All the stock ARAP bins I've looked at seem to have the same values in this table, a negative 7.82 from 3600 rpm and above. Does this mean the table would be subtracting fuel in those areas? I read an old thread that stated the numbers in this (and the PE vs temp table) reflected the percentage of stoich added/subtracted to fueling. Is this an accurate statement?

I'm chasing some tip in & fairly heavy throttle knock counts and I wanted to play with these tables since AE vs LV8 hasn't totally solved my issues. Thanks!

See attached!

 

Did anybody watch the movie Ferris Bueller?

Anybody class, anybody?

 

yeah, the negative numbers means its pulling fuel out. Add more positive numbers to increase the fuel amount.

I've found that 12-15% at a time is about 1 whole point in air fuel ratio. Seems that way for the most part.

 

Yes, great movie!!
Also,
Ae tables are for initial pump shot during tip in, but will decay over a set amount of time, if you need short term fuel increase go here, if long term, go to PE tables. arap bin has some weird pe tables, I don't understand where it gets the enrichment from if its "pulling" fuel out during WOT?

However, I do know that by giving what my engine wanted, my PE tables have about 40-50% enrichment added from 2400-6400rpm.
If in doubt, go pig rich than back off. Do you have a wideband sensor?

 

ARAP has a lot more enrichment in the PE vs coolant temp which is used in WOT. You will see alot more fuel there than in another L98 bin like the AUJL bin that came in my 89 L98.

My AUJL i had to add almost 90% in the 4400-4800 range for peak torque and low 80's for peak hp at 6000+ rpm I am not sure if you could add 100+ % or not but if I ran out, you just go add it in the coolant temp tables.

 

Good morning & thanks for weighing in on this guys! I've only been tuning just over a year now and have a pretty good bin with the exception of this tip in KR and some WOT pinging but that's another post when I get that far. I don't have a WB and I'm thinking this issue is exactly why they're so necessary..........I may be shooting in the dark here somewhat until I can justify the cost to get one. Until then I'll have to just do what I can with what I've got.

I understand from research that AE is a pumpshot and PE is more a secondary kick-in using older terms; and these two areas are where I get my fuel when I get on it (I've zeroed out my PE spark). I've been playing with AE vs LV8 and that hasn't cleared up the problem completely so I've watered down my timing a bit as well in those RPM/L8 areas but I still have some tip in KR. Am I stuck at this point until I can get a wideband or is there something else I can continue to do? Here's a screenshot of my current AE vs LV8 and timing tables; the car is a 421 CID w/ a SR & AFR heads:

 

Your right, this is the time when you really need the WB, with it you know the AFR is in check. You can tune by reading plugs, but unless your ready to do WOT runs and shut down at the side of the road, its not going to work well.
What is your compression ratio? And what octane fuel do you run?
Your WOT timing is only 21*?

 

The timing at the top is at 21.80 degrees right now...........after 2 or 3 WOT runs I knocked it down incrementally to keep from breaking any rings. I finally just said the heck with it & went conservative. It's definately a work in progress, I just wanted to keep it safe at this point since I'm finding it pretty difficult to stay away from WOT all the time.

I thought I might be running into an impasse w/o a wideband darn it, is there anything I can do or try for a month or so until such time as I can free up a few hundred dollars?

I'm currenty running a 10.6 static C/R with a dynamic of 8.2; not really pushing the envelope too much as my quench is fairly good at 40 thou. The gas is crummy out here in the San Fran area, the best we have is 91 octane absent of any racing fuel or additives. I *think* I should be OK with what I've got. The car is just built to be a weekend warrior anyway, I don't do any drag racing anymore. Thanks!

 

with the stock narrow band o2 working, watch the milivolts at WOT. Keep them around 900 mv for now until you get a wideband it will be fine. Put timing back into it. 28-30 is conservative, 21 deg is wayy short. Tune from there.

from the stock PE table, I am willing to bet you are pretty lean so be very careful here. On a mild 360" combo I had to add a few % to the arap table to get it rich enough. Went from -7.8 to a positive 10-12% in some rpm spots if I remember right. You can add 20-30% right now from 3000 on up just to make sure you have some fuel to start with before doing some WOT runs

 

I had my timing at 34* for the longest time, finally brought it back down to the 29*area, my car loves it!
Like Orr said, 28-30 is a good safe area to start with, and yours should be safe in that zone.
I pulled most of my PE vs temp way back, and used the Pe vs rpm table to work my WOT.
I was also chasing what I thought to be knocking/pinging, but I have yet to hear a single ping with this engine. Is your knock audible?
I would also try adding some fuel additive, just to see if it makes a difference.

 

iF the knock sensor is doing its job, it will detect and pull timing due to any knocks well before ever hear anything. If you can hear it, then your WAY beyond the safe point

 

I totally agree!
I think the problem is how to tell the difference between true knock counts , and false knock counts. It seems like a good majority of modded cars here have the same issue with knock counts at tip in, and high rpm areas.
I have been trying to tune knock counts out for some time now, but no matter what I do, it stays the same, that would lead me to believe my counts are caused by engine and exhaust noise, and not pinging.
I may just test mine out by shutting off the ESC and listening for the tip in pinging if there is any.

Ironically, my 2004 6L sierra pings at high rpms all the time! I have owned no fewer than 5 6l trucks and am almost certain everyone had slight pinging in the same area! Go figure, makes me wonder how well the GM ESC systems work!

 

if its false you can desensitize the sensor. Go into the attack rate tables and lower them, and in the esc recovery rate and increase those values to get spark added back into the motor quicker

 

Thats exactly what I did. Seems to work well.

 

Wow, there's a lot of good stuff here for me to start playing with, thanks vey much guys. I knew I was soft at the top of my timing table, but I was very concerned about the spark knock and just went to where I felt I was safe. The pinging is not audible it just shows up on my logs. I'm pretty sure it's valid though, because I got rid of it in the mid range when I took out a couple degrees. Just for giggles, I went back in & put back 1 1/2 degrees and the knock counts returned..........this made me more confident in the validity of the KS, so I think I need to respect it.

How does this sound for a plan on my next steps?

1. Restore and ramp some timing to about 28*

2. Play with AE vs LV8 a bit more
(is there a narrowband mv to look for in PT similar to WOT?)

3. Pull back my PE vs Temp as suggested, this is a global table, right?
(any recommendation as to how much?)

4. Work PE vs RPM as my main WOT adjustment table looking for 900+ mv as suggested and what I've read about previously. If I get this correctly, that will ensure I'm rich enough that I can then look at timing in the absence of a WB?

I'm not too sure I have the ***** to desensitize the KS quite yet, as I believe it to be fairly accurate at this time......I wish I knew how serious to take this knock retard as an "early warning system". Maybe I can learn more and grow into playing with it's decay & recovery over time.

This is exciting to have a direction, I really hate being in over my head & just playing with things not understanding their effects. Thanx a lot guys, I'll report back when I can get some more logs.

 

SOunds like a plan. You can take out some temp PE stuff but you'd have to compensate by adding it back into the pe vs rpm side of things. There is no part throttle mv to shoot for, thats what the wideband is for.

trust the knock sensor for now. Work fueling and spark since those are really the only 2 items that can cause problems at this time. If you cant get alot of spark into the motor, check the spark plug heat range...it may be a touch to hot for the setup and a step colder can make all the difference.

What compression and cam are you running? That can give an idea of what to expect as far as timing goes and spark plug heat range

 

Caboboy, I like your approach, and patience!
Just to add.
As you already know, the NB jumps around at all ranges if not maxed out high or low, so you can't tell a thing by looking at it for mid range areas, Like Orr said high 900's puts you at a good afr base before you get a WB hooked up.
I cant say why I started to PE tune with mainly the PE vs rpm table, I must have read it somewhere and continued to do it this way , I have my PE vs temp down into the 10% range in all cells, and Pe versus rpm in the 45-55% above 2800rpm-6400, you can carefully try it this way!

I forgot to ask you. Are you tuning in open or closed loop?

 

With my 383, I set the timing table to what i wanted to run first, and then did some cruise tuning. Stock MAF tables were close enough to BLM 128 that I didnt have to do any adjustments. Idle tune air fuel was abit off so I richened it up some. Ignored idle BLM due to cam overlap.

My base bin had PE vs RPM set to 40% above 3600 rpm on up to 6400 peak. I left it there to start. I knew this was gonna take some fuel.

Then I started rolling into the throttle to enter PE mode and watched WOT air fuel via wideband but you can watch the o2 voltage on narrowband. In PE mode it will stop switching back and forth and actually level out to a set value, which depends on air fuel ratio. Like said, around 900mv is ~12.5-13.0 to 1.

As as I saw air fuel abit lean, I started adding in PE vs RPM values to the rpm spots I noticed were lean. Eventually I got to go WOT and saw WAY lean but didnt hurt the motor with only 34 deg timing on AFR's chambers. Immediately added 20% and tried again. Still lean, so kept adding 10% increments til I got air fuel near 13.0. Eventually settled at about 86% PE at peak torque rpm and 78-80% at peak HP rpm but a big dip between peak tq and peak hp. Not really sure why that is but peak torque rpm is peak airflow demand and should require most fueling, so most PE should be added there. Then as rpms rise, it will increase fuel demand eventually where peak hp rpm happens.

Thats how I tuned WOT with PE vs RPM. I didnt need to use any other tables. I didnt have to adjust AE much either. Not sure if I had tip in knock counts or not, but I wasnt worried, car felt fine on throttle response and it didnt pull timing anywhere else during a pull. So I left it alone and didnt waste time with AE. I only had a slight bump in the AE vs Delta LV8 table. MUCH less than the values in this thread, but give what the motor wants.

 

My thanks to you guys and to all the others that share their knowledge so willingly here, your helpfulness is just amazing! I wish I could figure out how to multi quote, but apparently that too is a bit beyond me

Orr, my static C/R is 10.6 and the cam is an LPE 219...........not too wild at all for this size motor I don't think. It idles rock solid @ a commanded 750 W/O any lope at all. I think the plug heat range might be a real good thing to look at if & when I get backed into a corner. Great suggestion!

Mark, I'm doing this tuning in closed loop. When I start the car up, it's pretty solid @ 127-129 idle & light cruise; and currently I have my OL/CL timers shortened on all my startup temps.

The thought occurred to me that since this motor is using quite a bit of air (I had to bump my scalar in table 1 and I'm right on the edge in table 2), maybe I should expect to use a lot more fuel proportionately in my AE and PE?? Previous runs show I max my MAF by about 31/3200 at WOT. I have the airflow vs RPM set to max at 2800 RPM and beefed up substantially below that.

I'm pretty tied up right now, as I coach football and this preseason has been all consuming, so my datalogging is going to drop off to once every week or two now............maybe even less. Bummer, because I'm all hot 'n bothered about getting into these options now!

Here's a log file from 2 weeks ago, it will show some of these tip in areas that prompted me to start this thread. Thanks very much again!

 

See thats what I was thinking here, if the cam was small for the size and the compression was high, it may need less heat range in the plug and also less timing. Higher compression motors with small cams like this have high dynamic compressions and that generally is used to determine pump gas compatibility, heat range and timing. Its not the end all be all parameter, but helps alot.

So based on a higher dynamic compression, you will want to keep timing low in the lower rpm, higher load sections. 28-30 overall timing at WOT may not be a bad idea for peak power. It may not need the conventional 34-36 deg that most SBC's run. Only one way to find out and thats to track it or dyno it and watch for knock counts/timing retard.

Give it what it wants!

This very well could be the case. You have smaller heads that already have fast velocity ports. With slight throttle, the amount of air that may pass through the valve could be huge compared to a similar 4.00-4.03" bore 350-383 type motor. 400+ inch motors use ALOT of air, and its hard to go too big on heads for those motors. With your setup, it makes sense that it requires a large pump shot of fuel for even slight throttle openings.

Give it what it wants!

Its evident by the fact that you max the MAF at 3200 rpm. Thats insane. My 383 would do it by 4500 I believe, and thats about where peak torque was. I made 400whp/380wtq. More torquey setups require alot more air at peak torque rpm, so around 3200 is likely the peak torque rpm on that setup, and it probably makes ALOT of torque.

I was helping tune a big inch TPI based motor once and saw it was maxing out the MAF very early as well. The car had a small cam with lots of lift and good flowing heads...recipe for big torque and good broad power!

 

Orr, you've hit the nail right on the head on peak torque, that happens at just over 3000 RPMs and starts to drop off quickly after 4500. I might be a good candidate for one of tequilaboy's MAF packages but I better learn to walk before I try running! The DCR is right at 8.2 or 8.3, I was very cognizant of that when I built my motor. Especially since we have such crummy gas out here @ 91 octane. The last thing I wanted was to back myself into a corner on detonation. I'm going to start hitting the AE vs LV8 much more than the 5% increments I've been using, maybe that will help.

Thanks to you & gbayfisher for all your help on this!

 

With your heavy MAF flow at low rpm, you may benefit from rescaling the LV8 calculation. This idea combined with more delta LV8 gain will allow you to achieve more AE effectiveness over a broader flow/rpm range.

As it is now, your LV8 will saturate quickly. Once this occurs, the delta LV8 which drives AE will also be 0.

Of course, all other LV8 dependencies will need to be considered.

As already mentioned, an extended range MAF conversion would also provide benefits for fuel control where your current MAF is pegged, reducing the reliance upon artificial PE enrichment. This could easily be reversed as required for CARB related inspections.

 

Wow, that's some intriguing info, how would I go about rescaling the LV8? This kind of thing might well be beyond my technical abilities, (especially since I'm stumbling w/the AE & PE stuff already) but I'm thinking it would be fun stuff to learn. Even more so because my datalogging is going to be somewhat sporadic for the next few months. I'm really looking forward to putting my plan above into motion, but I'm thinking this concept would be pretty cool to play with.........it sounds pretty logical! Thanks!

 

In ARAP look at LC 5B0, it is set at 1.25 calculated or 50 hex. I have a 383 with a smaller cam. I reset this at 1.17 calculated and 48 hex.

What this does is bring your load (LV8) up faster, I found peak torque and max air flow maf and used that spot to bring the max load up to 255. This brings all your fuel in at that spot. My maf flows at 235 max so there was some adjustment to be gained

Most say don't touch, adjust some thing else. I have never read where anybody as adjusted this value. if you can max the maf and the load (LV8) then this adjustment won't help.

Tequila Boy has been way down into the tunes, He is the first that I know of to even mention adjusting it.

I have a spread sheet that converts the PE % to AFR, it uses both the temp and rpm and gives a calculated value. This is always offset from the WB numbers but gives you guide to how much you are changing the values.

I also use a spread sheet for the open loop stuff too.

HoJo

 

I've seen small cam 383 TPI based motors quickly max out LV8 and MAF at low rpms, just as this 421 motor is doing. So adjusting the value wont help anything? With the MAF maxed and LV8 maxed, its all PE fueling now correct?

 

In my case I am still running the stock TPI, so that may be why the lower Maf numbers come from. I have a first intake to install, that may open things up a bit.

 

For example, lets say you're at 2400 rpm with a moderate MAF flow of 128 gm/sec. With normal LV8 scaling, the LV8 will already be maxed at 255.

Since the LV8 is maxed, there can be no delta LV8 to drive additional AE.

By reducing the LV8 scaling factor and increasing the AE delta LV8 gain factor, you can extend the flow/rpm range over which AE can be effective.

 

Ahh that makes sense. I never thought of that before since I've never been in that situation. I've maxed MAF before but that was in WOT mode and PE already kicked in, so no more AE was necessary. I wasnt going 1/2 throttle to WOT either, it was always cruise and stomp on it, or drag racing from a dig with off idle delta LV8 changes above 180 or so

 

Since this has gone well beyond my understanding, I think it best to just stay the course with my plan. I bumped my AE vs LV8 another 10% and it seemed to help reduce the tip in knock counts.........next up will be an even greater increase hoping I can make more of a dent. I'll continue to add AE in increments hoping to subdue this knock.

Once I get a handle on this AE stuff, I guess my next step is to move along to the PE tables.

This is pretty stimulating stuff, some day I hope to be able to wrap my head around it...............thanks to all!

 

Hummm, now that I'm starting to understand this, is there no add'l AE to be had anywhere at a static 255 LV8 at part throttle?

 

I didnt see any additional values anywhere. So if your at part throttle and its near 255 and you then slam on the throttle, there is no delta LV8 anymore as explained above. You'd have to add alot of fuel to the lower part of that delta LV8 table I think but then that would throw off the AE feel at lower load increases.

Might be time to look into speed density swap

 

Going to speed density isn't an option for me as I'm smog legal here in Cali and need to keep it that way.......I guess ethics are getting in my way (or more likely stubborness)

I'll have to look at my logs and determine what conditions have put me into a 255 LV8. If as described above, if I'm cruising/mildly accelerating at 100+ LV8 and I stomp it, would that put me into PE and engage an entirely new set of parameters? In other words, is this roadblock only in the way at less than WOT conditions and PE can then provide add'l fueling in WOT?

 

AE and PE are 2 different things. PE can enable in less than WOT conditions. Theres a minimum LV8 variable that enables PE and minimum throttle position values to enable PE. You can adjust those to get PE in sooner and that may help.

AE is pump shot on throttle opening changes. Rapid change in airflow into the motor requires a quick rapid shot of fuel to compensate.

How does the car feel when your cruising and then going WOT? If it feels good and your only getting minor knock counts on that transition, then I wouldnt worry about it as long as air fuel ratio is spot on, while in WOT mode

My car used to get knock counts on the initial WOT hit but it quickly went away after the initial throttle stomp. It wasnt pulling timing through the pull so I wrote that off as false knock. It may have been from lack of AE fuel but the car FELT good to me when doing the WOT transition from cruise. So I left it there.

 

The car seems to feel pretty good as I recall, but frankly in the past year since I've been tuning and have made myself aware of the KR, I've really laid off going WOT very much. I think I'm just being a pu$$y and/or too **** about the dangers of pinging but it's there and I believe it to be real.

Maybe the modified motors like we run here on these boards are just subject to some degree of KR because of the highly increased demand on airflow and I need to get my panties a bit looser as long as it's not knocking too frequently....... just during the beginning of a quick blast.

I don't know, the log file above in post 19 shows my typical KR starting at frame 3521 and all I really did was roll into it a bit to a TPS voltage of 1.27.... not very much at all.

 

I didnt open your zip yet, but i'll try to take a look today.

Just make sure you have plenty of fuel during WOT operation and perhaps check your PE settings to make sure its enabling early enough. Need a good wideband o2 for this, but can use the narrow band to verify. Just look for 900mv.

Maybe try a step colder spark plug as you do have higher compression with a small cam for the cubes. It may want less timing overall due to the high dynamic compression and thats ok. Least amount of timing you can run to make power is exactly what you want to run.

If you rolled into it to TPS of 1.27, then its likely too much part throttle timing. TPS 1.27 isnt alot and may not even get into PE mode. So its still alittle lean and too much timing. Could pull some out and see what happens, or add a colder plug, and or richen it up some.

 

Thanks Orr, I'm going into the AE in increments before I take out any timing. I just gave it another 10% on my last bin which will make a total of around 35-40% over the stock ARAP numbers. I just did plugs less than 1K ago..... that figures

What is an accepted W/B ratio at WOT............did I read somewhere 12.5 to 13-1 depending on power? (I'm asking for a buddy)

 

Depending on gas, but normal pump gas i'd say as close to 12.8-13.0 as you can. Some like richer. More ethanol fuels may like closer to 12.2-12.4 to 1.

If you use lambda, tune for .85 or so, which is 12.5 to 1 on pump gas scale. E85 is more like .71-.78 or so but stoich for that stuff is like 9.87 to 1 compared to gas 14.7 to 1. If your wideband isnt configured for E85 scale, then on gas scale it would be anywhere from 10.5 to 11.5 to 1 for max power

 

Ok i see your logs. I see what you mean but its small knock retard (less than a deg) until alittle ways in it wasnt happy. It pulled 3-5 deg. That was at 2100-2200 rpm or so, and you have PE kicked in at this point with o2 milivolt around 910-920 which may be touch rich but ok. 23 deg timing there. I think I'd pull 2 deg here. It liked 21 deg timing at 2000 rpm but soon as it went to 23 at 2100-2200 it starting yanking timing.

Then at 3200 rpm or so, timing was 17-18 deg with lv8 at 206 and only part throttle. MV was 940's so thats rich here. I'd go up there a little bit on timing and pull alittle PE vs RPM at 3200 or so, but hard to say since this is only part throttle and your loading up alot already. Very torque motor thats breathing alot of air. Most setups I've run near full timing by 3200 but I never had a motor this big sucking in that much air.

Theres a small AE dilema possibly at line 3175 thru 3181 or so. You are at 2300 rpm , 1.53 v tps and go to 2325+ rpm quickly and up to 1.83 v tps. Lv8 went from 183 to 209 quickly, a delta of 26. MAF rose from 84 to 97 quickly, with base pulse width jumping from 6.36 to 7.37. MV drop from 910 to 896 quick then back to 914 then 919. Looked like a quick pump shot that showed a slight lean dip on the narrowband but could have just been variance in o2 sensor reading at that point. Hard to say.

At 3521 the big knock retard happens, and that MAY be from too rich. MV is in the 930 range. I'd lean it out some if possible. PE mode % at 2400 rpms thru 2600. Could try that. I mean your LV8 aint high there, the timing aint high, the rpms are fairly low, part throttle, so its not loaded up too hard. I'd expect much leaner fuel conditions there.

Tough combo to tune. You can end up being under any part of the fuel curve at various LV8 loads, so its gonna be picky on timing and fuel input. If you took out PE fuel below 2800 to make part throttle alittle better, whenever you run WOT at those rpms there wont be enough fuel!

May beable to adjust the PE enable LV8 value and use MAF flow to adjust fuel levels in part throttle situations, and have PE come in at high LV8 to make sure its getting fuel.