Ultimate ls harness and trans controller NO SPARK 🙁
I bought the harness and trans controller for a lq4 I am using the factory intake and injectors. I finally have everything together and wired up and noo spark . so when I crank I do not see any rpm on the hand held when I let off of the key i see the rpm bounce up to 40-70 for a second on the handheld. I changed the crank sensor and no change I ohmed out all the wires on the plug back to the ecu connector. all good there. so i hooked the battery back up and the ecu and checked the plug for 12v and that was good.. so at this point I am very frustrated. I have tried multiple programs. and even tried the system reset that bryan from fitech sent me.
soooo if anyone has any suggestions I am open . Thank you in advance
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Check your harness plugs and pins carefully. Factory coil harnesses also were known to wear out. Replace cam sensor. Are you getting power to the coils? Just throwing stuff out there. This could be any number of issues.
Very common is your switched wire not remaining 12v during crank. When the voltage drops during crank, the ecu shuts off like you turned the key off.
i actually just checked the switched wire and it was dropping to zero while cranking so i moved it and now it is trying to fire!!
but it isn't staying running
These things we have to work through. If they plugged and played, this website wouldn't exist.
you are correct sir. Thank you for your help and now I need to trouble shoot this stalling issue. I wish I would have installed a pressure gauge on the fuel rail now. but i feel like its a programming thing it will start and run for a few seconds then stall and then it wont restart unless i shut the key off again and cycle power.
If you could point me in any direction i would greatly appreciate it.
side note: I am super geeked this project is like ten years in the making. putting a lq4 in a 82 gmc short bed 🙂 it sounds great for a few seconds anyway lol. it is all stock except for schoenfield headers.
Hey Austin, So i just read something you posted somewhere else about exhaust and it throwing off the 02 sensors I only have like 18 inches of exhaust behind the headers could that be one of my issues with it stalling immediately?
Do you have a pressure gauge on the fuel line?
no I dont. I wish I would of put one when I ran the fuel lines.
now I will have to do that or maybe I will grab the $20 fuel pressure kit from harbor freight to check it
Open exhaust will produce incorrect O2 readings.
OK.... update. When you install a new fuel tank and lines put more than 2 gallons of gas in it... DOH.
so I was thinking about it today after i went out and bought a fuel pressure tester and realized i probably didn't put enough gas in it.
so i threw another 5 gallons in it and bam it purrs like a kitten even without full exhaust but Im sure it will be much better once I get the exhaust on it.
Thanks every one for your help.