Which should be attacked first, VE tuning w/&w/out MAF or the idle?

Both need to be done, just trying to figure out which needs to be done first.

 

I scaled the VE table first, then raised the idle to 900, then tuned the VE table without maf, then calibrated the maf.

 

personally i would attack ve first, your idle should fall into line or get close. Old schoool methods reduced the ve table by 40-60-80 in the 400 800 1200 colums and then moved on to fooling with idle

 

Idle first so it doesn't suck to drive while you're tuning ve.

 

Good point

 

So, what's the consensus?

I don't want to do one and then cause more issues with the other and vice versa. So which would be the best to do baseline and not have major adverse effects on the other.

 

Make a backup of your current stock tune, then try one way and if you don't like it go back to your original tune and try it the other way.

 

I tried the VE first in SD mode. After getting the VE inline my idle was PERFECT. It NEVER surged on hot idle, cold idle, anything. I then calibrated the MAF and plugged it back in. Now my idle surges on cold start up until it gets into closed loop and surges a little at the stop lights(Fuel trims are perfect still). Im not sure how to fix this. I tired messing with the RAF table but had no luch?

 

I'll assume you're tuning an M6 car since it seems like everybody down there yanks their A4's if they have them...

An M6 car might idle adequately with a pretty healthy cam with a stock idle tune. My cam is over 230 duration, and it idles with nothing more than a slightly bumped up idle speed.

That being said, I'll vote for tuning the VE first.

 

you can pretty much cut the first 3 columns of VE down quite a bit if you got a big cam, that will make life easier. another thing to do to make initial tuning easier is to set idle to 1000+rpm.
Then go do VE in SD mode, and as you gather that data, you can also start gathering data for MAF. don't put them in yet, you probably won't have enough of it to be precise.
By the time you get your VE dialed in, you should have enough data to get your MAF in line. try it, put it back in MAF mode and see how it behaves. if it's good, congratulate yourself, if not, just turn it back off and go for some more logging, and just keep on adding data. that's what my spreadsheet is really good for.

I don't like a lot of tricks others do, like disabling DFCO or PE. So far i'm yet to find a reason to do it. my car's been tuned to a tee, and despite changes around it (new injectors, super humid/hot weather, etc) it's still dialed it damn near perfect.

mostly though, don't be afraid of trying things, just try them one at a time

 

trying to tune idle with the fueling incorrect will make it hard.

Stabilize spark, and idle is easier to deal with.

Ryan

 

idle first it sucks when its dying and your trying to log, you can always go back and adjust idle params.

 

i got my idle decent but didnt work too hard on it, then worked on the ve a great bit and got it where i liked it, esp at idle cells, and then i got to tuning the idle. you will never get the idle right if your ve is off because it will throw off your ltit's and act funny. just by resetting the fuel trims after some ve adjsutments my iac counts droped from 50's to the 30's

 

could someone post a config file to do IDLE tuning? I'm trying to get a big H/C/90/90 car to idle right, and right now it's surging. i did the 70/80/90% cut like 5 times already, reseted fuel trims every time, and the last time i did it it idled fine for ~30secs, then went back to surging. i'm not sure what to observe really. i tried playing with the idle screw and resetting TPS as per all the posts, but numbers changed, but it still idles like ***. what is the goal? what do i regulate to get what numbers, and how do i measure it?

 

For idle airflow tuning i use the regular stuff on the left side of the table display and the right side has IAC position, dynamic airflow, idle desired airflow, and fuel trim cell. The goal is low IAC position when warm (i like less than 30), dynamic airflow=idle desired airflow=idle airflow (table in editor). You can monitor STIT and LTIT if you have room and they should be close to zero. The reason I monitor fuel trim cell is because it should be ftc 19 when doing this.

For idle fueling, i just use ltft and stft like normal ve tuning.

 

i can send u my file when i get home, it worked ffor me

 

Here's some information that I have collected from the EFI Live Forum and HPT Forum on idle tuning. It should get you where you need to be.

Idle (transition) tuning procedure for C5's (drive by wire).

A collaborative effort between Nick Williams and myself. A lot of testing on many cars has been done to ensure the process works. Besides it makes sense. There are pieces of information that have been stated by others, but seem to have been somewhat ignored. The MAPS in EFI have helped make the tuning process easier. We are very open to ideas,or the need for clarity. You can prove the process by logging the information suggested, from a stock car and you will see the results make sense.

The following assumes a reasonable tune has been done to the car. Here is a quick outline of my preferred method.
-Put back all stock airflow and timing values.
-Input the stock IFR values for stock injectors, or calculate new values for larger ones.
-Put in A/F multiplier values(PE RPM), calculated to your preference. (ex.14.7/12.8 = 1.15 mult.)
-Work on VE's with the MAF zeroed. (You can do speed density. I just don't feel it's worthwhile if you run an MAF. JMO. Others can do what's right for them.) Bring the MAF back on line and adjust it for ltrims.
-Then do Idle Transition Tuning.

Idle transition tuning:
-Start with Ltrims reasonably negative and your Standing Idle is set where you are happy with it at all temps.
-If your VE's are off by 20% or more they need to be set.
-Return all airflow tables to stock, except idle, idle airflow parked(IAC Park) and idle airflow(RAF). This is so the car will idle. If you can return all the airflow tables to stock, go ahead.
-Set up Maps for Maf gms/s and Desiac gms/s, by ECT. Use the format in the PCM.
-Log, IATc, ECTc, SAE MAF gms/s, GM DESIAC gms/s.
Since you are in open loop when you first start the car, watch for your trims to show(closed loop) and your idle to settle to where it's set and start the tuning log.
Log while parked, from the coldest engine temperature to fully warmed.
Log for at least five minutes after warm up to get better averages and since this is the temperarture where problems are noticed.
-If it's an a4, log in gear with the A/C on. You may want to repeat this process in neutral later or just check to see if your RPM's stay up when driving and you put the car in neutral.
-If it's an M6 log in neutral.
-Input the logged MAF values into the idle airflow (raf) table, by temperature.
-Raise or lower idle airflow parked (IAC park ) values.
You want to match logged desiac and maf values.
This is done within each IAT range. You will need to watch Desiac and Maf results in Dash f10.
Raising/lowering IAP raises/lowers desiac.

The idle airflow parked table is the difficult part for a number of reasons.
-The temperatures are IAT. Some think they are ECT.
-The temperature scale is in 20c increments.
-Raising the IAP values raises logged desiac, and raises expected airflow. The TB closes some and you could get stalling surging, etc., if your target is wrong. The opposite scenerio would be racing. This is important, since you are working with logged averages and may/probably need to make small adjustments and the affect is counter intuitive.
-This need to be done on different days in order to set within each IAT range as weather changes push your intake temperatures up or down.

-Finally, timing will help idle and flare at start up. If you have EFI Pro you
can use BI-D Controls to test(SOP)timing changes, otherwise program
timing changes a little at a time. Make the changes in Base Spark in
Gear and Base Spark in Park/Neutral.
-Check, ltrims, AFR and adjust.
-When you change IFR's, MAF #'s, timing and airflow table values, the
trims are affected

This process will help eliminate, stalling, surging, false idle learn and unlearn, colds, headaches, etc. My opinion is that many of the problems that occur after a cam are a result of not understanding the IAP table. You will notice that your ltrims and strims become flatter.

There are some situations that make perfection a little harder.(Maybe impossible). Don't have knowledge past a G5X3.
-Really big cam. ex. Mine is a 228/589/112 in an a4 and tuning is easy.
-Long tubes that place the 02 sensors far back, which allow them to cool fast and take longer to heat up.
-Cold air intake, which causes rapid IAT changes.
-Any throttle body with a ridge that's been worked.*
-Descreened MAF/ not properly calibrated.
-Low rear gears(3.73 and lower) and a stock or almost stock stall converter.
-The tuners ability.


* I continually read opinions that the 90mm TB is hard to tune. The N. Williams 90mm TB and stock TB's are not hard to tune. It's the cam.

Don't look for perfection in the numbers, they do bounce around. If after you do this it idles and transitions well, be happy.


HPT Info

Monitor your two LTIT's and STIT in the scanner. You will notice the LTIT should settle to a constant value after a few minutes (idle learn process) in PN and Gear for A4's and Gear for M6's. After the LTITs have settled take note of the following:

- the LTITs should be within the min/max limits shown in the editor (see the help file)
- the STIT should be close to 0

If the LTIT's are at either the min or max limit you have a problem with your base running airflow (if LTIT is max and the STIT is positive then your base running airflow is too low, if LTIT is min and the STIT is negative base running airflow is too high). Also it's good to watch your STIT when the fans come on so you can see if the correction is ok.

I tend to keep the limits at the factory settings and just change the base running airflow numbers and the various compensation factors.

The important thing to remember is the base running airflow is the starting point for the adpative idle routines. Most cruise control and rpm drop issues when coming to a stop are symptoms of the LTITs being at their limits due to base running airflow being out to much. This is most noticeable after a camshaft change.
The main one is the "Cooling Fan Airflow" this is the extra IAC airflow required to compensate for the alternator load when either one or both fans are on.

There is also the throttle cracker which opens the IAC based on RPM and mph, and the throttle follower which is a dampener/decay function for when you close the throttle suddenly.

The other is the AC. The AC is a little different as it is torque based, you'll need to head over to the Engine -> Torque Management -> Engine Torque section and look at the "AC Compressor Torque" tables. Again, watching your LTIT and STIT when the AC comes on will tell you which way you need to move things.

 

Where are the LTIT and STIT PIDs in HPT? I can't find them

 

they are under idle airflow, or idle i cant remember what it was called exactly but it has to do with the idle

 

I don't think my version of HPT has the LTIT and STIT. I can't find it anywhere on the scanner.