i am in the process of tuning my 96. i am using jets dst. i got a base tune from madtuner.com and from what i am reading i should be starting off with the ve tables. i am wondering if i should attempt to tune it in speed density first? i am worried about doing anything with my maf tables or if i should even need touch them at all after i attempt tuning in SD. any tips or recommendations are welcome and appreciated.


mods to car if anyone is wondering
ported lt4 heads and lt4 intake, 245/253 @.050 with .612/.612 on a 107 lsa, fully forged 385ci with 12.3:1 compression, SVO42lb/hr injectors, comp pro magnum 1.6 rockers, EM long tube headers, slp exhaust, EM gladiator 44 diff with 4.10 gears, racetronix hot wire kit, 12.5lb fidanza aluminum flywheel, carolina stg 3 clutch, 52mm tb

 

Haven't seen too many here tuning late LT1's with MAP and MAF
Might get more help on LT1 tuning forums?

http://www.ls1lt1.com/forum/forumdisplay.php?f=77

 

On a '96, speed density is only for backup if the MAF fails. If the car runs with it's current tune, there's really no reason to mess with the back-up unless you're bored.

Before you do any tuning you should save a backup of your current file (if your software allows you to do that). If it does not, then write down the stock MAF values so that you have them. Next tune your MAF table. After the MAF table, fine tune the timing tables, especially in the low rpm cells so that you have decent driveability and idle characteristics. Once idle and part throttle are complete, you'll need a chassis dyno to tune WOT via the PE table and the timing tables.

 

well i clicked the box for a speed density tune.. the car hardly runs.. so if i did have a failure i would be up ****s creek. i barely made it out of my driveway let alone back up it.. its there for a reason isn't it? i can make as many different tunes as i want. i have a few base tunes and adjustments from there out.

 

94-97 lt1's have both maf and map

 

really? nobody has any input?

 

It is kind of interesting. I have also found a lack of input on tuning on CF. I have gone over to Thirdgen.org and found some input there. Also on some sites just for EFI issues. Not sure why.

I converted to MAP from MAF and did not find it difficult to tune the MAP for basic driveability. Since that is your failover mode I would start there and at least get it right for non-WOT driving conditions so you can get home.

Are you tuning with a wide band O2 sensor?

I just started with idle and adjusted the VE table until I got the A/F ratio where I wanted it then took the RPM up to 1k, 2k, and 3k and adjusted there. Then put it in get to get a little load and did it again. Finally went out on the road and checked several load / driving conditions to see how the AF was looking. Finally went back over the VE table and adjusted surrounding cells to smooth it out. Got it going OK just doing that.

The Holley manual for tuning their system has some really good info for startup / basic tuning. Even though it is focused on their software and hardware it is still good info.

 

i have an innovate LM-1 and am logging afr rpm and kPa.

 

I have the LC 1 with the display inside on the dash. I like knowing what the AF ratio is all the time when I am making changes just in case I screw up something on one of the tables. I use the O2 reading to get the VE table set where it needs to be.

I had a couple minor issues getting the LC 1 set up to feed the display and the ECU different values at the same time but it is working now.

 

It was running about 12:1 at idle. I back the values down on the ve table a bit in the areas where I got data from. Now it seems really really rich and won't start. This was a mail order tune to start off with and I have gone over a lot of the data to make sure it was correct.

 

Cams with a lot of duration are notorious for running rich at idle. To solve it, many people run Open Loop.

If the car runs poorly in speed density mode, then program that first (idle and part throttle) and then move to MAF tuning. Finish by tuning for WOT.

 

To get the SD done right requires quite a bit of steady state driving/running at most of the load vs. rpm ranges. It can be done but from your perspective will be very time consuming especially if you've never worked with it before. So, uncheck the box and go back to MAF. You will need to start from scratch and knuckle down and do some tuning. You can start with the open loop stuff if cold start and run is that bad. From there you will need to start working the maf tables in closed loop.
However, more than likely based on CR, and the type of fuel you should be using you will probably end up doing an OL tune on it. Doing it that way, and since you have an LM it shouldn't be that bad to tune.
BTW, I'd start more like 13.0-13.5:1ish at idle

 

Thanks for the input mick. My cam allows enough bleed off to run pump gas. I don't mind spending time to do it properly. I was surprised when it went from running about 14:1 to 11:1 after going to speed density. I then went into my log and decreased the ve value in its idle areas and loaded the tune and it wouldn't start and fouled the plugs. Trying going back to a known tune and it wouldn't start still so until I get some new plugs I am stuck for a bit.

 

This is a big cam with lots of overlap, you will have issues with the SD tune at idle because the idle vacuum will be so low (manifold pressure will be high). If you are rich at idle you will need to lower your VE at the new idle positions (probably KPA of 70 to 85) to the same numbers your stock tune has at 40 KPA as a start point to see if the car will run. Once it is running you need to fine tune the idle VE until the AFR is what you want.

The MAF tune will be much easier to get correct because the engine knows how much air is being used and then adds the correct amount of fuel. One easy trick to start the tuning process is to run the car in MAF mode and record the grams of air per second that the engine is using at idle. Compare this reading to the amount of air that the engine should be using at the same RPM if it was operating at 100% VE. Actual air use / 100 % VE will give you actual VE at that RPM which will help you dial in your base VE table faster.

 

I don't actually have a stock tune. All I have is the pcmforless tune from my last engine and the madtuner mailorder for this engine. The madtuner was seriously rich to the point it was fouling plugs within a half hour of running. I need to get my scan tool to record some data so I can make sure what I am getting on my lm1 is correctly converted

 

ok. so i figured out where i was going wrong.. once i read what bjankuski wrote i realized that i wasn't making adjustment far enough over in the graph to effect where my car was actually idling. a few more adjustments and it will be where it needs to be. then on to the extended map.