I hope one of the great tuners can help me figure out this problem. I went to my local dyno shop to tune my car today for NO2. First I wanted to get a good baseline pull with no NO2 and set my AFR to 13.0 to 1 without the juice. I have LS1 Edit. I have already been working on getting my AFR were I wanted it. So anyhow today we hook everything up and start the car. The car was ideling with an AFR of 13.8 to 1. So we began the dyno pull. The AFR was a perfect flat line of 13.8 with no changes at all!! SO I put the stock program back in thinking I must have done something wrong. Again 13.2 to one at idel and a perfect flat line. All I can tell you is the only code I had was P0420 cat efficiency low bank 1. But it always throws this code after I spray. No other codes. So can anyone tell me were to start looking or if they think I screwed up the PCM to cause this problem. The O2 sensor is a wideband sensor that you stick a sniffer in the exhaust pipe. I thought maybe I have a plugged converter or maybe a bad spark plug. Please chim in with any answers or ideas.

 

When you "set the AFR to 13.0", how did you do that?

There are some params, and I think PE is one of them,
where increasing the value makes you leaner and
decreasing makes it richer (real tuning experts will
correct me if I'm backwards on the upside-down).

Since whatever you did made you leaner instead of
richer, maybe just try the opposite, starting from
the original baseline? Then you should have a pretty
good idea of the {setting} vs wideband O2 result,
and if it looks anything like a nice straight line, post
up the values and results so's we all get smarter.

 

I am sorry, I think I must have said it wrong. I have dynoed this car with the AFR sevaral times before I had LS1 Edit. Always before you could see the AFR was tracking 14.8 to 1 while you were btinging the the engine rpms up to 3500 were I would start my pull. At 3500 is were we would got to WOT and pull through 6000 rpm. At the instant we go to WOT we would see the AFR drop from 14.7 to 12.2 on all the old runs. This makes sense because the car is in closed loop while at cruise and normal exeleration mode and when you go to WOT it goes in to open loop (I think that is right or it might be open loop then closed loop, whatever it is this is what you see). Now what happend today was what I was talking about earlier. While ideling the AFR was 13.8 and it stated that +or- 0.2 the entire time. no matter if the car was in closed or open loop. No matter if you were ideling, part throttle or WOT. I have never seen it do that before and I do not belive it should do that. Now those numbers are with my tune (which all I changed was the MAF calibration and nothing else). SO I thought I must have done something wrong so I put the factory tune back in. Now it ideles at 13.0 +or- 0.2 and stays there no matter what. Same as the tune I had just leaner.

So why is it all of a sudden flatlining like that. I stayed and whatched 3 other cars get dynoed. 1 1981 vette, and 2 2001 vettes. They all had pretty much the same flatline on the AFR like mine did. SO I asked the dyno tech to pull up other LS1 cars from the past to see what the all did. The were all around 15 until they went to WOT at which time the AFR would drop to 12 or 13.

To finish this novel. At first I thought something was wrong with my car. But after seeing that I am pretty convinced something is wrong with their monitor. I do not think it should be perfactly flat like that. So if you have any ideas what could cause this situation on my end please help. I am at a loss. They think it is something to do with my car and not their equipment. I did not attempted to tune the car for the juice. I just do not trust those numbers and until i fix my car (if it is my car) or they fix their monitor, I will not use the juice or change my programing. Please help

 

It sounds like their wideband is bad.
Either the sensor is going out or if they use a tailpipe sniffer, there is a problem with the pump that pulls the exhaust gas to the sensor, or a kink in their tubing.

 

Yes, that is what I am thinking too. The one thing that tends to lead me to think this is the pulls I made today with the factory tune are with in 5 hp are the pulls I made last summer with the juice and without the juice. I would think if there were something wrong with the car then the hp numbers would be significanly different. I just have no way of convencing them. So I paid for pulls that I could not use. Oh well, I am sure they will come to the same conclusion sooner or latter and get it fixed. I am still going to make some checks to see if there is anything else that could be wrong with the car in the mean time. Thanks for your input