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Author Topic: 2.5 petrol manual estate misfiring  (Read 10363 times)

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terry paget

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Re: 2.5 petrol manual estate misfiring
« Reply #45 on: 11 August 2018, 20:37:15 »

For testing purposes you can plug the pipe on the breather bridge, but do not use the car like this...  ;)
Tick Tock has a purge valve stuck open, and has been advised to just carry on with it. I understand from Haynes that this may shorten his catalyst life. I tried to bodge something with two hoses one stuck in the other, but it failed. I have found this in my spares heap, which looks similar, but has both pipes sticking up, and comes with a hose. Tomorrow I will try to fit it.

 
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Re: 2.5 petrol manual estate misfiring
« Reply #46 on: 11 August 2018, 21:38:26 »

Trying that valve is your best solution.

Here's why:

Plugging the breather bridge will temporarily fix the air leak. Running with the purge valve able to vent tank vapour to the engine bay is not a great recipe.

Bypassing the purge valve could potentially allow the engine to 'inhale' air/vapour from the tank. Which in extreme conditions could collapse the tank.
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terry paget

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Re: 2.5 petrol manual estate misfiring
« Reply #47 on: 12 August 2018, 16:31:42 »

Thanks Doc. Placing my old purge valve alongside my new found valve, I discover that they are identical, except someone has blanked off a pipe on the old valve.

As it came with the correct hose I installed it with hose from RH wing one side and hose to breather bridge on the other. Reassembled everything and took it for test drive.
Perfect for the first 10 miles, then it got hilly. Then the engine got hot, 100 degrees, and it misfired full throttle 4th gear 25mph. Got home, the engine overheating symbol flickered on, fans were blowing, temperature slowly fell to 95. I suspect blocked radiator.
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Re: 2.5 petrol manual estate misfiring
« Reply #48 on: 12 August 2018, 17:33:40 »

Did you do anything to test whether the replacement purge valve fully closes and fully opens? Or if stuck, is it stuck open or closed?
Also was the coil pack a known good pack?
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terry paget

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Re: 2.5 petrol manual estate misfiring
« Reply #49 on: 12 August 2018, 18:11:58 »

Did you do anything to test whether the replacement purge valve fully closes and fully opens? Or if stuck, is it stuck open or closed?
Also was the coil pack a known good pack?
No, did not check the purge valve, cannot of hand think how to do it.
The coil packs were genuine Vauxhall as far as I know. They were both salvaged from Vx 2.5s I scrapped in the past, and labelled KOV and X84, identifying the cars they came from. Neither was displaying the splits in the outer casings I have seen on failing coil packs.
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terry paget

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Re: 2.5 petrol manual estate misfiring
« Reply #50 on: 12 August 2018, 21:00:01 »

My first 3.0 manual suffered a blocked radiator. Temperature kept rising on a journey from Oxfordshire to Somerset, and I had to keep stopping for 15 minutes to allow cooling before I could make it home. New radiator cured the problem. I suppose it could be failing thermostat.
I see I can buy a new  radiator for £52 online. I have 2 radiators in my spares heap, salvaged from Omegas I have scrapped. I imagine they are still serviceable.
I know the car is not worth much, but it is strangely rust free, and is a nice drive.
Please advise.
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Re: 2.5 petrol manual estate misfiring
« Reply #51 on: 12 August 2018, 21:11:59 »

Does the top hose get hot suddenly or gradually, or relatively not at at?
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terry paget

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Re: 2.5 petrol manual estate misfiring
« Reply #52 on: 13 August 2018, 08:25:52 »

Did you do anything to test whether the replacement purge valve fully closes and fully opens? Or if stuck, is it stuck open or closed?
Also was the coil pack a known good pack?
How did you become aware that uour purge valve was stuck open?
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Re: 2.5 petrol manual estate misfiring
« Reply #53 on: 13 August 2018, 08:55:03 »

Did you do anything to test whether the replacement purge valve fully closes and fully opens? Or if stuck, is it stuck open or closed?
Also was the coil pack a known good pack?
How did you become aware that uour purge valve was stuck open?
It throws a fault code :y
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Tick Tock

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Re: 2.5 petrol manual estate misfiring
« Reply #54 on: 13 August 2018, 09:44:27 »

It obviously doesn't in all cases  :(  Well not at least on my 2.5.

Thinking about the purge valve, I can only assume a fault code is thrown if the ecu detects vapour / additional gas on the inlet? But there's nothing in the plenum before fuel injection that could detect this?

Talking of PCV, if the plastic feed line from the canister is blocked, an open valve wouldn't make much difference..... there can be a lot of crud in there from time to time.

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Re: 2.5 petrol manual estate misfiring
« Reply #55 on: 13 August 2018, 09:57:28 »

Did you do anything to test whether the replacement purge valve fully closes and fully opens? Or if stuck, is it stuck open or closed?
Also was the coil pack a known good pack?
No, did not check the purge valve, cannot of hand think how to do it.
The coil packs were genuine Vauxhall as far as I know. They were both salvaged from Vx 2.5s I scrapped in the past, and labelled KOV and X84, identifying the cars they came from. Neither was displaying the splits in the outer casings I have seen on failing coil packs.

With a 12v connected to the valve, you should be able to detect it clicking when it opens and closes. Mine is dead with no life when presented with voltage and is still stuck open.
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terry paget

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Re: 2.5 petrol manual estate misfiring
« Reply #56 on: 13 August 2018, 12:46:41 »

Does the top hose get hot suddenly or gradually, or relatively not at at?
Top hose warms up with the engine, gradually. at 103 degrees the fan kicks in, temperature falls to 95 and the fan cuts out again.
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terry paget

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Re: 2.5 petrol manual estate misfiring
« Reply #57 on: 13 August 2018, 12:52:12 »

I changed the ECU temp sensor, hoping it would produce a fast idle on cold start - it didn't. In fact the idle when warm is 900rpm, higher than before. I appreciate this could be an air leak somewhere else, like purge valve or its plumbing.
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terry paget

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Re: 2.5 petrol manual estate misfiring
« Reply #58 on: 13 August 2018, 12:58:32 »

It obviously doesn't in all cases  :(  Well not at least on my 2.5.

Thinking about the purge valve, I can only assume a fault code is thrown if the ecu detects vapour / additional gas on the inlet? But there's nothing in the plenum before fuel injection that could detect this?

Talking of PCV, if the plastic feed line from the canister is blocked, an open valve wouldn't make much difference..... there can be a lot of crud in there from time to time.
Yes, I did think I should have checked it with 12v across it (but which way?) and if it clicked, tried blowing though it. I hoped it might throw up a fault code, otherwise how would I ever know it had died?
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terry paget

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Re: 2.5 petrol manual estate misfiring
« Reply #59 on: 13 August 2018, 13:56:17 »

It obviously doesn't in all cases  :(  Well not at least on my 2.5.

Thinking about the purge valve, I can only assume a fault code is thrown if the ecu detects vapour / additional gas on the inlet? But there's nothing in the plenum before fuel injection that could detect this?

Talking of PCV, if the plastic feed line from the canister is blocked, an open valve wouldn't make much difference..... there can be a lot of crud in there from time to time.
If no code, what inspired you to investigate it?
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