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Discussion Starter · #1 ·
Sorry to bring up the subject of idle actuators again, but on my '99 146ti...
I took mine off after first removing the throttle body, opened it up to see if there was anything amiss that could be causing the erratic idle (900 down to 500rpm and the occasional stall), couldn't see any problems so put it all back together after giving it a clean. Also cleaned the throttle body and throttle disc. Put it all back together and it now idles at about 2200rpm!I've taken it apart another couple of times and put it back making sure that there's no force on the throttle disc causing it to open - as far as I can see.
The mechanism seems to be a small electric motor driving a worm and cog segment, the cog is linked to the throttle disc by a wheel with a hole that engages on a pin on the throttle. I think I have set this up correctly with the cog segment fully anti clockwise (looking on the opened actuator). I assume the motor is then supposed to drive the cog around by a few degrees to give fast idle - the force of the motor balancing against the throttle return spring. When I look at the position of the throttle disc after the engine has run, it seems to be slightly rotated (maybe 1mm movement max at the disc edge)as if the acuator has put some preload on it that hasn't released.
Has anyone experienced this before or know what could be the cause. It's not undriveable, but a bit embarrassing revving the engine at every roundabout and junction.
 

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check if the little drum closes completely, if it does not fully close the ECU tries to open and close it time after time and making the idling erratic (up and down), the drum must run completely smooth.
Your problem may also be related to the lambda sensor, check that also.
keep us posted....
best of luck
 

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Discussion Starter · #3 ·
It's not hunting up and down anymore, just a constant 2000+rpm after I blip the throttle. If I drag the revs down to say 1000 with the car in gear and then put it into neutral without touching the throttle pedal, the revs stabilise at about 1500. after the GP I'm going to check there's nothing binding on the throttle return spring and try to set it up once again!
 

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could be the airflow sensor
 
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Rarebear

I have still got problems with the idle on my 146ti.
I have changed the actuator but still the problem remains. I have been reading this thread and have the same symptoms as Johne. I would like to know if there is a way of testing the air flow meter,is it a case of measuring resistance or voltage at different speeds??

Regards

Neil
 

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johne,

Believe it or not, I did exactly the same thing to my 145QV ('99) at the weekend. I found that the throttle butterfly was not moving freely because the inside of the throttle body was all black and sticky. Once I cleaned all this off it seemed OK. However I started the car and guess what....it was running at 2000-2500rpm and hunting around.

After taking it apart and putting it back together again twice to check, I rang my local independant Alfa specialist this morning. It turns out that if you disconnect the idle actuator, even with the battery disconnected, you run the risk of the engine management loosing it's settings eek!
Apparently this is a known issue with the Bosch engine management system (don't you luv 'em :mad: ).

Anyway I limped mine the 15 miles to the garage this morning, looking embarrassed every time I stopped at roundabouts or lights! They re-set the ECU brain paramaters this afternoon (the engine has to be stone cold apparently) and she now runs like a dream. All the stuttering at idle has gone, as has the hestitancy when backing off and back on the throttle. She now runs the best she has in my 16 months of ownership. The re-set takes about half an hour.

I think you will need to get the same done on yours.......
 

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I thought you could reset the ECU by disconnecting the positive battery lead and leaving it off for a while ..
 

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Adam,

Tried that!

Aparently this is a full re-set and requires the diagnostics to be hooked up. All the ECU paprameters are re-set (as I understand it). This is more than is done by simply disconnecting the battery for while. Judging by the drive home it has made a major difference. The guys at Palmer & Philips said it can cure a lot of problems if done properly!
 

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Ok - I'll think twice before I pull the IA out then!!
 

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Unlucky! I wouldnt have thought it would have that much effect, so I would have done the same!!
 

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Discussion Starter · #13 ·
Thanks for all those contributions, the missus isn't going to be using her car for the next couple of days so I think that'll be the ideal opportunity to give the 36hr disconnection a go.
Just to clear up a couple of points before I boldly go....
Does the engine need to be cold before I disconnect?
When I reconnect is there a procedure such as turn ignition to MAR, wait 10 seconds, start engine, leave on idle until warm?
Will disconnecting the battery affect anything else, the stereo (ok), or the alarm for example?
 

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I have never tried it, and somebody else may be able to clarify, but it may affect the alarm/immobiliser.

Other than that, just take the ground side from the battery and make sure it is insulated.

Whaen you put it back on, it will spark a little, but there should be no side-effects.
It may not start first time because of the idle level being lost, but should start on second attempt. :)

The best thing to do then is take it for a good hard drive (let the oil warm first!) to set the limits of the ECU again.
 

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Discussion Starter · #15 ·
aj... and others thinking about taking their idle actuator off,
At the risk of telling you something very obvious, that you probably know already - but I didn't a week ago....
The 146ti idle actuator is an electric motor geared to act on the throttle valve and is completely sealed unless you choose to open it up. Other systems on other cars use a bypass to the throttle valve with the idle actuator in this bypass line, i.e. the IA has its own valve. As far as I can tell there is no way the 146ti IA should get dirty internally and should not need to be removed unless it is actually broken. I now assume that the advice to remove and clean the IA which I have seen on many websites is for the bypass valve type IA.
If the 146ti IA is sticking/erratic it is probably, as ChrisM said, the main throttle valve that is dirty/sticking.
 

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No, I don't think it's actually gum Bob...
:rolleyes:
I think its residue that comes out of the petrol or something....
:D
 

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<blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:<hr /><font size="1" face="Verdana, Helvetica, sans-serif">Originally posted by johne:
<strong>aj... and others thinking about taking their idle actuator off,
At the risk of telling you something very obvious, that you probably know already - but I didn't a week ago....
The 146ti idle actuator is an electric motor geared to act on the throttle valve and is completely sealed unless you choose to open it up. Other systems on other cars use a bypass to the throttle valve with the idle actuator in this bypass line, i.e. the IA has its own valve. As far as I can tell there is no way the 146ti IA should get dirty internally and should not need to be removed unless it is actually broken. I now assume that the advice to remove and clean the IA which I have seen on many websites is for the bypass valve type IA.
If the 146ti IA is sticking/erratic it is probably, as ChrisM said, the main throttle valve that is dirty/sticking.</strong><hr /></blockquote><font size="1" face="Verdana, Helvetica, sans-serif">Ok, that is interesting I will try and remember, for when I take it off when I get bored....cheers
 

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I had erratic idling last week (1.8 TS) and took the IA off and cleaned it as per other threads. It had carbon build up inside, I did the best i could to clean it without dismantling it (wouldn't dare!), seemed to cure the problem, but who knows if it was an intermittant fault due to something else. The cure could be coincidence.

Is the 146 ti IA different from the 1.8TS in a 145?
 
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