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Idle question

 
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adamcookie
Alfa Arna


Joined: 16 May 2014
Posts: 12
Location: Bristol, Somerset

PostPosted: Mon Mar 02, 2015 2:06 pm    Post subject: Idle question Reply with quote

Hello all,

So I recently replaced my TB vacuum lines and cleaned the Idle valve.

The idle valve is now working as it should... I think? Its my understanding that when unplugged RPM will increase with a correctly functioning unit?

Before, a cold start would result in an idle of about 1300RPM that slowly dropped to 900RPM over a minute or so. This was great as the engine would warm up quickly and the alternator would kick in. This started happening after I calibrated the throttles a couple if months ago.

Now the car starts from cold and sits at a steady 900, and must be blipped for the alternator to begin working.

The 2000rpm hesitation when cold has also come back.

I'm now confused.

Was it better before or after?

What should be happening on a cold start?

Do I have a dodgy lambda?


Questions questions questions


Thanks
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john 33_16v
16 Valve


Joined: 27 May 2005
Posts: 1406
Location: herts, uk

PostPosted: Tue Mar 03, 2015 8:32 am    Post subject: Reply with quote

"a cold start would result in an idle of about 1300RPM that slowly dropped to 900RPM over a minute or so" - This sounds about right, maybe a bit less than 1300rpm but it should settle after about a minute. I've found it's best to leave the throttle alone until the car settles on it's own- it will run sweeter.

Try disconnecting the battery for a couple of minutes to reset the ecu and see if it changes anything even if only temporarily.

I changed the idle valve on mine when it would occasionally just cut out at idle- literally just like turning the ignition off with the key.

You could try unplugging the throttle switch too to see if any change.

If the lambda is U/S the car will run like sh*te and run very rich.

Hope that helps.
John
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If it aint broke, fiddle with it until it is!
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08 Fiat Grande Punto Exotica Red
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adamcookie
Alfa Arna


Joined: 16 May 2014
Posts: 12
Location: Bristol, Somerset

PostPosted: Wed Mar 11, 2015 4:54 pm    Post subject: Reply with quote

Thanks John.

Tried resetting with no change and all the sensors seem to be working fine.

Still no fast idle.


Ah well! Who needs it...


Cars due a good professional tune up after belts this weekend so maybe it will sort itself after that.
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john 33_16v
16 Valve


Joined: 27 May 2005
Posts: 1406
Location: herts, uk

PostPosted: Wed Mar 11, 2015 6:27 pm    Post subject: Reply with quote

Hi,

I actually ran mine the other day on a pretty cold morning and on start up it idled at about 1450rpm, dropping to about 1200 and then about 900 and then ran sweet.

I think the ecu governs the idle depending on temp from the coolant temp sensor (not the gauge one) and intake air into the airflow meter.

If your car runs ok i wouldn't worry too much. The best tune-ups are 'italian' tune ups which only cost in terms of fuel consumption...


John
_________________
If it aint broke, fiddle with it until it is!
- - - - - - - - - - - - - -
93 33 16v Mirtle Met
08 Fiat Grande Punto Exotica Red
90 Yamaha FZR600 Genesis- Silky white/red/blue
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