Ok here is the story, i have a 2000 Ls1 with 35,000 miles on it. Car has stock ported T.B., lid, air filter,Slp y-pipe, borla muffler. That is it, the computer has never been touched. I pulled the car in the shop the other day pulled the cats off, gutted them put them back on the car. Pluged all the o2s back in started car. Let car warm up and went for 2 passes to 90 Mph 5,800rpm shifting. No big deal, pulled back to the shop car is smoking like mad!!?? It is a blue,gray color smells like raw gas. So i reset the ECM and unpluged the back two O2s and started car does the same thing?? Oil level is full drove car for 50 miles oil is still full. The inside of the tail pipes are coal black.
Now for the funny stuff, when i frist started car after gutting cats i gave it some gas to about 3500 rpm i saw the traction control light flash one time??? After unpluging the back o2s and driving 50 miles no check engine light?? When you turn key to run and start car the car the check engine light never comes on at all?? I think it should when you frist start??

PLEASE HELP the motor can not be junk can it?? If it is man i dont know what to do?? But all this after i gutted the cats??


THANK YOU MAtt

 

P.S. Oil Psi is good, power is good too.
Thank you

 

You messed with the cats and are not running 02 sims. Gutting the cats leans out the mixture to the rear 02 sensors, and now they're adding a ton of fuel to compensate for what they think is a major lean condition. That's why it bogs, smells of fuel, and runs like ***. You're super rich and the PCM is confused as all hell.

Three choices:

1) Replace the cats
2) Get LS1 Edit and delete the rear 02s from the PCM
3) Get a pair of $70 02 sims and plug them in back there.

Any one of the above will fix your problem after you do it and reset the PCM. Option #3 is the best chance you have with the least money invested. If you were to scan your PCM in real-time with something like Auto-Tap, you'll probably find your block learns (BLMs) and fuel trims maxed out at 28, giving the realization that your PCM is dumping fuel for a "lean" condition that doesn't exist.

Welcome to Advanced OBDII

 

Uh...he's smart. ^^^

I'm surprised actually that you don't have a SES light on. Basically, like Bone Maro said you're PCM is quite confused. If I were you, I'd only drive it if I had to until I fixed it.

 

Thanks, I've been studying.

That, and you learn a lot when playing with supercharger and nitrous tuning

 

THANK YOU MAN!! I have some O2 sims comming will have Friday!!
Now i can sleep!! P.S To reset the Ecm what is the best way?

 

One of two ways:

1) Pull the negative battery cable for about 10-15 minutes

2) Remove the PCM BATT and PCM IGN fuses from the underhood fuse block and turn the car to one click before start(idiot lights pop on and the fuel pump primes, etc). Turn the key back and remove, then replace the fuses.

Both of those sufficiently reset your PCM, but I prefer the battery cable method

 

Just a couple of quick notes.

The rear O2s have absolutely NOTHING to do with the tune. The computer uses them to see if the cats are working only.
Sims are a good cure for keeping the SES off after removing the cats.
You'll need to have someone with Autotap scan your car to see what's going on with the rich condition.

To reset the computer.
Turn the key to run without starting the engine.
Pull the PCM batt and PCM ign fuses
Wait about 10 minutes with the key on
Turn off key
Re-insert fuses.

Hope this helps

 

Also..when you plugged your o2's in make sure you plugged them in the right spot. My friend has a 99z and for the longest time he drove around with his o2's plugged in wrong. He had his rear o2's deleted, but plugged his front o2's into the rear o2 plugs. It ran ok..but got poor gas mileage. Try checking your connections. As said above the rear o2's only check if the cats are working.

-Corey

 

The rear 02s have limited control over the A/F ratio of the vehicle. So yes, they can still throw the PCM into confusion.

Also apply login into the situation. What was the last thing he did to the car before it started running rich? Gutted the cats. So what's the likely problem? The cats being gutted, which in this case, will throw off the rear 02s.

Like stated. They're not there to only look at the cat operation, they also show limited functionality in adjusting the A/F ratio of the car via the PCM.

I've also seen this first hand during 6.5 hours of tuning and scanning.

 

Yep, my rear O2's were starting to throw an SES light so instead of buying new ones I was just gonna gut the cats and throw on the sims. Well before I did this I was getting 150miles to a tank of gas. After gutting the cats and throwing on the sims I am now getting 240-250miles per tank with no changes in driving.