S6 c5 4,2 AQJ, Stuttering on idle and during acceleration. No fault codes!
04-01-2017, 07:24 AM
#12
You can have misfiring without a code. When a spark coil is bad, with vcds you can monitor each cylinder for misses and spot a bad coil. Common problem.
Vacuum leaks will show up as multiple cylinder misfires.
If you really punch it, you can normally get a CEL to pop when misfire count exceeds a limit with either a spark coil or vacuum leak problem
Another possibility is MAF sensor, if the misfiring only shows up after warm up when closed loop operation begins. If idle miss smooths on warm engine with MAF unplugged and returns when plugged in, the MAF is bad.
You could also have a bad cat converter, but this normally will throw a code unless you have O2 sensor spacers installed on the post cat sensors.
As already noted, fuel pump is another possible source.
You really need to scan with VCDS or equivalent to get a complete picture.
Vacuum leaks will show up as multiple cylinder misfires.
If you really punch it, you can normally get a CEL to pop when misfire count exceeds a limit with either a spark coil or vacuum leak problem
Another possibility is MAF sensor, if the misfiring only shows up after warm up when closed loop operation begins. If idle miss smooths on warm engine with MAF unplugged and returns when plugged in, the MAF is bad.
You could also have a bad cat converter, but this normally will throw a code unless you have O2 sensor spacers installed on the post cat sensors.
As already noted, fuel pump is another possible source.
You really need to scan with VCDS or equivalent to get a complete picture.
04-01-2017, 01:34 PM
#14
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Today i opened the airfilterbox due to popping sounds inside the airinlet. The popping stopped when i disconnected the maf sensor. Bad maf sensor?
Yesterday i did a test on the maf. 255 g/s peak at full throttel in 2 gear. Stabel at 6 g/s on idle. Also monitored o2 sensors. O2 Bincode 111 and 011 sometimes. How can i check coils with vdcs?
Yesterday i did a test on the maf. 255 g/s peak at full throttel in 2 gear. Stabel at 6 g/s on idle. Also monitored o2 sensors. O2 Bincode 111 and 011 sometimes. How can i check coils with vdcs?
04-04-2017, 07:26 AM
#17
Today i opened the airfilterbox due to popping sounds inside the airinlet. The popping stopped when i disconnected the maf sensor. Bad maf sensor?
Yesterday i did a test on the maf. 255 g/s peak at full throttel in 2 gear. Stabel at 6 g/s on idle. Also monitored o2 sensors. O2 Bincode 111 and 011 sometimes. How can i check coils with vdcs?
Yesterday i did a test on the maf. 255 g/s peak at full throttel in 2 gear. Stabel at 6 g/s on idle. Also monitored o2 sensors. O2 Bincode 111 and 011 sometimes. How can i check coils with vdcs?
You may have a bad MAF, but usually when they go bad, the jerkiness will appear when the MAF is in closed loop ie warm engine. I would sort the spark misses first. If the misses are concentrated on one cylinder, that's the bad coil. Note that you will often see misfiring on other cylinders, too, but not as severe as the cylinder with bad coil.
04-04-2017, 07:36 AM
#18
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I like johnkk's advice. However, look carefully at the connector to the MAF. I have one car that has several cracked/broken wires at the connector that were not easy to see. I was getting odd behavior and when going to unplug the MAF discovered the bad connector. Also heard of others who have had a similar issue.
04-19-2017, 10:17 AM
#19
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For some reason i cant get any information with measuringblock 15 and 16. its blank and it says binbits. My Cel does not come on when i turn on the igniton but did a test on the instrument lights with vcds and the cel did come on. Still noe fault codes, jeg problem is getting worse, realy hard to know what to do without a singel code