LQ4 Swap in a Jeep
09-01-2011, 11:12 AM
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Join Date: Sep 2011
Location: Warrenville, IL
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LQ4 Swap in a Jeep Hi,
I just joined this forum... figuring you all could help.
I just recently put a 6L LQ4 in my 94YJ replacing the original 2.5L POS. I fired it up on Sat night... it sounded beautiful. I did that several times over the course of the evening. Next morning, I go out and can't even get it started. It turns over just fine. I quickly did a check of fuel pressure (about 55- 60psi). I pulled the plugs... bad carbon fowling. Cleaned em up and started it up again. It started, but I had to work the throttle to keep it alive. Something is different between Sat night and Sun morning.
FYI, right now I have no O2 sensors on the harness... but I'm in open loop on the PCM so I believe it shouldn't matter.
I'm kind of at a loss as to what to check next. I have spark, I have fuel, just runs like crap cold. I don't want to let it go too long because it will never reach closed loop given I have no O2 sensors.
I plan on cross checking all the grounds and making sure my harness is tight.
One last question... how do I know the PCM is working properly? I hear the fuel pump come on for about 2 seconds when I turn the key, but I get no codes despite not having O2 sensors in the system. I did have an issue with power to the PCM on Sat night and I ended up toggling it's power lead several times inadvertently.
Thanks in advance for any advice.
I just joined this forum... figuring you all could help.
I just recently put a 6L LQ4 in my 94YJ replacing the original 2.5L POS. I fired it up on Sat night... it sounded beautiful. I did that several times over the course of the evening. Next morning, I go out and can't even get it started. It turns over just fine. I quickly did a check of fuel pressure (about 55- 60psi). I pulled the plugs... bad carbon fowling. Cleaned em up and started it up again. It started, but I had to work the throttle to keep it alive. Something is different between Sat night and Sun morning.
FYI, right now I have no O2 sensors on the harness... but I'm in open loop on the PCM so I believe it shouldn't matter.
I'm kind of at a loss as to what to check next. I have spark, I have fuel, just runs like crap cold. I don't want to let it go too long because it will never reach closed loop given I have no O2 sensors.
I plan on cross checking all the grounds and making sure my harness is tight.
One last question... how do I know the PCM is working properly? I hear the fuel pump come on for about 2 seconds when I turn the key, but I get no codes despite not having O2 sensors in the system. I did have an issue with power to the PCM on Sat night and I ended up toggling it's power lead several times inadvertently.
Thanks in advance for any advice.
