This is my first post and ya I'm a new F-body owner (2000 TA). Anyways, I'm still learning these LS1's, but I've worked with many caveman engines. With that being said, if one of my old engines was doing this and I already tried most of the things mentioned here then I'd suspect either the mixture is too rich (or bad gas), a plug wire arching or mis-routed to the wrong cylinder, or perhaps the timing is off or too advanced. How long did it run after you made all those changes? If something was installed improperly that'd definately account for the current issue. If it ran ok for several months after the changes then it's a fair assumption that this is a new issue and could be unrelated. Was anything changed just before it started running rough? Even something minor?

Rich or bad gas:
I've seen this exact symptom when the issue was bad gas. White smoke, runs rough, and may not start... yup sounds familiar. Your gas may catch on fire, but that doesn't mean it's suitable for a 10.5:1 cylinder. Try pouring some STP gas treatment in the tank - that cleared me up once. The tank is particuarly vulnerable to this condition when it is low on gas and the tank walls develop moisture from the outside air and it drips down into the gas.

Ignition:
To check the wires, you can set a multi-tester to ohms and check the resistance in each plug wire. A consistent reading from all wires is what you're looking for, but typically stock wires report approx 2000 ohms resistance per foot and a good aftermarket wire can be as low as 50-200 ohms per foot. This test won't always find an arch though. You could try starting it in complete darkness to actually look for this if ya wanted Also, I know you said that you checked the plugs for spark but I've seen a weird issue more then once that is worth mentioning. On an FI Honda CBR bike and an FI Nissan my brother owns all the plugs fouled at once following a cold start and an "on-purpose" instant shutoff. Try to start them the next day and all the plugs were fouled.

Timing:
This thing doesn't have a distributor so that kinda screws me up. I know it has opti-spark and is timed both mechanically (proper install of components) and then dynamically using the computer. So as a guess - if it is a timing issue, would disconnecting your battery for a few minutes and then trying to start it again reset the obd and maybe allow you to atleast get it running and pull some data-logging off it?

Good Luck!

 

Cams has been in for around 8 months.

The motor sounds fairly normal when trying to crank. Don't know for sure because it used to fire off within 1 second.

The plugs are definately black however they still spark when you pull them out.


Reluctor ring? Yes, no, maybe so?

 

Not to be a friggin nag, but you ought to drain the gas tank, and put in some new gas . . . You've tried everything else, just about. Purge the lines where you can. Best of luck.

 

I'm surprised nobody has mentioned the security system. Check to see if the security light is on disabling the fuel injectors. If this is the case... try a new key because if i remember correctly, if there is no signal to the computer from the pass key, it diables the fuel after 3 starting attempts. Just a thought. Good luck.

 

My security light was on the other day (2000 TA) and the starter would not turn at all. It wasn't until I armed and disarmed again that it would turn over and start. Do some years only cut the fuel? Seems like this was just a fluke cause it hasn't happened again.

If the fuel injectors are not spraying (or the alarm has disabled the gas flow) how would you account for what he describes as white smoke and wet plugs?

I'm still thinking bad gas man... atleast try the STP gas treatment and let us know how it goes. It's only like $2.99

 

When my security light came on, it would not crank at all. So, there's more than just a fuel cut happening. Once the ingnition cylinder was replaced and a new key made with the right resistor for that cylinder, the problem was solved. Started right up.

 

The car has spark air and fuel for all 8 cylinders. Verified three times by me and twice by a speed shop

 

Well, the car starts now. Haven't touched it and it starts. Go figure. However according to the tech 2, everything is as it should be except the car runs like ***. Found a broken valve spring however.

I know one broken valve spring would not cause a no start condition.

As far as I am concerned, the problem is still not fixed. I still can not determine what made this car not start.