged by dirt. You can gently clean the hot-wire by spraying it with a contact cleaner that doesn't leave a protective film. I cleaned minewith brake cleaner since it evaporates completely but it could be a littleharsh for the vulnerable hot wire..

Never remove the mash screen! It serves both as a protection and hasits effect on the airflow.

You can check the MAS voltage at the ECU (see ECUcontact diagram) with a volt meter.

It should read ~0.8V with ignition on (some people get 0.08V on theTechtom) and ~1.5V at idle, unless you've got a vacuum leak somewhere...

ah yeah think I had seen that, I will get the air leak fixed up and then if it doesn't solve it look into the Maf :)