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Omega Help Area => Omega General Help => Topic started by: Chopsdad on 27 December 2006, 20:30:54

Title: Cruise & dodgy idle speed
Post by: Chopsdad on 27 December 2006, 20:30:54
OK my idle speed is still erratic but it now has a twist.  If I slow down in gear to less than 1000 rpm as soon as I slip it into neutral ( it's a manual) the revs bounce back up to 1100/1200 rpm and won't drop until the speedo hits 0. When speedo hits 0 it drops to 7/800 rpm but if I slip it into neutral with the wheels turning it won't drop below 1200 rpm.  It operates smoothly in every gear and does not seem to stick at all.

I've cleaned the breathers, replaced the throttle body gasket after cleaning it and lubing with 3in1 oil.  I've even renewed the little semi clear pipe just in case but it's no different.  I borrowed a working MAF from a 2.2 recently and it made no difference. All the hoses are in good order and I cannot find any splits or leaks. Emissions light is still on.

Q. As the throttle seems to be linked to the speedo could it be some kind of feedback from my cruise upgrade?  
Title: Re: Cruise & dodgy idle speed
Post by: Omegatoy on 27 December 2006, 21:06:38
Hmm dont take this as gospel as i know it from gsi carlton 24v!!! however they do the same thing as the idle control valve is controlled by the ecu and gets a feed from the speed sensor, follow that ? now if you slip the car into neutral at any speed above 5mph the ecu tells the icv to hold the revs at approx 1200 to make sure you still have pas and brakes available, when the car finally slows below 5mph the tickover will reduce tonormal, am guessing that the Omega has an even bigger safety margin and wont let the revs drop till it gets a msge from the speed sensor that says zero>>>> make sense to ya?
course i could be totally wrong but thats my take on it mate
Omegatoy
Title: Re: Cruise & dodgy idle speed
Post by: tunnie on 27 December 2006, 22:09:01
Quote
Hmm dont take this as gospel as i know it from gsi carlton 24v!!! however they do the same thing as the idle control valve is controlled by the ecu and gets a feed from the speed sensor, follow that ? now if you slip the car into neutral at any speed above 5mph the ecu tells the icv to hold the revs at approx 1200 to make sure you still have pas and brakes available, when the car finally slows below 5mph the tickover will reduce tonormal, am guessing that the Omega has an even bigger safety margin and wont let the revs drop till it gets a msge from the speed sensor that says zero>>>> make sense to ya?
course i could be totally wrong but thats my take on it mate
Omegatoy

I'll have to try that in mine, never put it in neutral while going along, i picked up a habbit my dad did, going though the gears as you approach a roundabout.

I'll give mine a go...

Chopsdad, you checked the breather pipe (thin one) and throttle body? Could be clogged or partial blockage?? Cleaning that very thin pipe made mine run smoother.
Title: Re: Cruise & dodgy idle speed
Post by: Chopsdad on 27 December 2006, 22:56:58
Quote
Quote
Hmm dont take this as gospel as i know it from gsi carlton 24v!!! however they do the same thing as the idle control valve is controlled by the ecu and gets a feed from the speed sensor, follow that ? now if you slip the car into neutral at any speed above 5mph the ecu tells the icv to hold the revs at approx 1200 to make sure you still have pas and brakes available, when the car finally slows below 5mph the tickover will reduce tonormal, am guessing that the Omega has an even bigger safety margin and wont let the revs drop till it gets a msge from the speed sensor that says zero>>>> make sense to ya?
course i could be totally wrong but thats my take on it mate
Omegatoy

I'll have to try that in mine, never put it in neutral while going along, i picked up a habbit my dad did, going though the gears as you approach a roundabout.

I'll give mine a go...

Chopsdad, you checked the breather pipe (thin one) and throttle body? Could be clogged or partial blockage?? Cleaning that very thin pipe made mine run smoother.

I did better than that Tunnie - I bought and fitted a new one today as I thought this may be the source of the air leak.  PS I have to knock it into neutral round town or it keeps the revs at 1200 and feeds in enough fuel to match - hence pushing the car along when I want it to stop (and brakes are much cheaper than gearboxes.)


Thanks Omegatoy - it drops sharply and holds at 1200 so you could well be right.  Maybe my ECU or Speed sensor is picking up the wrong lower end speed - ie 0?
Title: Re: Cruise & dodgy idle speed
Post by: TheBoy on 28 December 2006, 10:56:35
Quote
OK my idle speed is still erratic but it now has a twist.  If I slow down in gear to less than 1000 rpm as soon as I slip it into neutral ( it's a manual) the revs bounce back up to 1100/1200 rpm and won't drop until the speedo hits 0. When speedo hits 0 it drops to 7/800 rpm but if I slip it into neutral with the wheels turning it won't drop below 1200 rpm.  It operates smoothly in every gear and does not seem to stick at all.

I've cleaned the breathers, replaced the throttle body gasket after cleaning it and lubing with 3in1 oil.  I've even renewed the little semi clear pipe just in case but it's no different.  I borrowed a working MAF from a 2.2 recently and it made no difference. All the hoses are in good order and I cannot find any splits or leaks. Emissions light is still on.

Q. As the throttle seems to be linked to the speedo could it be some kind of feedback from my cruise upgrade?  
Did they update the ECU software at same time? Just wondering if its a new trait of newer software?
Title: Re: Cruise & dodgy idle speed
Post by: Chopsdad on 28 December 2006, 11:38:09
I'm not sure TB - it was all done with a nod and a wink.  Plus it never worked as there was no clutch switch.  I'll ask the Techie but I think he just enabled the cruise function but it's a new place to look.  Thanks
Title: Re: Cruise & dodgy idle speed
Post by: Marks DTM Calib on 28 December 2006, 18:16:20
When you removed the throttle body did it get a realy good clean including the edges of the throttle disc and sides of the throttle wall?

Were all the vac pieps re-connected including breathers tank purge valve and brake solenoid.....I assume all these are in good nic with no holes etc.

Is the climate/heating etc working all a ok.
Title: Re: Cruise & dodgy idle speed
Post by: Chopsdad on 28 December 2006, 22:21:29
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When you removed the throttle body did it get a realy good clean including the edges of the throttle disc and sides of the throttle wall?

Were all the vac pieps re-connected including breathers tank purge valve and brake solenoid.....I assume all these are in good nic with no holes etc.

Is the climate/heating etc working all a ok.

Throttle body was black underneath but now cleaned with Carb Cleaner to as new condition (http://i123.photobucket.com/albums/o317/chopsdad/IMG_1084.jpg). Breathers were ok with the exception of the metal pipe from the sump (http://i123.photobucket.com/albums/o317/chopsdad/IMG_1081-1.jpg) all vac pipes reconnected and the small one renewed.  Climate operates normally with no concern. Throttle disc does not close completely - it sits slightly open when at rest.  Fuel consumption way down on normal. 30 mpg at 75 mph on 40 mile M6 trip.  Oil changed today (6m old) & very dark.
Title: Re: Cruise & dodgy idle speed
Post by: tunnie on 28 December 2006, 22:25:52
Errmm thats the main back breather pipe?? Correct me if i am wrong but it should not have that brown kak in there!  :o
Title: Re: Cruise & dodgy idle speed
Post by: Chopsdad on 28 December 2006, 22:29:19
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Errmm thats the main back breather pipe?? Correct me if i am wrong but it should not have that brown kak in there!  :o

It hasn't anymore - lots of short trips since moving house  :-/ & never been cleaned in 3 years / 40k..
Title: Re: Cruise & dodgy idle speed
Post by: Chopsdad on 30 December 2006, 11:14:21
I've been to Vx today and the Techie is off till next week. So I'll have to wait to find out what he did - if anything  :(
Title: Re: Cruise & dodgy idle speed
Post by: Auto Addict on 30 December 2006, 16:22:14
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Errmm thats the main back breather pipe?? Correct me if i am wrong but it should not have that brown kak in there!  :o

It hasn't anymore - lots of short trips since moving house  :-/ & never been cleaned in 3 years / 40k..

But it could be clogged up inside the cam cover....
Title: Re: Cruise & dodgy idle speed
Post by: Chopsdad on 30 December 2006, 20:52:25
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Errmm thats the main back breather pipe?? Correct me if i am wrong but it should not have that brown kak in there!  :o

It hasn't anymore - lots of short trips since moving house  :-/ & never been cleaned in 3 years / 40k..

But it could be clogged up inside the cam cover....
[/quote]

The inside of the filler cap is spotless and no trace of water in the oil I changed this week so I hope not.


Title: Re: Cruise & dodgy idle speed
Post by: Auto Addict on 30 December 2006, 21:41:55
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Quote
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Errmm thats the main back breather pipe?? Correct me if i am wrong but it should not have that brown kak in there!  :o

It hasn't anymore - lots of short trips since moving house  :-/ & never been cleaned in 3 years / 40k..

But it could be clogged up inside the cam cover....

The inside of the filler cap is spotless and no trace of water in the oil I changed this week so I hope not.


[/quote]

(http://i71.photobucket.com/albums/i143/Auto_Addict/1_Cam_Cover_Breather.jpg)

I meant the metal tube (cam cover end) that the rubber hose slides onto, did you make sure that was clear?
Title: Re: Cruise & dodgy idle speed
Post by: Chopsdad on 30 December 2006, 21:53:29
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Quote
Quote
Quote
Errmm thats the main back breather pipe?? Correct me if i am wrong but it should not have that brown kak in there!  :o

It hasn't anymore - lots of short trips since moving house  :-/ & never been cleaned in 3 years / 40k..

But it could be clogged up inside the cam cover....

The inside of the filler cap is spotless and no trace of water in the oil I changed this week so I hope not.



(http://i71.photobucket.com/albums/i143/Auto_Addict/1_Cam_Cover_Breather.jpg)

I meant the metal tube (cam cover end) that the rubber hose slides onto, did you make sure that was clear?
[/quote]

Are you having a giraffe AA?  :o  The pic posted in the thread is the top of the metal pipe with the rubber hose removed before I took it off and cleaned it up - as per the helpful guide you made me  :y
Title: Re: Cruise & dodgy idle speed
Post by: Chopsdad on 30 December 2006, 22:01:36
And I've just had the top of the hose off where it joins the cam cover and poked around inside with my finger - all clear except for a trace of nice fresh oil.  No gunk.  :)

Title: Re: Cruise & dodgy idle speed
Post by: Auto Addict on 31 December 2006, 07:45:59
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And I've just had the top of the hose off where it joins the cam cover and poked around inside with my finger - all clear except for a trace of nice fresh oil.  No gunk.  :)



 :y
Title: Re: Cruise & dodgy idle speed
Post by: hotel21 on 01 January 2007, 15:40:45
No real offer of a cure from me, other than to say I have a similar situation with my 3 ltr manual.

With the original (freshly cleaned) Idle Valve installed, car starts from cold OK, sits circa 1200 revs for a few minutes (think this is normal) then settles to 500/600 revs idle when warm.  Sometimes revs settle at 2000 for no reason, can be stationary/neutral or when the car is being driven.  Depressing the clutch sees the revs rise.  Similar effect to cruise control jamming on.

Fitted alternative (freshly cleaned) ICV from scrappies.  No 'cold start' rise in reves, idle is 1000, no hunting or increase in revs any other time.

Swapping the ICV's around simply swaps the faults/characteristics.  When the revs are being held high if I remove the electrical connector at the rear of the ICV then the revs fall and get a warning light on the dash.  Reconnect, revs stay low/where they should be for a while, but then can rise.  warning light goes out again.

 ::)
Title: Re: Cruise & dodgy idle speed
Post by: rpont on 01 January 2007, 17:06:01
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When the revs are being held high if I remove the electrical connector at the rear of the ICV then the revs fall and get a warning light on the dash.  Reconnect, revs stay low/where they should be for a while, but then can rise.  warning light goes out again.
Engine should stop then due to lack of air as ICV closes by the spring. Are your throttle bodies clean and butterflies closing properly?

I hope that's right because the butterflies on mine are closed and the engine stops if I unplug the ICV.
Title: Re: Cruise & dodgy idle speed
Post by: Chopsdad on 01 January 2007, 23:19:27
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When the revs are being held high if I remove the electrical connector at the rear of the ICV then the revs fall and get a warning light on the dash.  Reconnect, revs stay low/where they should be for a while, but then can rise.  warning light goes out again.
Engine should stop then due to lack of air as ICV closes by the spring. Are your throttle bodies clean and butterflies closing properly?

I hope that's right because the butterflies on mine are closed and the engine stops if I unplug the ICV.

I don't have an ICV as its DBW but throttle housing & breathers are now spotless.  Butterfly does not close properly - see clip http://s123.photobucket.com/albums/o317/chopsdad/?action=view&current=MVI_1237.flv
Title: Re: Cruise & dodgy idle speed
Post by: Chopsdad on 01 January 2007, 23:21:00
Sorry guys I seem to have pissed about a bit here - please post any helpful replies to this thread http://www.omegaowners.com/forum/YaBB.pl?num=1167604887  Cheers  :y