|Topic Review (Newest First)|
|11-10-2018 08:43 AM|
BTW - if someone needs the Idle Valve grommet, found some here:
|11-10-2018 07:03 AM|
Birra Moretti's on me.
|11-10-2018 06:04 AM|
|11-10-2018 05:24 AM|
and adjust the TPS.
Basically, the throttle stop was set too low. As the ambient temps dropped there wasn't sufficient air to hold the idle with the ICV connected when the car was cold - ok when warm.
Looks like the ICV lets more air in when disconnected.
The key thing was understanding that the ICV affects the idle even if it's disconnected.
Re: leaks - might have some small ones - will have to check with the air pressure method,
but considering I can pull the OVS hose off and it doesn't stall, I'd say it was def. not a leak.
|11-10-2018 04:05 AM|
after all that it was really a vacuum leak? .....Gubi suggested that way back in post #2
where exactly was it and how did you find it?
|11-10-2018 03:59 AM|
Originally Posted by Gubi View Post
Pulled the switch out and there's one cable but it's not connected to anything - maybe it disconnected when I pulled it out but there was no resistance.
The only other loose cable I found in there is a different gauge.
Connecting the 2 does nothing.
Do you know if the chime sound comes out of the same thing as the lights buzzer?
The lights buzzer does work consistently, but the chime thing was intermittent.
|11-10-2018 03:29 AM|
Yep, that was it. Thanks guys.
RPM"s dropping fast to about 1200 RPM and then very slowly to idle speed would be a vacuum leak?
|11-09-2018 02:22 PM|
Yeah, that's the thing I didn't realize - the ICV was affecting the idle disconnected,
and may actually let more air through than when connected.
That would explain the stalling. Fingers crossed.
|11-09-2018 02:17 PM|
Was looking at: https://www.alfabb.com/bb/forums/eng...-position.html
This "If when you get it back together you find that the revs hang when you lift off the throttle, that's a likely sign that you need to open the butterfly a bit more."
That happens here so that might indeed be the issue.
The thread contains several procedures for adjusting the throttle stop - I'll go with Clayton105's.
Key part is blocking the ICV and then setting the throttle stop and TPS.
|11-09-2018 02:08 PM|
this was a means of setting the throttle stop on a TS if you didn't have the factory gizmo.
I believe it would be the same on the S4, as they are not dissimilar and both are motronic.
the idea of blocking the ICV (not just disconecting the plug) sounds useful...
the guy also had a problem with the TPS.
they are not rocket science inside, a microswitch and some points:
|11-09-2018 01:52 PM|
In both cases, though, the throttle plate (and idle air bypass in the case of L-jet) need to be set right or there still won't be enough air to cold idle.
|11-09-2018 01:43 PM|
Originally Posted by Gubi View Post
I tried this before but I didn't change the TPS because the idle was quite high so I thought it's pointless.
However, it sounds like the ICV might actually be less open when connected than when disconnected - that's what I didn't account for.
I'll try increasing it by about 100-200 RPM and then adjusting the TPS so it knows it's at idle,
and if the ICV is less open that might actually drop the high idle.
But what I don't understand is - why is it Ok with the current settings when warm and not ok when cold.
Is the O2 sensor active immediately or only after it warms up?
|11-09-2018 01:19 PM|
I'm probably not explaining it well, but if you look at an unpowered ICV you'll see the opening where the air flows. The rotation of the valve is in the direction of making that opening smaller, not larger.
The throttle plate isn't supposed to be completely closed. There's a calibration to set the correct air flow at idle, but it requires Alfa flow tools that you don't have. Since it's been messed with anyway, maybe try *opening* it a bit more using the adjustment screw? It sounds like you're not getting enough air at idle, and if the throttle plate is too closed that might be part of the problem.
I would try progressively opening the throttle adjustment until it'll idle cold with the ICV connected, see if that makes a difference. Note that you'll likely need to adjust the TPS in parallel so that the idle switch is still closed at idle.
|11-09-2018 01:08 PM|
As I recall the butterfly looked 'closed'.
This was messed with, however, I doubt that's the issue because I backed it off completely
and there's no change. I set it to touch + a tiny bit.
Plus, if I keep it running for a few minutes until it warms up,
it will idle with the ICV connected. It hunts a bit, but it won't stall.
It only stalls with the ICV connected when it's cold.
If that was the problem it would persist when it was warm, no?
To back up to the beginning:
When I first got it in summer, when the ambient temp was high, it idled with the ICV connected.
It was oscillating between about 900-1000, but it didn't stall.
It started stalling as it got cooler outside.
If I warm it first, either by keeping up the RPM's or disconnecting the ICV, it idles like before - some hunting but it doesn't stall.
When I first start it, it smells rich. About the time it warms up a bit and stops smelling, it will idle with the ICV connected.
So what controls the idle if the ICV is disconnected? With the ICV disconnected the idle won't drop below 1k even with the throttle stop backed up all the way.
|11-09-2018 09:56 AM|
I can imagine if the butterfly is not almost closed it would cause all sorts of idling problems.
The throttle stop is factory set and capped off, but some PO mess with them when there is a problem elsewhere, like a bad ICV or bad TPS etc.
check the throttle stop is just in contact with the throttle mechanism and not so far screwed in it is keeping the butterfly open.
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