problems getting engine started

Bad news. I took my injectors to NAPA so they could flow test them. They flowed great. So now i'm wondering if maybe the injectors are not getting the necessary electrical signal, and how can I check for that? They flowed 78cL in 15 seconds??? Whatever that means. So, anyways I thought I was on to something, but now I'm not so sure. Is there a way to tell if the injectors are getting the necessary electrical signal?
 
I'm not sure I know what engine function signals the injectors to fire. Cam sensor maybe? I have never looked into it.
 
81cuttysupreme said:
Bad news. I took my injectors to NAPA so they could flow test them. They flowed great. So now i'm wondering if maybe the injectors are not getting the necessary electrical signal, and how can I check for that? They flowed 78cL in 15 seconds??? Whatever that means. So, anyways I thought I was on to something, but now I'm not so sure. Is there a way to tell if the injectors are getting the necessary electrical signal?
Click to expand...

Yep. If the engine runs, the injs are likely getting power and commanded ground. You could get a noid lite from NAPA.. Inexpensive tool. While you have the injs out, check each plug w/ the noid. Just be sure you pull the fuel pump fuse first!
Noid will flash every time that particular inj is commanded to fire...[If the circuits are working, that is.]

Without a data log using EFILIVE, HPT, etc, it's pretty hard to detect any problems.....You know NE1 that has such?
 
I don't know anyone that has that diagnostic equipment nearby. I just replaced the cam sensor and it made no difference. I will try a noid light next. Then I guess I'll try the crank sensor. If the light or cranksensor don't do anything I will once again be out of ideas. But until then........
 
first let me say thanks to you guys for hanging with this thread and helping me through this missery.

so i got a noid light and it seemed to show a signal from each of the injector plugs. so with good fuel pressure and electrical signals, i gotta beleive that the cylinders are getting fuel. i checked the spark plugs already and saw that thery are all getting spark. is it possible for the fuel and spark events to be out of time? I replaced the cam sensor just for the fun of it, and it made no difference. i have a new crank sensor also but i dont think it will make a difference either. so is there some way i'm not getting fuel and spark? i'm stumped again now.
 
You don't have the inj harness/ coil harness on backwards, do you?
If you are getting a tach signal, the crank sensor is working.
Timing is set in the tune. If it wasn't messed with thru a tune, it won't change.

Where are you located?
 
no harness isnt on backwards. I am getting a tach signal. I'm located in DE. A long ways from everyone it would seem.

I measured the voltage at the crank plug yesterday, and got something a little weird. From pin A to C i got 10.6 volts, i thought it should be 12 volts??? Does this mean anything to you guys? I also checked my engine ground again by putting one pin on the engine block and the other on the passenger side fender since my engine is grounded to the body then to the battery. The ohm meter read 0 resistance. So it would seem the engine is grounded just fine.

Any other ideas???
 
I had a no start issue going from the LS1 cam sensor to the ls2-3 cam sensor. The ls2-3 is located in the front cover, I had to swap wires A and C to pick up cam signal with the new sensor.
Hope this helps...
 
I would check voltages on both cam and crank sensors. I agree with chuck it's tough to diagnose without proper data. Time to order up a HP tuners, efi live etc.
 
"since my engine is grounded to the body then to the battery. " Huh????? Where is this taking place" I was just pointing out that my engine isnt grounded directly to the battery. It is grounded to the firewall, through the body, and then to the battery in the trunk. But b/c my fender is all sanded down i put the test probe on it to make sure the engine has a good ground.
 
I did use a simple continuity test from the engine block to a couple different places on the body. Why would that be an invalid test? According to the meter there was 0.1Ohm resistance. I have two ground straps from the engine to the firewall, one braided strap and one 1 gauge wire. Not sufficient?
 
So why would testing continuity from the engine to the body not be an accurate assesment of how well the motor is grounded? Does it not show how efficient. It is? No measure of capability to flow amps?
 
to give an update.....i hooked a cable from the engine to the engine and battery just to see if the motor had a bad ground. it didnt make a difference. i also pulled alll of the injector plugs off so i could test them with the engine at a steady speed, not trying to start and sputter. each inector flashed twice right at starter onset and then quit even though i kept holding the starter going. so i know the injectors are not getting the right signal, but idont know why. does anyone know anything about re-learniing the crank? how? why?
 
81cuttysupreme said:
to give an update.....i hooked a cable from the engine to the engine and battery just to see if the motor had a bad ground. it didnt make a difference. i also pulled alll of the injector plugs off so i could test them with the engine at a steady speed, not trying to start and sputter. each inector flashed twice right at starter onset and then quit even though i kept holding the starter going. so i know the injectors are not getting the right signal, but idont know why. does anyone know anything about re-learniing the crank? how? why?
Click to expand...

Id check the vats. I know you had it removed, but id bet they didnt remove it. Theres ways to bypass it with a theft detterent from a 96 caprice police package. The box sits behind the dash and all you need to do is get a power source for it and connect the blue wire to the ecm pin for the vats signal.It will send the correct pulse width signal to keep the ecm happy and your injectors firing. I have no experience with the LS engines but the LT1s I swapped throughout the years had similar problems. You need that signal to keep it running. My .02
 
i checked the vats again, it is still turned off. it does sound exactly like a vats problem though. the only thing i can think of is something wrong with the crank signal????
 
Problem solved. VATS! Even though i asked one shop to check it twice, and they swore up and down that they turned it off. I took it to another shop and the first thing they saw was that it was still turned on. Go figure. If it looks like a dog, smells like a dog, and barks like a dog......................

Thank you to all the guys who stuck with me on this.
 
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