CAT3

iTrader: (9)

Is it a MAF function, VE or what? My idle is 12.8-13.3, way too rich for me. I like the 14.7 stoich.
Cruise is good, and WOT I need to dial some more fuel in, tad to lean. But, looking through, I cant seem to recall wtf I did three years ago to mess with the idle fueling, thinking it was scaling the MAF, but cant remember, would it be decreasing the value (making the pcm think there is less air therefore pulling fuel)?

Silverhawk_02TA

Well, it depends whether you're running closed or open loop. In open loop it's no problem, just scale the MAF table (if using the MAF) or the VE table (if running SD) in the offending area. If you're running closed loop, you're SOL, and here's why: O2 sensors measure the amount of unburned oxygen in the exhaust gas to determine the A/F ratio. At idle, the overlap in your cam (I'm assuming you have a cam, you didn't include any info in your post) is letting lots of unburned oxygen through, making the PCM think the mixture is lean, so it dumps in extra fuel. The only way around it is to run in open loop, so you can set the fueling using the MAF/VE table without worrying about the O2's mucking things up.

dynocar

Just decrease the air numbers (whatever your software calls it) in your MAF table for that frequency, should correct your problem.

jimmyblue

iTrader: (11)

Idle uses mostly the speed density airflow numbers
in its airflow "soup". The Dynamic Airflow value is
what's being used. You may see it fairly different
than the MAF g/sec value. That would be because
the VE table misrepresents the actual air pumping,
if so. The MAF makes some contribution but you'll
see more effect, percent for percent, in moving the
VE low end around. Question the MAF table trimming
you did as well, but don't fixate just on that.

But the other thing is that the closed loop depends
on O2 sensors being fast and awake, or you will be
(mis)trimmed rich at lower exhaust gas flows. The
shoot-through air is another way to fool the O2s.
To distinguish these look at the character of the O2
sensor waveforms; they should be very active and
symmetric. If they spend more time pegged low than
high, and the swing is stop-to-stop, then they are
probably not giving good enough response. Some
fooling with the proportional fuel stuff might help a
little, thermal wrap on the headers might as well,
higher watt heaters (though just having put headers
with Denso 'vete rears, I see them looking pretty
groggy at idle in the cold so those ones are not a
cure-all; maybe Bosch are better, or not). If the
sensors are bright and bouncy but you're still trimmed
rich by wideband, you'd want to look at exhaust air
as the error source (overlap, leaks).

Bad30th

iTrader: (13)

If you mean at startup, there are also post-startup fueling modifiers. Try adjusting the afterstart enrichment modifiers before you change the MAF table.

If you mean warm running idle, then yeah, adjust MAF cell and/or VE.

Rob (Bad30th)

CAT3

iTrader: (9)

Damn sorry for not giving all the info, I know I get grumpy trying to help someone with partial info.

Here goes:

Just installed:
Forged 347, 11.62:1cr, ETP 11* 225cc Heads, 231/242 .637/.622 114* LSA cam by EDC, Kooks 1 7/8" LT headers.

Looking at the LTFT's I am +10+/- at idle// part throttle & cruise, off idle, is -4 to -7 and WOT locks at +1.6 rather than Zero. Idle is obviously rich due from sight of slight exhaust smoke, smell and WB reading 12.8-13.2, not the nice 14.7:1.
Reading through this I know remember the basic cam tuning, reducing the VE Table from 1200rpm & below, 60/70/80% etc.
The richness is at idle, warm and probably a little worse when cold (havent logged too much cold start). I would want to reduce the VE in the rpm vs g/sec area correct? So it thinks there is less incoming air, and thus introduces less fuel?

Jimmy, the O2's seem very active after warming up a little. It does take a minute for them to get to temp's, as would be normal for a LT header setup. There hasnt been any sluggishness to take my attention, either high or low, they seem to cover the spectrum quite well and cycle frequently.

Silverhawk_02TA

I like info.

Lemme say this, so we're both on the same page: The O2's are going to maintain a 14.7:1 AFR (or more accurately, what they THINK is a 14.7:1 AFR) the entire time the engine is in closed loop operation. Positive or negative fuel trims are not indicative of your engine running lean or rich; they are simply the amount the PCM is modifying the base fuel map based on the signals it is receiving from the O2's.

That being said, you are running rich at idle because the overlap of your cam is letting lots of unburned oxygen through your engine, which your O2's are reading as a lean condition. Thus, your PCM is adding in fuel until your O2's read 14.7:1 (at +10 LTFT), though in reality your actual AFR is 12.8-13.2. You can modify your MAF/VE tables to your heart's content, but it won't matter a bit because the PCM is still going to shift fueling until the O2's are happy. The only way around this problem is to run in open loop. Period.

Initial startup is a different story, as the engine is running in open loop until it reaches the closed loop enable temperature. This is why the 60/70/80 method of reducing the VE works when you are tuning your cam/head/whatever car to start and idle correctly. Changes to the MAF/VE tables will affect your AFR normally, but once the closed loop enable temp has been reached, the O2's take over again.

The reason you have positive trims at WOT and not 0 is because your LTFT's at idle are +10. If the PCM has learned significantly positive trims, it adds in fuel when it hits PE mode at WOT (reflected by the +1.6 LTFT's). You can fix that by tweaking the MAF/VE tables in the idle area until your trims come down to 0 or slightly negative.

A rich idle is just something you have to live with if you're running a cam with healthy overlap and a closed loop tune. If it bothers you that much, just run an open loop tune. Also, I wouldn't think that an AFR of 12.8-13.2 should be causing your exhaust to smoke. I would imagine that it would have to be a good deal richer than that, but I could be wrong. Perhaps someone else could chime in on that point. Are you sure it's not oil, or coating burning off from the inside of the headers or exhaust?

Bad30th

iTrader: (13)

Very nice explanation Silverhawk_02TA.

That's also a nice size cam ya got there !

What's the commanded A/F when you're reading 12.8-13.1 on the wideband ?

Is that the A/F that's being commanded ? Have you tuned your running airflow (RAF)?

Rob (Bad30th)

CAT3

iTrader: (9)

Ok, much clearer explaination, thank you very much Silver...
Q) I'm not sure about the overlap difference, but my old cam, TSP 231/237 .595/.595 112* was able to warm idle at 14.7, after tweaking the VE Table?

Q) I am not sure of the Commander AFR as I have never logged that. Is there any particular PID I need other than Cmd AFR or is that it?

I have not ran the RAF1_2, I do have it, but havnet used it yet. I need to have a whole day to just that at my work or a friends. My neighbors will get my fined for noise if I try it here.

Here is funny thing you mentioned Silver, the +LTFT of 1.6 at WOT, being based off idle being +x.xx. I always thought WOT locked in for WOT trims based off the last cells reading prior? Meaning, if I was cruising and my LTFTs were -4, then I should lock at 0 WOT. But, at cruise my LTFTs are -7 average, and WOT is still +1.6. I need to relook and make sure COT is turned off as well, since I just removed the cats and manifolds *oops, forgot that lil piece*

The cam specs look decent, but the sound is very mild, slightly aggressive nothing too ballsy though, at least I dont think so. EDC really pulled through on this one.

Silverhawk_02TA

I'm not sure what the overlap differences between those two cams are. Did you change anything else besides the cam? I know that at hot idle my AFR floats around 13.4-14 with my Torquer.

Yes, just log the Commanded AFR PID. I can't think of anything off the top of my head that would be pulling it from 14.7 at idle, but maybe something we're not accounting for is affecting it? Can't hurt to check it out.

I'm pretty sure that your LTFT's can go positive at WOT if the PCM has learned significantly positive trims in ANY cell. That's certainly what I've found to be true.

EDIT: I see that you swapped out the stock manifolds and cats as well. That's also contributing to your AFR at idle being richer than it was before you removed them.

ninobrn99

iTrader: (8)

do you need a WB to log the commanded a/f or is that taken from your tune?

Silverhawk_02TA

Nope, it's a PID you can log in the scanner. It's the AFR the PCM is commanding at any particular point in time. The ACTUAL AFR is an entirely different story, and needs to be logged with a WB.

ninobrn99

iTrader: (8)

ok, thats what i thought. thanks.
Nino

CAT3

iTrader: (9)

Silver....

I'm not sure on the overlap as well, but am curious to find out. I actually swapped engines, to include heads.
I went from stock bottom with PP 5.3L heads, TSP 231/237 cam Jet Hot LTs to
Forged 347, ETP 225cc 11* heads @ 11.62:1 cr, EDC 231/242 cam, Kooks 1 7/8" headers.
I am thinking the RAF may have some effect on all this, but I am not sure. As for tuning differences, the only thing I have done is open the TB Blad a little more and lowered the timing for the increased cr. I know I need to go through and tune the entire car, especially since I want to swap to an 02' operating system. I have transfered almost everything over to a 2002 .bin, but havent loaded it yet, still worried something may go wrong and I will be *** out of car for a couple days, so waiting for the wife to fly to Miami, I'll have her Trailblazer
I know the deleting of the cats makes the exhaust smell rich, but on my old setup, logging would always show it hovering ~14.7 +/- .2 But this has me seeing slight puffs on cold startup which do go away once warm, but still the afr is rediculous. I will log the commanded afr in a bit and get back to you. Got me curious now, and since its still early, the neighbors cant complain too much.

CAT3

iTrader: (9)

Ok, I was able to log some cmd afr, not all the way from cold to warm, as the neighbors are bitching...but,
At cold start it is 9.xx then start to slowly climb. It made its way to 10.xx before I had to roll out to a nearby parking lot. I know the pcm adds fuel for cold starts, but damn, thats too much for me to feel comfy with. I'd rather see high 12's to mid 13's for cold start. 9-10 makes me think of washing cylinders down, even though it probably only lasts until ECT get up to xxx temp. *EDITED* I FOUND THE OPEN LOOP AND ALTERED IT DOWN A LITTLE SO IT WONT BE AS RICH. HOPEFULLY THIS HELPS. I KEPT IT WHAT I BELIEVE WILL BE SAFE. W/ EQ OF 1.12 FOR TEMPS -40 UP TO 32* AND MAP FROM 20 TO 35. WHAT IF MY MAP IS LOWER THAN 20? MINE IS ONLY 12 OR SO?
Upon warm starting the CMD AFR is 13.3 and climbs to 14.63 within about 10sec.
Warm idle is 14.6.
I also began a few minutes of warm RAFG via Marcin's RAF 1_2.
Will me not being in FTC's like normal Auto's matter? I have a TH350, so the FTC's are not seen like they used to be. I will have to do some indepth, from cold start to warm, and all "normal" driving conditions to report which cells I actually use.

Charlie

227Hawk

iTrader: (1)

This is where i'm at now. Cutting the multiplier down. At cold start my cam runs you
out of the garage. So i'm looking for help too.
Hawk

CAT3

iTrader: (9)

227...I went to the open loop modifier, and reduced the rpm vs temp area for idle. I am just waiting to make sure there wont be any ill (damaging) effects. For what I could log this morning, it starts up at 9.8:1, and moves into the 10.2:1 rather quickly, but hangs around the 10.xx too long... I hate having to roll my car w/o it being warmed up some, but with the db level its putting out now, I have to or I get a fine.