maft/mas tuning help needed in GA please

[smoking rr]

i just got my 3 year build ready to go back on the road. i have a lot of new parts (16T's, FMIC, adjustable cam gears, 120K, pistons, rings, bearing, clutch, pressure plate, GM MAS, MAFT. still oem injectors/fp/fpr till i get it all broken in and running right) but i could use a hand with getting the MAFT tuned. is there anyone that can come give me a hand with getting my tuning right?

its been 3 years sense this thing has been on the road and i am ready for it to run right. i am in the snellville area. Any help would be greatly appreciated.
you can hit me up on here or call/text. thanks to all in advance,
Jeremy
770-616-6410

[smoking rr]

Anyone?


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[B-Man]

Do you have the MAFT manual? You should basically be able to zero out the setting (since you're on stock injectors) and it should be pretty close. Setting idle is pretty easy and as long as you have a wideband to watch, it's super easy.

I can't think of who in the GA crew would know MAF-Ts

[smoking rr]

I thought so too but.... All my trims are around 83%. And how steady should My wide band be at idle? Are we talking pegged at 14.7 or back and forth across it?

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[B-Man]

If you still have narrowbands, it should float back and forth.

[smoking rr]

I have my 2 narrow bands running to the factory stuff and my wide band for me to watch

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[B-Man]

Try turning the 'IDLE' knob counter-clockwise a click or two.

[B-Man]

Here's from the manual on how to get the MAFT running:

-Set the Mode switch per the vehicle configuration above, ensure Mode 4 is OFF
-Select the injector size from tables in Appendix A at end of manual and set the AUX and BASE knobs accordingly
-Ensure the ECU is reset (disconnect the vehicle battery for a minute or so)
-Connect any datalogging equipment and start the vehicle.
-The vehicle will enter closed loop within a minute of starting.
-Make sure that the idle O2 sensor is not overly lean as indicated by a constant low voltage signal or overly rich as indicated by a constant high voltage at warm idle. If needed, adjust the idle knob as shown in the Idle, Mid, and WOT tables further below
-Make a test drive and log the fuel and O2 trims
-Adjust the BASE knob to keep the total trim# between 80% and 100% during steady state driving (35-45 mph). To lean out the fuel curve, set the AUX/BASE to a larger injector size. To richen the fuel curve, set the AUX/BASE to a smaller injector size.
-You will need to readjust idle if you make changes to the base setting
-Perform some light accelerations in 4th gear starting at about 2000 RPM and watch what the total trim does as the airflow value climbs. Adjust the MID# control if the total trim value at moderate flows (300-400hz, high trim) is significantly different than the low flow (100-150hz mid trim) total trim.
-Increase the acceleration to half throttle or so and watch to be sure you stay rich before trying WOT.
-Make some WOT runs and watch the O2 readings on a datalogger, O2 monitor, EGT gauge, or Wideband AF Monitor. Use the WOT knob to adjust the fuel delivery. A little too rich is better than a little too lean.
-Each change in these settings of stored in Flash memory so the dials can be used for RPM mode below

http://fullthrottletech.com/attachment.php?attachmentid=72&d=1103666303

[smoking rr]

from what i read you have to adjust the "base knob" first to get the trims close to start bc base effects all the settings, then the individual knobs after that. or am i just misunderstanding that?

[smoking rr]

Here's from the manual on how to get the MAFT running:

-Adjust the BASE knob to keep the total trim# between 80% and 100% during steady state driving (35-45 mph). To lean out the fuel curve, set the AUX/BASE to a larger injector size. To richen the fuel curve, set the AUX/BASE to a smaller injector size. [/url]

thats for the recap in the directions. ok, i read that part. so if im at 83% am i lean or rich at that point? i think thats my confusion. or better yet, at 83% do i need to go clockwise or counter clockwise with the base knob?

[mb3000]

An 83% trim means the ECU is trying to take away 17% fuel. Anything above 100% would mean the ECU is trying to add fuel.

[B-Man]

counter-clockwise is leaner
clockwise is richer

For stock injectors base = 2 Aux = 8

[smoking rr]

I will give it a try again tonight when I get home.

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[smoking rr]

counter-clockwise is leaner
clockwise is richer

except for the base knob. i started at base = 2 Aux = 8 and did a little driving. still in the 80's for the low end. so i went to base 3. still the same. how far should i be going? i feel that i am missing something somewhere bc i am having to lean it out and i am running stock injectors. any ideas?

[B-Man]

Do you have a wideband? Did you do any driving to get you out of the low fuel trim area (ie JUST low trims are rich)? Are you sure your narrowband are even good? If you have the stock MAS, I'd suggest running it and seeing if it's still doing it (assuming you left the harness and intake intact.

[smoking rr]

yes i have a wide band. i got a little into mid trim but not much, (traffic wasnt helping) they dropped into the low 90's if i remember correctly. i dont have my headlights in yet so i cant drive once it starts to get dark. my narrow bands cycle and seem to be ok. i dont have the stock mas any more. yes the harness is still intact. the MAFT is under the hood but i am tempted to move it into the car so i can tune while i drive.

[B-Man]

Does your wideband cycle with the narrowbands?

[smoking rr]

the wideband seems just as jumpy (although i think the logger lags a tad bc the computer is so slow) but i will put them side by side tomorrow and see if they match. if one or both of my narrow bands was bad what would i be looking for?

[B-Man]

Usually they'll stop cycling.

[smoking rr]

They def still cycle.

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[B-Man]

If your wideband is reading above 14.5 at cruise, I would keep leaning it out.

[smoking rr]

Ok... I thought above (for example 17.3) was lean and below (for example 12.2) was rich. Am I reading it backwards?

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[mb3000]

Ok... I thought above (for example 17.3) was lean and below (for example 12.2) was rich. Am I reading it backwards?

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No, you're right.

[B-Man]

14.7 is stoich (ideal for cruise and idle) greater than 14.7 (closer to 20) is leaner, less than 14.7 (closer to 10) is rich.

If at cruise you're reading richer than 14.5, I would continue to lean it out.

[smoking rr]

Ok. That makes sense. How lean should I go?

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[B-Man]

Whatever it takes to make your wideband read ~14.7 at cruise

[smoking rr]

Ok. I thought you were saying Leaner than that.

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[B-Man]

I usually run ~15.0 for cruise, but I have better control with an EMU than you do with a MAFT.

[smoking rr]

That makes sense.
next question.
If my wbo2 reads 14.7 but my trims are still in the 80's do I keep adjusting to get my trims closer to 100 and hope that my ecu well keep me adjusted close to 14.7?

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[Roybatty]

Your trims @ 80 are good. At this point u adjusting air fuel mix. 80 trim just means ur injectors not maxed

Sent from garage

[B-Man]

That makes sense.
next question.
If my wbo2 reads 14.7 but my trims are still in the 80's do I keep adjusting to get my trims closer to 100 and hope that my ecu well keep me adjusted close to 14.7?

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I'd probably ignore the narrowbands at that point. Can you post a log? Be sure it's after the vehicle is warmed up and in closed-loop

[B-Man]

Your trims @ 80 are good. At this point u adjusting air fuel mix. 80 trim just means ur injectors not maxed

Sent from garage

You should probably read this:
Stealth 316 - 3S Fuel Trims (http://www.stealth316.com/2-fueltrims.htm)

[smoking rr]

I'd probably ignore the narrowbands at that point. Can you post a log? Be sure it's after the vehicle is warmed up and in closed-loop

I will try to tonight. I have only watched it, never recorded it. I will have to doggie out how to do that. Lol

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[smoking rr]

You should probably read this:
Stealth 316 - 3S Fuel Trims (http://www.stealth316.com/2-fueltrims.htm)

I will read that in my lunch. Thanks for the info.

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[B-Man]

The link was more directed to RoyBatty, but it's good info either way.

I would warm up the car. Turn it off, reset the ECU (disconnect battery for 10sec) and then run it. It should go into closed loop about a minute or so later. Get a log at cruise.

[smoking rr]

I will read anything that will help me get my car finally running right.

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[smoking rr]

Ok. I don't know how to revise the log yet but here is a quick tits bit of where I stand at the moment. I drive for about 20 miles today.

87 degrees out side.
Water temp 188
Oil temp 217
Wbo2 reads about where it should.
Real bad stumbling/bucking problem while in light throttle between 1800 - 2800 rpm's or so.
Goes to 12.6 ish afr when on it hard. Building to about 9 psi or so.
This pic is at idle after driving.

http://img.tapatalk.com/d03640af-1093-4fa0.jpg

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[B-Man]

Without seeing an actual log, the Mass airflow is a little higher than mine and IPW looks a little long. I'd say keep leaning it out (at least the idle, if you've gotten into mid trims a lot you should be fine)

[smoking rr]

I put 20 miles on it, most of it between 40-80 mph.

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[smoking rr]

Would it all being a tad rich account for the bucking? I am thinking it might be bc of a vacuum leak but it happens in that RPM area in just about any gear.
I am chasing a boost leak, but can't find it yet. It sounds like it's coming from under my intake. Maybe it's leaking at my injectors? Also I seen to have air coming out if my rear valve cover. That doesn't sound right to me, or am I just over thinking it?

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[B-Man]

Rich can account for bucking. Boost leak test will be important to getting this tuned. Air coming out of your valve cover is bad. It usually indicates a broken pcv system.

[smoking rr]

yeah, i assumed the PCV, so i have the line that runs from the lower intake manifold to the pcv valve unhooked and the line that runs from the rear turbo pipe to the rear valve cover unhooked when i am pressure testing. i still get more air than i think is normal out of the valve covers.

[B-Man]

idk, that one's beyond me.

[smoking rr]

hahaha. ok, atleast i am not the only one. i fear that i have a valve leak. but i JUST had the heads fully rebuilt so.... i hope not.