I have a 96 TA with a 383 and all the trimmings, the car runs ok but when it is in open loop, like when it is warming up, she runs great. I have a stoich meter on her and it shifts from lean to rich continuously, but every now and then it will just stay in the rich and run like a dream, the computer is reprogrammed from the turbo shop in cali, but not programmed with the car hooked up. Can I just disconnect the MAF and the o2 sensors and make it run in open loop all the time?

 

All you need to do is just disconnect the O2s to run in open loop, you don't need to disconnect the MAF. Also, if you are going to program her, you can just set the open loop to closed loop settings so high that it never reaches the conditions to switch to closed loop. This seems to be a pretty common thing, especially if you are running a super/turbocharger. Open loop is much easier to tune as well, you don't need to worry about all those extras that closed loop tuning has.

 

I have also heard of this also but if he remains in open loop, wont his gas mileage go to hell. I remember when I had to disconect my o2's and had to run in open loop and my gas mileage was HORRIBLE. for then simple reason is the car is running continusely(sp) rich and then computer has no way to tell if the car is running right.

 

Yes, that is correct, the PCM sets the AFR to a richer setting than what the closed loop usually sets it at. But, if he is going to have it tuned, he can tune the open loop settings to a leaner condition, allowing for better gas mileage and power. Open loop tuning is MUCH easier than closed loop tuning.

 

Thanx for your help. I have had the computer redone already when the engine was in the shop getting done, I have screwed with the mass airflow sensor a couple of times and made it go into open loop and on the stoich gauge it reads really rich but she runs so damn smooth, I want it to run that way all the time, when shes running normal its like the computer starts to get confused and she doesnt run as clean. I dont care about gas mileage, and like you were saying she is blown and n2o injected so that and the flowing heads and cam might make her a little finake in the first place huh??

 

All you would need to do is use tunercat and raise the temp of the "min cool temp for cloosed loop" as high as you can go, which is 150 C. Thats around 300 deg F, a temp you motor would never reach.

 

I've never heard of just disconnecting the O2's to make the car use open loop. I would think that would set off a code or 2 and put the car in some sort of "limp" mode. Not sure though...like I said, no experience.
If you've got that much $$$ in the car...do it the right way and have the computer programmed to run in open loop...exactly how texanmutt explained.
Is your car OBDII or have you converted to OBDI and who did the programming for it?
I'm going to take a wild stab and guess that if your car doesn't run well in closed loop that there might be something wrong in the programming. Injector offsets or size or something.
As soon as you trick the car into staying open loop I'm guessing it is in more of a "limp home" mode. Again, not quite sure.

Do it right and have an open loop program written for your car before you have some potentially serious problems.

 

Your right, it will set off a SES code, once the conditions are met for closed loop it will come on. It's basically the same thing as having a bad O2. But the limp mode is only when you have a problem with your MAF, according to everything I've read at least. But I definitely agree to have it correctly programmed instead of simply unplugging the O2s.

 

My tuner (in sig) wound up raising the closed loop enable temp so high that it would not go into closed loop. For some reason after installing 1.6 RR's, closed loop operation was overheating my headers during the "cruise around test" (to the point of dulling my 2100* Paul Barry coating). It remains a mystery as to why because on the dyno it read 14.7:1 like it should during a steady low load. We theorized that the integration was just too wild and was heating things up. Once he installed a custom bypass valve and disabled the closed loop he tuned it block by block in open loop like you would tune a DFI setup. Despite 900 mv's showing on the Scanmaster when cruising he said my true wideband cruise A/F wasn't so rich at 13.7:1 ....apparently correct because it gets great MPG and no problems so far. I like the steadiness of the readings ....it really seems like the car runs better when it's not integrating fuel so wildly too, it just runs smoother overall when cruising around.