ive seen people say that the VE tables are not used by a car with MAf. afew minutes ago i was scannign my car saw that i had a reading of 119 on both LT BLMS in cell 6 at 2050 rmps at 35 to 48 map. its been that way for about 2 weeks. well thats where im driving in 6th gear at 75mph. so i wated to change and get my blms back to the 126 128 area.

well i went and change the ve tables at 2000 rpms a 35 to 50 map and added 12% to each of those percentages to see what happen well i went and did another scan and the blms at the same rpm and map were now at 127.

so i guess this is proof that the ve tables are used on a maf car

just thought it may help someone else. after all i was wondering how i was going to change the numbers in that one fuel cell and thats what worked for me.

i dont want to start a controversy on this topic agian but just wanted to let people that are learning the things that work for me.

 

Put the VE tables back to the way they were, and see what happens. If what you say is correct, then the blms should go back to the way they were.

 

ive already done that and they went back to the ecxact same place. and i also reset the pcm before i did the first scan to erase all block learn memory so the pcm had to relearn everything (BLMS) and when you reprogram the pcm it atoumaticly resest the pcm. so each time i scaned the car the pcm was reset beforehand. and i also put it back and the blms went back to 127 once agian.

 

I wonder how this cell shift affects cell sellection in all the other gears at the same map/rpm areas changed? If it does another gear may have been very rich and this would make it go to an unavailable cell number (require over 160). I doubt it would, these cars are usually too rich, I am just asking really.

Hal

 

the ve tables are changed by map vs rpm sence cell 6 operates between the map of 30 and 50 and betweent the rpm of 1200 and 2000 and thats where my problem was. so i wetn to the ve tables and at 2000 rpms and the map of 35 though 50 i increase them by 12 which told the pcm the engine is more effeicent at those paramaters and it decreased the pulse width and subtracted fuel thus raising the blm sence it was showing a lean condition. the injector pulse width went from 5.49 to 4.98 so now the pcm is almost not all adding fuel to correct for what would be a rich condition. all the other cells are still the same.

 

If you're a 97 are you still OBDII or OBDI?

I've screwed with the ve tables in my car, which has been converted to OBDI, and saw little to no difference. Others on this board have said the same thing with the OBDI maf cars.

Then there have also been those who have said that the ve tables do work on OBDII LT1 cars and on the LS1 cars.

So I don't know, although I am going to try tuning the ve tables on a car this weekend that is an OBDI maf car. I think I'm just going to set it to run in speed density mode, adjust the ve tables as needed, and then set it back into maf mode. We'll see what happens. I hope it really does work.

 

first off i would like to thank you dan for all the help youve been on the board with tuning.

yes i have converted over to obd1. im like you about reading and seeing that people say it doesnt work on obd1 cars. well i have to say it does on my end. try it you may be surprised.

 

I am a firm believer of VE tables in OBD2 cars. I have a 1997 OBD2 LT1 383 stroker with a large cam and many mods. My MAF tables are STOCK, all tuning was done in the VE tables and Sark tables. I saw a 40 RWHP gain on the dyno with my own eyes with my own car by changing hte VE tables.

However, When you increase a number in the VE tables it tells the PCM the engine is more efficient at burning the amount of air metered by the MAF. Therefor INCREASING the fuel delivered by the PCM.

In your case it may have added enough fuel to where the O2s made the PCM compensate and subtract fuel so you saw a BLM change. I wonder what would happen if you subtracted 12% in that area?

 

ill find out this afternoon.

 

ok i pulled out the 12 which made back to where i orignaly started and then pulled 12 more. the lt blms shot up to 138. so it had the opisite affect when making it less effeicent. so then i put it back to where i started agian and (stock ve taBLES) and went for a drive had the same problem i began with. but i noticed to purge canister flashing 100% which i had disable the electrical failure code for it but never unpluged it. so i unpluged and scanned it again and with the tables back stock the lt blms went to 127. so acctually i didnt need to do any tuning just unpluged the canister. but hey i learned alot about the ve tables and i will use them in my tuning practices as well.

what was my purge canister doing to the fuel? can someone tell me.

 

I dont know what effect the purge canister has. Before I accounted that as the reason for the BLM's I would 1st make sure your car was at the same operating temperatures as your first measurments. The timing tables change according to engine temp. But I honestly Im not sayingn it was the cause either.

As far as changing your VE tables....Its not a normal practice especially on a mildly modified car. Even changing a cam doesnt always mean you need to edit your VE tables. But once you start adding a cam AND heads you might see a gain. For the most part the PCM can learn the variences for a mild and moderatly modified car without chanign the VE tables. MY engine is extremely radical and the VE table changes were a must and do not resemble the stock tables what so ever. EVERY number is different, but I also make over 500 fly wheel HP N/A and ru na 260/260 Solid roller Nitrous Cam

If your looking to get a littel more power out of a stock INTERNALS engine Start by increasing the WOT spark advance a couple of degrees ( you can ad even more between 4000-5000 RPM range because this is pea TQ range). Then on a wideband dyno lean out your A/F ratio to about 12.8:1-13:1 using your POWER ENRICHMNET tables for WOT. Also try editing your cooling fans to come on a little sooner to keep the engine cooler. These things would be about hte only thing I would do to a STOCK internal/heads/cam engine.

Good Luck

 

When those changes were made in the VE tables, did the pcm throw any DTCs during normal driving conditions?

Wait a minute. You're running OL when using the VE mode of operation, aren't you? In thata case, DTC issue is a mute point.

 

Yes i run OL mode but I still use the MAF sensor. Even in open loop mode when I edited the tables inncorectly ( too low ) that car was going lean and the PCM picked up mulitple misfires and detonation. Luckily I kept the stock agressive knock retard settings so that I did no damage to my engine. I made the error of assuming if the VE tables can add/ subtract fuel that I can use them to TRICK the PCM into putting the amount of fuel I wanted in. Well this was wrong, the PCM wants the TRUE VE so it can use this number to properly calculate fuel delivery with the MAF and IAT. Faking out the PCM just caused fueling issues all across the board. After gettign the correct VE tables dialed in ( with Joe Overtons help) the car ran much better but still not quite there. Lately I have been fidiling with the injector offset and injector constants and this is the best place I have found to adjust an OPEN LOOP VE modded tune for part throttle driving. Infact I threw the car into closed loop mode to see how it drove in closed loop and to see what kind of fuel trims it would get. Everything was great and even data logged it, but due to the overlap of the cam anything under 2500 RPMS ( normal part throttle driving ) was syrging a little because hte O2's couldnt decide if it was lean or rich ) So i went back to OL mode