Misfire at highway speeds
#21
08-05-2015, 11:43 AM
I'm only a casual user of VCDS (although I spent $375 on the full-boat Ross-Tech scan cable) the "measuring blocks" are VAG's way of showing the readings from sensors or the condition of things powered by the ECU. They are groups of date that are related, such as blocks for the O2 sensor readings. For instance, if you disconnect an injector while the engine is running, you will have a CEL, but VCDS will show which cylinder misfires in a misfire block, and the open circuit of the injector in another group. So you know which cylinder, and which injector. For a number of years I used a simple serial port cable and VAG-COM freeware from Ross-Tech, later I paid to get the unlock code to use all the features of the early version, which was fine for a B5 car. Later we got a B6, and still later a Touareg, which are too advanced for the early VAG-COM.
#22
08-05-2015, 02:06 PM
I'm pretty sure I made a mistake in not buying the cheap version of vcds (mine is only $250?) when I got the car. It would have saved me tons of time and money.
#23
08-11-2015, 02:56 PM
Well I finally took it to a shop and they ran a bunch of diagnostics and took it test drives. They replaced/checked all the stuff I did and finally decided to replace the ECU... and it turns out that was it.
Unless it is hibernation and decides to rear it's ugly head again down the line, we'll know it was the damn computer. I'm annoyed two-fold, one in that I could never replace or test this myself. And two, in that from what I understand it's almost NEVER the ECU (unless you have an aftermarket chip with the 1.8). Logic says it's about 15 other things before the ECU and I did them all before giving up, and wouldn't you know it...
Anyway, what I've been chasing for a year and spent hundreds on turned out to be a $100 fix... but I would have never tried it before the others. And now I'm out what I spend trying to fix it myself + $450 at the mechanic. Oh well.
Unless it is hibernation and decides to rear it's ugly head again down the line, we'll know it was the damn computer. I'm annoyed two-fold, one in that I could never replace or test this myself. And two, in that from what I understand it's almost NEVER the ECU (unless you have an aftermarket chip with the 1.8). Logic says it's about 15 other things before the ECU and I did them all before giving up, and wouldn't you know it...
Anyway, what I've been chasing for a year and spent hundreds on turned out to be a $100 fix... but I would have never tried it before the others. And now I'm out what I spend trying to fix it myself + $450 at the mechanic. Oh well.
I hate to say it but I'm almost relieved. I'm certainly not happy I sent it to the shop and payed $450 for literally nothing... but I was really unconvinced it was the ECU. To me that was some cop-out fix which didn't really make sense. So now I know it's not that.
This all being said, the next day I did run into trouble starting it when I came back from my trip and was hit with a p0322 - Ignition Engine Speed Input Circuit No Signal code, but after a bit of research it MAY, sorta, kinda, cause a misfire... SOMETIMES. So my dying hope is that my new ECU detected this AS WELL as the misfires - which my old ECU didn't. Now I can replace the engine speed/crankshaft position sensor and that MAY fix it.
Anyway, I'm trying to just keep a log for people who run into this issue and find this thread. Nothing is more annoying than searching the internet, finding a thread with the exact same issues but the OP didn't come back to say what finally fixed it.
#24
08-11-2015, 10:32 PM
Mine misfired today for the first time on the highway and scared the **** outta me I thought it was going to stall but then again it's got 400k on it I've never had this happen to me yet so my guess was just a bad mix fuel ratio in the cylinder but what your describing if its happening all the time could be getting to much gas or if it is something to do with air flow which you said you checked that, you should deadpan the bitch an just dump the oil to see if that helps and stop mixing gas don't matter if you always get premium try to keep the same grade an pump not saying that's affecting why it's miss firing
Goodluck bro
Goodluck bro
#25
08-12-2015, 03:55 PM
Yeah I'd clear the code and see if it comes back. Could have been a fluke.
And yeah I've tried a bunch of different gas stations/pumps/etc. I always use premium too. I also tried using exclusively non-ethanol gas for a while but it still misfired.
The shop also did a MotorVac, which may be one of those "hey pay for this" services that doesn't actually do a lot, but I'm fairly certain its not the fuel or fuel system.
And yeah I've tried a bunch of different gas stations/pumps/etc. I always use premium too. I also tried using exclusively non-ethanol gas for a while but it still misfired.
The shop also did a MotorVac, which may be one of those "hey pay for this" services that doesn't actually do a lot, but I'm fairly certain its not the fuel or fuel system.
#26
08-14-2015, 02:10 AM
Sadly the crankshaft position sensor (causing the p0322 code) didn't help the misfires. It did fix the non-starting, which was obviously a more pressing issue, but nothing with the misfires.
It got me thinking though, about any other "random" sensors or pieces to the car that I've missed that may cause it. Assuming 0 codes were thrown to help narrow down the search I'm wondering if there's some random sensor that may be causing this that nobody would have though of initially. I'll admit I had no clue a crankshaft position sensor even existed before 5 days ago, so I'm curious what other small pieces I don't know of that could cause a misfire. Suggestions are welcome as always.
It got me thinking though, about any other "random" sensors or pieces to the car that I've missed that may cause it. Assuming 0 codes were thrown to help narrow down the search I'm wondering if there's some random sensor that may be causing this that nobody would have though of initially. I'll admit I had no clue a crankshaft position sensor even existed before 5 days ago, so I'm curious what other small pieces I don't know of that could cause a misfire. Suggestions are welcome as always.
#27
09-07-2015, 12:02 AM
To anybody wondering, I'm still attempting to diagnose this.
For the most part cylinders 1 and 3 only misfire once or twice before the reset. I can only see that they do in a log or when I have a passenger actively watching vcds. Cylinder 4 is the problem child.
I have never got them all to misfire in a single setting. Usually 4 will do it, and drag a few along with it, but never the other 5 all together. One or two will always be ok, but the ok cylinder always moves around. Could it be because there's only enough oxygen for 4 or 5 of the 6 cylinders? Only enough fuel? Is the fuel not being spread evenly over the 6 cylinders? Only enough voltage from the battery? Man I sure do wish I new what goes on in the inner workings of the car, especially during long, hard accelerations.
I've logged a typical situation:
The early time stamps are removed when I was driving to the onramp (they were all 0 anyway). You can see they start at 86 seconds, just as I start to hard-accelerate on to the highway.
side note: When driving around town or idling at lights, one or two will occasionally misfire, but not more than once before it resets. I read somewhere this was normal for an old car - not great performance-wise but nothing to be too worried about.
Also note I have switched the camshaft position sensors and the misfires didn't switch sides, so I think I can assume its not those.
While researching I read another place to look may be the cam chain tensioner?
I also read of somebody with too much oil causing it to hit the crankshaft and aerate which caused misfires. I changed my oil recently, filled it to just the 'low' line and still regular misfires. So that's one random cause to eliminate.
In any event I'm determined to figure this out. Onward!
For the most part cylinders 1 and 3 only misfire once or twice before the reset. I can only see that they do in a log or when I have a passenger actively watching vcds. Cylinder 4 is the problem child.
I have never got them all to misfire in a single setting. Usually 4 will do it, and drag a few along with it, but never the other 5 all together. One or two will always be ok, but the ok cylinder always moves around. Could it be because there's only enough oxygen for 4 or 5 of the 6 cylinders? Only enough fuel? Is the fuel not being spread evenly over the 6 cylinders? Only enough voltage from the battery? Man I sure do wish I new what goes on in the inner workings of the car, especially during long, hard accelerations.
I've logged a typical situation:
The early time stamps are removed when I was driving to the onramp (they were all 0 anyway). You can see they start at 86 seconds, just as I start to hard-accelerate on to the highway.
side note: When driving around town or idling at lights, one or two will occasionally misfire, but not more than once before it resets. I read somewhere this was normal for an old car - not great performance-wise but nothing to be too worried about.
Code:
Cyl 1 Cyl 2 Cyl 3 Cyl 4 Cyl 5 Cyl 6 86.31 0 0 0 86.56 0 0 0 86.81 0 0 0 87.06 0 0 0 87.31 0 0 0 87.56 2 0 0 87.81 0 1 0 88.06 4 1 0 88.31 0 1 0 88.57 4 1 1 88.82 0 2 0 89.07 7 1 3 89.32 0 2 0 89.57 8 1 3 89.82 0 2 0 90.07 9 1 3 90.32 0 2 0 90.57 10 1 4 90.82 0 3 0 91.07 11 1 5 91.33 1 3 0 91.58 13 1 5 91.84 1 3 0 92.1 14 1 6 92.35 1 3 0 92.6 14 1 6 92.85 1 3 0 93.11 14 1 6 93.36 1 3 0 93.61 14 1 6 93.86 1 3 0 94.11 14 1 6 94.36 1 3 0 94.61 14 1 6 94.86 1 3 0 95.11 14 1 6 95.36 1 3 0 95.61 14 1 6 95.86 1 3 0 96.11 14 1 6 96.36 1 3 0 96.61 15 1 7 96.86 1 3 0 97.12 16 1 8 97.37 1 3 0 97.62 17 1 8 97.87 1 3 0 98.12 19 1 8 98.37 1 3 0 98.62 20 1 8 98.87 1 3 0 99.12 21 1 8 99.38 1 3 0 99.64 22 1 8 99.9 2 3 0 100.15 23 1 9 100.4 2 3 0 100.65 24 1 9 100.89 2 3 0 101.15 26 1 9 101.41 2 3 0 101.66 27 1 9 101.91 2 3 0 102.16 28 1 9 102.41 2 4 0 102.66 28 1 9 102.91 2 5 0 103.16 0 0 0 103.41 1 0 0 103.66 1 0 1 103.91 1 0 0 104.16 3 0 1 104.41 1 0 0 104.67 4 0 1 104.92 1 0 0 105.17 5 0 1 105.42 1 0 0 105.67 6 0 2 105.92 1 0 0 106.17 6 0 2 106.42 1 1 0 106.67 6 0 2 106.92 1 1 0 107.17 6 0 2 107.42 1 1 0 107.67 6 0 2 107.92 1 1 0 108.17 6 0 2 108.42 1 1 0 108.67 6 0 2 108.92 1 1 0 109.17 6 0 2 109.43 1 1 0 109.68 6 0 2 109.93 1 1 0 110.18 6 0 2 110.43 1 1 0 110.68 6 0 2 110.93 1 1 0 111.18 6 0 2 111.43 1 1 0 111.68 6 0 2 111.93 1 1 0 112.18 6 0 2 112.44 1 1 0 112.69 6 0 2 112.94 1 1 0 113.19 6 0 2 113.44 1 1 0 113.69 6 0 2 113.94 1 1 0 114.19 6 0 2 114.44 1 1 0 114.69 6 0 2 114.94 1 1 0 115.19 6 0 2 115.44 1 1 0 115.69 6 0 2 115.94 1 1 0 116.19 6 0 2 116.44 1 1 0 116.7 6 0 2 116.95 1 1 0 117.2 6 0 2 117.45 1 1 0 117.7 6 0 2 117.95 1 1 0 118.2 6 0 2 118.45 1 1 0 118.7 6 0 2 118.95 1 1 0 119.2 6 0 2 119.45 1 1 0 119.7 6 0 2 119.95 1 1 0 120.2 6 0 2 120.45 1 1 0 120.7 6 0 2 120.95 1 1 0 121.21 6 0 2 121.46 1 1 0 121.71 6 0 2 121.96 1 1 0 122.21 6 0 2 122.46 1 1 0 122.71 6 0 2 122.96 1 1 0 123.21 6 0 2 123.46 1 1 0 123.71 6 0 2 123.96 1 1 0 124.21 6 0 2 124.46 1 1 0 124.71 6 0 2 124.97 1 1 0 125.22 6 0 2 125.47 1 1 0 125.72 6 0 2 125.97 1 1 0 126.22 6 0 2 126.47 1 1 0 126.72 6 0 2 126.97 1 1 0 127.22 6 0 2 127.47 1 1 0 127.72 6 0 2 127.97 1 1 0 128.22 6 0 2 128.47 1 1 0 128.72 6 0 2 128.97 1 1 0 129.23 6 0 2 129.48 1 1 0 129.73 6 0 2 129.98 1 1 0 130.23 6 0 2 130.48 1 1 0 130.73 6 0 2 130.98 1 1 0 131.23 6 0 2 131.48 1 1 0 131.74 6 0 2 131.99 1 1 0 132.24 6 0 2 132.49 1 1 0 132.74 6 0 2 132.99 1 1 0 133.24 6 0 2 133.49 1 1 0 133.74 6 0 2 133.99 1 1 0 134.24 6 0 2 134.49 1 1 0 134.74 6 0 2 134.99 1 1 0 135.24 6 0 2 135.49 1 1 0 135.75 6 0 2 136 1 1 0 136.25 6 0 2 136.5 1 1 0 136.75 6 0 2 137 1 1 0 137.25 6 0 2 137.5 1 1 0 137.75 6 0 2 138 1 1 0 138.25 6 0 2 138.5 1 1 0 138.75 6 0 2 139 2 1 0 139.25 6 0 2 139.5 2 1 0 139.75 6 0 2 140 2 1 0 140.25 6 0 2 140.51 2 1 0 140.76 6 0 2 141.01 2 1 0 141.25 6 0 2 141.51 2 1 0 141.75 6 0 2 142.01 2 1 0 142.26 6 0 2 142.5 2 1 0 142.75 6 0 2 143.01 2 1 0 143.26 6 0 2 143.52 2 1 0 143.77 6 0 2 144.02 2 1 0 144.27 6 0 2 144.52 2 1 0 144.77 6 0 2 145.02 2 1 0 145.27 6 0 2 145.52 2 1 0 145.77 6 0 2 146.02 2 1 0 146.27 6 0 2 146.52 2 1 0 146.77 6 0 2 147.02 2 1 0 147.28 6 0 2 147.53 2 1 0 147.78 6 0 2 148.03 2 1 0 148.28 6 0 2 148.53 2 1 0 148.77 6 0 2 149.02 2 1 0 149.27 6 0 2 149.53 2 1 0 149.78 6 0 2 150.02 2 1 0 150.28 6 0 2 150.52 2 1 0 150.78 6 0 2 151.02 2 1 0 151.28 6 0 2 151.54 2 1 0 151.79 6 0 2 152.04 2 1 0 152.29 6 0 2 152.53 2 1 0 152.79 6 0 2 153.03 2 1 0 153.28 6 0 2 153.53 2 1 0 153.78 6 0 2 154.04 2 1 0 154.29 6 0 2 154.53 2 1 0 154.79 6 0 2 155.04 2 1 0 155.29 6 0 2 155.54 2 1 0 155.8 6 0 2 156.04 2 1 0 156.29 6 0 2 156.54 2 1 0 156.79 6 0 2 157.05 2 1 0 157.29 6 0 2 157.54 2 1 0 157.79 6 0 2 158.04 2 1 0 158.29 6 0 2 158.54 2 1 0 158.79 6 0 2 159.04 2 1 0 159.3 6 0 2 159.56 2 1 0 159.8 6 0 2 160.06 2 1 0 160.31 6 0 2 160.55 2 1 0 160.8 6 0 2 161.05 2 1 0 161.31 6 0 2 161.57 2 1 0 161.81 6 0 2 162.07 2 1 0 162.32 6 0 2 162.57 2 1 0 162.82 6 0 2 163.07 2 1 0 163.31 6 0 2 163.57 2 1 0 163.82 6 0 2 164.09 2 1 0 164.34 6 0 2 164.59 2 1 0 164.84 6 0 2 165.09 2 1 0 165.34 6 0 2 165.59 2 1 0 165.84 6 0 2 166.09 2 1 0 166.34 6 0 2 166.58 2 1 0 166.84 6 0 2 167.09 2 1 0 167.35 6 0 2 167.6 2 1 0 167.85 6 0 2 168.1 2 1 0 168.35 6 0 2 168.6 2 1 0 168.86 6 0 2 169.1 2 1 0 169.35 6 0 2 169.6 2 1 0 169.85 6 0 2 170.1 2 1 0 170.35 6 0 2 170.6 2 1 0 170.86 6 0 2 171.11 2 1 0 171.36 6 0 2 171.61 2 1 0 171.87 6 0 2 172.12 2 1 0 172.36 6 0 2 172.61 2 1 0 172.86 6 0 2 173.11 2 1 0 173.38 6 0 2 173.62 2 1 0 173.87 6 0 2 174.12 2 1 0 174.38 6 0 2 174.64 2 1 0 174.89 6 0 2 175.15 2 1 0 175.4 6 0 2 175.65 2 1 0 175.9 6 0 2 176.16 2 1 0 176.4 6 0 2 176.65 2 1 0 176.9 0 0 0 177.15 0 0 0 177.41 0 0 0 177.66 0 0 0 177.91 0 0 0 178.16 0 0 0 178.42 0 0 0 178.66 0 0 0 178.91 0 0 0 179.16 0 0 0 179.41 0 0 0 179.66 0 0 0 179.91 0 0 0 180.16 0 0 0 180.42 0 0 0 180.66 0 0 0 180.91 0 0 0 181.16 0 0 0 181.41 0 0 0 181.66 0 0 0 181.91 0 0 0 182.17 0 0 0 182.42 0 0 0 182.68 0 0 0 182.92 0 0 0 183.17 0 0 0 183.42 0 0 0 183.67 0 0 0 183.92 0 0 0 184.18 0 0 0 184.43 0 0 0 184.69 0 0 0 184.96 0 0 0 185.22 0 0 0 185.48 0 0 0 185.73 0 0 0 185.98 0 0 0 186.23 0 0 0 186.48 0 0 0 186.73 0 0 0 186.98 0 0 0 187.23 0 0 0 187.48 0 0 0 187.72 0 0 0 187.98 0 0 0 188.23 0 0 0 188.49 0 0 0 188.74 0 0 0 188.99 0 0 0 189.24 0 0 0 189.49 0 0 0 189.74 0 0 0 189.99 0 0 0 190.24 0 0 0 190.49 0 0 0 190.74 0 0 0 190.99 0 0 0 191.24 0 0 0 191.5 0 0 0 191.75 0 0 0 192 0 0 0
While researching I read another place to look may be the cam chain tensioner?
I also read of somebody with too much oil causing it to hit the crankshaft and aerate which caused misfires. I changed my oil recently, filled it to just the 'low' line and still regular misfires. So that's one random cause to eliminate.
In any event I'm determined to figure this out. Onward!
Last edited by elduderino200; 09-07-2015 at 04:14 AM.
#28
09-07-2015, 12:08 AM
I should also mention I read that unplugging the MAF was a troubleshooting step so I tried it.
Interestingly my car seemed to run MUCH smoother after but I read that didn't necessarily mean much, just that the computer puts in a constant amount of air, instead of reading it from the MAF and adjusting.
VCDS also won't check for misfires when it's unplugged. It constantly says the misfire status is "disabled" and never registers a single misfire.
The shop I took it to also said the MAF was running fine (though they didn't provide any proof - but atm I have no reason to believe they lying).
Interestingly my car seemed to run MUCH smoother after but I read that didn't necessarily mean much, just that the computer puts in a constant amount of air, instead of reading it from the MAF and adjusting.
VCDS also won't check for misfires when it's unplugged. It constantly says the misfire status is "disabled" and never registers a single misfire.
The shop I took it to also said the MAF was running fine (though they didn't provide any proof - but atm I have no reason to believe they lying).
#29
09-21-2015, 07:49 AM
Hey Mate,
Just reading your thread..Sorry I cant give you much advise but "Keep it up"
You will find the bug and kick it out the door.
Real interesting read, I really hope you will get your answer soon.
Please keep posting. And keep us all in the loop.
Best Regards
Steve
Just reading your thread..Sorry I cant give you much advise but "Keep it up"
You will find the bug and kick it out the door.
Real interesting read, I really hope you will get your answer soon.
Please keep posting. And keep us all in the loop.
Best Regards
Steve
#30
09-21-2015, 03:44 PM
Thanks for the support! It's been a pain but the upside is the car has been otherwise driveable.
Unfortunately I'm stuck with a different issue right now. The car wont even run so I can't even troubleshoot this one.
I do have another theory on the misfiring though - When I changed the plugs I changed a few other things and the misfire briefly went away. I thought it was a fluke (given the misfire is so intermittent) so I disregarded the fix, and just as expected the misfire came back. I then went back to normal troubleshooting.
Interestingly enough, the shop changed the plugs at the same time they changed the ECU. They too then read 0 misfires when they took it out and attributed it to the new ECU. Of course as I got the car back and took it out for a spin the misfires came back... but I didn't think about how both times the plugs were new.
My new theory to check (once I get it working again) is to put new plugs in once again and see if the problem is again temporarily cured. My guess is the plugs get fouled REALLY quickly due to something, I'm just not sure what. I've also inspected the plugs probably a dozen times and seen no major issues (carbon, oil, etc.), so I have no reason to suspect somethings wrong with them except they were the common denominator the last two times the car ran smoothly - albeit briefly.
In any event, thanks for the support, and like I said I'm really justly writing all this to keep a log for anybody who has a similar issue down the line. I keep updating the OP with symptoms and steps taken.
Unfortunately I'm stuck with a different issue right now. The car wont even run so I can't even troubleshoot this one.
I do have another theory on the misfiring though - When I changed the plugs I changed a few other things and the misfire briefly went away. I thought it was a fluke (given the misfire is so intermittent) so I disregarded the fix, and just as expected the misfire came back. I then went back to normal troubleshooting.
Interestingly enough, the shop changed the plugs at the same time they changed the ECU. They too then read 0 misfires when they took it out and attributed it to the new ECU. Of course as I got the car back and took it out for a spin the misfires came back... but I didn't think about how both times the plugs were new.
My new theory to check (once I get it working again) is to put new plugs in once again and see if the problem is again temporarily cured. My guess is the plugs get fouled REALLY quickly due to something, I'm just not sure what. I've also inspected the plugs probably a dozen times and seen no major issues (carbon, oil, etc.), so I have no reason to suspect somethings wrong with them except they were the common denominator the last two times the car ran smoothly - albeit briefly.
In any event, thanks for the support, and like I said I'm really justly writing all this to keep a log for anybody who has a similar issue down the line. I keep updating the OP with symptoms and steps taken.