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Author Topic: 2.5 v6 running rough  (Read 2405 times)

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craig

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2.5 v6 running rough
« on: 08 September 2008, 09:54:07 »

as above my car feels like one of the plug leads have gone when driving it holds back then it'll clear,then rough etc....and as for the fuel :-Xits knecking it >:(but opened the bonnet and there is quite a loud hissing,airy noise coming from what sounds like the back of the engine ::)so could it possibly be an air leak???,spark plug???any ideas please??if so could you point me to the how too's if availiable :y

thanks in advance :)
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craig

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Re: 2.5 v6 running rough
« Reply #1 on: 08 September 2008, 09:56:15 »

just had a price for leads and plugs £98+vat for the leads and £3.84+vat for plugs ::) :-/ does this price sound right?? ::)
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craig

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Entwood

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Re: 2.5 v6 running rough
« Reply #3 on: 08 September 2008, 10:10:48 »

Have you checked for fault codes using the paperclip method ??

http://www.omegaowners.com/forum/YaBB.pl?num=1189022687

Always the best place to start .. :)

A vaccuum leak will give problems ... use some carb cleaner, sprayed LIGHTLY around the engine whilst ticking over, if the engine note suddenly changes as you spray near the component .. you've found the leak ...   :)

Changing things on spec is usually both pointless and expensive ! find the problem first .. then fix it  :)
« Last Edit: 08 September 2008, 10:13:47 by entwood »
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craig

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Re: 2.5 v6 running rough
« Reply #4 on: 08 September 2008, 10:16:22 »

Quote
Have you checked for fault codes using the paperclip method ??

http://www.omegaowners.com/forum/YaBB.pl?num=1189022687

Always the best place to start .. :)

A vaccuum leak will give problems ... use some carb cleaner, sprayed LIGHTLY around the engine whilst ticking over, if the engine note suddenly changes as you spray near the component .. you've found the leak ...   :)

Changing things on spec is usually both pointless and expensive ! find the problem first .. then fix it  :)




but there is no warning lights lit ::)or no emlight!!no checks nothing :-/
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cem_devecioglu

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Re: 2.5 v6 running rough
« Reply #5 on: 08 September 2008, 10:17:16 »

Air leaks on miggies are common..Even the gaskets seem to be not

damaged dont trust them..New is new.

Some points are:

down the plenum 6 big o-rings..

Idle Air Control valve gasket (cleaning from time to time sooner or later makes the gasket leak)

O-rings Under the black ecotec bit..

Connection gasket from EGR (if you have) pipe to plenum..

and the connection surface behind the throttle part (necessary a big gasket to be cut-the mechanic friends oppose me but it helped)

and as an experience in old engines valve stem seals are also necessary to change..

and finally some critical sensors like lambda loose efficiency in time..

ps: when you have time to clean the injectors (by any method) -they also have small gaskets- change them..

pps: mostly this hissing noise come from the black ecotec bit channels..they become dirty in time..
« Last Edit: 08 September 2008, 10:19:05 by cem_devecioglu »
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Entwood

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Re: 2.5 v6 running rough
« Reply #6 on: 08 September 2008, 10:18:06 »

Does the EML light come on for a few seconds when you turn the ignition on without starting the engine ???
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craig

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Re: 2.5 v6 running rough
« Reply #7 on: 08 September 2008, 10:19:50 »

Quote
Does the EML light come on for a few seconds when you turn the ignition on without starting the engine ???


yes and oil etc.... then goes of as it should ::)
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Entwood

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Re: 2.5 v6 running rough
« Reply #8 on: 08 September 2008, 10:22:25 »

Thats good, in which case I would try and find the cause of the airleak (hissing) and fix that before spending any cash . :)
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craig

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Re: 2.5 v6 running rough
« Reply #9 on: 08 September 2008, 10:30:39 »

Quote
Thats good, in which case I would try and find the cause of the airleak (hissing) and fix that before spending any cash . :)



i will try ::) ;D are them leads,plugs any good?? as i think i might change them anyway as i've got no idea when they were last changed,only had the car a few months and i was going to try and give the car a service with the help and advice of my fellow oofer's ::)and the how too's :y
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craig

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Re: 2.5 v6 running rough
« Reply #10 on: 08 September 2008, 10:35:41 »

Another thing is that the car still ticks over at 500rpm!!! if it was the leads,plugs,air leak wouldn't it tick over erratically???
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dbug

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Re: 2.5 v6 running rough
« Reply #11 on: 08 September 2008, 10:40:21 »

Quote
Quote
Thats good, in which case I would try and find the cause of the airleak (hissing) and fix that before spending any cash . :)



i will try ::) ;D are them leads,plugs any good?? as i think i might change them anyway as i've got no idea when they were last changed,only had the car a few months and i was going to try and give the car a service with the help and advice of my fellow oofer's ::)and the how too's :y

There are a number of members on OOF that do NOT recommend using the 4-electrode plugs on the 2.5V6 - better to stick with the twin electrode Vx ones.

Believe the Bosch plug leads will be OK.
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Darth Loo-knee

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Re: 2.5 v6 running rough
« Reply #12 on: 08 September 2008, 11:17:45 »

Quote
Another thing is that the car still ticks over at 500rpm!!! if it was the leads,plugs,air leak wouldn't it tick over erratically???

Your car is a v6 mate and they do tick over at 500rpm... until you put on the air con then it lifts to around 600rpm (this is as long as there is gas in the air con system).
Air leaks do cause poor mpg, like already said try to find it... start the car listen for the hissing then run your hand around the vac pipes located where you think the hiss is from.
I would start there before buying anything mate :y
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craig

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Re: 2.5 v6 running rough
« Reply #13 on: 08 September 2008, 11:25:50 »

Quote
Quote
Another thing is that the car still ticks over at 500rpm!!! if it was the leads,plugs,air leak wouldn't it tick over erratically???

Your car is a v6 mate and they do tick over at 500rpm... until you put on the air con then it lifts to around 600rpm (this is as long as there is gas in the air con system).
Air leaks do cause poor mpg, like already said try to find it... start the car listen for the hissing then run your hand around the vac pipes located where you think the hiss is from.
I would start there before buying anything mate :y


cheers :y will an air leak feel like a dodgy plug lead??and will it cause the problems in the first post????
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Darth Loo-knee

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Re: 2.5 v6 running rough
« Reply #14 on: 08 September 2008, 11:33:08 »

Personally I would sort your air leak mate first...you will be suprised.. if after you still think it is the same, plugs are cheapest try that, apparently leads from Halfords are ok.
When my plug leads were past there best the tick over was a little erratic not sitting at 500 rpm.
Hope this helps
« Last Edit: 08 September 2008, 11:33:59 by Loo-knee »
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