Random misfires on bank 1: timing/cams dead on
#1
03-12-2011, 04:01 PM
Random misfires on bank 1: timing/cams dead on
I've been diagnosing the timing in my car for quite some time now. I'm running low on ideas.
Ever since I did a timing belt change I've been getting misfires on Bank 2. So I took the front off again and noticed the intake and exhaust cams on bank 2 were off so I adjusted it properly. Bank 1 intake and exhaust cams were dead on. I reset the timing dead on with the cam lock bar and crank pin. Couple rotations back to TDC and bar slides on perfectly. Start the car and within a minute or so I'm getting flashing CEL and random misfires on bank 1. Consistently repeatable after clearing codes.
Spark plugs good, coil pack resistance good, ignition wires good, cam position sensor good. What could be the problem?
Ever since I did a timing belt change I've been getting misfires on Bank 2. So I took the front off again and noticed the intake and exhaust cams on bank 2 were off so I adjusted it properly. Bank 1 intake and exhaust cams were dead on. I reset the timing dead on with the cam lock bar and crank pin. Couple rotations back to TDC and bar slides on perfectly. Start the car and within a minute or so I'm getting flashing CEL and random misfires on bank 1. Consistently repeatable after clearing codes.
Spark plugs good, coil pack resistance good, ignition wires good, cam position sensor good. What could be the problem?
#3
03-12-2011, 08:37 PM
The furthest off they've been has been less than 1/2" too high on the cam lock bar between exhaust cams. In other words, when I had the cam lock bar on bank 1 exhaust cam, the pins that should fit in to the bank 2 exhaust cam were about 1/2" too high with the crank pin installed.
I did run it like that with misfires on bank 1, then I fixed it so the cam lock bar was **** on. After I fixed that, the misfires were on bank 2, which was probably due to the intake and exhaust cams being off by one tooth. I fixed that, reinstalled timing belt **** on again, now the misfires is in bank 1.
Were those tolerances enough to have the pistons interfere with valves? If I had any sort of issue with valves, I'd definitely notice it, right? Vag-com isn't giving me much information, except that all the systems appear to be working. I took a sample of some engine stats, maybe that can help?
So on...
I did run it like that with misfires on bank 1, then I fixed it so the cam lock bar was **** on. After I fixed that, the misfires were on bank 2, which was probably due to the intake and exhaust cams being off by one tooth. I fixed that, reinstalled timing belt **** on again, now the misfires is in bank 1.
Were those tolerances enough to have the pistons interfere with valves? If I had any sort of issue with valves, I'd definitely notice it, right? Vag-com isn't giving me much information, except that all the systems appear to be working. I took a sample of some engine stats, maybe that can help?
Code:
Saturday,12,March,2011,16:59:28 3B0 907 551 BP,,2.8L V6/5V G 0001, ,Group A:,'001,,,,Group B:,'002,,,,Group C:,'003 ,,Engine RPM,Coolant Temp,Oxy Sensor 1,Oxy Sensor 2,,Engine RPM,Engine Load,Injection Timing,Mass Air Intake,,Engine RPM ,Mass Air Intake,Throttle Angle,Ignition Angle ,TIME,,,,,TIME,,,,,TIME,,,, Marker,STAMP, /min,°C,%,%,STAMP, /min,%, ms, g/s,STAMP, /min, g/s,%, °BTDC ,0.85,0,21.0,0.0,0.0,0.24,0,100.0,0.00,0.00,0.54,0,0.00,5.9,0.0 ... ,8.10,1160,21.0,0.0,0.0,7.49,1160,23.3,5.44,8.14,7.80,1160,8.22,6.3,35.3 ,9.00,1160,21.0,0.0,0.0,8.40,1160,24.1,5.78,8.64,8.70,1160,8.64,6.7,18.8 ,9.91,1160,21.0,0.0,0.0,9.30,1160,23.3,5.10,8.33,9.61,1160,8.47,6.3,20.3 ,10.81,1160,21.0,0.0,0.0,10.21,1160,23.3,5.10,8.31,10.51,1160,8.14,6.3,18.8 ,11.72,1160,21.0,0.0,0.0,11.12,1160,22.6,5.10,8.19,11.42,1160,8.25,6.3,18.0 ,12.62,1160,21.0,0.0,0.0,12.02,1160,22.6,4.76,8.14,12.32,1160,8.08,6.3,17.3 ... ,100.42,840,24.0,-1.6,-6.3,99.82,840,18.0,3.40,4.67,100.12,840,4.67,3.9,19.5 ,101.33,800,24.0,-6.3,-3.1,100.71,840,18.0,3.06,4.67,101.02,840,4.64,3.9,21.8 ,102.23,840,24.0,-0.8,-2.3,101.63,840,18.0,3.40,4.61,101.92,840,4.61,3.9,22.5 ,103.14,840,24.0,-2.3,-7.0,102.53,840,18.0,3.40,4.67,102.83,840,4.67,3.9,19.5 ,104.04,840,24.0,-7.0,-2.3,103.43,840,18.0,3.06,4.67,103.74,840,4.67,3.9,21.0
#4
03-12-2011, 10:58 PM
Well, don't start a car unless the timing is "**** on" this ain't a chevy, lol. One tooth off, i don't think would smack a valve though. But you were elbow deep into the motor, first thing is to go through everything you took apart, bumped, twisted, nudged...make sure you didn't loosen something or whatever.
#5
03-13-2011, 04:17 PM
I took some logs of about a 2 minute period where I idle the car, rev up to 2000, back down, and up to 2000 slower while recording misfires on bank 1.
0 misfires on bank 2 during this period, but I can hear the misfires pretty consistently when rpm is above ~1300.
#6
03-14-2011, 12:49 AM
That's great and all, but you need to double and triple check for problems related to the disassembly and repair that was just performed. 9 times out of 10 an issues that starts right after major service was caused by something sloppy in the service.
Not saying you did anything is wrong, but you have to be sure before you can proceed with diagnostics.
Not saying you did anything is wrong, but you have to be sure before you can proceed with diagnostics.
#7
03-14-2011, 05:56 PM
I double/triple checked all the electrical connections I may have bumped... still the same issue.
Could it possibly be an issue with a clogged/restricted fuel rail/injectors on that bank? I ordered another set of OE spark plugs. The spark plugs I just put in (from O'Reilly... ugh) were NGK but the one-electrode plugs as opposed to the dual electrode plugs. Perhaps that is the difference?
Could it possibly be an issue with a clogged/restricted fuel rail/injectors on that bank? I ordered another set of OE spark plugs. The spark plugs I just put in (from O'Reilly... ugh) were NGK but the one-electrode plugs as opposed to the dual electrode plugs. Perhaps that is the difference?
#8
03-15-2011, 11:25 PM
Well, First thing is to try to move the miss. It's simple to do, and though it's unlikely you lost three coils or injectors, it's not impossible. So swap the coils over, you can also swap the injectors. Just one is fine, that would tell you if you have an issue further up the line. Personally i would check fuel pressure on that bank, but im thinking you dont have a gauge.
If the miss doesn't move, then you need to look further up, at some commonality between those cylinders, Fuel rail is a good place, check wire looms, etc. I'm not 100% certain, but i don't think it would be an ECU problem, in my experience (with non-Audi cars) an ECU issue would effect all cylinders.
You're into hardcore diagnostics here, I would imagine it's an issue with the fuel rail, or something like the wiring to the coils grounding or something else just as irritating.
Good Luck.
If the miss doesn't move, then you need to look further up, at some commonality between those cylinders, Fuel rail is a good place, check wire looms, etc. I'm not 100% certain, but i don't think it would be an ECU problem, in my experience (with non-Audi cars) an ECU issue would effect all cylinders.
You're into hardcore diagnostics here, I would imagine it's an issue with the fuel rail, or something like the wiring to the coils grounding or something else just as irritating.
Good Luck.
#10
03-24-2011, 09:04 PM
Just did a leak down test and all cylinders are within the range of 5 - 13%... thankfully my valves/head aren't damaged.
Here's a video of what's going on:
http://www.youtube.com/watch?v=B2-dwwVAWyk
Here's a video of what's going on:
http://www.youtube.com/watch?v=B2-dwwVAWyk