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Author Topic: Major misfire on idle, 2.2 petrol manual  (Read 26475 times)

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terry paget

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Major misfire on idle, 2.2 petrol manual
« on: 01 April 2018, 11:08:22 »

This is the car I am preparing for MOT. I reported last week about a poor idle; did a diagnostic check, both lambda sensors were steady on 'lean', so I have changed the first lambda sensor and the MAF meter. Nothing has changed. I now suspect massive induction system air leak. I have been here before on a 2.5 after I trapped an O-ring replacing the plenum. The question for me is where is it on a 2.2. I suppose the whole breather system is supect, and the whole induction tract from air cleaner onwards.
Any tips most gratefully received.
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TheBoy

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Re: Major misfire on idle, 2.2 petrol manual
« Reply #1 on: 01 April 2018, 11:29:17 »

What is the maf reading?
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JamesV6CDX

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Re: Major misfire on idle, 2.2 petrol manual
« Reply #2 on: 01 April 2018, 11:48:19 »

Any steam from the exhaust Terry?

My 2.2 was rough only at idle and it was due to a HG fail
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Doctor Gollum

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Re: Major misfire on idle, 2.2 petrol manual
« Reply #3 on: 01 April 2018, 14:00:16 »

Check all the rubber hoses connected to the throttle body... probably a simple air leak ;)
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terry paget

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Re: Major misfire on idle, 2.2 petrol manual
« Reply #4 on: 01 April 2018, 16:07:07 »

What is the maf reading?
At 2000rpm steady running on all four22Kg/h, 1.35v;
at a hesitant idle (firing on 2?) 16Kg/h 1.00v.
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TheBoy

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Re: Major misfire on idle, 2.2 petrol manual
« Reply #5 on: 01 April 2018, 17:11:19 »

At idle, sounds high.

What is the LTFT doing?
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Doctor Gollum

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Re: Major misfire on idle, 2.2 petrol manual
« Reply #6 on: 01 April 2018, 17:16:26 »

Check all the rubber hoses connected to the throttle body... probably a simple air leak ;)
Presumably the coil pack is dry and happy...  :y
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terry paget

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Re: Major misfire on idle, 2.2 petrol manual
« Reply #7 on: 01 April 2018, 17:19:06 »

I checked all the induction hoses for cracks or leaks, but could find none. So I moved on to checking the compressions on all cylinders. There was some oil in 3 & 4 but I ignored that, and did not siphon it out before the tests. The results surprised me.
No. 1 13.5bar
No. 2 13.6 bar
No. 3 18 bar
No. 4 20bar.

Perhaps I should have siphoned the oil out from above the plugs first.
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Doctor Gollum

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Re: Major misfire on idle, 2.2 petrol manual
« Reply #8 on: 01 April 2018, 18:14:41 »

You think... ::)

Still, at least you now know why it's misfiring...

Sort the camcover, change the plugs, check the coil pack and report back :y
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Chazza12

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Re: Major misfire on idle, 2.2 petrol manual
« Reply #9 on: 01 April 2018, 18:22:43 »

check the small breather pipe from the cam cover blow down it. if blocked clean it out. i changed the pipe on mine went to mush and just blocked up. also changed the t bar on the vacuum line as the rubbers were leaking, misfire went after that.  changed all the rubber links on the vacuum lines, so they all new now. and the breather line for the air vent for the tank.
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terry paget

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Re: Major misfire on idle, 2.2 petrol manual
« Reply #10 on: 01 April 2018, 19:02:34 »

You think... ::)

Still, at least you now know why it's misfiring...

Sort the camcover, change the plugs, check the coil pack and report back :y
Thanks Doc. I was about to enquire - could the oil in plug wells 3 & 4 have caused the low speed misfiring? I was hoping you might think it worth while to replace the cam cover gaskets, coil pack and plugs and try again.
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Re: Major misfire on idle, 2.2 petrol manual
« Reply #11 on: 01 April 2018, 20:29:58 »

That is exactly what I would do :y
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terry paget

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Re: Major misfire on idle, 2.2 petrol manual
« Reply #12 on: 02 April 2018, 13:40:57 »

Any steam from the exhaust Terry?

My 2.2 was rough only at idle and it was due to a HG fail
Thanks for the suggestion, James. I suspect you are right, having changed MAF sensor and first lambda sensor I was at a loss to sort my emissions. I looked in vain for a major inlet air leak, and found none. I was in the process of checking head gasket by compression when I stumbled across oil in plug wells. It's so easy correcting the oil in plug wells first that it's worth the effort.
 I suppose I should remove my good cat section (just fitted) before I fire the engine up with new plugs and cam cover gasket, to avoid all that oil poisoning it. Bother.
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VXL V6

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Re: Major misfire on idle, 2.2 petrol manual
« Reply #13 on: 02 April 2018, 13:52:53 »

Once the cat is up to temp it'll burn off any oil etc.
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Andy A

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Re: Major misfire on idle, 2.2 petrol manual
« Reply #14 on: 02 April 2018, 15:05:55 »

Any steam from the exhaust Terry?

My 2.2 was rough only at idle and it was due to a HG fail
Thanks for the suggestion, James. I suspect you are right, having changed MAF sensor and first lambda sensor I was at a loss to sort my emissions. I looked in vain for a major inlet air leak, and found none. I was in the process of checking head gasket by compression when I stumbled across oil in plug wells. It's so easy correcting the oil in plug wells first that it's worth the effort.
 I suppose I should remove my good cat section (just fitted) before I fire the engine up with new plugs and cam cover gasket, to avoid all that oil poisoning it. Bother.

Terry, I had oil in the plug wells and it was down to blocked breather pipes from the cam cover. Cleaned throttle body and pipes and it cured the misfire and the oil leak. It must have been a build up of pressure causing the oil leak on my Desmond.
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