The situation...

A/F will generally be spot on during warmup and initial driving. Corrections are +/- 5% and make sense -- e.g. bank one goes a little lean then the ECU instantly adds 5% to bring it back and vise versa.

Once the car is warmed up and I'm just light cruising, maintaining speed ect, everything is fine for maybe 30 sec then all the sudden the A/F on both banks will begin slowly dropping... hovering between 12.5 and 14.0. At the same time, the ECU is ADDING FUEL, sometimes up to 10-15% on both banks.

As soon as I get on it a bit the A/F jumps back to the target A/F.

Things I've done since this started happening -

1. Installed non-foulers (2" length approx.) as I was getting codes due to my HFC's
2. Upgraded from 440-600CC
3. Retuned to the 600CC's (but this happened both before and after retune)

And yes, I do have the correct dead time and latency dialed. I even tried making it excessively low and it made no difference at all in my problem other than expected, e.g. decel became too lean.

It just makes NO sense that the A/F target is 14.7, the upper sensors read 12.5-14.0, and the ECU keeps _adding_ more and more fuel!!

So... does the ECU sometimes switches to the lower o2 sensors for corrections at which time my non foulers are f'ing everything up??

Any clue?

 

in for answers.. 'bout to do my afr and UTEC tuning too.

You seem to ask all the questions for me man....im taking table scraps here.. haha.

 

^^ LOL thanks

I guess the best thing to do is remove the non foulers and see what happens...I can live with codes if it means my low load A/F will stabilize...but I was just hoping someone knew how the ECU worked. It's pretty crazy how limited the knowledge is about our ECU's compared to other platforms.

 

^^^ Why do you have antifoulers in for your downstream sensors. You can just disable the codes as well. Also to answer your question in the other thread. I beleive Minimum effective Injector pulsewidth is the lowest value the ECU wants to see your injectors at so with 600cc injectors ur prob right around 2.0ms at idle so if you have left that value at stock(2.4ms) then try lowing that value. I always set that value for the 600cc cars i do to 1.5ms

 

I had to do it to get thru emissions recently and left them on since it's a PITA to get under my car being so low.

I tried everything with the injector latencies (starting with the actual values from DW) both dead time and 12-14v values everything from 1.0 to 2.0 msec and it did nothing to stop the low load fluctuation, all it really did is cause excessively lean or rich decel.

i really hope its the antifoulers as I never ever had this issue before and i'm sure my gas mileage is taking a huge hit (probably the cats too).

 

^^^ the pulsewidth and latencies are different things. The puslewidth is the actual on/off time of the injectors, the latency is how fast they are reacting. so the minimum pulsewitdh is the actual on off time of the injectors...

 

^ I'm running 1.5ms dead time already, I think I went as low as 1.2 or so but no diff in low load stability (other than lean as heck decel).

I'll note that this also happens sometimes under moderate load where the injector time is well over 2ms..it's not LIMITED to low load but is more typical there.

Either way, I'll pull off the nonfoulers and we shall see if anything changes.

 

Maybe Im misunderstanding you or maybe you are just using the wrong terminology. That value (injector min effective PW) isnt considered dead time. that is the actual on time of the injector while it is running. So at idle your are at 2ms at cruising you might be at 3-4ms and WOT you might be up over 13ms...these are just general values for example BTW

 

I understand how each setting works but I do mix up the terminology... Thanks for helping the community in clearing up my nonsensical banter!

 

^^^ its cool... Is your car a 2004.5 with widebands btw??

 

Yes sir

 

Well I pulled the non foulers today and went for a quick drive... I didn't see any more A/F 'float' and the car actually feels a little more peppy down low...it was only a 10 minute drive so I don't know for certain if it's 100% fixed but it's definitely better...

 

Drove another hour tonight and A/F held strong at cruising and idle.

Both upper wideband and lower narrowband are very much used at least by the stock ECU auto-trims on a 2004.5.

Non foulers = FTL

 

just utec tuned, pulled my defoulers off as well.

 

Yea I can't believe it.... those lower o2's do alot more than everyone led me to believe over the years. The antifoulers really turned my idle and cruising tune to ****. Without them the A/F is now dead on 14.7 with almost no variance in idle and cruise now. Even the occasional overshoot when going on/off throttle are corrected within a second or two instead of hovering around aimlessly rich until I either get on it or let off.

Summary: if you've got antifoulers on your lower o2, take that **** off.. They mess your tune up in ways that cannot be tuned out. Not just lower MPG's but possible HFC damage as well based on what I saw my A/F doing.

 

Damn this is good to know. Thanks for the info...I'm gonna go take them shiets off tonight

 

Do ART pipes have anti-foulers?

 

According to motordyne they are built into the art pipes so you're stuck with 'em.

 

How do I go about disabling the codes? Is this something that would be possible with UpRev Tuner? I have test pipes and was about to install non-foulers and purchase Osiris Tuner until I read this thread.

I'm also a 2004.5 with wideband, so this thread was perfect timing for me too.

Thanks!

 

Load your Rom in the rom editor. Click on DTC. double click on the code to toggle off and on. (You will need your cable plunged to do this.) Once done save your rom and flash the car.