Schurters LT1

I have been try ing to get my car to idle right but my fuel trem is maxed out on long and short,

how much do i need to addjust my MAF, or is there a better place to start.

95Blackhawk

Clean out your mailbox. I cannot send you anything.

Give me an e-mail at work at ben@hennesymech.com.

This was the first issue I dealt with after my heads, headers, etc. were done.

I have an excel spreadsheet showing how to modify your MAF to calibrate it.


But you also mentioned your 30 lb SVO injectors. Give Dan K a shout, he knows what constant to use with our car's fuel pressure (its not 30 lb BTW).


Ben

Dan K

Yeah, I tried to respond to your pm but I can't...your mailbox was full.

From what I remember the correct ECM injector constant for the 30's is 31.6 due to the different fuel pressure that the LT1 operates at. The Fords are flowed at 39psi, and our cars are supposed to run at 43.5psi. Due to the variance in fuel pressure on the factory fuel pressure regulators, you might need to adjust the injector constant a little to get you blm's into an acceptable range. I've found that 32.2 to 32.6 seems to work fairly well with the stock fuel pressure regulators.

Someone correct me if I'm wrong on the 31.6 though....that's what I remember.

CRCDUDE

After reading ur post i went and checked my injector constant setting (we have a set of 30# SVO inj in my buddy's T-A) that i do all the tuner cat work on and yes mine is set @32.12 lbs/hr.
But we also have an adjustable reg that I set down to 40Psi fuel. The BLM's are great on the short term but a little lean on the long T. I'm workin on gettin it to idle better also. Tends to wander a bit and likes to stall after a WOT pass.

Dan K

Sounds about right considering the lower fuel pressure.
Don't worry too much about short term blm's. Focus more on the long term corrections.

What cam/heads/ci/compression?
Sounds like you've got the injector constant about right. Start playing with closed tps spark advance. Set the 400, 800, and 1200 all to the same value so that it doesn't jump around quite as much. Then try different values between, say, 24 and 34 degrees. Watch map at the different timing and shoot for the lowest map you can get. That will require less fuel at idle.
Make sure the TPS and IAC are in check, and that the idle rpm in and out of gear makes sense for the cam/ci/compression.

Schurters LT1

My heads are LT1 advanced inductiopn/ gm 847 cam/ 52mm tb and all the other bolt on,.s

i addjusted my fuel pressure up to 49 vac on to see if it would change LTerm but no shoud i addjust it back down and play with the inj constant

i have timing at 27* map is at around 67-69 kpa i know it could put in more but is this not allot of timing?

pm box open there was nothing in it?

Schurters LT1

i did some changes still have high lterm, could it be because of the cam?

i will drive around and come to stop they will be great and outher's they go high.

how would i up load the datamaster file?

Schurters LT1

When you are tuning for driving how much +/- is good

how do you tune the wot and know how much +/- in fuel

thx

Dan K

Set the fuel pressure to 43-44psi with the vacuum line off. 49 with the vacuum on is probably close to 55 or so with the vacuum line off.
Then start with your injector constant at 31.6. Drive the car and run a datalog. See what the long term fuel trims learn to. If they are less than 128 in most fuel trim cells try bumping the constant up to 31.8 and do it all over again. If they are above 128 then lower the injector constant to 31.4 and try again.

Probably not. Keep fiddling. You're giving up too easy.

If you want to e-mail me the datamaster file I will take a look at it and give you some help.

Get rid of the plus minus. Change it to counts instead of percentage. Easier for me to think of, and it seems most others just go by counts too. As long as the computer can adjust via blm then the car is not running rich or lean at part throttle. It's correcting itself based on O2 sensor feedback. If you want to be picky about it try and get them between 118 and 138. That's a close enough range and should work just fine.

You tune wot with a wideband. No real other way (unless you want to try Ben's method ) than that.
If you want to use O2 voltage it's a complete crap shoot. I would say as long as you are between 860 and 960 you should be OK. But I really wouldn't recommend you use O2 voltage, just as a guideline until you can do it correctly with the wideband.

Schurters LT1

ok i will keep on playing with the inj constant, i think i am close

with the tuneing at wot i am going to a dyno and wide band i was just want to know how to tune that part.

how do i addjust at diff rpm say 2500 in city driving 4th (m6) i need to add fuel or take away

back to idle
146/135 LT
map 64.6 kpa
spark 28*
fuel cell 16

i would love to email the datalog i don,t have clue on how to do that?

my fuel pressure is so high trying to make the inj bigger, i have 2 fuel pumps and i hit 97% DC at one point 6300rpm pluse.

i will be sping my car to about 67/6800rpm can the datamaster go that high?

thx foe all you help
Jeremy

Dan K

Use the pe tables. That's what they're for.

That's what the injector constant and maf tables control. Once you get the injector constant to where you have consistent blm's between 118 and 138 then you can adjust the maf tables if you want to get them closer to 128.
But, again, as long as the blm's are adjusting your part throttle fueling you are neither rich nor lean. The computer is making all the adjustments for you to try and maintain a 14.7:1 a/f ratio.

That's a little bit of a split. You can do a search on idle blm splits if you want to try and correct it. MAP seems pretty high to me. I would think you should be able to get it a little lower...probably in the upper 50's. Try setting the closed throttle tps table to 32* at 400, 800, and 1200 rpm and see what happens to map at idle. Keep adjusting the timing here a little bit until you get the lowest map. I would think 30-34* would be perfect. That's shy I told you to start at 32*.

Attach it to an e-mail and send it to me.

Sounds like you need more injector. Not a band-aid fix like upping the fuel pressure.

The new version should be able to. It is a beta version that you can get at TTS' site.

Schurters LT1

Thx for all the help Dank,

i have my timing at 30* i will put it at 34*,
i made a change to the injector constant today went from 31.50 to 32.00 and my LTerm maxed out ? 160 ? now when i had the 143/134 cell 16/18 i was driveing the car for 20 min and let it idle.

Today i made that change and started the car,closed loop and then they maxed out 160 ? do i have to drive the car to get it up to temp?

Reveiw
So inj constant to set idle ,when that is set maf tables to tune driving do i add to the maf tables to get more fuel?

there is no pe tables i think it is % of air at wot i will have to look.

as for the email with att i don,t know how to do that .

will make some changes and have another datalog

THX!!!!

Dan K

Try a couple of different things. You can get it about perfect if you keep bumping it up or lowering it by 1*. Just depends on how much effort you want to put into it.

At idle? All part throttle? Where? If they maxed out at 160 then you're going the wrong way with your injector constant. It's too high and the computer is lowering the injector pulsewidth. Now you've got the constant too high and the computer is raising the blms in order to try and increase the injector constant.

No. Use the injector constant to get the blms in all fuel trim cells in a reasonable range. They don't have to be 128 all the time, or at all. As long as the blms are adjusting your part throttle fueling you're fine.

Rasing the maf tables will add fuel because you're telling the computer that it is seeing more air, therefore it will need more fuel.

% change to fuel/air ratio vs cool temp @ wot and % change to fuel/air ratio vs rpm @ wot are the pe tables. Both affect wot fueling. Be careful messing with them until you're sure you know what you're doing.

Open a new email, address it to me, and somewhere there will be an icon or a button for attaching files. Click it. Then you can browse your computer. Go to the folder where you save your .uni files and double click the one you want to send to me.

Schurters LT1

thx Dan,
I want this to be bang on! i will put in full effort

Timing set at 34* map at 61/63 what would be the max for timing at idle.

Sorry at idle they max out , driving aroud town they look good.

Ok i have the inj constant fig out (i know what to do with it )

With the maf how do i know where to adj the maf tables

i will try and send you a email with att.

thx

Dan K

I've done a couple of cams really similiar to the 847 and they usually like 32*. I've not seen any advantage going past that. I can usually get idle map down around 55-57. Idle rpm also plays a big part in this too. Don't forget that. It all works together. Get the idle rpm where you want it (probably between 900 and 1000) and then adjust your closed TPS timing.
As far as max, I don't know. I wouldn't worry too much about max in your situation as you should be good right around where I mentioned. Try 28 and log. Then get an average of idle map. Try 29 and do the same. Try 30...and so on. You'll see a sweet spot develop somewhere.

Then it's time to fiddle with the maf tables. Look at the values near AFGS in datamaster. This is how much air is coming in through the maf sensor. Now look in your maf tables in tunercat. You will see on the right side of the tables numbers that look about like what you logged.
For example, in the datamaster log you might see that at a warm closed loop idle you are getting right around 10 g/sec. Look in your maf table and you'll see some values close to 10 in the right hand column. Got it?
Now, where the values are 10 you would want to change it to 10.2 to add a little bit of fuel. This should help bring your blm down. Make very small changes and datalog the results.
Remember to adjust the adjacent values in the maf tables so that you keep a smooth "flow". Make sense?

Yeah, if I could see a datalog I could help you more easily.