I'm still pretty new to tunercat but I did some logging today and had some questions. If the O2 values at idle are at 900 for the left and 1100 for the right, what would cause the PCM to not adjust to get those values to where they are supposed to be? This is on a supercharged 355. TIA for the help.

 

Did the log confirm the PCM was in closed loop? Is it possible the tuner diabled learning?

 

The PCM was in closed loop. There was no knock retard at all. I just don't know what would keep the PCM from adjusting to obviously rich O2 sensors. All the relevant tables seemed normal.

Is there a table that i'm missing that would disable learning?

 

Were the O2 sensors oscillating? E.g. going from 900 to 400, and back, etc.? If they are not oscillating, it may be in some sort of open loop mode for some reason.

You can check to see what the minimum coolant temperature for closed loop operation is (should be one of the constants). Also, do you have any trouble codes? Certain trouble codes may cause the system to run in open loop.

 

The O2's were oscillating at all. The left was at around 900 and staying there, the right was at about 1100 and stayed there.

No trouble codes at all. Datamaster showed the PCM being in closed loop. Is it possible that some requirement wasn't met causing the PCM to show closed loop but the O2's still act as if theyre running in open loop?

 

If the PCM was in PE mode, this would happen.

Can you email (vince@trifectaperformance.com) me a log file? I'll take a look at see if anything looks out of place.

 

Even in PE mode the STFTs are active. They will add fuel anyways, don't know if they will pull fuel out???
I've seen before that an intermittent injector fault will cause the PCM to ignore the o2's while still stating that it is in Closed Loop.
Have you had the PCM tuned previously? If so, check to see if the BLMs or the INTs have been limited.

 

I forgot to add that the Short terms were trying to adjust but the Long term counts weren't dropping at all. They just stayed at 128.

Vince, I'll email you the log file when I get home from work.

 

Are you sure you don't mean the long terms are active, IF the PCM was adding fuel in closed loop? The short terms go to 128 in PE mode.

 

Nope, I mean the short terms. I had set TPS% for WOT to 0 up to 1200 rpm. Datamaster logs show Closed Loop and PE enabled. LTFTs locked at 128. STFTs kept climbing to 193. Maybe there's a difference in PCM versions?

Since he has a supercharger, if he had it tuned I could see the tuner locking the maximum adjustments made by the BLMs and INTs. Wouldn't want to have it pulling out fuel when going into WOT. I'd check to see what the Maximum/Minimum Integrator Values and the Maximum/Minimum BLM values are set to in the ECM Constants table.

 

Vince, I sent you the log file. Thanks for checking out for me. Please let me know if you find anything that catches your eye.

 

I reviewed the log file. It is curious that the O2 sensors do not oscillate at idle, but they seem to oscillate normally under light throttle conditions. As far as I can tell it is in closed loop. Does this engine have an aftermarket cam in it? I have seen "big cams" cause the O2 sensors to do funny things at idle (e.g. not oscillate correctly).

 

Yes, it does have an aftermarket cam in it. I noticed the O2 sensors looking okay at part throttle too. The cam is a 224/232 on a 114 lsa. According to a wideband, A/F ratio was 14.5-14.7:1 at cruise rpms. It was as rich as 12.0-11.9:1 at idle.

 

Sounds like the tuner put it in PE for idling. This effectively negates any fueling changes at idle to compensate for extreme cams, etc., by making the PCM think it is at WOT at those idle RPMs.

You do this by putting TPS % for WOT to 0 for 0-1200RPM. Then you tune those respective tables in the PE/WOT tables to get a desired AFR.

That would be my guess as to what is happening, from the sound of things.

 

Interesting. Actually, a buddy of mine did the tuning. I have a copy of the tune so i'll have to take a look at it.