Stumped and completely out of ideas....
Stumped and completely out of ideas.... Starting a new thread to consolidate everything Ive done thus far.
This started with a simple cylinder head swap to a set of Stg 3 243 heads (along with factory gaskets, LS7 lifters, new trays, 7.375 pushrods, comp trunion upgrade, ARP bolts all around.) The car is a 2003 Z06 that was already equipped with a 230/232 592/595 111 cam, dynatech long tubes with cats, FAST 90/90 and a custom tune.
After installing the heads and triple checking everything, the car fired up right away with no immediate problems. Oil pressure looked good at 40 psi at an idle of 800-900 RPM. After getting up to operating temp, I checked under the car to verify no leaks of any kind. Thats when I noticed that the cats and the x-pipe were glowing bright red. I shut the car down to trouble shoot.
After trouble shooting for a few days and armed with an infra red thermometer, I tried starting the car again and let it run for 20 minutes. After 20 minutes, the cats and exhaust looked good and was running at a normal temp, as was everything else. Suddenly, the car sputtered and died. I tried to start it again, it sputtered and died immediately. I tried 3 more times, but it would only turn over and wouldnt fire. I pulled the spark plugs and found that the passenger side bank was running pig rich. The spark plugs were absolutely black. The drivers side didnt look too bad.
Today I replaced the plugs all around and gave everything a once over. I found that I had the front O2 sensors crossed with the driver side sensor plugged into the passenger side harness. With that problem solved, I attempted to restart the car. Again, it turns over, but wont fire, doesnt even sputter. I pulled the fuel rails and they were full of gas, so I am getting fuel to the injectors.
Lastly, throughout this entire process, there have been absolutely zero codes, none at all. Not even history codes. I have talked with Ed about getting the car tuned when he gets back in town sometime next week, but at this point, its going to be hard to tune if I cant even start it.
Im completely stumped. Any assistance would be much appreciated.
This started with a simple cylinder head swap to a set of Stg 3 243 heads (along with factory gaskets, LS7 lifters, new trays, 7.375 pushrods, comp trunion upgrade, ARP bolts all around.) The car is a 2003 Z06 that was already equipped with a 230/232 592/595 111 cam, dynatech long tubes with cats, FAST 90/90 and a custom tune.
After installing the heads and triple checking everything, the car fired up right away with no immediate problems. Oil pressure looked good at 40 psi at an idle of 800-900 RPM. After getting up to operating temp, I checked under the car to verify no leaks of any kind. Thats when I noticed that the cats and the x-pipe were glowing bright red. I shut the car down to trouble shoot.
After trouble shooting for a few days and armed with an infra red thermometer, I tried starting the car again and let it run for 20 minutes. After 20 minutes, the cats and exhaust looked good and was running at a normal temp, as was everything else. Suddenly, the car sputtered and died. I tried to start it again, it sputtered and died immediately. I tried 3 more times, but it would only turn over and wouldnt fire. I pulled the spark plugs and found that the passenger side bank was running pig rich. The spark plugs were absolutely black. The drivers side didnt look too bad.
Today I replaced the plugs all around and gave everything a once over. I found that I had the front O2 sensors crossed with the driver side sensor plugged into the passenger side harness. With that problem solved, I attempted to restart the car. Again, it turns over, but wont fire, doesnt even sputter. I pulled the fuel rails and they were full of gas, so I am getting fuel to the injectors.
Lastly, throughout this entire process, there have been absolutely zero codes, none at all. Not even history codes. I have talked with Ed about getting the car tuned when he gets back in town sometime next week, but at this point, its going to be hard to tune if I cant even start it.
Im completely stumped. Any assistance would be much appreciated.
I'd start by rechecking all electrical connections affected by the swap and the ground on the back of the DS head.
When you get the front 02 sensors swapped around, as soon as you go closed loop, the car runs like A**.
Not knowing what codes may be disabled in your existing tune, not having set any codes may not be indicative of what is going on.
When you get the front 02 sensors swapped around, as soon as you go closed loop, the car runs like A**.
Not knowing what codes may be disabled in your existing tune, not having set any codes may not be indicative of what is going on.
Great success! The car was running rich in the right bank because I had the O2 sensors crossed and it died and wouldnt start because the grounding wire on the back of the drivers side head had worked lose. Swapped the O2 sensors, tightened the grounding wire, it fires right up. After 10 minutes, it was idling perfectly with no problems and no hot cats.
Staging Lane
Joined: May 2011
Posts: 69
Likes: 0
From: Finleyville
I had this same problem with my 5.3. Aside from the cats glowing because i dont
Have any. I bent one of the prongs on the coolant temp sensor. And this was the cause. On my initial startup it ran for about 10 minutes and was running so rich I had to keep in the throttle just to keep it running. I'm guessing when the motor doesn't get a proper signal from the CTS it defaults to the bottom of the idle table (can't remember what its called right now)and runs fuel for -40' try cranking in clear flood mode a few times for 5-6 second intervals. And then try a normal start. It might fire back up but will load up again and die out. This is just a hunch but may be worth a try
Have any. I bent one of the prongs on the coolant temp sensor. And this was the cause. On my initial startup it ran for about 10 minutes and was running so rich I had to keep in the throttle just to keep it running. I'm guessing when the motor doesn't get a proper signal from the CTS it defaults to the bottom of the idle table (can't remember what its called right now)and runs fuel for -40' try cranking in clear flood mode a few times for 5-6 second intervals. And then try a normal start. It might fire back up but will load up again and die out. This is just a hunch but may be worth a try
