LLY: Injector Electrical System

[bullfrogjohnson]

I have a 05 Kodiak that I have been working on and off for quite some time. It lost the #1 piston over a year ago. I looked at the truck and it had a balance rate of +15 on #1. I did a compression and sure enough it was zero on #1. The owner had a buddy pull the motor and rebuild it. Well the buddy didnt know what he was doing and caused alot more issues. I looked at the truck again to see what was going on it had a terrible rod knock. I had to completely rebuild the motor. Before the motor came out I checked the balance rates and cylinder #1 had a +15 balance rate again. After I tore the motor down I never found anything that would cause the high balance rate on #1. The owner replaced the #1 injector and put the motor back in the truck. I helped him get it running the other night and everything is fine but cylinder #1 still has a +15 balance rate. I swapped #1 and #7 injector and the high rate did not follow the injector.

So I know there is nothing wrong internally in the motor to cause the ECM to think #1 is low on power. I know the injector is not faulty. I am starting to think the FICM is bad.

What does the ECM look at to calculate balance rates? I am assuming it the acceleration of the crank/cam reluctor wheels when each injector is fired?

 

[DAVe3283]

I believe that is how the ECM determines balance rates.

If you shut the #1 injector off with EFILive, does the engine sound change, even momentarily? I can usually notice a split-second glitch when I turn on/off an injector with EFILive. If you don't get that, then it is entirely possible the FICM isn't actually powering the injector. If the FICM is the same on the Kodiak and the regular LLY, you could try swapping a known good one in and see what happens.

 

[ripmf666]

You check the injector harness for chaffing. Eric carries the kit onhis site I never added it. It says 7 and 2 but I think I saw it can happen on 1 also.
http://www.merchant-automotive.com/llyinjectorharnessupgrade.aspx

 

[slipclutchms]

I was dealing with a similar issue on a lly...turned out to be the bale connectors on top of the motor. Found one loose pin not making good contact and the balance rates were all over the place and the truck ran like crap.

 

[SHOTZY]

Well I'm in the boat too boys! Number 1 on mine has seen +8.0 and don't have a clue. Truck runs fine. Was goin to check valve lash. Egt's creep up during idle too.

 

[DIGGLER]

i would say broke crank had you not had it apart a couple of times. i had a 12 balance rate on my #2 cylinder, good compression on all cyls, turning off each injector one at a time didnt reveal anything. went ahead and replaced that injector with a new one. continued knocking like a mofo and taking several rotations to get started.
wound up being a broke crank beside the #2 rod.

 

[Chevy1925]

I have a 05 Kodiak that I have been working on and off for quite some time. It lost the #1 piston over a year ago. I looked at the truck and it had a balance rate of +15 on #1. I did a compression and sure enough it was zero on #1. The owner had a buddy pull the motor and rebuild it. Well the buddy didnt know what he was doing and caused alot more issues. I looked at the truck again to see what was going on it had a terrible rod knock. I had to completely rebuild the motor. Before the motor came out I checked the balance rates and cylinder #1 had a +15 balance rate again. After I tore the motor down I never found anything that would cause the high balance rate on #1. The owner replaced the #1 injector and put the motor back in the truck. I helped him get it running the other night and everything is fine but cylinder #1 still has a +15 balance rate. I swapped #1 and #7 injector and the high rate did not follow the injector.

So I know there is nothing wrong internally in the motor to cause the ECM to think #1 is low on power. I know the injector is not faulty. I am starting to think the FICM is bad.

What does the ECM look at to calculate balance rates? I am assuming it the acceleration of the crank/cam reluctor wheels when each injector is fired?

arent the injectors ground triggered (i cant remember of the top of my head)? have you ohmed the #1 wires from the connector back to the FCIM?

 

[paint94979]

Travis did you ever solve this?