Ok at start up the car is death how do i clean this up , i have nop cat but the car should not stink likr this, do i make the change in
AFR X10 vs coolant temp
now do i add to lean out or
take away to lean out
thx

 

Ok #1 What year car, OBD1 or OBD2 ?

Tunercat or LT1_edit ?


Just some ideas, to lean out your fuel mixture at idle first you need to hook up a scan tool and see what KPA the car idles at. Then go to your Volumetric Efficency tableand start lowering the numbers in this table area. Once you have the idle tuned, you will need to smoothen out your VE tablearound where you changed so that it smoothly transfers to the next VE table upon acceleration.

Also make sure your fuel injectors have hte correct offsets or tunign is absolutly useless

Chopping up your MAF tables is not recomended, causes irratic acceleration problems.

Subtracting values in the VE table subtract fuel. Basically your telling the engine it is less efficient at X value so it adds less fuel.
A Pro I will not name whos on this forum, told me VE tables is the place to tune.

ALSO VERY IMPORTANT, Your car probably idles in a different MAP range than it used to. You MUST Increase the spark timing in this KPA range to what your car would usually be in when it was stock.
Stock LT1s usually idle between 25-35 KPA, so transfer these timing numbers to the KPA range your car now idles at. This will help your idle richness alot too.

 

OBD1 car/tuner cat

-what KPA the car idles at, my car idles at 55-60 kpa

-Volumetric Efficency table, what dose this do/for/how much to start with

- you will need to smoothen out your VE tablearound where you changed so that it smoothly transfers to the next VE table upon acceleration.
i thought the ve table was for speed den/ cars

-Also make sure your fuel injectors have hte correct offsets or tunign is absolutly useless, i have 30lbs svo offset at 31.68, F/P set at 43 vac off.

ya i have played with the maf tables and i can fell the tip in/ put it back to stock.

will this help with the high/low blm

i have my timing up to 34* in the closed tps table

this is great info need more thanks

 

VE tables are for speed density cars. If you want to do a little experiment, change your ve tables to all 100's...I'll bet it doesn't make one bit of difference on a mass air car.

That is your injector constant, not the offsets.

 

I beg to differ DAN K. I have a 97 OBD2 LT1 383 stroker. On the dyno We tuned the VE tables and gained 40 HP. The VE tables are used in MAF cars and DO have an effect.

Basically if you have the VE set to 87 at 3000 RPMS @ 100 KPA this means the PCM will think the engine efficiently uses 87% of the air ingensted into the engine when at Wide open throttle @ 3000 RPMs. Subtract from this number and the PCM sees the engine is less effecient and subtracts fuel and vice versa.

Now the MAF tables allow the PCM to compensate for air temp, humidity and such. Which does change the actual fueling of the PCM. But the PCM starts with the VE tables and uses the MAF and O2s to make changes based on the NUMBERS in the VE table.

Im not certain where the rumor or theory that VE tables do nothing for MAF cars came from or who researched it. I know for a fact someone thats on this board that some of you have even paid for tunes from, has told me VE tables is where its at. My car is the most radical solid roller LT1 383 stroker you can imagine. And the MAF tables are STOCK, the Injector constants are NOT TWEAKED, and the O2s are fully functional, even the PE tables are BARELY increased from STOCK numbers. I tuned with PE table and SPark Advance Table only.


Schurters LT1

As far as closed throttle spark advance 34 is a good number for idle. I actually use 40 degrees at closed throttle. But make sure when you tip into the throttle that the KPA area in the timing tables are GREATER or EQUAL to the closed throttle position or you will get a stumbling. What you should do is find a spark advnce number where you get no spark retard at an idle and work it all the way to 100 KPA. So your timing tables need to be revised from 60KPA to 100KPA.

My timing tables only operate in 75-100 KPA, so at 75-85 KPA I ahve 41 degrees of timing at lower RPMs, 85-95KPS I have 39-40 degrees and at 100 KPA I ahve 39-38 degrees of timing in lower RPM talbes.

You should first try these spark numbers all teh way to about 3500 RPMS then slowly start pulling timing out at 100 KPA until at 6000 RPMs its at about 33 degrees. Then test for spark retard, if you do not get any then you can increase the timing at WOT. Now the lower the KPA at the same RPM you should increase the timing. EXample: AT 4000 RPMS @ 100 KPA ( full throttle) I have 37 degrees of timing, but at 4000 RPMs @ 90-95 KPA I have 38 degrees of timing, 4000 RPMs 80-85 KPA I have 39 degrees and 70-75 KPA @ 4000 RPMs I have 40 degrees of timing.

The key is to make all transitions smooth and even, yo ucant have the timing tables or VE tables all over hte palce or your car will perform " all over the palce"

 

I am sorry but i realy don't understand the ve table i see that i can add/sub with this change my fuel rich/lean sorry can you give me a better walk through on this i want to now all this i think it is very cool

your timing table so you are saying
0-rpm to 4000rpm in the 75-85 kpa 41*
85-95 kpa 39*-40*
95-100 kpa 38=39*

 

tell me about the ve table frist then when i get that timing
thxJeremy

 

well you need to adjust your timing table 1st before you go adjusting your VE tables.


im aboutto watch the dolphins game. But email me a copy of your tune to tripintaz@bellsouth.net I will take a look at it and see what I can do for ya

 

If you're only running too rich at idle when you first start the car, then you should only modify (raise) the AFR x 10 vs. Coolant table, since you'll be in open loop at that point.

VE tables will affect both open and closed loop.

 

I over read that part, If you are only rich while cold idle(open loop) then adjusting your AFR tables in that area is the way to go.

Remember the higher the number the LESS fuel.

14:1 A/F ratio is 14 parts air to 1 part fuel(leaner)

10:1 A/F ratio is 10 parts air to 1 part fuel (richer)

 

When I first got into tuning LT1's I started by doing searches in this forum for different things and reading the LT1 Edit list archives. Most of what everyone said was that on an OBD1 maf car the ve tables were not factored into the the cars fueling at part throttle.
There wasn't much discussion about wot fueling being affected by the ve tables. To me it seems like it would more involved than just using the pe vs rpm table anyways, so I never worried about it.
I have seen files from just about every tuner that has done LT1 stuff. Most have not altered the ve tables in any way. But a couple have. The 1 thing that I noticed was that the high rpm/high map ve area was all set at 99.6, which I believe is the highest value that tunercat shows. I never knew why this was done.
When you were doing your tuning on your car, how did you know what to change in the ve tables, and why?
What is the advantage of using the ve tables to tune wot rather than just using the pe tables?

And whether or not ve tables are used at part throttle isn't worth debating. As long as the long term fuel trims are adjusting between 108 and 160 then the PCM is correcting your fueling and you aren't running rich or lean...you're right at 14.7:1.

So to me the only advantage to using the ve tables would be for wot, but why would you do that rather than just use the pe tables?

 

Simple..... VE tables allow for a much more accurate Tune for Part throttle and WOT.

The MAF tables are kind of like a crap shoot and the PE talbes are only applied at WOT. my MAF tables are stock and my PE tables are near stock. all I did was add 2% more fuel ontop of stock PE.

As for tuners leaving the VEtabels stock, its perfectly ok to use the stock PE tables for small cams such as the LT4 hotcam or cc306. The PCM can compensate for a small cam like these with minor tweaks to the MAF tables and injector constants and timing tables. However ask anyone of them using the MAF table changes, if not done correctly will always result in a stumble at any given RPM when the MAF tables were not changed SMOOTHLY. ITs basically tricking the PCM which works just fine for some applications. But if your Mods are more radical like mine you HAVE to use the VE talbes. Actually all tunes should use the VE tables but it requires dyno time to get them right. So aslong as the PCM can be tricked while keeping the BLMs between 108-160 your "mail order" tune will be ok. Not putting them down one bit and they are well worth the money.

However I have a huge solid roller custom ground cam and changing the VE tables was the only way to get this thing to run properly. The person that helped me with this tune not only had has a cam almost as big as mine, but had his car on the cover of High Tech GM magazine, and he uses OBD1 and tunercat. He only changes his VE tables and Timing tables.

Even aftermarket PCMs like FAST and DFI 7 and MOTEC use the VE tables for tuning, However the MAF is not even used. So the car does not compensate for weather changes such as air temp and humidy as well as a MAF car would.

 

I can see that. Since the ve tables allow for more of a defined change (rpm vs map) rather than the maf tables (afgs) then it would make sense that you can get more accurate with the fueling.

So what are you changing by changing the ve tables? For the part throttle stuff are you just targeting a 128 blm?
I'm still not sure why it would matter what your long term fuel trims are as long as they have the ability to adjust. Shooting for 128 or whatever just seems like overkill.

How is changing the ve tables resulting something different than changing the ve tables.? Either way you're changing the way that the PCM calculates it's fueling. Both ways are based on airflow that the PCM reads from a particular sensor...and the maf should be a more accurate way with regards to weather conditions. In otherwords, what is the advantage of a maf sensor if all fueling changes can be more accurately made by changing the ve tables.

Very unclear as to why?

Why? What are you targeting with the ve tables? I guess for part throttle you are targeting a 128 blm? Why does it matter for part throttle anyways if blm is adjusting your fueling to achieve a 14.7:1 a/f ratio.
Then for wot you're using wideband a/f data? Why is this better than just using the pe tables for simplicity purposes?


Why do you consider maf table and injector constant adjustments "tricking"? Aren't these changes doing the same thing as your modifying the ve tables?

Ok, then I will. I have yet to personally see a mail order anything be remotely close. Seen quite a few things on here, but in person I've never seen 1 even close.

I hope this doesn't really mean anything...

Very interested in this as I may be tuning a large solid roller car in the spring.

 

in the AFR x 10 vs. Coolant table vs map what does this mean if the table has a number in it say (142) is that accually 14.2 to 1 a/f ratio the X 10 part is throughing me of what does that mean in the table. what im trying to say is what does the 142 mean. and if i wanted to lean it out i would raise the number corect.

 

14.2 X 10 = 142

so 137 = 13.7 X 10

the lower you go the more fuel is added.