Tuning the MAFT - Grimm

[rakkasan]

Hey Grim, can you give me some more details on the tuning part. I have mine installed & have my volt meter installed. When I drive 35-40 mph, I'm sitting between 2.9 & 3.3 volts. I should bump the base down, right?

After I get the base set at 2.5v, then adjust the Idle, then mid, then WOT? I'm guessing that Idle should be 1.25v, mid 2.5v & WOT 5.0v, correct?

Also, I don't have a wideband. Am I being stupid trying to tune the MAFT without one?

Thanks

 

[GrimJack]

Actually, that's a fine reading for the base right there, don't touch it at all. And all the readings should come out close to 2.5v in the end, regardless - with the exception of the WOT setting, that one is going to be odd unless you have a wideband.

Do you have an EGT? What other mods are you running, and how hard are you driving it - i.e., what PSI are you running.

 

[rakkasan]

Actually, that's a fine reading for the base right there, don't touch it at all. And all the readings should come out close to 2.5v in the end, regardless - with the exception of the WOT setting, that one is going to be odd unless you have a wideband.

I finished getting it installed last night, but I didn't nave time to tune it much. It's giving me between 3.3 an 4.8. I'l see if I can get it adjusted after work today.

Do you have an EGT? What other mods are you running, and how hard are you driving it - i.e., what PSI are you running.

3" w/ a cooleeze DP, hardpipes, MHG & now MAFT. I'm hitting fuel cut at 10 psi. I'm looking for a EGT today.

 

[GrimJack]

Ok, no worries then. You are seriously unlikely to cause any damage if you are still hitting FC at 10psi. Get that EGT and you can use it to tune the WOT settings - I think you will find that you can increase FC by a LOT without seeing your EGTs spike significantly.

 

[rakkasan]

Ok, no worries then. You are seriously unlikely to cause any damage if you are still hitting FC at 10psi. Get that EGT and you can use it to tune the WOT settings - I think you will find that you can increase FC by a LOT without seeing your EGTs spike significantly.

That's cool. I did hit the road today with the Volt Meter as you stated to in your manual. My problem is that at idle I was at 5V, and no matter what I did, I couldn't get it to drop at Idle. I could get the mid to drop to 3.75v, but no lower. Of course I'm not going to try WOT until I get the idle & mid tuned, so I can't report on that.

I tried to lower the base setting, and I could tell that it took fuel out of the map because the car was very slugish (I immediately stopped), but I couldn't get it to drop below 5v. Any Ideas?

 

[cnewingham]

you need to richen that up some. I have mine set to #1 on the base setting which I believe is for 420cc injectors and that evened mine out. Also anytime your computer is over 2.5 it is trying to add more fuel so you are always better to stay under the 2.5. I had someone set me straight on this because I was so confused. I will see if I can find it and copy it over to here for you.

 

[cnewingham]

AHHH here it is. I hope it helps and also the link to the actual thread with good info.
tuning via VF thread

first, just use the a/f on your wideband. dont worry so much about the vf. thats is mostly for people that dont have a wideband.
second, you are kinda confusing what the actual voltage means.

0v means the ecu is leaning the fuel calculation, not that you are running lean. it means you are richer than you should be.
5v means the ecu is richening the fuel calculation, meaning you are leaner than you should be.

2.5v of course means it is right where it thinks you should be. so long as it is any where from 0v-2.5v you are fine. remember vf is only useful in closed loop (less than 75% throttle) and not wot.

either way, just refer to the wideband and keep the vf under closed loop in the 0v to 2.5v range.

hope this helps clear things up

dave

 

[rakkasan]

you need to richen that up some. I have mine set to #1 on the base setting which I believe is for 420cc injectors and that evened mine out. Also anytime your computer is over 2.5 it is trying to add more fuel so you are always better to stay under the 2.5. I had someone set me straight on this because I was so confused. I will see if I can find it and copy it over to here for you.

Please send what info you had. I've tried to lean the base out, but the voltage doean't respond. I guess what I was trying to say earlier is that when I leaned out the base, I could feel it in the trottle response, but the Vm still read 5v. I had my Vm tested, so I know it works, but something isn't right.

 

[cnewingham]

why are you leaning out your base if it is reading 5v!!! If you are reading 5v then you are LEAN already!!!!!!

Basically it goes like this
0v to 2.5v means you are safe and running on the rich side and the ecu is taking away fuel
2.5v is perfect meaning the cpu is doing minimal changes
over 2.5v to 5v means you are running on the lean side and the ecu is adding fuel.

 

[rakkasan]

why are you leaning out your base if it is reading 5v!!! If you are reading 5v then you are LEAN already!!!!!!

Basically it goes like this
0v to 2.5v means you are safe and running on the rich side and the ecu is taking away fuel
2.5v is perfect meaning the cpu is doing minimal changes
over 2.5v to 5v means you are running on the lean side and the ecu is adding fuel.

DOH!!! Damn, I thought it was the other way around. Let me try this again, I'll get back to you in a minute....

BTW, thanks.

 

[dbsupra90]

good call cnewingham, was just gonna mention. the Vf values can be a little confusing since they are sorta "backwards".

also, did you set to the appropriate sensor size? appropriate injector size? was the #4 dipswitch in the right postion when you changed the initial setup and base tuning? did you reset the ecu everytime you made a change? all these things will have an impact of how it runs, idles, and tunes.

as a side note, i wouldnt tune wot using Vf, nor would i go too far w/ an egt. you could get a rough tune out of it, but by no means would i keep pushing the edge and wait for egt temps to rise before backing off. also, at wot your Vf voltage should go to 0V.

good luck!

dave

 

[cnewingham]

Actually Dave it was you who set me straight on this in the beginning. THANK YOU again. I have had no probs since you explained how the vf thiing works.

 

[rakkasan]

I still can't get rid of the lean condition, I'm starting to think I have fuel issues. I'm going to change the fuel filter & see what happens.

 

[dbsupra90]

again, you sure you have it set up right? could also try turning on the idle enrichment feature to see if that makes a difference. also, if your 02 sensor is going bad by default it will just start pouring in fuel to keep it safe. so it may not be running lean at all, just as a failsafe it is dumping in fuel. that make sense?

cnewingham- thanks for the kind words

dave

 

[rakkasan]

again, you sure you have it set up right? could also try turning on the idle enrichment feature to see if that makes a difference. also, if your 02 sensor is going bad by default it will just start pouring in fuel to keep it safe. so it may not be running lean at all, just as a failsafe it is dumping in fuel. that make sense?

cnewingham- thanks for the kind words

dave

I didn't have dipswitch #4 off as I should have, so I changed it & reset the ECU, but I'm still inable to get below 3.75v. I'm gonna replace the fuel filter (needs to be anyway) & check the o-sensor.

 

[cnewingham]

What are your setting on your MAFT!!!!!!!!!!!!!!!!

Here are mine:
-Dip #1, #2, & #4 OFF
-Base 1
-Idle 0
-Mid 3
-Wot 0

These are my settings and yours maynot be exact but try there and see what happens

 

[rakkasan]

What are your setting on your MAFT!!!!!!!!!!!!!!!!

Here are mine:
-Dip #1, #2, & #4 OFF
-Base 1
-Idle 0
-Mid 3
-Wot 0

These are my settings and yours maynot be exact but try there and see what happens

-Dip #1, #2, & #4 OFF
-Base 2
-Idle 0
-Mid 0
-Wot 0

My problem is that any adjustment I make, I stay at 5v. It my drop to 3.75v for a few seconds, but jumps right back to 5v again.

Wouldn't you think that it's possible that either the injectors or the fuel filter are clogged (or worse, both)? Could I have a bad O-sensor as dbsup mentioned & the ECU is pulling(?) fuel? I'm just trying to get it fix correctly, I'm not going to drive it until I do.

 

[cnewingham]

change your base to 1 and you will see that it will drop. Mine did the same as yours set at 2.
The maft thinks that injectors are 420cc when they are really at 440cc which means the injectors are still flowing at 440 but the maft thinks 420 so you are getting 20cc's more and that should even out your vf reading.

 

[rakkasan]

Maybe I should re-check all of my electrical connections......

Well what do you know, my AUX wire had slid out of the connector. :icon_roll

It's down to 2.5v, I'm going for a test ride to how it works now.

 

[cnewingham]

thats weird cause I dont even have my aux wire connected.