Perplexing PLX !!**??

[Dirty Howie]

Bill ( and anybody else)

What do you think would happen if I tune my VE to 15.5 AFR in OL then enable CL ?????

Do you think that would be diagnostic if then the WB stays reading 15.5 in closed loop ??????


DH

[5_Liter_Eater]

You can tune your OL to whatever you want. When you re-enable CL it will use the fuel trims to get the AFR back to 15.5:1. I gar-own-tee it.

[TrekGTO]

You can tune your OL to whatever you want. When you re-enable CL it will use the fuel trims to get the AFR back to 15.5:1. I gar-own-tee it.

Ya I did it today! I dialed in my MAF OL (14.7) then went CL as much as 10% rich and then 10% lean High and Low table. Had same AFR (15.5) only thing that changed was Fuel trims +/-. Just wanted to try it, starting to ___ me off! There must be some work around that escapes me. Has anyone asked HPT if any fix is in the works?

[Dirty Howie]

You can tune your OL to whatever you want. When you re-enable CL it will use the fuel trims to get the AFR back to 15.5:1. I gar-own-tee it.

Thanks for saving me a couple of days of screwing around


DH

[S2H]

We're waiting to hear how it's working for you.

I'll let you know as soon as I have a tune to do with it

[Dirty Howie]

Did a cold start, ignition ON before cranking.

The AFR is close to 14.6 and the mV is close to 450 !!!!!!!

Doesn't this mean good WB/NB correlation until things start warming and or flowing?????????????

This is in CLSD


DH

[jknox]

14.6 just seems to be it's starting point. If you have the sensor unplugged, it reads flatline 14.6 all the time. I think they just start it out there until it gets the heater warm enough to see some feedback.

Since I got my pro wired up I've noticed that the closest I get to 20:1 is about 19.5. Since it appears to track true the rest of the time I'm not worried - it's not uncommon for A/D converters to have issues with voltage measurements close to the extremes of the power supply range (0 or 5V in this case).

Actually, I won't even swear that the plx's output gets that close to 5V either - and for pretty much the same reason...

[5_Liter_Eater]

This is a cold start, just as you said. I don't know what your CL ECT enable is set to but I'm sure it's higher than the 76 degrees you show in the screenshot. So you're open loop at that point.

As a test you could lower your closed loop enable to ~70 degrees but I'm not sure the narrow bands will hav heated up by then.

[Dirty Howie]

This is a cold start, just as you said. I don't know what your CL ECT enable is set to but I'm sure it's higher than the 76 degrees you show in the screenshot. So you're open loop at that point.

As a test you could lower your closed loop enable to ~70 degrees but I'm not sure the narrow bands will hav heated up by then.

I think its set to 92 degrees.

Anyways just thought it was interesting that the mV on NB and AFR on WB actually matched up for a few seconds.......


DH

[00000D0101]

Any new word on this? Did soundengineer test the different wideband?

[S2H]

Any new word on this? Did soundengineer test the different wideband?

My new wideband (NGK AFX) works great...seems to jive with the stock 0'2 on every vehicle so far...

[Dirty Howie]

My new wideband (NGK AFX) works great...seems to jive with the stock 0'2 on every vehicle so far...

Even heavily modified??? Headers, cams, big CI, etc .........

How much was it ?????


DH

[5_Liter_Eater]

Here's the results from trying another controller with the same sensor from my AEM. Still showing leaner than stoich in closed loop.

http://www.hptuners.com/forum/showthread.php?t=16029

[Dirty Howie]

Here's the results from trying another controller with the same sensor from my AEM. Still showing leaner than stoich in closed loop.

http://www.hptuners.com/forum/showthread.php?t=16029

Thanks Bill

I posted to your thread !!!


DH

[BADSZ28]

Mine seams to be in line. I am glad I am not having these issues. But no one is having issues in PE correct?

[5_Liter_Eater]

PE is open loop, there would be no way to verify whether any error in PE is due to WB sensor error or airflow metering error. So what happened to us is we calibrated our MAF or VE tables with the wide band in open loop to 14.7 and whatever AFR we wanted in PE and got the tune dead nuts on. Then we switched back to closed loop and our WB's were reading ~15.5 instead of 14.7. Closed loop should always be ~14.7 which is why we're using it to try and determine whether our WB sensors are out of whack or our narrow band sensors are.

[BADSZ28]

OK. Thanks for the explanation. I can't seam to find my log files but everything seamed in order from what the LM1 read on the dyno from my tuner.

[SK360]

Bump! Any progress?

I finally got a PLX Gauge for my SM-AFR to watch my AFR while spraying, and it bounces from 14.7-16 while in CL... seems to hover right around that 15.5 mentioned earlier.

I just replaced the WB sensor on Sunday and it also is doing the same, OLMAF seems to be fine.

this is on an 05 GTO with longtubes, catless mids and LPE CAI.

[5_Liter_Eater]

way to bring back a thread from the dead... :P

I will say that for me the problem seems to have been small air leaks around the WB bung. It was welded on the collector while on the car so it was tough to get a good weld. I used some exhaust patching goop around the bung and now my CL is alot closed to 14.7. This makes sense because the stock O2 bungs are much better welds and likely leak free.