Engine Stops - No Codes

[GentleBen]

I've had three instances over the past two weeks where, after sitting a red light for a long period, when I start moving (yes, with a green light) the engine quits for no discernible reason. No codes are sent to the DIC nor does my OBDII scanner report any set or pending codes.

It will immediately restart and either immediately quits requiring a second (or third) restart or continues to run with no further problem. It does not set any code that I can find and the most that shows is a few misfires (5 on plug 8, 1 each on plugs 7,6, and 5, with 0 misfires on all remaining plugs).

This has happened when (1 instance) the gas was a little below 1/4 filled and the last two times where the gas level was between 7/8ths and full tank. The air filter (K&N) was cleaned over two months ago and seems to be okay. Battery is a yellow top Optima and holds a consistent charge between 13.8 and 14.2 volts.

Anyone have an idea of what could be causing this?

ADDED: The car is a 2005 and it has a complete Lingenfelter 403 engine that has been in it for over five years with no problems before now, a one-year old Optima yellow top that consistently holds between 13.8 and 14.2 volts, K&N air filter that was cleaned over two months ago, and is a manual 6-speed Z51 vehicle.

[6spdC6]

First thing I would do is check all GROUND hook ups!
With all that you report I would hazzard a guess that you have a computer about to shit the bed if the grounds are fine!.

[GentleBen]

While researching the problem in LS2 forum as well as other forums it appeared that the problem could be caused by oil fouling on the MAF Sensor caused by the cleaning and re-oiling of the K&N air filter two months ago.

Accordingly, I cleaned the MAF Sensor and took the car out for a quick spin. Seemed to have cleared until the 15-minute mark when I was idling at a red light. Unlike earlier incidents, it did not stop while at the light but immediately after I started to move. It was not a stutter or stumble it just stopped - bang! It immediately restarted and I did not have another problem but this is becoming a real pain under the pistol belt.

To reiterate, the car is a 2005 Z51 with 6-speed manual, a Lingenfelter 403 engine that has not presented a problem in over five years, K&N air cleaner, yellow top Optima which holds 13.8 to 14.2volts, and it still shows no codes (posted or pending) on my scan tool.

I'm at a loss and hope someone can provide some more ideas on what to check next.

[GentleBen]

Now it is beginning to cut out while driving. I had gone approximately .5 miles past the stop light and, while driving in a straight line at about 2,000 rpm, the engine quit. It immediately restarted and I completed the drive to the office when another symptom began. When I pulled into the garage to park the car the engine began to oscillate between 1,000 and 500 rpm and run very rough until it just stopped. Again, no codes are showing on the DIC or on my OBDII scanner.

I will be "head down" in the engine bay this afternoon trying to see if I have a loose ground or if a spark plug boot is not firmly seated.

Anyone have any ideas of what could be causing this? I'm at my (half)wits end.

[6spdC6]

Originally Posted by GentleBen

Now it is beginning to cut out while driving. I had gone approximately .5 miles past the stop light and, while driving in a straight line at about 2,000 rpm, the engine quit. It immediately restarted and I completed the drive to the office when another symptom began. When I pulled into the garage to park the car the engine began to oscillate between 1,000 and 500 rpm and run very rough until it just stopped. Again, no codes are showing on the DIC or on my OBDII scanner.

I will be "head down" in the engine bay this afternoon trying to see if I have a loose ground or if a spark plug boot is not firmly seated.

Anyone have any ideas of what could be causing this? I'm at my (half)wits end.

Its more than a sparkplug boot! You would see misfires causing the oxy sensors to give crazy readings (Among other things). I hold to what I said in my original post.

GOOD LUCK!

[GentleBen]

Turns out that the crankshaft now has too much end play (on the order of .0030") which causes the crank position sensor to send a code to the ECM telling it to stop the engine. I suspect that the end play could have been caused by the new clutch I installed when the Luk Gold proved that it could not handle the horsepower and torque of the Lingenfelter engine.

Right now the Blue Beast is at 21st Century Muscle Cars in Texas having the crank bearings (especially the thrust bearing!) replaced and the engine "freshened".

However, the prospect of not driving a 'Vette for the remainder of the summer and all of the fall caused me to buy another toy - a 2011 GS convertible with a Callaway SC606 package and a few other toys.

[6spdC6]

Originally Posted by GentleBen

Turns out that the crankshaft now has too much end play (on the order of .0030") which causes the crank position sensor to send a code to the ECM telling it to stop the engine. I suspect that the end play could have been caused by the new clutch I installed when the Luk Gold proved that it could not handle the horsepower and torque of the Lingenfelter engine.

Right now the Blue Beast is at 21st Century Muscle Cars in Texas having the crank bearings (especially the thrust bearing!) replaced and the engine "freshened".

However, the prospect of not driving a 'Vette for the remainder of the summer and all of the fall caused me to buy another toy - a 2011 GS convertible with a Callaway SC606 package and a few other toys.

Sounds like you will suffer your way through this OK.