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Author Topic: 2.5 petrol manual estate misfiring  (Read 803 times)

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Doctor Gollum

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Re: 2.5 petrol manual estate misfiring
« Reply #30 on: 10 August 2018, 13:15:55 »

How many Omegas have you had ::)

That's the purge valve... Pipe from breather bridge and another to the plastic box in the driver's side wheel arch...

Not fitting the pipe to it will introduce a decent airleak...
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Doctor Gollum

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Re: 2.5 petrol manual estate misfiring
« Reply #31 on: 10 August 2018, 13:16:51 »

Incidentally, the plug and therefore item can be identified using the Haynes wiring diagrams  ;)
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terry paget

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Re: 2.5 petrol manual estate misfiring
« Reply #32 on: 10 August 2018, 13:56:04 »

How many Omegas have you had ::)

That's the purge valve... Pipe from breather bridge and another to the plastic box in the driver's side wheel arch...

Not fitting the pipe to it will introduce a decent airleak...
Thanks Doc. I have found one hose from the RH wing, but that had been plugged on no. 2 breather pipe. Sounds like there should be another hose from the RH wing, but I can't find one.
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Tick Tock

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Re: 2.5 petrol manual estate misfiring
« Reply #33 on: 10 August 2018, 14:53:38 »

That pipe from the wing isn't exactly in the wrong place when connected to the breather bridge, it just means the purge valve isn't included in the scheme any more. A recent investigation on my car found the purge valve to be stuck open, and am guessing it's no use in that state which is why it's the way it is on your car.

The advice I received was to just put it back on its bracket, connect the pipes up and forget about it, even though the valve is open all the time.
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Doctor Gollum

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Re: 2.5 petrol manual estate misfiring
« Reply #34 on: 10 August 2018, 15:29:23 »

How many Omegas have you had ::)

That's the purge valve... Pipe from breather bridge and another to the plastic box in the driver's side wheel arch...

Not fitting the pipe to it will introduce a decent airleak...
Thanks Doc. I have found one hose from the RH wing, but that had been plugged on no. 2 breather pipe. Sounds like there should be another hose from the RH wing, but I can't find one.
Hose from the wing connects to the purge valve.

The hose you're missing goes from the purge valve to the breather bridge.
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terry paget

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Re: 2.5 petrol manual estate misfiring
« Reply #35 on: 10 August 2018, 17:24:14 »

How many Omegas have you had ::)

That's the purge valve... Pipe from breather bridge and another to the plastic box in the driver's side wheel arch...

Not fitting the pipe to it will introduce a decent airleak...
Thanks Doc. I have found one hose from the RH wing, but that had been plugged on no. 2 breather pipe. Sounds like there should be another hose from the RH wing, but I can't find one.
Hose from the wing connects to the purge valve.

The hose you're missing goes from the purge valve to the breather bridge.
Exiting the purge valve at the bottom from a 10mm pipe and joining the plenum top breather on a 5mm pipe, challenging. Thanks Doc, now I understand. Things were simpler on my Velocette.
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terry paget

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Re: 2.5 petrol manual estate misfiring
« Reply #36 on: 10 August 2018, 19:00:47 »

That pipe from the wing isn't exactly in the wrong place when connected to the breather bridge, it just means the purge valve isn't included in the scheme any more. A recent investigation on my car found the purge valve to be stuck open, and am guessing it's no use in that state which is why it's the way it is on your car.

The advice I received was to just put it back on its bracket, connect the pipes up and forget about it, even though the valve is open all the time.
With the valve open at all times you were in the same place as me with the hose from the purge tank linked directly into the breather bridge. Haynes says this may slightly reduce catalyst life.
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Re: 2.5 petrol manual estate misfiring
« Reply #37 on: 11 August 2018, 03:00:02 »

Is the code 19 still present?
On the earlier V6 if you read the codes with the ignition on but engine off then it will always report code 19. It should clear when the engine is running. Else the sensor is foobar or the connector still has an issue.
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terry paget

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Re: 2.5 petrol manual estate misfiring
« Reply #38 on: 11 August 2018, 12:30:27 »

After all that, changed cam cover gaskets, plugs, etc. car still misfires under load. Must be the DIS pack, thought I. I have remove the DIS pack, and it looks all right - not split anywhere. I have a used spare, I suppose I fit it. Is there any way I can check a DIS pack?
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terry paget

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Re: 2.5 petrol manual estate misfiring
« Reply #39 on: 11 August 2018, 13:30:08 »

So, what can be wrong with this silly car? So far, I have changed the crank sensor, RH cam cover gaskets and checked LH cam cover gaskets, and now removed the DIS pack, which looks OK.
 DIS pack could still be faulty, have not yet changed either plugs or plug leads, and the crank sensor could be a dud, though it was a brand new genuine Vx item. This morning before breakfast a 2 mile test run seemed fine, but after breakfast a second run produced misfiring under load, full throttle at 25mph in 4th.
I am inclined to fit another DIS pack and another set of plug leads and try again.
If no change, then I change all 6 plugs.
If still no change, I change the crank sensor.

No EML has come on. I will check for fault codes when I get it going again.

Please advise.
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terry paget

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Re: 2.5 petrol manual estate misfiring
« Reply #40 on: 11 August 2018, 13:46:59 »

Forgot to mention: I changed the ECU coolant temperature sensor, and brought the purge valve into circuit. Car does not idle well; does not stall, but idle rate tends to rise to 1200rpm.
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Andy H

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Re: 2.5 petrol manual estate misfiring
« Reply #41 on: 11 August 2018, 14:57:14 »

So, what can be wrong with this silly car? have not yet changed either plugs or plug leads,

plugs are a consumable item (and cheap). Change (or at least inspect) the plugs before changing other parts
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Enceladus

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Re: 2.5 petrol manual estate misfiring
« Reply #42 on: 11 August 2018, 17:11:28 »

I too suggest you examine the plugs. You mentioned that the plug lead boot for cylinder 2 was damaged apparently due to arcing which might have been down to water in the plug well. So you replaced the plug lead for 2.  However if it's the coil pack actually faulty on plug 2 then you might find evidence of a spark fault on cylinder 5 in the opposing bank. That's because plug 2 is paired with plug 5 using the same coil with a wasted spark.

Plugs 6 & 3 and 4 & 1 are the other pairings.

As to the 1200rpm idle. Might the throttle cable be too tight following reassembly? Such that the butterflies in the throttle body don't fully close when the pedal is released?
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terry paget

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Re: 2.5 petrol manual estate misfiring
« Reply #43 on: 11 August 2018, 18:41:42 »

Thanks for the suggestions, chaps.
This afternoon I changed the DIS pack, disappointed to find the existing not cracked, but changed it anyway. I took the lower inlet manifold off to make the job easier. I changed all the plugs, and the plug leads. I discovered that my improvised lead from purge valve to breather bridge - it needs 1 end 10mm ID and the other end 5mm ID - had fallen apart, which may explain the idling problems. I guess I need the bespoke hose.
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Doctor Gollum

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Re: 2.5 petrol manual estate misfiring
« Reply #44 on: 11 August 2018, 18:45:05 »

For testing purposes you can plug the pipe on the breather bridge, but do not use the car like this...  ;)
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