Truck is giving me hell!!!!
07-26-2012, 10:35 AM
#1
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Truck is giving me hell!!!! I have swapped a 02 LQ4 w/241 heads and an ASA cam backed by a th350 into an 85 C10. I really want this thing to run and I am at my wits end with it. I got it to idle on its own but there was a miss that I could definitely feel. When We were able to put the scanner on it we were gettting P0200 and P0300 codes(Injector Circuit Problem and Random Misfire)
Here is what we have done:
1. I moved the grounds for the PCM from the body to the motor. All of my grounds for the engine/PCM are now on 1 ground on the back of the motor. I have 4 grounds from the PCM (pins 1 & 40 on each connector), 1 for each coil bank and 02 sensor and 1 for the MAF/IAT sensor.
2. hooked up noid lights to the injectors and 1, 3, 2, and 4 injectors weren't lighting up.
3. I checked all the injectors for keyed 12v and they all had 12.3v
4. Next I checked the continuity of the injector wires from the pin for the computer to the injector and all of them had connectivity.
5. I also swapped the injectors around to see if the problem followed the injectors but I wasn't sure if it made a differnece bc I could un hook all plugs from 1 side and no matter which 1 i hooked up it seemed to run a little better. This is where I stopped bc I ran out of time.
After talking to a buddy about how the noid lights worked I have come to the conclusion that it probably isn't an injector issue but probably either wiring or the actual computer itself. After reading and researching I have found out that there are drivers in computer for the injectors but I can't find out which injectors go to which driver anywhere. If I knew that it would help out. I am not sure where to go from here and I am tired of chasing our tails. I followed everything on LT1swap.com to a tee.
Here is what we have done:
1. I moved the grounds for the PCM from the body to the motor. All of my grounds for the engine/PCM are now on 1 ground on the back of the motor. I have 4 grounds from the PCM (pins 1 & 40 on each connector), 1 for each coil bank and 02 sensor and 1 for the MAF/IAT sensor.
2. hooked up noid lights to the injectors and 1, 3, 2, and 4 injectors weren't lighting up.
3. I checked all the injectors for keyed 12v and they all had 12.3v
4. Next I checked the continuity of the injector wires from the pin for the computer to the injector and all of them had connectivity.
5. I also swapped the injectors around to see if the problem followed the injectors but I wasn't sure if it made a differnece bc I could un hook all plugs from 1 side and no matter which 1 i hooked up it seemed to run a little better. This is where I stopped bc I ran out of time.
After talking to a buddy about how the noid lights worked I have come to the conclusion that it probably isn't an injector issue but probably either wiring or the actual computer itself. After reading and researching I have found out that there are drivers in computer for the injectors but I can't find out which injectors go to which driver anywhere. If I knew that it would help out. I am not sure where to go from here and I am tired of chasing our tails. I followed everything on LT1swap.com to a tee.
07-26-2012, 05:24 PM
#2
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I am gonna take a stab and say try checking for 12v at the injectors while it is running (with a load on the circuit) I have seen poor connections show good voltage when there is no load but break down when the load is placed on it.
07-31-2012, 10:21 AM
#3
I am having the exact same issue with my 5.3 in my 68. It fires right up and sounds great, then drops down and sounds like it's running on 2 cylinders. Getting same codes and have gone through the same diagnostics you have. Hopefully we can both get an answer here
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