LS3 NO power!
Thread Starter
Teching In
Joined: May 2011
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LS3 NO power! Hey guys,
I've got a bone stock LS3 e-rod crate engine installed in a Nissan 240SX and the engine ran completely fine before I made a 2300 mile journey from California to Michigan.
I had a fuel pump failure on the drive but have sinced fixed that. The engine runs completely fine under light load under 3500 rpm-ish.
As soon as I get on it though theres no power. The RPMs rise but theres just no power. I thought the gas was bad so I pumped up some quality 94 octane but the same thing is still happening. I then checked the timing and Im getting around 20 deg in 2nd gear under full throttle to about 5500rpm ( dont want to rev it higher).
I also checked the compression just to be sure the engine isnt hurt and it was 210 on all cylinders.
Do you guys have any suggestions as to what I can check on the engine to remedy this? It seems something electronic but no check engine light at all.
I've got a bone stock LS3 e-rod crate engine installed in a Nissan 240SX and the engine ran completely fine before I made a 2300 mile journey from California to Michigan.
I had a fuel pump failure on the drive but have sinced fixed that. The engine runs completely fine under light load under 3500 rpm-ish.
As soon as I get on it though theres no power. The RPMs rise but theres just no power. I thought the gas was bad so I pumped up some quality 94 octane but the same thing is still happening. I then checked the timing and Im getting around 20 deg in 2nd gear under full throttle to about 5500rpm ( dont want to rev it higher).
I also checked the compression just to be sure the engine isnt hurt and it was 210 on all cylinders.
Do you guys have any suggestions as to what I can check on the engine to remedy this? It seems something electronic but no check engine light at all.
TECH Enthusiast
Joined: May 2008
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Any way to check fuel pressure under load? If it ran right before the replacement fuel pump, would be the first thing I'd check. Might also check fuel filter. If it's downstream of a pump that ate itself, may have deposited some debris in filter or line.
Thread Starter
Teching In
Joined: May 2011
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Well today I re-wired my fuel pump to ensure consistent voltage to the pump. It went from having 12v to now having 14v. Unfortunately it hasnt solved my problem.
Tomorrow I'll check my fuel filter but I dont think theres a chance in hell thats the problem. Its a small Earl's inline AN filter but its as old as the engine is (2300 miles). I also think that if it was the filter then it would be hard to get good fuel pressure at idle which I can easily set at 60psi.
Im am waiting till this weekend to install a fuel pressure gauge but I too am doubting it is a fuel delivery issue. The more I think about it the more it seems related to electrical.
Out of curiosity does anyone know what the 02 sensor voltage should be under full throttle? Is the voltage supposed to go down under load vs cruising? I am monitoring it with my OBDII scanner and see that it drops voltage as I apply the gas.
Tomorrow I'll check my fuel filter but I dont think theres a chance in hell thats the problem. Its a small Earl's inline AN filter but its as old as the engine is (2300 miles). I also think that if it was the filter then it would be hard to get good fuel pressure at idle which I can easily set at 60psi.
Im am waiting till this weekend to install a fuel pressure gauge but I too am doubting it is a fuel delivery issue. The more I think about it the more it seems related to electrical.
Out of curiosity does anyone know what the 02 sensor voltage should be under full throttle? Is the voltage supposed to go down under load vs cruising? I am monitoring it with my OBDII scanner and see that it drops voltage as I apply the gas.
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What ECM do you run?
The voltage should be constantly fluctuating till you go WOT. I can fire up the laptop and tell you what my voltage is at WOT, but it is an LS2 with E40 ECM. Not sure if it is the same for all of them or not.
I also don't think that 20 degrees of timing at WOT is right.
The voltage should be constantly fluctuating till you go WOT. I can fire up the laptop and tell you what my voltage is at WOT, but it is an LS2 with E40 ECM. Not sure if it is the same for all of them or not.
I also don't think that 20 degrees of timing at WOT is right.
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Teching In
Joined: May 2011
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Well guys. I want to slap myself over the head.
All this week I have been slowly going through the possible causes of this problem. Started off with draining the gas thinking it could have been that, then swapped the fuel pump again thinking that could be the problem. Re-wired the fuel pump with a thicker gauge since I had 12V at the pump (now have 14V) and still the same problem.
Today I decided to tackle the fuel filter as it was the last possible bottleneck in the fuel system. When I pulled the filter off it was kinda gunked up inside so I cleaned it out (Its a small Earls AN fitting style filter). I then noticed that it had an arrow pointing on it with the flow direction... funny because when I installed it I didnt really remember seeing that. After digging through some old photos sure enough I had the filter installed backwards!
So after cleaning the inside and installing it in the proper flow direction, the car is back to normal
It feels SOO good to have power again.
The puzzling thing is that before I made the 2300 mile journey the engine ran fine and felt strong with the filter on backwards. I am assuming a combination of the debris and flow direction caused my fueling issue.
I'm just glad to have figured it out though, thanks for all the help!!
All this week I have been slowly going through the possible causes of this problem. Started off with draining the gas thinking it could have been that, then swapped the fuel pump again thinking that could be the problem. Re-wired the fuel pump with a thicker gauge since I had 12V at the pump (now have 14V) and still the same problem.
Today I decided to tackle the fuel filter as it was the last possible bottleneck in the fuel system. When I pulled the filter off it was kinda gunked up inside so I cleaned it out (Its a small Earls AN fitting style filter). I then noticed that it had an arrow pointing on it with the flow direction... funny because when I installed it I didnt really remember seeing that. After digging through some old photos sure enough I had the filter installed backwards!
So after cleaning the inside and installing it in the proper flow direction, the car is back to normal
It feels SOO good to have power again.The puzzling thing is that before I made the 2300 mile journey the engine ran fine and felt strong with the filter on backwards. I am assuming a combination of the debris and flow direction caused my fueling issue.
I'm just glad to have figured it out though, thanks for all the help!!
Thread Starter
Teching In
Joined: May 2011
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You can see my entire build thread here: http://zilvia.net/f/chat/385069-ls3-...h-hate-v8.html
The engine bay & car look like this.
The engine bay & car look like this.
The thing with these kinds of swaps is everyone always thinks when theres a problem to look at the PCM or wiring related etc. The second a computer is involved with a swap car its natural to just think that this is where to look for problems because no one truly knows all what they do by memory alone. However after years of swapping computer controlled engines I can honestly say aside from forgetting to wire the O2's up at the PCM end on one particular car the issues we faced were always some small mechanical oversight just like this and worth laughing at afterwards.
Glad you got it sorted Pete. Clean swap
Glad you got it sorted Pete. Clean swap
