156 V6 idle speed out of control!!!! - Alfa Romeo Forum
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(Post Link) post #1 of 10 Old 25-11-07 Thread Starter
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156 V6 idle speed out of control!!!!

Hi, I've got a 2000 156 V6 with a mere 40,000 miles on the clock which has always happily ticked over at about 600rpm. Last night the revs went out of control and it took itself almost to the red line! Now, today its ticking over at about 2000rpm and it just doesn't want to drop.

Any ideas?
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Re: 156 V6 idle speed out of control!!!!

Hi, i had trouble with the idle on my 156 and it turned out to be the air flow meter.
However it wasnt as bad as yours seems to be.
Does it drive ok otherwise?
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Re: 156 V6 idle speed out of control!!!!

Yeah, its absolutely fine other than the idle speed. I've just cleaned the butterfly valve in the air intake.

It seems to be sticking at the 2000rpm mark; if you start it and don't give it any gas it just idles at its normal speed. If you blip the throttle it will fall back normally then stop at 2000rpm(ish), but if you put your foot under the peddle and slightly lift it, it will go back to normal idle speed.
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Re: 156 V6 idle speed out of control!!!!

Disconnect the MAF, start it up and tell us what happens!

It's an electrical connector on the air intake pipe towards the front right of the engine bay, above the air filter housing, just unplug it.
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Re: 156 V6 idle speed out of control!!!!

Ok! Wont be able to do it till tomorrow, as it is now dark. Could it be the answer? Will I be able to reconnect it once I've started it? Or does this just aid with the diagnosis?
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Re: 156 V6 idle speed out of control!!!!

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Originally Posted by mucca View Post
Yeah, its absolutely fine other than the idle speed. I've just cleaned the butterfly valve in the air intake.

.

This can break it, you cant touch electronic butterflies.

Was this before or after?

Disconnect the battery for 20 minutes or so, then reconnect, start it up and DONT TOUCH the throttle for 10 minutes while it re-learns (assuming its not broken) the idle opening. Then take it for a fast run.

Failing that you need a new throttle body.

If the MAF is faulty, it will run better with it unplugged.
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Re: 156 V6 idle speed out of control!!!!

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Originally Posted by cj romeo View Post
This can break it, you cant touch electronic butterflies.

Was this before or after?
Really? This tip came from the alfa156.net website. I'm just trying to exhaust the options which wont cost me any money! Anyway, I ran the car after I had cleaned the butterfly and it hadn't made a difference to the problem.
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Re: 156 V6 idle speed out of control!!!!

All sorted! It was an iffy electrical (funny that!) connector which was creating a greater resistance, so the computer thought I had my foot on the throttle. The local Alfa specialist sorted it for £52.
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Re: 156 V6 idle speed out of control!!!!

Good stuff - but dont touch that throttle butterfly again - you have got away with it this time!
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Re: 156 V6 idle speed out of control!!!!

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Originally Posted by cj romeo View Post
Good stuff - but dont touch that throttle butterfly again - you have got away with it this time!
I can understand the caution, and it's probably good advice in the main for newbs, however I have cleaned mine every 10-20K miles for the last 5 years by *gently* holding it open with a gloved finger whilst using carb cleaner and a good cloth to clean it. One quick throttle reset, an hours mixed driving and she purrs.

Maybe I`m just lucky but I hit 224K miles today on the original throttle
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