robertf97

Ok got my 416 ci stroker back with TSP VVT1 cam yesterday and need some help with driveability tuning. It idles OK but stumbles on take off and generally has surging/crappy response until above 1800 rpm or so.

I posted my tune and a low speed/idle log file on the HP Tuners forum:
http://www.hptuners.com/forum/showth...999#post363999

I've been using this you tube guide and it is getting better but this ECU works a little different than the one he is using so any expert advice is appreciated.

Higgs Boson

Need to tune fueling and spark timing, they are stock

Cordes Performance Racing

You also need to play with how the e-diff is seeing expected torque. That is another area that will cause these cars to feel terrible down low than around 2500-3k rpm feel like you hit a nitrous button lol.

Higgs Boson

even with the stock tune and no ediff mine feels like I hit a 15 shot right around there....definitely room for improvement with the torque tables.

robertf97

Yes, I have been doing that, they are not stock. These are the differences. Should I be adjusting another table?

robertf97

Thanks for the input. I looked in the TCM parameters and didn't see anything labeled as e-diff though. What menu do you adjust?

Higgs Boson

Need to tune tables:

MAF Calibration under Airflow General
Use tables in Speed Density tab under Airflow to create VE table and tune it

use your fuel trim errors at part throttle to tune the tables then use a wideband for WOT/PE cells

tblu92

The tables ypu show are for open loop---mostly only used on both cold starts and then again only breifly on warm starts--I don't see them as a reason for your issues
Right of the bat with a new VVT/DOD deleted cam you need to make sure you deleted all the DOD tables and adjusted the VVT tables to reflect the cam phase limiter--
Also the cars have "double pulse fueling and spark-- typically you need to add timimg in the normal hi oct table and the double pulse table to get them to idle--also adding a % to the desired airflow
The TQ response table didtate how aggressive the ECM will be in attempting to achieve the TQ you ask for---Setting these numbers too high will in the lower MPH and lower TPS ranges will make the car feel like you added an NOSshot---simply means you have been to agrressive in the TQ response tables---It all about drivers preference but if too aggressive at low TPS the car is too jerky and not fun to drive-

robertf97

Thanks much for the input. How to change the closed loop parameters was not straightforward.

I read here "In the speed density table we still have VE CoEfficient tables To tune it under the dynamic table, you’ll have to drop the high RPM disable from 4000 to 200 and Re-Enable to 150 RPMS"

https://www.corvetteforum.com/forums...-computer.html

Doing this seems to have allowed the changes I made in the "VE Initial Correction Factor" table have an effect.

My dual spark mode is disabled. Should I enable it?

If you don't mind please have a look at these tables. I want to pull fuel and add spark at idle to account for the cam. My O2 millivolts are oscillating from 900 down to 30.

Higgs Boson

Robert, what you are asking about is tuning basics, editing you actual airflow tables to reflect the new airflow through the engine.

forget about all the other tables besides what I listed above. until you edit your maf curve at a minimum, you will not find resolution.

there are a lot of write ups on hptuners forums about how to tune your maf and how to tune your ve table(s). you simply need to do it.

set up your histogram for logging stft error (disable your ltft and clear your trims before logging in the scanner) on the maf table. disable ve, and go drive around and log. set up necessary filters to keep the info clean. copy/paste half % into the tune and flash. repeat until fuel trims are -2 to -3 at part throttle driving. next disable the maf, use bluecat software to convert your ve info into a ve table, log and tune trims into ve table just like the maf, reconvert the info to virtual ve and correct the tune.

next do the same thing for wot with your wideband.

then you can fiddle with fine tuning the idle integral and proportional tables, etc.

if your fueling is wrong, nothing else will ever be right.

injector data first, then airflow data, then all else.

robertf97

Thanks for the input Higgs. The car has been tuned at a professional tuner for the last two weeks and he can't figure it out so I took it back. He has been to tuning school and done hundreds of LS motors and has already tuned the MAF tables significantly above stock on a dyno so I was looking elsewhere.

There are a lot of tables under the speed density tab I don't understand as there are no units on the columns and the numbers are all over the place, no logical order to it that I see. So I don't want to change those without understanding wtf they do. What would you change on this Speed density tab? Thanks, Robert

Higgs Boson

Ask him why your MAF curve and VE tables are all identical to a bone stock C7 file.....at least on the tune file you posted. The whole reason I learned to tune was because of my improperly tuned C5Z 408 ci nitrous motor.....Yeah, I learned on 850 HP.

There is no more traditional VE table, if your tuner did something to the MAF curve in some other tune file that isn't posted, and he left the Virtual VE tables, some of which are in your pic above, the car wont run right. You (or your tuner) must use Bluecat software to gather the data in the tables (and others) that you have pictured and form a traditional VE table that can be edited with corrections from the Scanner histogram (for tuning a VE table) and then corrected and reformulated back into Virtual VE tables.......in other words, it's not like it used to be, but it is still what has to be done.

If you posted the tune that is currently in your car, the airflow tables are a problem. Until I can see that the airflow tables ARE edited (correctly) then there is no way to move on, we are just poking around.

btw, adding timing to make a car idle is a band aid and not the right way to tune, you will disable the ECMs ability to adjust timing properly to maintain idle under varying circumstances.....and these cars do not use dual/split pulse functionality.

robertf97

Thanks for your patience, I think I just had a eureka moment and modified the EQ Ratio on the speed density tab from 1.0 to .9. Will try it in the AM

Higgs Boson

That isn't going to do anything for you. That is related to throttle opening 100% at WOT. Leave at 1.0

tblu92

What are your other mods besides your cam ?
Did you do new heads ?
new intake manifold or T-Body?

IF you only did a cam swap my opinion on a daily driver is to leave the VE Tables alone
The increases in HP or throttle response is not the significant to have to spend hours and hours of complicated data logging to get maybe 5 HP---Your car has a MAF---use it--
The times I use strictly a total SD tune is only when required which is typically when you outgrow your MAF HZ table---With onlt a can change you have plenty of room left to grow and are still fine using the STOCK open /closed loop MAF tune
When using the stock system (OL/CL) the only time the ECM will use the VE tables are during "Rapid changes in airflow" and then only as another reference and use the average fuel from both the VE tables and your MAF tune to set the final fueling--So spending hours on a midly modded engine while using the MAF is not entirely needed--
You need as mentioned earlier to sort out all your issues 1st with idle-surging dying etc
before you ever attempt to mess with VE---And VE changes don't happen immediately so you find yourself chasing your tail and at evry VEchange you need to drive the car 25 miles or so to take full affect---
Whereas a change in your MAF HZ table takes no learning or driving--It happens immediately Get all your LTFT's at "O" or slightly negative--
As far as I know there is not yet to date any tables to correct many issues as in previous LS type engines---No throttle follower--no throttle cracker-no Min idle airflow or Max idle airflow---So far all we have is idle speed--- timing for hi and low oct and then for double fuel pulse mode---No separate idle timing table either (base timing in gear and P/N with the throttle closed----

Higgs Boson

there is a follower table.

tuning the ve table doesn't get you 5 extra hp, it isn't even used above 4k rpms. it's for driveability and throttle response, smooth transitions under 4k. the maf is slow to respond at low rpms and its a huge mistake and compromise to go maf only, even though it "works" it doesn't mean it's right. ve changes are immediate.

stop giving hack recommendations and inaccurate advice. you are pointing people in the wrong direction.

robertf97

OK thanks. I just downloaded the Bluecat 3.5.hpl and will start using it.

robertf97

Thanks for the input. The engine is 416ci, 220's cam with +32% fuel lobe, ported heads, supercharger, ~9.5:1 compression. this is what the idle page looks like:

jim2092

A stroked and supercharged C7 may not be the right engine to "sharpen" your tuning skills on. You probably need actual hands on by one of the few who are familiar with the new ECM in this car. You will wear Higgs out doing this via the internet.

robertf97

Yeah I am communicating with Bluecat at the moment to try to hire him to do this for me.