What gives when I reduce my VE tables so I should be at 128 BLM's and then the car reads a rich condition and starts immediately lowering them. Within 20 min I am at 108 again at idle.

I have done 8 iterations of adjusting my VE tables based upon the rich condition and have gone from the stock VE of somewhere in the 40's to now the low 21's for the idle blocks (800 RPM/ 20-30 KPA).

My mods are 1.6 lifters, mild porting, larger valves, headers. Do I have a vacuum leak? my upper RPM and KPA values seem to be unaffected, but they don't run the vacuum I do at idle and I do not operate in the upper RPM/KPA area nearly as long as I do at idle.

Please any input is appreciated.

Ben

 

The VE tables are only going to help you in open loop....they are not used in closed loop.

 

Damn, REALLY?

How did I miss that little tidbit of info? I have used vemaster software and they do not mention that it is only for open loop.

Thanks for the info. So what should I adjust to keep from going rich?

Ben

 

Are you sure?

I always thought the VE table was used only in SD mode and it ran of the MAF tables all other times (open and closed loop)

 

The VE tables thingy is still a big toss up among the 94+ fbodys. Some say it works others say it doesnt. Its probably a good thing to tune your VE tables using VEMaster so that if your MAF goes out then your car will still run fine in SD mode. One thing you can try is unplugging your MAF and tuning your car using VEMaster so you can get your VE tables squared off. Then replug the MAF and start tweaking your MAF tables to get your BLM's squared off.

I think I read somewhere that if the SD mode (using VE Tables) was more accurate then in MAF mode then it would switch over. This could be a reason why some cars will see results tuning their VE Tables. Or am I smoking crack again?

 

Well, I did research into VE tables and found that they are used in closed loop operation. So is it a good idea to possibly change my MAF tables?

I could change the MAF to read less air (at lower RPM's only) coming in and thus it reads a lean condition which might offset my rich condition I cannot overcome by modifying the VE tables?

However in the end, if I have an underlying problem within my engine this is just a bandage. What problems can I have to cause this constant rich condition no matter what I do to change the VE tables?

Could it be a vacuum leak, fouled plugs (I will take them out here in the next few days) problem sensor (map, maf, o2's) or something else.

 

I wrote VEMaster and what Wilson said is correct AFAIK. The VE tables are only used in SD mode (MAF disabled). Try resetting your VE tables to stock and disabling the maf, then log some data and run VEMaster. I wouldn't run with the tables as they are now, because if you run VEMaster over and over again, it's going to keep lowering (in this case) your VE tables based upon blm's, but they're not changing because the MAF is being used for fueling.

Some people have seen changes when using VEMaster during normal (maf) operation. Others have not. I would say you fall into the latter category.

Ben, so where are your BLM's at cruise? I didn't see a cam listed. How about a TB? Are both sides 108 or just one? 108 means rich, a vacuum leak would cause high blm's, where the computer is adding fuel to correct what it sees as a lean condition. You still running the stock injectors at stock fuel pressure?
Joe

 

Just a thought, but why don't you try setting the injector size as 2 - 3 # larger than what you actually have in the car. That will cause the computer to adjust the pulse widths down to compensate and that may lean you out a bit.

All this assumes your O2 sensors, plug wires, and opti and ... and ... and all the electrical stuff is in good working order.

You may want to have the car scoped to check it out further.

Hope this helps

LWM

 

Well, you would only want to adjust the injector constant only if your BLM's are off throughout the entire rpm range. If your BLM's are only off at low rpm then you would start tweaking your injector pulsewidths. If your having problems with your BLM's at mid-upper rpms & load then your want to tweak your MAF tables.

 

Thanks Joe for your research into this. What you say about constant reiterations with vemaster is what is happening.

My BLM's at cruise are now in the low 110's. at idle (or 0 TPS from high rpm) I am at 108 or close to it - both sides. Yes I am running stock fuel pressure with stock injectors. My cam and TB are also stock. I guess the only thing I did is took out my TB screen. I "thought" since I had a scoop that my air would be more laminar than a stock setup and therefore would not need it. I could be wrong.

Ben

 

Wilson,

Please restate what you just said here. I think it is critical, but your message may have come across garbled.

Thanks bud.

Ben

 

Ben,

I don't understand it. Something must be wrong somewhere. Especially with a stock cam. How are your O2's looking? Are they swinging back and forth at idle/part throttle? I assume you descreened the maf, not the tb. I did that way back when before I knew better, but it hasn't adversely affected me.

What the other guys are saying is that you could raise the injector constant - that would in effect lean you out across the whole rpm range. And your blm's should rise. If they go back to 108, you know something mechanical is wrong. Make sure the intake tract is sealed between the maf and tb.

Joe

 

Ben,

At this point its probably best if you post your datalogs.

One log should be part-throttle driving and the other should be WOT. This way we can help you figure out whats wrong.

 

Hey all, thanks for the help!

OK tonight I am going to set my VE tables back to stock and see what happens. I guarantee you that the idle blocks at the very least will head towards 108 in a matter of minutes.

After that, I am gonna start playing with my MAF tables and see if I can lean it out only in the lower RPMs/AFGS range because that is where I am having problems.

I will post my results to you all.

BTW, is there a way of me getting you all access to a file I have? How can I do that through the internet? Can I attach a file here on this board or do they not allow it?

 

You can email it to me at wilson@wilsonch.d2g.com

And if you want me to post it online just let me know and I'll put it on my webserver.