Ronny

iTrader: (1)

WB showed a very high(lean) idle A/F on WB(16.0/1) and now that WB sensor is dead I am seeing mV on NB in WU at 22-25 mV? Past month was dependent on NB02 for data. Maybe the WB was not calibrated adequately?

If I am commanded A/F at idle OL-AFR-CTS-VAC at around 13.7 and am in OL at idle would not the mV be over .450?.

Idle quality is OK at 875 rpms commanded to 775 rpms in table(IAC not seated @ 5 steps) and throttle stop screw may be holding the idle up a bit. off idle the NB toggles over .450 with target CL A/F at 14.2/1.

Edit: Also I note that the 02 swings are as low as 40 mV to 860 mV in CL cruising at 50 MPH? Is that normal? I was of believe it should swing tighter to stoich or 450. NB02 sensor is new and a heated GM Delco

RednGold86Z

iTrader: (1)

The low mV at idle does mean it's lean. Doesn't mean it's bad, but yeah, it doesn't match your commanded 13.7, which would show as ~600-850 mV.

GM's old closed loop is not a very tight control one, so, you'll see a wide swing. You can change the P and I to make it a tighter loop, but slower. In GM, I believe P is used to keep the O2 switching, and tries not to use I unless there's error. So, try to find the closed loop Proportional gain, and reduce it, and it might get a tighter swing. But, if you go to low, Integrator might be used a little.

Ronny

iTrader: (1)

thanks. a new WB sensor is going in tomorrow a bit further back in ext stream. i will them be able to see how my commanded A/F compares to reality.

rockit

iTrader: (3)

on this topic, a nb 02 is supposed to "swing" ? i've been datalogging my gta i'll see it sometimes being a steady reading, and alott of the time it'l just be going crazy, multiple attempts to datalog in tunerpro have failed or i would have posted this seperately. by going crazy i mean that the reading will rapidly jump up and down followed sometimes by it dropping and leveling out briefly then quickly jumping back up again. it seems too eratic to be normal and the o2 sensor has less then a month on it, single wire bosch autozone replacement.

Dominic Sorresso

Here's what my O2 Idle Window settings for C/L were. Doing this helped with the overlap issue I had with cam. ECM thought "lean" condition was OK.

RednGold86Z

iTrader: (1)

When in "CLOSED LOOP" the O2 will swing from low 0-300 to high 600-900 and back and forth and back and forth. That's what closed loop does. It goes a little lean, a little rich, a little lean, a little rich. The average is about equal to 14.7:1. The min and max are about 14.2-15.1. It uses INT (integrator) to do this correction. BLM stores the average long term correction.

The flat response at cold engine is from either a cold (not ready) O2 sensor that reads 450mV, or OPEN LOOP when low voltage or high voltage.

The momentary lean and rich during driving is usually from throttle movements, where the INT (Integrator) has to make extra correction from the "base" pulsewidth at that load and RPM.

The long lean (low voltage ~0 mV) during deceleration is from DFCO fuel cutoff.

The long rich (high voltage) during very high throttle is from Power Enrichment (PE).

There's also Highway Lean Cruise mode that is not enabled in a factory bin, but can be easily turned on. That will show a steady low O2 voltage.

Ronny

iTrader: (1)

Quote:The flat response at cold engine is from either a cold (not ready) O2 sensor that reads 450mV, or OPEN LOOP when low voltage or high voltage.

I have a new heated NB and a new WB sensor freshly calibrated. My WB Q A/F at idle is 16.0/1 and in the OL idle tables it is commanded 13.7-14.0/1 for warm engine.

reduce the proportional gain? I already have done that. I reduced it a little so may reapproach that.

I posted this also in another thread and RBob stated the lean(16/1) may in fact be a false lean due to cam 224/230 @ .05 114 LSA. the WB after all reads 02 content not A/F as I understand. I find if I raise idle speed to 1000 the A/F goes to 14.0/1. so overlap a possibility. Idle quality is good so it may be a non issue.

Dominic Sorresso

That's why I posted my Idle O2 Window Terms. It causes the ECM to think the lean condition is correct because of the cam overlap. I think my cam had more overlap than yours does and it idles just fine with those terms. Also, Idle Prop Gain should be adjusted and very likely lowered if the O2 is swinging rapidly at idle. Shows up as a surge.

rockit

iTrader: (3)

so, when it switches, which makes total sense to me, how fast does this switch happen, are we talking about looking at alternating platues in tp moniter window, or are we talking more like a zig zag up and down rapidly.mines more like i took chalk put it in my mouth, and imitated being electrocuted on a chalkboard. this also worries me as i have intermittant drops in mv's, like it'll just drop and then curve and level out, traces a smooth curve across about 90 degrees, then shoots back up to the zig zagging again.

anybody have any thoughts? my explanation of what happens resembles an adam west batman episode. my weekend just hit, so i'll get a datalog going on somehow and post it up for clarification unless somebody has input before then..

rockit

iTrader: (3)

wow summers just flying on by aint it?
okay i've learned alot about tpi, and i've done alot of work on my car since my last post, the problem has gotten alot better and is now consistant, but still there.

i understand i have a natural swing in 02 volts, mine swings wider then i would like, enough that as the car sets at idle it will steadily raise and lower in rpm just a tad, one notch on my digital dash actually.

looking back over this post i undertand much more of what was going on, however i'm missing a peice.

dominic posted up a table of 02 terms, my 32b def file does not have this,can i add this on a maf 165 car or not and how?

i believe tightening the swing will eliminate this idle rpm surge, but could it also be aggravated by a tiny vacuum leak? i've replaced alot of old vacuum hose in the car, a toasted ignition system, and retuned the idle in the prom, this has all served to steady the problem, now i want to finish it!

Dominic Sorresso

Flattening the SA in the idle rpm areas helps. Look for Idle Prop Gain table as I said above. The stock prop gains may be too much for a modded motor running higher FP.

gta324

If/when I have my BLM activated at idle, it goes up and down some, trying to reach 470mV on the NB O2. Even if the Ve is perfect and BLM is 128 after a while I see the EGT changes and BLM goes up and down and so does the WBO2 ( cant remember how much but I'll se if I can dig up the scan if someone want to see it.)

So with my engine it doesnt work to have BLM activated at idle, so I turned it of and tune after WBO2. But at cruise it works fine, even If I dont use it......

/N.

rockit

iTrader: (3)

okay you guys have alot of tables i don't have, i don 't have proportional gain, i see it all the time in reference to map cars, mine is maf. i wish it was map i understand those much better, dealt with tbi for a bit..

to expand, i've had very little luck in tuning my idle, i don't know an appropriate idle spark advance amount it runs 20* ish stock, i have flattened out the curve in the 32-62 lv8 region of those rpms in both fuel and spark, it didn't help much infact it seems every tune i made the problem got worse. i also feel i can't find the right amount of fuel at idle, since the o2 swings steadily very rich then very lean i can't find that happy medium, blm's aren't helping me because the data coming is skewed from the wide swing. if the blms are 5% lean and i add 5% fuel it will become 15 percent rich and 5 percent lean on the swing for example. the mixture goes in the right direction just sometimes way too much or way too little. once again since it swings so wide (we're talking top to bottom of the chart) it's difficult to tell whats going on.
another difficulty i'm having is knowing WHERE to add or subtract fuel since not only does my o2 swing but my rpm as well, between 625 and 775 rpms. so i'm in a lil box on both fuel and timing, boxes that i have flattened out(i'm referring to the table cells in tuner pro) but i'm traveling up and down and diagonaly as well, very tricky to tune no?

i ended up trying a slightly modified stock tune from an 88 t/a and the problem left, the new problem is it's using the calc method instead of the fuel table 32b has as i'm afraid the surge will return.. what gets me is the stock tables aren't nearly as "smooth" yet idle far better and at a lower rpm! the idle has a bit of a shake to it with this tune though.

i did however learn why ARAP did not work for me the first time! i put 8 in the "number of cylinders" constant window, when it seems it should be zero, otherwise i get a 6000 ish rpm reading all the time, sound right?

rockit

iTrader: (3)

oh and my motor is not modded a bit, i have a 3 inch custom cat back with a joke of a muffler(i've set off car alarms and scared children with my exhaust), other then that it's just cleaned up, no AIR, no A/C, 160* thermo(the car will idle at 160 but drives around town at about 200*). hell i have the stock for 87' maze of an intake bellows still, as well as stock manifolds. and no egr.
i don't have higher fp or anything. 14.49 at 94 was my best pass at the 1/4, 2.0 60 ft. that's on 225/60/16's before i replaced my burnt up plugs plug wires and and ORIGINAL cap and rotor. now i've got ngk ur5's delco premo 8mm's and accel cap and rotor, hopin for 13's on full exhaust, full tune, and 1.6 ratio rockers by the way, my rear brakes weren't setup right on that pass or any of them before that, i could only launch by flooring it on the last yellow so it wasn't even wound up at the line!

rockit

iTrader: (3)

okay wrap up:

re read the CORRECT and complete procedure for setting tps and iac, did it, timed the motor, then installed ARAP with a few minor changes= problem solved.

lessons for anybody else reading the portions of this thread involving me, do the simple stuff right or the hard stuff gets harder!

now i get to play with 6E!

TPI-Formula350-

I'm wondering if I'm having this issue due to my cam. I'm using the Comp 280XFI cam, 230/236 .576/.571 113LSA. My WB O2 gauge shows a surging between 14.2-17.2...I also get an RPM surge that follows alone up and down a few 100 RPM when warm. I made a data log today an if you guys take a look at it you'll see the NB O2 bounces between 4.44mv-830.mv?? I dont have a vacuum leak I checked with a smoke machine. I replaces my TPS,Coolent temp,O2 sensor. I also adjusted my IAC. New plugs ,wires,cap,rotor. Fuel pressure is 43psi.. The car idles better in gear and runs great...14.4-15.2 driving normal, 12.2-13.1 WOT. Could this issue just be the cams over lap?? please take a look at the datalog....thanks

TPI-Formula350-

TTT

Ronny

iTrader: (1)

230/236 113 LSA is not a wild cam. should produce a reasonable idle IMO. I run 224/230 114 LSA. Sounds like a lean condition at idle. I cannot open datalog. Does your def file allow open loop idle? Can you flatten the SA in surrounding cells that you idle in? Are you SD or MAF?

TPI-Formula350-

its a closed loop tune, Can you flatten the SA in surrounding cells that you idle in? Not sure I understand???? Its a MAF car

Ronny

iTrader: (1)

MAF. I am not versed on MAF. Is there not a table for SA vs RPM? I understand MAP is not used for MAF. I am just wondering if RPM surging in part due to SA changing based upon RPM change or VAC change. SD has a table for SA that has two axis one being RPM and the other MAP. So is idle surges it will find differing values for both SA and VE fuel. Mine are all same around cell 700rpm/40MAP.

Orr89RocZ

iTrader: (20)

Your spark table should be pretty much flattened around the idle rpm. It appears to hold constant value in your bin which I recall is a modded version of my old 383 file.

I think you can try different amounts of sparks and tweak the fueling with MAF table 1 to see if the motor wants to be richer or leaner. I got a feeling going abit leaner than typical blm of 128 will help..but sometimes going 128 at idle means air fuel in the 16-17 to 1 range. Try it and see if that works. I got a 280xfi car idling pretty good with stock ARAP based bin with alot of timing advance at idle but lean air fuel ratio.

Ronny

iTrader: (1)

Orr: When closed loop at idle with a 128 BLM why would a lean condition result?

Orr89RocZ

iTrader: (20)

o2 swing parameters are alittle different at idle areas than other areas. If you look at the o2 tables you can see different values in the low air flow areas used in idle vs cruise areas. I think the switching back and forth using those higher values as a reference creates a leaner condition when blm is 128 at idle vs at 2000 rpm cruise.

Makes sense as you dont need alot of fuel at idle vs 2000 rpm.

You can try to alter those swing points, i believe you will see blm change when you change the o2 sensor tables and air fuel will stay the same. Its been along time since i played with those, but on my 383 I had a lean condition show up at idle and my blm never was close to 128 with 14.7 air fuel but the motor was "happy" there. idle was good enough for the cam i had in it. I eventually went straight open loop and enjoyed that alot but it ran ok in closed loop, just that idle was never 128 blm. I changed the o2 tables and got the blms to show closer to 128 but went open loop soon after since my lean condition was at first startup right after a engine shut off.

It would start up idle ok, then go lean, stutter almost stall for a few seconds before coming back to life. I think it was o2 ready timers...it just wasnt ready yet. I think I could have solved the issue now but then I wasnt sure what was going on.