Motor will turn over but not fire
09-02-2008, 06:32 AM
#1
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Motor will turn over but not fire I originaly posted int he conversion section, but have not gotten any responses so I thought I should go where the experts are.
https://ls1tech.com/forums/showthrea...8#post10028528
I have put a LS1 and 4L60E into a 1950 ford and I can not get it to start.
https://ls1tech.com/forums/showthrea...8#post10028528
I have put a LS1 and 4L60E into a 1950 ford and I can not get it to start.
09-02-2008, 07:51 AM
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There are several potential problem spots. Having a custom harness may be one of them. Assuming you have at least: crank signal, IAT, ECT, TPS, and MAP hooked up, you should be able (in theory) to run the engine. Do you see any data for any/all of these sensors when scanning?
If you re-built the engine (bottom & top ends), you may have physical issues with the reluctor wheel, crankshaft end play, cam installed incorrectly, etc.
The PCM has to have a good working crank sensor to run the engine. As long as the PCM receives the CKP sensor 24X signal, the engine will start. The PCM can determine the top dead center for all of the cylinders just by using the CKP sensor 24X signal. The PCM uses the CMP sensor 1X signal in order to determine which stroke the cylinder, at the top dead center, is on.
Your diagnostic approach on the CKP sensor sounds correct.
Hopefully your tuning company disabled the security features of the PCM. That could be one problem.
If you re-built the engine (bottom & top ends), you may have physical issues with the reluctor wheel, crankshaft end play, cam installed incorrectly, etc.
The PCM has to have a good working crank sensor to run the engine. As long as the PCM receives the CKP sensor 24X signal, the engine will start. The PCM can determine the top dead center for all of the cylinders just by using the CKP sensor 24X signal. The PCM uses the CMP sensor 1X signal in order to determine which stroke the cylinder, at the top dead center, is on.
Your diagnostic approach on the CKP sensor sounds correct.
Hopefully your tuning company disabled the security features of the PCM. That could be one problem.
09-02-2008, 08:12 AM
#3
I read the other post.. You said the engine is cranking and backfiring.. That would lead me to think you have fuel and spark.. Just in the wrong time frame.
If the engine is firing, I'm wondering why you have no tach signal??
No tach signal would mean no fuel pump operation?
Does key on/engine off trigger the fuel pump prime?
What's your FP read while U R attempting a start?
If the engine is firing, I'm wondering why you have no tach signal??
No tach signal would mean no fuel pump operation?
Does key on/engine off trigger the fuel pump prime?
What's your FP read while U R attempting a start?
09-02-2008, 12:19 PM
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Thanks for the help.
I will take another look and see if I have power in the actual start position vs the run position. But, if it does not have power at start, how would the motor pop and back-fire?
I did pull the crank sensor plug and try to crank it and the computer did throw a code, so I assume that the computer is getting something from the sensor. I then cleared the code, plugged in the sensor connector and cranked the motor again and I did not get any new codes.
Should I do the same check on the cam sensor (check input voltage and confirm ground is Okay)?
I am new to EFI-Live, so I am still trying to find my way through the program. How do I see what the sensors are reading (Intake air temp, water temp, etc.) prior to cranking? If I go to the dashboard tab I do not see anything (I could be looking at the wrong thing I would not doubt it).
If this was a SBC with distributer I would think that the timing is off the way it is acting (popping, back firing, etc.). This is the most trying thing to figure out and I find myself double guessing myself and think I might have bitten off more than I can chew. I am sure that with everyone's help I can solve the problem but it is frustrating.
I will take another look and see if I have power in the actual start position vs the run position. But, if it does not have power at start, how would the motor pop and back-fire?
I did pull the crank sensor plug and try to crank it and the computer did throw a code, so I assume that the computer is getting something from the sensor. I then cleared the code, plugged in the sensor connector and cranked the motor again and I did not get any new codes.
Should I do the same check on the cam sensor (check input voltage and confirm ground is Okay)?
I am new to EFI-Live, so I am still trying to find my way through the program. How do I see what the sensors are reading (Intake air temp, water temp, etc.) prior to cranking? If I go to the dashboard tab I do not see anything (I could be looking at the wrong thing I would not doubt it).
If this was a SBC with distributer I would think that the timing is off the way it is acting (popping, back firing, etc.). This is the most trying thing to figure out and I find myself double guessing myself and think I might have bitten off more than I can chew. I am sure that with everyone's help I can solve the problem but it is frustrating.
09-03-2008, 06:18 PM
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Thanks for everyone’s help. I have done the wise thing and that is contact the person who I got the harness and computer from. I should have done this in the first place, and wow all I can say is that they are more than helpful and a wealth of information.
It looks like I am now on the right path to getting the car running, and finding out where I screwed up. For anyone asking yes I did confirm that the computer is programmed for the correct relucter wheel, and yes the VATS is disabled. I knew this was the case, but it was confirmed. I have a good starting point and the Harness people have given me a wealth of information already.
I was really thinking that I had bitten off more that I can chew with this project, but after talking to these guys I am feeling that this is a solvable issue and the car should be up and running soon. Unless I discover something that I completely screwed up (let’s hope not).
It looks like I am now on the right path to getting the car running, and finding out where I screwed up. For anyone asking yes I did confirm that the computer is programmed for the correct relucter wheel, and yes the VATS is disabled. I knew this was the case, but it was confirmed. I have a good starting point and the Harness people have given me a wealth of information already.
I was really thinking that I had bitten off more that I can chew with this project, but after talking to these guys I am feeling that this is a solvable issue and the car should be up and running soon. Unless I discover something that I completely screwed up (let’s hope not).
