No, decreasing timing will make the combustion chamber temps lower but increase header primary temp, trust me, try putting in 0* of advance & see how hot your headers will get, they'll start to glow because now when the exhaust valve opens the cumbstion is not yet over & will continue to burn in your exhaust because you fired the spark plug too late in the event.

Now, as for widebands, if I'm in closed loop & let the o2s do their job my LM1 will read 14.7 at idle, so I'm sure it has no problems reading my exhaust at idle, then again my idle is also at 1000rpm & I have an o2 bung welded after the Y-pipe where the LM1 o2 goes in, & when I run it in open loop & o2s are at 100mv or so then LM1 reads 18:1 A/F so I can go by that.

The other thing, I keep running into these problems if I want to tune idle for PE:

To me it doens't work, reason being is even though my BLM's are locked to 128 for WOT, at idle the STFT still work for some weird reason & they compensate, I can easily tell this because when I come to a stop my o2's will read 100mv for a bit & then all of the sudden they start jumping around again, I can see why because the STFT are correcting event though the LTFT is locked at 128, its easy to see cuz when I come to a stop the injector duty cycle hangs around 1.6 & the o2s at 100mv where I want them, then all of the sudden the o2s start jumping around & the injector duty cycle is back to 2.1 where it would hang out in normal closed loop aswell, & if I lean the PE table out more within a few seconds of comming to a stop the injector duty cycle will come back to 2.1 again, if I returne just normal closed loop & disable PE the injector cycle now no longer goes to 1.6 when I come to a stop & then 2.1 but it just goes to 2.1 right away & stays there, so no matter what, for me in closed loop I still get the darn correction taking place.

The other problem? this one is funny, when I come to a stop, for those few seconds that the injector duty cycle is at 1.6 & the o2s are at 100mv I get a DTC (fuel system lean) & engine light comes on, then injectors go to 2.1 & engine light goes away. My STFT go to 150 at that same time while the LTFT stay at 128.

Matt.

 

Sorry Bunker, i misunderstood.

As far as the troubles you are having with using PE at idle is the same reason I gave up on it. No matter what I did the darm STFT's still compensated. The LTFTs that were learned while in NON PE mode were effecting the STFT's at idle in PE. OFcourse this could be eliminated by using the BLM locker but even then the STFT's in PE mode still screwed up the idle fueling

 

Yep, ok so far I think the only one that works & this is cuz my friend tried it on his car & I looked at his log but have yet to try on mine, he's using the revision "B" flash & on his log in PE both STFT & LTFT are both locked at 128, I've tried revision C/E with no luck, I need to now try the revision B version but its going to take forever to copy all the F*CKING tables over to the revision B flash & try it, if that does work I don't know then, Open loop is very annoying aswell, my right side runs too rich at parts of cruise compared to my left bank so only closed loop to can get right since the cylinder balance wont' work for someone that only gets a split only a sertain part throttles.

Matt.

 

in open loop mode how can one side run leaner then the other? both sides of the injector bank all fire the same. This is what I am trying to tell you that going by the stock O2 readings is dead wrong and throwing you on a wild goose chase.

 

You know what you're probably right, why do you think that is, reversion from the cam at sertain RPMs causing 1 cylinder to run a bit leaner making the one side go wild?

matt.

 

The cam reversion definatly has something to do with it. I have also heard cracked throttle bades can increase the variance in the O2's as well. But as far an a cylinder running lean due to reversion, this is highly unlikely. In open loop mode, no 02 learning is enabled and if you watch your scan tool you will see both injector banks firing the the same pulswidth. now there are the cylinder balance tables ( you should not touch these without an EGT setup) in LT1_edit that specifies the % change in fuel for each individual cylinder, but the stock amounts not only are not great enough to be detectable but have the same variences on both banks.

If you are seeing opposite O2 readings in OPEN LOOP you could have an exhaust leak somewhere causing this. IT could be a lazy O2 sensor. In open loop mode my left bank O2 goes from about .200mv to .960mv and my right bank goes from .120mv to .940mv and both O2s are brand new. There is a difference , but not a big one but I have learned to not even go by the O2 readings long ago. If you think the numbers on the O2s were good, well think about this. With those O2 readings the car was slightly lean on the wideband at partial throttle ( 15.5:1) and rich as a pig at WOT (11:1). but according to my scan tool and data logs the stock O2s were telling me the cars running great.

Large Cammed cars cannot rely on stock O2 Sensors, they are worthless. I cant see how you could possibly be lean on one cylinder with fuel injection, and I dont see how you could be lean/rich on one BANK in OPEN LOOP mode since all O2 feedback is ignored.

LArged Cam guys, take my advice and get yourself a LM1 wideband kit for $350 and stop chasing your tail with the stock O2s. You will thank me later.

 

except at parts of cruise I get 80 on left side & 900 on the right side, both cylinders firing the same & I have no header leaks at all I don't think, then again maybe the header is cracked somewhere or something I don't know, I switched my injectors from left to right with no difference & tried swapping o2s left to right with no difference, I've had this issue since day one, at other part throttle cruises I get the same readings on both sides, at idle I also get the same reading, its only at sertain map/rpm readings that it will show different & others not, I could be at 1500rpm & at say 60 map & it'll be split like 80/900 & 1500rpm & 70 map it'll be same on both. Both banks are firing the same, I also figured if its a header leak the difference would be varied by rpm, in this case I think its more MAP related then RPM.

Matt.

 

On a quick side note not to take this off topic....

By no means do I know everything but I have been working on f-bodies for about four years now and I thought I had a pretty good handle on these car until I recently started learning about tuning them(havent even done my first reprogram) and realized I've only scratched the surface when a topic like this one comes along. Just wanted to say thanks to everyone for "learning" the rest of us and sharing your experiences. Its posts like this one that keeps our hobby exciting and thriving

We now continue with your regularly scheduled program......

 

Interesting new addition guys...

I have the latest $EE version from tunercat...

Now whoever sends me an email with the attached older version i will gladly send you this version to not flood Tunercats email

highlander@cartechpr.com is my email

The interesting thing is:

The new definition has a few NICE additions to it that will help tune this cam:
1) Minimum Keep Alive BLM
2) Maximum Keep Alive BLM (don't know what it does yet, but im sure it helps)

most importantly
3) Minimum integrator value
4) maximum integrator value

It gives us a little bit more control on the BLMs w/o making the pcm go crazy....

5) Closed Loop Idle enable Vehicle Speed...

 

Cool about the vehicle speed closed loop enable.

& what is BLM integrator value?

Keep alive BLM is just that, its the BLM the PCM will retain in memory & start off from when you start the car in the morning, at 128/160, in the morning the car will start off from 128+ in open loop, so if in closed loop you ran past 128 say 130, it'll remember that the next morning, by lowring the 128 value to 120, it'll start off from 120 & remember everything from 120+. So if you ran at 125blm in closed loop, the next morning it'll remember the 125blm in open loop.

Matt.

 

BLM integrator is also known as Strim or Short trims in current terminology. The INT's are the fine tune for the Ltrims. The INT/Strim's count towards a richer or leaner fuel trimming from 128 to whatever their min/ max is set to then the Ltrimis decreased/ increased by one. The INTs then goes back to 128 and starts trimming again. The INTs move very quickly and can basically be thought of like a fraction of the BLMs.

I wouldn't alter their Min/ Maxes for any reason that I can think of since they're so small on the scale of fuel trimming.

Hope that makes sense,
-Christian

 

The one i didn't know is the keep alive... there are quite a few things...like startup tables and such.. didn't know that PCM was that "powerful".

Now, if we had a closed loop BLM idle table or something it would be totally cool.

I still don't see the blm blocker.. so i will add it and send you guys the changes...

 

Well I explained the keep alive BLM above, but anywho, now we need a closed loop disable MPH or open loop enable mph lol

Matt.

 

I bet its there

 

So are you getting flooded with emails yet Highlander. I know I emailed you as soon as I saw the post.