Misfires on 1, 4, 6, 7 (ever other in firing order)
08-11-2013, 03:31 PM
#1
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Misfires on 1, 4, 6, 7 (ever other in firing order) I built my first engine. It's a rebuild on a 2000 Z28 A4.
It has a new cam, similar timing to the hot cam with a bit more lift. I just set the timing on it using the dot-to-dot method. Other than that the parts were replaced only to refresh things rather than modify.
It runs, sounds great, and I can drive it. It does like to stall if I don't give it air, but I'm planning to raise the IAC RPMs after getting the misfire thing taken car of. What I'm seeing is that while the engine runs it is throwing the P0300 code very quickly. Before getting the individual cylinder counts I replaced the plugs and checked for vacuum leaks. I think the plugs looked similar on all cylinders when I changed them, but it also hasn't really run much. Checking the counts, I'm seeing the misfire counts go up on cylinders 1, 4, 6, and 7 very frequently. Since that's a weird pattern, I noticed that's every other cylinder in the firing order. What should I be looking into for this?
It has a new cam, similar timing to the hot cam with a bit more lift. I just set the timing on it using the dot-to-dot method. Other than that the parts were replaced only to refresh things rather than modify.
It runs, sounds great, and I can drive it. It does like to stall if I don't give it air, but I'm planning to raise the IAC RPMs after getting the misfire thing taken car of. What I'm seeing is that while the engine runs it is throwing the P0300 code very quickly. Before getting the individual cylinder counts I replaced the plugs and checked for vacuum leaks. I think the plugs looked similar on all cylinders when I changed them, but it also hasn't really run much. Checking the counts, I'm seeing the misfire counts go up on cylinders 1, 4, 6, and 7 very frequently. Since that's a weird pattern, I noticed that's every other cylinder in the firing order. What should I be looking into for this?
08-12-2013, 03:50 AM
#3
TECH Senior Member
Crank angle sensor error relearn.
If this does not do it then you need to edit the misfire tables and redo the CASE relearn
(i.e. don't just edit out misfire detection... adjust it to work with your cam, if you can).
If this does not do it then you need to edit the misfire tables and redo the CASE relearn
(i.e. don't just edit out misfire detection... adjust it to work with your cam, if you can).
08-12-2013, 08:56 AM
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I haven't double checked the valves yet because of the work involved. Compression test was next in my plan if the pattern of misfires logged wasn't either this or all left/right.
"Crank angle sensor error" sounds like something that would fit into my guess it's timing related because of the interesting pattern. I don't have a tool that will request the relearn, so I'll start looking into that. There seem to be a lot of threads on that already. Hopefully I'll post back here with results on that soon.
"Crank angle sensor error" sounds like something that would fit into my guess it's timing related because of the interesting pattern. I don't have a tool that will request the relearn, so I'll start looking into that. There seem to be a lot of threads on that already. Hopefully I'll post back here with results on that soon.
08-12-2013, 09:16 AM
#5
TECH Senior Member
Did you get the PCM tuned for your cam (and heads and anything else)...?
If not then you really should (it will run better) and you can get tuner to address the misfire detection.
If not then you really should (it will run better) and you can get tuner to address the misfire detection.
