Hey guys,

I am looking for some ideas on what type of issues that I may be having. I finally got to the cranking part of my build and was able to get the motor running for about 8 seconds until it cut off, and when I tried to crank it again, it would only turn over. It seems as if I have enough juice when turning it over, but it wont crank. It's a 2005 LQ4, mildly built for turbo. I am running a PSI Conversions Harness and PCM, Optima Red Top battery, Deka 80 lb injectors.

I have checked:
12 V to coil pack harness when key on
12 V to each injector when key is on
Fuses and Relays are good
Voltage when cranking = 10 V
I have fuel pressure at the rail.
Grounds - battery to frame, frame to block, head to firewall, firewall to frame - all clean/tight contacts

Any ideas from the experts?

Thanks!!

 

Check to make sure you don't have the coil harness wiring crossed, drivers side #1 cylinder should have a purple trace wire......#7 should have red trace wire.
Then the passenger side should have #2 red trace wire and #8 purple trace wire.

 

Thanks for the quick reply on the post cula8r, the wires on each coil and each individual injector are the correct wires. I hadn't considered checking the individuals and their placement until you mentioned it.

 

I'd like to also add that I currently do not have any exhaust other than headers installed (i.e. no O2 Sensors). Also not that I think it matters, I do not have the knock sensors installed, and the MAF sensor is not hooked up.

 

**UPDATE**

I pulled the plugs and they had a good amount of fuel on them, and the passenger side plugs were all slightly darker. I cleaned the plugs up and reinstalled them and also unplugged my fuel pump relay. The engine fired without hesitation as soon as I turned the key and ran great for about 15 seconds until I turned it off. I reinstalled the fuel pump relay and when I turned the motor over, it would not crank, only continuously turn over like earlier today. I then unplugged the relay once more and the engine fired right up.

It seems as if I am dumping too much fuel into the motor with the current tune and 80 lb injectors. I am going to give PSI Conversions a call Monday to discuss the issue with them. I think getting

Hope this helps with any future Non-Starts!

 

There's a tune diagnostics forum for this type of problem.....

 

Without a tune for the injectors you are dumping to much fuel in the motor. If you have the stock injectors you can put them to run it. You could damage the motor with 80 lb injectors without the proper injector data programmed to the pcm.

 

My apologies Old Buzzard, I posted here originally under the assumption that my issue was most likely mechanical or electrical, not tune related.

Thank you for the heads up on the potential for damage to the motor gagliano7. I have spoken to my tuner and will have the PCM retuned for 80 lb injectors before any future starts.

 

hubcap706 you can see how not giving all pertinent information in the original post kept anyone from seeing the problem of way to large of injectors for the engine to even start.
I hope others will try to think to give ALL build info when asking for diagnosis.
Glad you figured it out before you hurt it