Audi A8 with LOTS of new parts soon parting out
08-25-2018, 11:15 AM
#12
AudiWorld Senior Member
P0300
That code implicates timing, spark, fuel and vacuum leaks. The known common failure points on this car are the Ignition Control Modules ( aka the POS), and the fuel pump. Both go intermittent as they spiral toward death.
If this were my car, I'd get a real VAG COM cable, even an older used one. Then replace POS stages. If that didn't work, I'd focus on testing output on that fuel pump.
If this were my car, I'd get a real VAG COM cable, even an older used one. Then replace POS stages. If that didn't work, I'd focus on testing output on that fuel pump.
08-26-2018, 08:31 AM
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08-26-2018, 08:34 AM
#15
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The brown circles just make it easier to find the etched ones. The etched circles are your timing marks. The spark requires a good timing signal (N80), good coils, good spark plugs, and good Power Output Stages (POS) also called Ignition Control Modules.
The power output stages are a frequent point of failure. You can find replacements on Amazon for $23., and free shipping with Prime. You'll need two of them. The next place I would check is the fuel pump.
When checking for multiple misfires, I would move the coils from the cylinders where the errors are occurring to a position where there are no errors. If the errors moved with the coils, than the coils are suspects. If the errors stay at the original cylinders, then check the power output stages, and if all the errors are in the same bank, the cam timing or fuel pump.
The power output stages are a frequent point of failure. You can find replacements on Amazon for $23., and free shipping with Prime. You'll need two of them. The next place I would check is the fuel pump.
When checking for multiple misfires, I would move the coils from the cylinders where the errors are occurring to a position where there are no errors. If the errors moved with the coils, than the coils are suspects. If the errors stay at the original cylinders, then check the power output stages, and if all the errors are in the same bank, the cam timing or fuel pump.
08-26-2018, 08:52 AM
#16
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That code implicates timing, spark, fuel and vacuum leaks. The known common failure points on this car are the Ignition Control Modules ( aka the POS), and the fuel pump. Both go intermittent as they spiral toward death.
If this were my car, I'd get a real VAG COM cable, even an older used one. Then replace POS stages. If that didn't work, I'd focus on testing output on that fuel pump.
If this were my car, I'd get a real VAG COM cable, even an older used one. Then replace POS stages. If that didn't work, I'd focus on testing output on that fuel pump.
08-26-2018, 09:45 AM
#17
AudiWorld Senior Member
I'm not familiar with the 32valve engine. Does it have variable intake timing like 40V? Hard to tell from the photos, but those look pretty damn close. With the 40V engine, the cams are flipped from bank to bank...that is, one should have 16 chain links across the top and 15 underneath, while the other has 15 chain links on top and 16 underneath. That's because one chain pulls across the top, the other chain pulls across the bottom. If you got your head down low and peer at it form all angles, you will know. if it is right or not. Keep in mind, the nearest adjustment is a full chain link. Does it look that far out? I don't think so.
Have you tried moving the POS to see if the misfires move or stay in the same place? What misfires do you have?
Have you tried moving the POS to see if the misfires move or stay in the same place? What misfires do you have?
08-26-2018, 10:01 AM
#18
AudiWorld Senior Member
The fuel pump has a specific output of liters or gallons per minute. Dunno the exact measurement. if you are opening lines, ONLY use fuel injection clamps, not worm gear clamps. Worm gear will leak and... Carbecue.
The pump powers up momentarily on cranking then doesn't stay on until the ecu believes the engine is running...probably crank sensor signal of RPMs over a few hundred. To power it continuously, you could look for the two fattest wires int the connector under the carpet, right side of the trunk. One has continuity to ground, the other is a switched hot from the relay under the passenger side (right U.S. cars) footwell. You can remove the floor mat, three screws on the incline portion of the floor, one or two fasteners to slide out the relay tray, pop cover off of Fuel Pump relay, Key in RUN position, push FP contacts points closed with a folded matchbook or folded piece of soft plastic fuel line, or the rubber handle on a pair of pliers. Very lightly. Then the fuel pump should run continuously.
The pump powers up momentarily on cranking then doesn't stay on until the ecu believes the engine is running...probably crank sensor signal of RPMs over a few hundred. To power it continuously, you could look for the two fattest wires int the connector under the carpet, right side of the trunk. One has continuity to ground, the other is a switched hot from the relay under the passenger side (right U.S. cars) footwell. You can remove the floor mat, three screws on the incline portion of the floor, one or two fasteners to slide out the relay tray, pop cover off of Fuel Pump relay, Key in RUN position, push FP contacts points closed with a folded matchbook or folded piece of soft plastic fuel line, or the rubber handle on a pair of pliers. Very lightly. Then the fuel pump should run continuously.
08-26-2018, 10:05 AM
#19
AudiWorld Senior Member
Search is your friend for parts. I'm a big fan of FCP Euro for lots of stuff, but ECS has good deals some times, or spin the wheel of fortune and try Amazon, they are all hit and miss on pricing, and Amazon/ Partsgeek are also hit/miss on quality.
