The Jeep
28-11-2010, 10:56 PM
Hi - I'm going to give as much detail of the problem (in chronological order) as I can in the hope that someone out there can help. My Audi is a V-reg 1999 1.8l 20-valve A4 Avante.
Timeline:
Nov 15: Just returned from 250 mile trip and all is well, my car just needs its annual service.
Nov18: Mike, a mechanic, comes to look at the car and borrows my keys. The keys get lost somehow. Not in the car. Not under the bonnet on the engine, though they could've been left there and fallen down somewhere. A bit frustrating.
Nov 21: Mike comes round to service my car. He just changes the spark plugs and fires her up but there's a problem: misfiring, running rough, so he puts back the original plugs. Still backfiring and sounds like its only firing on 3 cylinders. He doesn't understand it and thinks he's jinxed with my car. I make him a cup of tea and say don't worry, surely it must be something fairly straightforward (and involving the missing keys?).
Nov22: Drive car 40 miles to garage, with very little power and much revving, to where Mike works and the owner puts it on his diagnostic machine. Comes up with some codes that don't really point to anything obvious (open circuit on bank 1, I think it was). He says he doesn't know Audis well enough and suggests I see an Audi specialist.
Nov 23: Take car (with some difficulty going uphill) to another mechanic, Peter, who has worked on the car before. He changes out the ignition coil pack, but it doesn't make any difference. However, it was an old coil pack and may be faulty. He puts it on his (very basic) diagnostic reader and it comes up with an error relating to a temperature device. He orders a replacement (£50).
Nov 25: Take car back to Peter and he changes out faulty item. Makes no difference, car still misfiring. He checks for spark and it seems intermittent: perhaps the coil pack is a dud. He orders a new one (£300). He also does a compression test on the 2 front cylinders which hold at 150 psi.
Nov 26: Reading on the Internet about how many people have had problems with Audi A4 coil packs. Symptoms are lack of power, sounds like its running on 3 cylinders, backfiring - my symptoms exactly, so I'm feeling optimistic (and believing that the spare he had was surely faulty).
Nov 27: Peter comes with brand new coil pack and fits it. Fingers crossed! Start her up and... no change.... oh dear, £300 spent for nothing. Peter feels the exhaust manifold from the front 2 cylinders and they are cold, so no combustion seems to be taking place. He reckons it's getting a spark, getting fuel (wet inside cylinder when he looked) and the compression is fine, so it must be a problem with the air intake (he also checked under the rocker cover for signs of damage to cams, but none visible). He loosens the clip holding the hose feeding the front cylinder and inserts a screwdriver blade under the hose to allow the engine to suck air in directly and... that cylinder's exhaust gets hot, so it seems to be firing OK. Our conclusion: something is blocking the airway feeding the front 2 cylinders. Take off the entire air intake manifold but find no signs of any blockage - how weird. So why does the cylinder fire when it gets air directly, but not via the air intake which seems entirely clear (checked the air filter, too, and its fine)?
So what do I do now? I can't afford to send the car to an Audi specialist, but three good mechanics can't figure it out.
Anyone read this far and got any ideas?
Many thanks
John (Banchory, Scotland)
Timeline:
Nov 15: Just returned from 250 mile trip and all is well, my car just needs its annual service.
Nov18: Mike, a mechanic, comes to look at the car and borrows my keys. The keys get lost somehow. Not in the car. Not under the bonnet on the engine, though they could've been left there and fallen down somewhere. A bit frustrating.
Nov 21: Mike comes round to service my car. He just changes the spark plugs and fires her up but there's a problem: misfiring, running rough, so he puts back the original plugs. Still backfiring and sounds like its only firing on 3 cylinders. He doesn't understand it and thinks he's jinxed with my car. I make him a cup of tea and say don't worry, surely it must be something fairly straightforward (and involving the missing keys?).
Nov22: Drive car 40 miles to garage, with very little power and much revving, to where Mike works and the owner puts it on his diagnostic machine. Comes up with some codes that don't really point to anything obvious (open circuit on bank 1, I think it was). He says he doesn't know Audis well enough and suggests I see an Audi specialist.
Nov 23: Take car (with some difficulty going uphill) to another mechanic, Peter, who has worked on the car before. He changes out the ignition coil pack, but it doesn't make any difference. However, it was an old coil pack and may be faulty. He puts it on his (very basic) diagnostic reader and it comes up with an error relating to a temperature device. He orders a replacement (£50).
Nov 25: Take car back to Peter and he changes out faulty item. Makes no difference, car still misfiring. He checks for spark and it seems intermittent: perhaps the coil pack is a dud. He orders a new one (£300). He also does a compression test on the 2 front cylinders which hold at 150 psi.
Nov 26: Reading on the Internet about how many people have had problems with Audi A4 coil packs. Symptoms are lack of power, sounds like its running on 3 cylinders, backfiring - my symptoms exactly, so I'm feeling optimistic (and believing that the spare he had was surely faulty).
Nov 27: Peter comes with brand new coil pack and fits it. Fingers crossed! Start her up and... no change.... oh dear, £300 spent for nothing. Peter feels the exhaust manifold from the front 2 cylinders and they are cold, so no combustion seems to be taking place. He reckons it's getting a spark, getting fuel (wet inside cylinder when he looked) and the compression is fine, so it must be a problem with the air intake (he also checked under the rocker cover for signs of damage to cams, but none visible). He loosens the clip holding the hose feeding the front cylinder and inserts a screwdriver blade under the hose to allow the engine to suck air in directly and... that cylinder's exhaust gets hot, so it seems to be firing OK. Our conclusion: something is blocking the airway feeding the front 2 cylinders. Take off the entire air intake manifold but find no signs of any blockage - how weird. So why does the cylinder fire when it gets air directly, but not via the air intake which seems entirely clear (checked the air filter, too, and its fine)?
So what do I do now? I can't afford to send the car to an Audi specialist, but three good mechanics can't figure it out.
Anyone read this far and got any ideas?
Many thanks
John (Banchory, Scotland)