hey guys I keep getting a code 13 while driving car is a 89 formula l-98 62000 miles mods are ud pulleys air foil cai and just a flowmaster 80 muffler I keep getting a code 13 cel I replaced my 02 sensor what else could it be thanks

 

the code 13 is set with a rich condition, sooty o2 or loss of o2 signal, check continuiety on the o2 wire to d7 signal of the ecm and d6 to ground. Using a scanner to see what the ecm is seeing is a help full tool or watching the o2 swing when the engine is warm using a analog vom. This also can be caused bye a faulty ecm.

 

ok thanks could changing out the stock muffler to the flowmaster cause the code 13, it started after having the muffler installed or is just a coincidence

 

Just a coincidence

 

thanks I am going to replace the 02 sensor again and give it a try, if that don't work will go from there

 

Do the tests first

http://www.chevythunder.com/o2_sensor_diagnostics.htm

 

can you eliminate the 02sensor by programming out of the ecm and if so how would the car run thanks

 

You could but the question is why would you ?
If you followed the procedure in the link I posted ;
you would have worked out what the cause of the DTC 13 is and FIXED it cheaper than getting the ECM reprogrammed

 

You can force the car into open loop all the time... there are ways to do that Im pretty sure. I dont think it's a good idea though. You want the car to run properly. Without closed loop it wont run right. It might be possible if you're really good at tuning get the open loop tune close enough that you might not notice but it's a whole lot easier to just check the O2 sensor circuit and replace the O2 sensor if the circuit is fine.

 

ok thanks I replaced the 02 again and still there I will do the check later tonight thanks if not the 02 what else bad plug or bad ecm sorry for all the questions just new and want to get it right.

 

Work through the O2 fault chart to find out!