ECM failed last month. I was able to remove the Diablo tune before towing it to the dealer for an ECM replacement. Got the car back and it did not idle well and lacked power. Reinstalled the Diablo 93 tune and it did not help with the idle or odd "fishbite" idle (as the dealer tech referred to the idle random misfire). I didn't expect reinstalling the tune to help. It is not logging a code for misfire. Fuel pressure is 60 psi. Removed the fuel rail and injectors, turned them over and pressurized the fuel rail. No leaking injector tips. All injector coils ohm good.
Installed new AC iridium plugs and wires. Ran a few data logs and found cyl #5 had a 0.15 second misfire an all three data logs. (logged as a single misfire)
Question; #5 cyl in the data log would be the fifth cyl in the firing order correct? That would be cyl #6 on the engine if I remember this correctly. Only thing left to replace is the coil.

 

Swap the coil with another cylinder to test before buying one.

 

#5 cylinder is driver side.3rd cylinder in counting from front of engine

 

I would check compression on that cylinder while the plug is out

 

The basic question is ; when reading a datalog, is the #5 cyl the fifth cyl in the firing order or the #5 cylinder of the engine? I did not think the datalog program can recognize the correct firing order for each type of engine.

 

coil wire too....

 

New plugs and wires to start with. Tested ohms on old and new wires.
The question is; change or swap coil, wire, injector ect. on the fifth cylinder in the firing order or #5 cylinder on the engine.
#5 cylinder misfire on datalog means; ??? fifth cylinder in the firing order (which is cylinder #6) or is it actually cylinder #5 that is having the issue?

 

What are you data logging with? HPTuner, EFI, SnapOn scanner, Tech 2?

Any misfire codes like P0305?

 

Move just coil/wire first since that will take like 2 minutes. After that I'd swap injector

Just swap cylinder 5 with cylinder 6, that will cover either cylinder being the culprit.

If still no changes/answers I'd try moving injectors around and see if anything changes.

 

Logging through a diablo I1000 into a panasonic toughbook. Looking at 1 - 8 cyl misfire counts.
No codes at all. I've replaced the coil with a new one and swapped several coils around from other cylinders. All the spark plug wires were replaced along with the plugs. I've swapped the new wire out with another known good plug wire on cyl #6. I stock a new set of plugs and wires, filter, belts ect for the LS motor. No problem replacing the plug wires and coil. I do not think the spark plug wire has been causing an issue. It has been moved are replaced several times. No change.
I still have the same question; When running a datalog, when it references cyl #5, is it looking at the fifth cyl in the firing order or Actually #5 cylinder?

 

If you're looking at 1-8 cyl misfire counts, at least with my scan tools, it is the actual cylinder. In this case cylinder # 5 itself, not the fifth cylinder in the firing order.

A lot of times a very slight misfire will not set a code, it is below the threshold to set, however the misfire diagnostic section on the scan tool will see them which is good.

 

Thanks. That is what I have been looking for. All of the diesel diagnostic software that I use will list a cylinder as the number in the firing order. I have been wasting time looking at issues with cyl #6. I'll swap out some new stuff on cyl #5 and run another log. Just updated the diablo data viewer and maybe that will speed things up when dealing with this dataviewer.

 

Where did you get the Diablo Data Viewer ?

Dave

 

Keep in mind, it is still a 'calculated' value based on crank position. It's not like there is a sensor in each cylinder checking for misfires. It's possible to be coming from the next closest cylinder, etc. Granted, it's just about always right. Ford trucks are famous for bad coils that set misfire codes. Using either the misfire diagnostics section or MODE 6 raw data will lead you to the bad cylinder every time.

Just a thought, did they do a crank position relearn after replacing the ECM?

 

I got my data viewer with the I 2030. It is a download directly off Diablosport's WS.

 

Yes, they did a crank relearn. That is why I had to take it to the dealer. The tech and I discussed the idle when I picked the car up. he said I may be chasing a ghost and good luck. That coil may have the issue while I was the track at Talladega last month. I think I finally have it fixed. Coil on #5. Been looking at the wrong bank. Seems to run better but will hit the highway this afternoon. Sounds better, idles better.

Downloaded the updated data viewer from Diablo. Also reinstalled the Diablo tune after seeing the same idle issue without the tune. Raised the idle speed 50 rpm and increased the fan duty cycles through the range of coolant temps. Logged two different 1 minute runs and no misfires. It was not a serious miss, just enough that I knew it was happening and wanted to find it.

 

Oops...wrong hole .

Glad you got it figured out.

 

mine was showing the same thing and it was the plug wire off the spark plug