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Discussion Starter · #1 ·
Hi Guys
Keep noticing every now and then that the idle on the GTA goes all weird on me, then it sorts itself out?

I drove home after work yesterday pulled up outside the house and started to reverse, i noticed that the car was idling very low and kept wanting to cut out the alternator light flashed on and then the revs built up and then cut etc etc
Then noticed that if you rev the car and hold it at a set number of revs it sounds like it is missing as you get a small pop through the exhaust, quite noticeable with the scorpion box fitted
If i left for about 1min it picked itself up to correct idle round 800rpm but if you reved it and let the throttle go it would try and idle again really low

I think when i looked the car was trying to idle at say 200rpm hmmm not good

Can anyone think to what it may be?

I did plug in my little OBD 2 reader to check for missfires or coilpack fault but no faults came up???????

dont want to be sitting at the lights and it cuts out on me
 
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Sounds like you have a misfire. What's causing it is another question.

Check the wiring to the coil packs, try disconnecting the MAF to see if that makes a difference and make sure the timing belt is ok, not rubbing against the outer covers.
 

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Discussion Starter · #3 ·
Timing belt is ok
If it were the MAF would i not notice a drop in power or power mpg? I haven't noticed this
I will give it a check though thanks :)
 

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Had this on my 156 2.5 v6.. dirty throttle body.... was constantly searching for idle, dipping low and stalling
 

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Discussion Starter · #7 ·
checked the rubber induction hose as that is exactly what i thought it was but it is ok, thanks John

I will try giving the TB a good clean, that was also another thought but i wanted to avoid as many people have said they are very fragile?
 

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checked the rubber induction hose as that is exactly what i thought it was but it is ok, thanks John

I will try giving the TB a good clean, that was also another thought but i wanted to avoid as many people have said they are very fragile?
Cleaned mine a couple of times in the past. As long as you're carefull opening the butterfly valve due to the nylon gears, there's no problem....

Don't have the problem myself anymore, as i've removed the connections of the crankcase ventilation. Just connected to the outside air now, via a filter. Keeps my throttlebody nice and clean, also better for power (no more hot oilfumes sucked into the cylinders) :cool:
 

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Discussion Starter · #9 ·
thanks for the advice jwq

interesting strut brace you got there? where did you get it from?
Looks to me like it doesn't get in the way of brake fluid reservoir or powersteering?
 

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Discussion Starter · #11 ·
Latest update, i have not had time to clean the throttlebody. Had to use the car to get to work, on way home the car would not idle it just cut out. Had engine management light come on. Plugged in obd reader an have error on mass air flow circuit. I reckon it still needs a clean on throttle body just more major now :(
 

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Discussion Starter · #13 ·
update on this, the induction hose had huge hole underneath dont know if this has happened since but the car has not been driven since Nov :(
anyway i have ordered a silicon induction hose from Autolusso in black :)
 

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Cleaned mine a couple of times in the past. As long as you're carefull opening the butterfly valve due to the nylon gears, there's no problem....

Don't have the problem myself anymore, as i've removed the connections of the crankcase ventilation. Just connected to the outside air now, via a filter. Keeps my throttlebody nice and clean, also better for power (no more hot oilfumes sucked into the cylinders) :cool:

How do you do this ? and where do you get the filter ?
 

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How do you do this ? and where do you get the filter ?
Just interconnected the crankcase breathers with sillicone hoses and a y-piece, closed off the vacuum connections, and added a pipercross filter to the end of the combined sillicone hose. See earlier picture (cleaned it up a bit since then, but don't have a current picture:


pipercross breather filter (with stainless steel mesh):
Accessories | Pipercross Air Filters
 

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Discussion Starter · #16 ·
I have fitted but the car still won't idle, therefore a good induction system clean is needed I reckon. Not worried as I needed induction hose anyway as the original was shot
 

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So why do engines have a connection from the head to the inlet tract? Is the intention to use the oil vapour to lubricate things on that route? Seems a bit odd - but perhaps engines like a small amount of oil mist down the valves / valve guides (can the vapour reach the guides down this route??), around the butterfly or somewhere.

Answers on a postcard.....
 

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So why do engines have a connection from the head to the inlet tract? Is the intention to use the oil vapour to lubricate things on that route? Seems a bit odd - but perhaps engines like a small amount of oil mist down the valves / valve guides (can the vapour reach the guides down this route??), around the butterfly or somewhere.

Answers on a postcard.....
It is purely for emissions, Euro legislation requires crancase ventilation to be closed otherwise when doing emisions certification the blowby needs to be measured as well which is slightly complicated and can make a clean engine seem dirty etc.
All competition engines and all heavy duty diesels run open crankcase ventilation.
Also with PCV systems such as the one on the alfa V6 you lose power due to pumping losses. I wouldn't be surprised if with open CV you get a benefit of 2-3hp at maximum rpm.
 

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Latest update, i have not had time to clean the throttlebody. Had to use the car to get to work, on way home the car would not idle it just cut out. Had engine management light come on. Plugged in obd reader an have error on mass air flow circuit. I reckon it still needs a clean on throttle body just more major now :(
I reckon mine has this too bcoz i eliminated everything else already. Induction hose: Is that the one that runs from the throttle body to the afm? Might get a silicon one too
 

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Discussion Starter · #20 ·
Yep it is. It is a good quality part :)
 
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