Why is there a difference??? Shouldn't the car perform the same since in PE mode the car goes into open loop or it doesnt use the O2 feedback???

I made 501rwhp today!!! but the car feels like a 350rwhp car or so...

I uninstalled one of my O2 sensors to install the wideband... and the car ran in open loop... hence how I tuned it... now.. the car is running in close loop and its not performing.. anyone got an idea??? Shouldn't the car run by tables??? It has happened to me twice with 2 different cars.. the car will not run the same in open loop as closed loop... WHY?


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Do you think your car is not going into open loop? Have you looked at the conditions that cause WOT? Maybe a bad TPS.

 

Open loop isn't the same as what happens in PE mode.
In a true open loop system the PE tables aren't used for wot fueling.
Not sure if that has anything to do with it or not...just throwing out ideas.

If you tuned the car on the dyno for an open loop program, why don't you just run open loop?

 

Then why by changing the PE tables I gained over 75rwhp...

There is one thing I thought ... When you adjust fuel pressure you will instantly gain but it will set herself back and loose the power gained...

WHY?

 

well I belive the cars PCM rely's on the O2 sensor temperatures to switch OUT of closed loop mode and INTO open loop mode. If you unscrewed one of your O2's to put the Wideband in this may be the cause it stayed in CLOSED loop mode. Nowthat you put the O2 back in and the car switches to OPEN loop mode which you DID NOT tune would most likely be the explanation of your problems.

I would say go back the the dyno and apply the tuning you learned from the wideband O2 on your last run to your OPEN loop
LEAVING the O2's inplace and not using the wideband ( since you already got its info)

Or just try to mimic the changes to your open loop tables without going to the dyno ( save money )

 

When I unscrewed the sensor... the car NEVER went into CLOSED LOOP... Hence I tuned the PE table while the car was in open loop...

Now on closed loop its not running like it did on the dyno when in open loop!!!!

 

for one thing in open loop mode the car doesnt adjust much of anything. You need to be able to tune your car while its in closed loop mode. Now you could change the cars PCM to stay in OPEN LOOP MODE until it reaches XXX temperature. ( if set at like 500 Celcius ) This will cause the PCM to stay in open loop mode permanetly. otherwise Im not sure what to do. I am going to be venturing into this on my Nitrous's 383 stroker later this month when its finally done ( been over 3 months in the making !!!!).....and your scaring me !!!!!! This is supposed to be easy to tune !
Im tellin my mommy!

 

Check this out: http://www.carprogrammer.com/Z28/PCM...OT_testing.txt

I trust Christian's info.

I think it's because the computer will use the blm to see that it is constantly adding or removing fuel and make the adjustments that it needs. It doesn't work like that on a speed density car or when you go true open loop only. Someone correct me here if I'm wrong.

 

Its a great site filled with lots of info.. but I beg to defer on one thing:

He says that the PEvsRPM is not used in open loop! well.. I gained over 75rwhp modifying those tables.. I had to add a lot to them but anyways...

Once I installed the other o2, she was able to go into closed loop, the car ran slower. When I check... its leaner on first and second, and not to mention 4th that is when the air is making an effect...

COnclusion I got? She uses the PEvsRPM but she uses the starting afr,for that equation, of the afr x 10 open loop table...

I fattened them up about a 15% diff and I noticed some difference.