Cycle key twice to start (has good fuel pressure)

[Ragin Cajun]

I have a 99 Camaro h/c/I ls1. Car runs good and have been driving it since Ive built and tuned it for quite some time but Ive had a issue with the car wanting the key cycled twice to start. The car has a fuel pressure gauge on the fuel rail and the first cycle the fuel pressure goes straight to 58 psi and stays but if you crank it on the first key cycle it wont start or it will take a while to start. I always just cycle it twice and it fires instantly every time so Im not real sure what the deal is, its just kinda annoying to have to do that every time. Have any ideas on what the issue could be or what to look at the fix this?

[MikeOD]

Have you ever had anyone help you check to see if you have spark/fuel the first time you hit the key? I'm wondering if there's something preventing the PCM from seeing the crank or cam sensor.

[Ragin Cajun]

Sorry for the late reply, but yes it does have spark every time so I don't believe its that

[5_Liter_Eater]

Could be cam sensor.

[jimmyblue]

My van acts this way but only when hot. I suspect that
I have some vapor in the rails that can't be pushed out
by only one prime cycle.

[c.u]

Ragin,try adding some to the cranking fuel table. See if helps.

[AutoWiz]

10 years before your car was made, in 1989, gm started putting this feature in their ecu's so that when the engine was cold, the ecu would have to see oil pressure before it would light the fuel injectors. this led to a notorious 5sec cranking time on cold startup on c4 cars. and the bypass for it was to turn the key on. and then off and back on and start the car. instant every time. I'm not saying that has anything to do with your problem, just that it would be interesting to have a noid light connected to an injector when it doesn't start and see if you aren't getting fuel delivery. a failed cam sensor should just bring about a long cranking time. but wouldn't change with a key cycle. the ecu needs to see ckp input without cmp input for x amount of time before it switches which revolution it hits the coils on. and the car should still run. cranking fuel also shouldn't impact cycling the key before starting. this smells like a failure and not tune related. something controller, or ground, or voltage or expanded pin related.

can you try disabling vats ?

[dab2pds]

cam sensor on recent 6.0 swap I tuned caused this intermittently. was not coding the cam sensor either
Dave

[AutoWiz]

honestly now, a failed cam sensor brought you to a point where you could cycle the key twice without cranking and it will start right up? consistently? really? a failed cam sensor will bring you to long cranking time. but the pcm must see ckp without cmp and the engine not light for x sec. before it will switch which stroke it fires on. that is doubly true if the pcm isn't even coding for the cmp. yea? tell me how would cycling the key impact a pickup coil?

a failing cam sensor on your 6.0L might have brought you to intermittent no starts, or repeated starting attempts and long cranking times at that to get the car to light. but not the above listed symptoms. just trying to be objective here and pay attention to the details

[badco01ta]

like said above go to fuel tab, cranking fuel, fa multiplier and increase this table in the area affected by about 2 to 5 percent added and see if it helps if so play with it until you like it, try not to add more than about 10 to 15 percent though as with that much added you may have some other fueling tables that need attention

[5_Liter_Eater]

honestly now, a failed cam sensor brought you to a point where you could cycle the key twice without cranking and it will start right up? consistently? really? a failed cam sensor will bring you to long cranking time. but the pcm must see ckp without cmp and the engine not light for x sec. before it will switch which stroke it fires on. that is doubly true if the pcm isn't even coding for the cmp. yea? tell me how would cycling the key impact a pickup coil?

a failing cam sensor on your 6.0L might have brought you to intermittent no starts, or repeated starting attempts and long cranking times at that to get the car to light. but not the above listed symptoms. just trying to be objective here and pay attention to the details

That's exactly what I saw. Maybe it works a little different on the vette with push button start but I would hit the button and it would crank and time out. Hit the button again and it would fire right up. I was no throwing any cam codes. I changed the sensor and then I started throwing the expected cam codes. Fixed the harness issue and the problem has been resolved.

[AutoWiz]

But, you're listed as a senior tuner? since 2005. over 3900 posts. You must be tired. please go and re-read the first post. then agree with me that this is not a cam sensor or cranking fuel issue.

[Howes]

what about something dumb like a carboned up throttle body/ iac passage? you cycling the key moves the iac motor depending how quickly you cycle the key the iac may be open enough still to fire more easily. can you tap the gas while cranking the first time and have it fire? that would point to restricted airflow. They are less sensitive when cold because they open way up.

[5_Liter_Eater]

But, you're listed as a senior tuner? since 2005. over 3900 posts. You must be tired. please go and re-read the first post. then agree with me that this is not a cam sensor or cranking fuel issue.

How about you blow me?