Well I have a good head scratcher that I can't seem to solve and hopefully would like to get the motor running before I take it to the tuner. Stock 2005 lq4 with 231/234 cam with 111lsa aftermarket intake and 4l80e drive by wire setup all from the same truck. Cut down the harness and had lane culver flash the computer so I could get it running around a little before I dyno tune it. It will fire right up for just a sec then cuts off like the injectors stop pulsing but during the 2 second start up it revs to 1000rpm sound good then just dies. I have tried many different way to address the issues but nothing changes anything. I have recheck the harness twice it is getting great grounds fuel pressure is stead at 58 at rest and slight dip of 2-3 psi during cranking. During cranking it does seem to be rich but hard to tell if that is left over fuel or if it is dumping way to much fuel. I unplug any sensor and no change to the way it runs. Changed the map and cam position sensor from my other rig and know they were working. Took the computer to lane just to make sure he cut the VATS off and of course he did it, it is also setup as speed density so shouldn't have to worry with MAF issues I don't have a good scanner so I can't see live data but for the life of me I can figure what is going on next thing I guess to try would be change the throttle body and crank sensor. I am kinda suck at the moment and hopefully someone has some great advice to help a brother out
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Help Support Hardline Crawlers :
Ls troubleshooting
- Thread starter jccarter1
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Im84
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Has the motor sat for any decent time? Injectors could be clogged, getting enough fuel on initial prime but not enough to keep up. Happened to me on my old buggy with an 8.1.
Other thought is are the white big rectangle plugs that go to driver side and pass side coils plugged into the correct side. They look the same and will plug into each other on mine and I got them mixed up doing similar stuff but with a little more of a miss. Switched them after I figured it out and been running since
Other thought is are the white big rectangle plugs that go to driver side and pass side coils plugged into the correct side. They look the same and will plug into each other on mine and I got them mixed up doing similar stuff but with a little more of a miss. Switched them after I figured it out and been running since
whiskeymakin
Well-Known Member
Sounds computer related to me. I had injector issues on a 5.3 that sat for a while. It wouldn't start period. Try and borrow a ecm from a buddy to see if there is any change....maybe Culver has a spare you could try....just to rule that out.
KPatterson
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Sound identical to what mine did. Turned out to be a bad sensor in the pedal.
KPatterson
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Just the sensor. Do you have throttle response? I had nonejccarter1 said:
KPatterson
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Crank, turn over. Sometimes fire then die. It started when it wanted and died when it wanted. No consistency. I was on the phone for hours with my tuner and the guy who built the harness checking everything, switching wires around.... I was sent a second tuned computer, did the same damn thing. Then, I send my whole harness, pedal, both computer and throttle body to them. They traced it down to the pedal sensor. I'm not saying go out and buy a new one, but it sounds pretty damn similar to the issue I had.
Well here is a little update still not acting right but might if found one issue. I was leaning towards the pedal due to the codes it was throwing so got a new pedal hooked it up still nothing so I checked the tac module and it had all the right voltage in an out but wasn't picking up the pedal so borrowed one off a buddy's truck and it cleared all the codes and gave me thorttle movement but still does run right it is doing the same thing I has been from the beginning not throwing codes and seems to be right just not running
Well I kinda figured this thing out and I say kinda bc it is running now but I can't explain why. So I over the last few days I have been trying everything asking anyone who would give me the time of day (thank you to the people who helped me out) tried so many different things cam sensor,crank sensor, throttle body, map sensor, check harness a few times checked voltage on sensors,grounds, input nothing worked still just would fire off and die. During this I checked the injector pattern and noticed they would fire like 2 pulses then stop so I was leaning to an issue with the ecm so took it and put it on another rig and the ecm worked great so that sent me back to the drawing board. Well I get back try a few more things and finally get pissed off and try to see if I could keep it running with starting fluid after the injectors stop pulsing. Well I spray it down and keep it running for like 15 seconds and then when I go to fire it up again I can now pedal it to keep it running I don't know what the starting fluid dose but it allows it to crank and then be able to stay running after that but if I unhook the battery it goes back to not staying running and I have to start it with starting fluid then it will allow me to pedal it to keep it running. It is a very weird issue I am glad it is running but still a little perplexed on wtf is going on with it
No I have it all out and hot wired to the battery pump isn't the issue it maintains 58 psi, the injectors them self quit pulsing after a few seconds but when I kept it running on starting fluid it all of a sudden starts to work correctly and will continue to work until you disconnect the computer from battery only thing I could think of would be I am fooling it and bringing it out of limp mode or it open loop
kmcminn
Well-Known Member
ranger11 said:
Clint who did your harness?
87_bigbadzuk
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I was having an issue on my 5.3 where it would start but barley run. No throttle. Turns out the alt charging wire was shorted somewhere and if the ecm senses the alt not working correctly it throws it in limp mode and kills the pedal. Pulled all the chassis wiring from the suzuki and redid the wiring and runs perfect. Doubt this is your problem.
