Huge misfire problem
Discussion
Was low on petrol (low fuel indicator had come on) so filled up with £20 worth of Tesco super unleaded ... drove out of Tescos, got back on the A120 and within 1/2 a mile noticed the car didn't feel right. Nearly didn't get home ... car is misfiring badly, won't pull cleanly from low rpm, and getting occasional huge backfire 'bangs' when going on and off the throttle. Prior to putting in the £20 worth of super, I've been running the car on normal unleaded with no problems.
What on earth has happened?
Have I got a duff batch of fuel?? I'm getting no error/engine check messages on the dash. Have never had any problems with the car before. Car is now back home in my garage. Is there an easy way of draining out the fuel, can I disconnect a fuel rail and make the fuel pump run somehow to drain the tank? Not happy at all
BTW car is an '04 CV8 with Wortec focus pac which has been running perfectly on both normal and super unleaded .... until now.
What on earth has happened?
Have I got a duff batch of fuel?? I'm getting no error/engine check messages on the dash. Have never had any problems with the car before. Car is now back home in my garage. Is there an easy way of draining out the fuel, can I disconnect a fuel rail and make the fuel pump run somehow to drain the tank? Not happy at all BTW car is an '04 CV8 with Wortec focus pac which has been running perfectly on both normal and super unleaded .... until now.
Edited by anonymous-user on Sunday 6th January 16:38
Have you tried your HT leads?
I went through 4 leads as they were melted by teh headers. I had exactly teh same symptons and after taking off the leads and testing them it became apparent which one was breaking. The other way to test is to let the engine run at idle and then systematically disconnect each lead an dthen replace it in sequence at the top of the engine and if the note does not change when you remove a specific lead - that is is your knackered lead.
Might be worth atry before cost and hassle of draining your fuel system!! The symptons are absolutely identicalincludign the odd big backfire as teh fueling is obvisouly all screwed if one or more of your HTs is gone.
I went through 4 leads as they were melted by teh headers. I had exactly teh same symptons and after taking off the leads and testing them it became apparent which one was breaking. The other way to test is to let the engine run at idle and then systematically disconnect each lead an dthen replace it in sequence at the top of the engine and if the note does not change when you remove a specific lead - that is is your knackered lead.
Might be worth atry before cost and hassle of draining your fuel system!! The symptons are absolutely identicalincludign the odd big backfire as teh fueling is obvisouly all screwed if one or more of your HTs is gone.
You know if you put diesel in as you get clouds of blue smoke from the exhaust as the oil is burnt.
I'd be very very careful using the fuel rail to drain the fuel as it'll be under very high pressure.
The best way (this is generic method not monaro specific so may not be the best) is to remove as much fuel from the fuel tank using good ole rubber tube and then when you can't get any more fuel out, start the car and let it burn off the rest. Shouldn't take long and you know there's nothing left in the system.
It could be some crud in the fuel tank thats been sucked up into the fuel pump/filter. Should be fairly straightforward to check that. A duff batch of fuel is unlikely but it can and does happen. The most common cause is not so much the fuel but rather the way it's stored. Supermarkets and petrol stations all get their fuel from the same places so mistakes with the fuel are very rare. However, a few supermarkets have problems with water getting into the underground fuel containers contaminating the fuel.
I'd be very very careful using the fuel rail to drain the fuel as it'll be under very high pressure.
The best way (this is generic method not monaro specific so may not be the best) is to remove as much fuel from the fuel tank using good ole rubber tube and then when you can't get any more fuel out, start the car and let it burn off the rest. Shouldn't take long and you know there's nothing left in the system.
It could be some crud in the fuel tank thats been sucked up into the fuel pump/filter. Should be fairly straightforward to check that. A duff batch of fuel is unlikely but it can and does happen. The most common cause is not so much the fuel but rather the way it's stored. Supermarkets and petrol stations all get their fuel from the same places so mistakes with the fuel are very rare. However, a few supermarkets have problems with water getting into the underground fuel containers contaminating the fuel.
Edited by ads_green on Sunday 6th January 17:41
Fixed!
Checked all the plug leads and - yes - two loose leads! Drivers side engine bank, the rear two cylinders, both lead caps just resting on the plugs and not pushed in at all! Pushing the metal heat shield is no good at all, you have to push the rubber bit at the top and 'feel' for a click as the lead connects to the plug.
I wonder why the car decided to do this just after I filled up with fuel, and not when I started it up from cold, and drove to the petrol station, when it drove fine ???
Normal service has been resumed, thanks all!
Checked all the plug leads and - yes - two loose leads! Drivers side engine bank, the rear two cylinders, both lead caps just resting on the plugs and not pushed in at all! Pushing the metal heat shield is no good at all, you have to push the rubber bit at the top and 'feel' for a click as the lead connects to the plug.
I wonder why the car decided to do this just after I filled up with fuel, and not when I started it up from cold, and drove to the petrol station, when it drove fine ???
Normal service has been resumed, thanks all!
www.hsv.org.uk strikes again!! That would have cost £200 in a garage..... Who said this forum was shite 
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