Help! LS conversion won't start!
Help! LS conversion won't start! I have been fighting this thing for 4 days now. I have a 2000 truck harness that was remorked to make it stand alone and converted to the Ls2 injector plugs. The ECM is from an 04 standard 5.3. I have confirmed that there is 12 volts at the ECM, coils and injectors.
I know the red blue connectors are not supposed to be compatible with the blue/green ECM. I have gone through the pinouts and the 2000 and 2004 pinouts and they are the same from what is used for a stand alone system. I did change the connector insert to match the ECM.
I have 60 pounds fo fuel pressure at the return regulator which is AFTER the fuel rails.
When trying to start it cranks strong and sputters. I thought that maybe VATS had not been removed, but I took the ECM to a local tuner and he confirmed that it was disabled. I had a 3.3 Bar map sensor and he said the 5.3 ecm would not work with the ecm. He reflashed the ecm and set it up for the 2 bar map sensor since I will not be running more than 15 pounds of boost. I picked up the new sensor last night and turned the key to get the same result.
The plugs smell like fuel which leads me to believe the injectors are pulsing.
I hooked up my autometer tach to the tach output from the ECM last night and turned the key. When I turn the key to ON the tach goes to 0. Should I be seeing any rpm register during cranking? I expected to see the needle move some while cranking. This is a new build with all new parts. I ma leaning toward a bad crank sensor, but wanted to make sure the 2004 didn't have a different reluctor on the crank.
I am trying to finish the car to get it to PINKS All out this weekend!!!
Thanks!
I know the red blue connectors are not supposed to be compatible with the blue/green ECM. I have gone through the pinouts and the 2000 and 2004 pinouts and they are the same from what is used for a stand alone system. I did change the connector insert to match the ECM.
I have 60 pounds fo fuel pressure at the return regulator which is AFTER the fuel rails.
When trying to start it cranks strong and sputters. I thought that maybe VATS had not been removed, but I took the ECM to a local tuner and he confirmed that it was disabled. I had a 3.3 Bar map sensor and he said the 5.3 ecm would not work with the ecm. He reflashed the ecm and set it up for the 2 bar map sensor since I will not be running more than 15 pounds of boost. I picked up the new sensor last night and turned the key to get the same result.
The plugs smell like fuel which leads me to believe the injectors are pulsing.
I hooked up my autometer tach to the tach output from the ECM last night and turned the key. When I turn the key to ON the tach goes to 0. Should I be seeing any rpm register during cranking? I expected to see the needle move some while cranking. This is a new build with all new parts. I ma leaning toward a bad crank sensor, but wanted to make sure the 2004 didn't have a different reluctor on the crank.
I am trying to finish the car to get it to PINKS All out this weekend!!!
Thanks!
Teching In
Joined: Mar 2008
Posts: 29
Likes: 0
From: La Canada, California
crankin it Pull out a spark plug, ground it (away from the cylinder so it doesn't ignite the fuel) and crank the car, ensure that you have spark. Do this on several cylinders.
Rather than assuming that the injectors are pulsing, you can verify it very fast. Take a screwdriver (bigger is better) and place it on top of each injector. While cranking, put your ear next to it. When I was first told to do that, I thought it was silly, but believe me, if they are pulsing you will hear it rather loudly through the screwdriver.
Now you have spark and fuel, all you need is air.
When pressing the accelerator, ensure that the throttle body is opening and closing properly and while cranking, ensure that it is pulling in air. Check to ensure that you have plugged ALL possible vacuum holes, check every square inch all around the engine. The largest vacuum opening on my LS1 is exactly on the rear of the engine where it is hard to see.
Those are the basic preliminary checks. If that all checks out then I would suggest that you connect an OBDII scanner to your ECM and see if it is complaining about anything. It might just tell you what is wrong.
Someone else might want to report on the potential issues if your reluctor signal is bad.
Rather than assuming that the injectors are pulsing, you can verify it very fast. Take a screwdriver (bigger is better) and place it on top of each injector. While cranking, put your ear next to it. When I was first told to do that, I thought it was silly, but believe me, if they are pulsing you will hear it rather loudly through the screwdriver.
Now you have spark and fuel, all you need is air.
When pressing the accelerator, ensure that the throttle body is opening and closing properly and while cranking, ensure that it is pulling in air. Check to ensure that you have plugged ALL possible vacuum holes, check every square inch all around the engine. The largest vacuum opening on my LS1 is exactly on the rear of the engine where it is hard to see.
Those are the basic preliminary checks. If that all checks out then I would suggest that you connect an OBDII scanner to your ECM and see if it is complaining about anything. It might just tell you what is wrong.
Someone else might want to report on the potential issues if your reluctor signal is bad.
I connected an ODB scanner and it was throwing no codes. All sensors were working. I went back to the pinouts and the 04 does not have a TP circuit! Going to pick up an 02 Camaro ECM and move on. Thanks for the help guys! I used a timing light to ensure consistent spark. Had air, fuel, and spark....no TPS information though so throttling had no effect.
Oh, and with the tach changed to 4 cyl instead of 8 it does read rom during cranking.
Oh, and with the tach changed to 4 cyl instead of 8 it does read rom during cranking.
