which tables should i be changing to add or take away fuel?

the %Change to Fuel/Air Ration vs. RPM @WOT (& the coolant table)
or the MAF sensor calibration tables?

my lterms are reading about 140/139 on and off the bottle so i need to get a little more fuel. i have ford 30lb injectors and my injector constant was set at 32.23lb/hr. ive read that 30lb injectors should be set to 31.68lb/hr. i'm going to back my constant number to 31.68, but i dont know if or how much i will see from just that change, so which other table should i change? or should i change both of them?

 

VE tables for part throttle and WOT tables for WOT ... WOT table basically takes the VE values and multiplies them by the value on the WOT when you're at WOT (damn, there's a lot of WOT's in that sentence).

I've never tried this but theoretically, if you've got the WOT values on the VE tables dead on target, shouldn't the WOT tables be just Zero?

Edit: some people say just going with only the MAF tables will suffice too.

 

dont the ve tables only work when the car is in speed density mode or not using the maf sensor? if thats the case, or not, when does the car go into speed density mode anyway?

 

Well, I know a lot of people have argued about this since the beginning of time and will still argue about it after we're dead and gone, but here's my findings and they seem to imply only one thing!

After my cam install, my BLM's were running above 128 (adding fuel) on closed loop operation and would run lean on WOT after warm up (which is the only time I will get into it). I added fuel in the VE tables, nothing else was changed in the MAF or WOT tables and took a long drive. BLM's changed and started going down. A couple drives/tunes later, BLM's are running a little lean (122-126 range, pulling fuel) and WOT fueling has richened up more. I had to do a wee bit of WOT tuning and it was DONE! No, my isn't in SD mode, actually, the car would shut off if the MAF was disconnected.

Also check out http://para.noid.org/~lj/PCM%20Tutorial/PCMtutorial.htm for more supporting evidence and PCM tutorial.

 

i was under the assumtion that lterm reading of lower than 128 was richer and higher than 128 was leaner. thats what the help file i read was saying i'm pretty sure

 

Yes that is right. What I meant to say was that the engine is running richer but the BLM's are pulling fuel out (hence the lower values) to make it leaner and get it closer to stoich. I've gotten used to saying BLM's are leaner when the engine runs rich and vice versa. Sorry, didn't mean to confuse anyone.

 

ok thanx, i got it now. hey i meant to ask about your cam. how does it compare to mine? you seem to have a nice 1/4 mile time for the mods that you have. do you have a copy of your tune (.bin file) you have in your car now? I've been trying to do some comparing. alright thanx again
ryan

 

The %change air/fuel vs RPM vs WOT is the power enrichment table used at WOT conditions. If you want to add or subtract fuel at wot then you need to use that table and that table only.

The VE tables you can change if you like but nothing will happen.

If the BLMs are above 128 in just about every cell then simply lower the injector constant to between 30 and 31lb.. that should put you right in there but youll need to experiment for best results.

Fuel pressure cant be changed with PCM settings. Its a mechanical device call the fuel pressure regulator located on the back of the intake but it wont help you.

Last thing here. If you are running nitrous then you will always run rich at wot OFF the bottle.. there is no other way around this. There is only 1 setting with wot which is either on or off so with nitrous you need to always account for the nitrous or the motor will run dangerously lean.

Hope that helps.

 

i lowered my injector constant value a little and also messed around with some %change fuel/air ratio tables and the maf tables, and now my lterms seem to be right around 128 for the most part, so its getting better.

I always wondered why they sell adjustable fuel pressure regulators for our cars? and when i was on the dyno last month for the first time, my a/f was 13.1 on the bottle and 13.5 on the motor.

 

Sent you mine. Read instructions on email!

Edit: I don't think messing with the injector constants is the best way to go 'cos everything is dependent on it (but not linearly). I believe that not tuning the VE tables and only Tuning the MAF/WOT and Injector constants is just a big bandaid to not going into the VE tables. The VE tables hit and miss and are pretty hard to tune, but that's where the actual fueling is!

 

Yeah I didnt explain what I said about always being lean with nitrous. If its a wet kit you should be alright but a dry kit will never run safely at WOT without tuning.

 

my BLM's are bottoming out at idle and the exhaust smells like fuel. This is a new hotcam install, and I noticed that the MAP is running lower at idle (duh, due to bigger cam) and therefore making the car run rich. I have taken fuel out of the corresponding cells in the VE table.......800 rpm and 55 Kpa, and then smoothed out the curve on the graphic, and the car still runs rich at idle.

THe VE numbers started at around 47, and i am now down to like 35 or so, and still running rich. Should I keep going?

The BLM have gotten a little better, like up to 110 -112 or so.

Also, In Datamaster, you can go to setup, display units, and change the counts to percent, and to me, this makes a little better sense when looking at them.

Actually shows 0.0 in open loop, or when no corrections are being made, and shows a + and - for percent change to the VE table.

Also, what about changing MAF settings, this to me seems wrong, will work, but why lie about the Air, when you can adjust the fuel??

 

Mind sending me your file? I'd like to take a look at it and compare it to mine to see what changes were done. Mine (although not a Hotcam) is pretty close to yours and idles a bit rich, although not as much as you say yours does. I preffer to have a little bit of a rich mixture for when you drop it from a dig 'cos the fueling stays good through the RPM range.

 

i will get them off of my laptop this evening, and email them to you.

hit me with you email.

wwarnke@satx.rr.com

 

Because you cant adjust fuel(except for WOT fueling) unless you are running in open loop. That is just one of the many limitations you must acknowledge and accept with the stock PCM. SO in order to lean out the idle you have to either raise the injector constant which will affect ALL cells or tell the PCM its not seeing as much air as it believes at idle by decreasing the value in the MAF table corrisponding to the amount of air its showing at idle.