The area I have highlighted, does that look like something is wrong? Could that be the cause of my sometimes surging idle?

 

Yeah that doesnt look good at all. Should be much much smoother. Should steadily increase from low rpm to higher rpm and from low kpa to higher kpa values. You dip up and down which will cause random rich lean shots and spike rpms up and down

 

that describes my problem 100% exactly.


So how should I correct that? would you agree the high rpm table looks good? And its just the lump in the low rpm table that needs to be addressed?

 

If you had a wideband and or were in closed loop to watch int/blm you can try to manually hold throttle at the low rpms and certain kpa values to see what air fuel ratio or blm/int is produced, the adjust ve at that specific spot accordingly. You have to manually click on the graph to drag points around your rpm hold test point to smooth it out. Then retest by holding those rpms and looking at different kpa's and seeing what air fuel does. Can brake stall alittle to build more load to hit higher kpa's.

Other graph looks better but still can use some work in the low kpa 2000-2500 rpm range. That can be a higher mph cruise point or coast down spot in higher vacuum

Wideband o2 makes it much easier lol

Graph lines should be smooth for most part between cells. Depends on engine characteristics like cam size and where it starts to come alive but generally smooth increase as rpms go up and kpa goes up towards 101

 

I though you already lowered the ve in that area

https://www.thirdgen.org/forums/diy-...e-surging.html

 

Hmm if it was cold only idle problem i would leave ve alone and tune open loop vs coolant temp. Ve would effect both cold and warm tune

 

I do have a wide band, it swings rich lean rich lean rich lean at an idle sometimes at the same time the rpms surge

 

I never did because I changed my throttle body and fixed my stalling and I though took care of this problem so I left it alone. but it didn't fix the surge just the stall...

 

it does it cold and warm.... used to be worse cold before I swappe my throttle body out

 

Well definately work to even out that ve table. 700 rpms 50 kpa for instance should take just a tiny bit more fuel than 600 rpms 50 kpa. 700 rpms 55 kpa should take abit more fuel than 700 rpm 50 kpa. Flatten that area out abit, give it just a mild rising slope as rpms go up and kpa go up. Shouldnt have anymore surging issues.

Also for now try making all timing values around idle cells the same. Like 500 rpm 40 kpa to 800 rpm 60-65 kpa all the same value like 24 deg. Should help reduce some idle rpm swinging

 

will do. thanks man

 

Make certain no exhaust leaks.

This is from Raucher. It applies if you are cammed:

For highly tuned engines (IE: hot street stuff), the proportional
gains can to too high. The effect is the engine surging under steady
state cruising. Reducing the gain and multiplier values can reduce
this problem. The values in these tables can sometimes be cut in half.

 

im gonna clean up the tables tonight and upload them to see what you guys think.


its fairly obvious what i need to do to the low speed table, but what about the high speed?

 

High speed table? Are you not getting BLM data in it? Higher RPM Higher MAP BLM data is available just need to hold gear till you see corrections. Some will set PE TPS at a high % so as to disable it BUT you need to be carefull and dont forget to reset it afterwards. TunerPro has a smoothing option for all tables .7 is a greather smoothen than .9... It il pull down some peaks and raise valleys.

 

Yup, try to hold gear and hit the various kpa's and rpms to see what its doin. Tune from there. You have abit of a valley in the lower kpa 2000-2600 rpm range and thats sorta a spot thats rarely seen during engine operation but possible. Have a slight peak around 2400-ish rpm and appears to be 70-90 kpa area? Again a harder spot to hit unless heavy load at low rpm but still should eliminate these spots

 

Ronny,

I've tried using the smoothing but I don't really understand what the meaning of a .9 v a .5 factor really means or does. What would be a value of practical
use?

 

The closer your ve table is to correct values for your motor, the less smoothing you need to do so use a higher decimal number .8-.9's. if you are way off and have significant peaks and valleys, try lower decimals .3-.5. Generally i try to do it by hand, manually adjusting the points on the 3d graph itself to make a somewhat uniform smooth table. Test it and make changes as necessary, then do smoothing with .7-.9 values so it makes small adjustments at a time

 

I do it manually as well. Try to identify the "in between" cells which had no hits and then adjust to the overall path of the curve.
When u use smoothing, do u use it over the entire table or specific sections?

 

Mostly specific sections because my engine is funky. Theres a point where the cam comes alive in the lower 2000 rpm range and kpa of 70 and higher. Theres a huge jump in ve there so i do not smooth that section.

Also at 120 kpa in boost my second fuel pump comes on and spikes pressure. Theres a huge drop in ve in that region before rising again at 140-150 kpa. So i dont smooth across those sections

 

here are my new VE tables.

what you guys think?

 

here are my SA tables. I did not touch these outside of just adding 2* across the board. Base timing set at 6* then added 2* across the tables. So Basically Running 8*

 

Looks better. Now drive and see how it reacts and fix trouble spots.

Timing is ok too, but does that included pe mode advance? You can zero out pe mode advance and add those numbers into the main table just to make it easier. Could also bring max wot timing in sooner. Could also try locking out idle timing. In cells 400-600 rpm and 40-60 kpa you see 22.15 in all of those. Thats locked timing. It only stays one value as rpms fluctuate around stock idle. If cammed, and you idle higher say 700-800, those spar values start increasing in your table. You could try making them 22.15 as well but with a cam i would just add 2 deg to make it 24. Should also help stabilize surging

 

i never touched pe mode advance.... to be honest not sure what it is...

 

Look for the table. It adds spark when you get into power enrichment aka pe mode. So in main table the value at peak rpm at full throttle may be 28 deg but in pe mode it may add 3-9 deg or so depending on bin file so actual commanded timing is 31-37 deg. I usually add those values into the main table and make pe mode table all zero so it doesnt add timing in.

 

oh ok i see what you mean.

and going back to what you said before do you mean basically take the table 40-60, 400-800 rpm and make them all either 22.15 or 24?

i do have a crane 2032 cam which i guess is considered very mild. keep in mind at 22.15 that is already bumped 2* over stock since I took teh whole table and add 2* if i go to 24 thats 4*

 

Yeah make them all the same. Try the 22.15. Stock cars idled 500-600 and the timing was all the same. It does help tame cam surge/lope when this is done. Also playing with stall saver functions at the same time when you adjust idle speed. If they arent configured right you can enter a surging effect.

What rpm is the cam wanting to idle at? I would think 600-700 would be plenty.

 

the desired idle is set between mainly 600-800 depending on temp and drive/rev- park/Neutral


so basically just make it 22.15 right thru the 800 rpm line? and i shouldnt have to touch the 1000 line, correct?

 

I would maybe try 24 if you idle 700-800 at times. Rest of it looks fine

 

24 across the board just at 800 or 400 600 and 800?

 

I think he means the RPM and MAP cells that the idle SA is occurring in. IE if you see idle moving cell to cell then place in SA cells the same values. You dont want SA changing at idle.

Also if you see it moving synch fuel to asynch back to synch due to PW needs you should lock synch fuel. It may not happen but watch for that in log.

 

Yup across the entire idle area. 400-800 and whatever map cells idle sees

 

ok will do

 

I should have jumped in here sooner. There is an option flag to have a set idle spark advance value. This is set in the supplied calibrations, when this flag is checked:

Option Word 2 - Bit 1 - IdlSa

The idle SA is from this parameter:

SA - Idle State SA

Even with this set, the idle SA can still move around due to the idle SA compensation tables. There is an idle high and an idle low compensation table. The purpose of these tables is to prevent a rolling idle speed.

The value used for the idle state SA should also be used in the area of the low speed SA table of idle. This is to provide for a smooth transition from idle SA to off idle SA.

RBob.

 

ok so
Option Word 2 - Bit 1 - IdlSa - check that - i think mine is checked

SA - Idle State SA is that a flag or table? match that to what i was going to do from previous post in this thread?



i guess the ecm knows its idling from VSS & TPS?

 

The SA - Idle State SA value is a single value in the scalars area. Yes.

> i guess the ecm knows its idling from VSS & TPS?

Yes. Note the ClsdThrt and Idle indicators on the main WUD display.

RBob.

 

how does this look?

 

Yes & no, it depends. It's been a few days, how does the engine like it? And, is there a smooth transition from idle to off idle? If so, then all is good.

Another way to look at the above SA table, where does the engine idle (RPM & MAP), and where does the RPM & MAP go when pulling out from a stop. If the idle MAP is say, 40 KPa, and it goes to 60 Kpa on tip-in, then there is going to be a jump of 4*'s of spark advance (24* to 28*).

That may be enough to cause a 'jump' in engine torque and make the driveability less then desired.

If the engine idles at 55 KPa and goes to 70 or 75 KPa at tip-in, there is less of a jump in SA. Making for a smoother transition.

Think of SA as a torque setting; within reason, more SA is more torque. So lower RPM & load SA is mostly geared toward driveability. While medium RPM & load is geared more toward emissions and mileage.

With higher RPM & load geared toward power.

RBob.

 

yeah im gonna have to take it for a ride and see how it reacts