MAFT tuning hell

[Bouche Dag]

Car is a 92 AWD, mod list as follows: 3 in. exhaust, FMIC+pipes, 550cc injectors 3in GM MAF, wally 190lph, all free mods, godspeed project rad/12 in. pusher slim fan, -6an steel braided fuel line from sender to high flow summit racing fuel filter, and MBC.

I have my settings for 640cc injectors and a 3.5 in. MAF and my trims are:
L trim fluctuates between 98-118
M trim: 105
H trim: 100

I record 1 count of knock randomly every time I drive, I assume this is just phantom or nothing to be concerned with, correct?

Here's the real issue: If I turn the boost up any higher than stock I get crazy knock. And if I increase fuel with the WOT knob A). My car will bog and miss like crazy. And B). my injector duty cycle goes way high. I tried to run 17 lbs. and I hit 100% duty cycle and bogged like crazy. When I turn the fuel down even one click I'd record 12 counts of knock.

Is there something wrong here? Should 17 lbs with 550s and a 190lph pump max out my injectors like this? Should I switch to WOT fine tuning to get rid of my knock? I know my knock sensor is good. Motor came out during spring time and the sensor still had the goop in the back, it hadn't leaked out exposing the screw.

 

[bastarddsm]

You probably have a bad knock sensor. Get out a timing light, retard your timing a bunch, and try it again. If it still knocks your sensor is bad, if it goes away something else is wrong.

If the ecu detects the ks circuit is faulty it will automatically make the knock sum goto 42 when ever the load is high enough.

Also, when the sensor gets old it can pick up other noise and register it as knock.


Also you should be ok with 550's at 17psi. Maybe ditch the maft for an afc/ 2g maf.

 

[black91awdturbo]

I am going to assume you have a 14b correct? If so no 17psi with the fuel support you have wont drive you to 100% or even close for that matter. I would suspect a faulty knock sensor, or bad calibration.

 

[Bouche Dag]

Sensor is near new. Still has the black goop in the back. It has also never recorded 42 counts of knock - highest its ever recorded was 12 counts.

Plus if I turn the boost down back to stock (9 psi for my car) then I get no knock and can run it lean as hell (~.80-.82 o2 voltage (I know it's not the most reliable measure of AFR, especially since my ECU is a 90 - but its still lean IMHO))

It's a 14b.

By bad calibration do you mean my MAFT is bad?

 

[okm12346]

Why do you have 3'' GM maf and your MAFT is set for 3.5'' one? Why are you injectors dialed as 640cc when you have 550cc?


What are you BASE and AUX dials ?

 

[Bouche Dag]

I also don't have a 15/16 or 24mm crow foot so I didn't torque the sensor to spec.

Could this be my issue? I heard that if you don't torque it to spec it can cause weird knock sum behavior.

Why do you have 3'' GM maf and your MAFT is set for 3.5'' one? Why are you injectors dialed as 640cc when you have 550cc?


What are you BASE and AUX dials ?

The car wouldn't run with the dipswitch set at 3" maf. Couldn't even get it started. I switched it to 3.5" maf and it ran perfectly.

I had to adjust to 640cc injectors to achieve my near 100% trims. Setting it to 550s caused it run way rich. I just kept dialing it up until I got 100% trims and ended up at 640cc injectors.

BASE:1, AUX:6

 

[okm12346]

you should try base = 5 , Aux = D and both dipswtches off = 3'' maf

 

[jmartinez1228]

I didnt see a fuel pressure regulator in your list do you have one?

I've never run 550s on a 190 but I have on a walbro255hp at 17psi with no issues on my old maft setup w/ 3" maf blowthrough though.
What version translator are you running?
Where do you have the maf setup?

Translators can be a pain to dial in honestly. I had to add a safc for more fine tuning to get it to run right for me.

 

[black91awdturbo]

Why do you have 3'' GM maf and your MAFT is set for 3.5'' one? Why are you injectors dialed as 640cc when you have 550cc?


What are you BASE and AUX dials ?

This is what I was saying by bad calibration the settings you have dialed in on your car. Also what are you using for intercooler pipes? Remember these things are finicky as hell..

 

[Bouche Dag]

Well does the MAF setting and injector size really matter at this point since my trims are zero'd out?

Stock FPR, TD05 14b (could be a small 16g, previous owner did not know and I've never cared enough to measure the hot side), MAF is setup blow through, DEJON UICP so it's a few inches away from the TB, MAFT 2.02

My IC pipes are kind of weird. They are 2.5 in and the lower is kind of a cluster f***. J pipe points straight down to a silicone 90* elbow to a hard pipe to another silicone 90* elbow to the FMIC to a coupler to a hard pipe to the UICP. I guess it's not too crazy, but I think the previous owner just kind of pieced together some random pipes because none of them are flared.

Maybe I will try to switch it back to 3 in.

When I tried it at first I could barely get the car running. It would buck and miss like crazy and the O2 fuel trim was pegged at 199%

 

[okm12346]

you sort of balanced it out between the base and aux dials, but that doesnt mean its correct.

Fuel trims do not change instantly, it takes some driving to do that. I'd say check the trims at the end of each day after some driving.

Try base = 5 , Aux = D and both dipswitches off = 3'' maf, all other knobs to zero.

^These are the correct settings for your setup. Reset the ECU before you start driving it with new settings.

 

[black91awdturbo]

Easy to tell if its a G series turbo check and see if it has double blades on the compressor.. I would reset it to 3inch mass, and dial it in from there. I talked with full throttle's tech department years ago with problems similar to yours, and they said sorry cant help. The reason being this setup in blow through it to finicky it matters on your setup how far the mass is from the Tb and which way the plug is facing even... Thats why I said they are finicky you just have to tune, and play and tune and play... Then when the weather changes minor retune all in all it works ok for what it is. But be you will get frustrated with it.

 

[Bouche Dag]

I've had the trims solid for a few months now.

I'll try dropping down to a 3 in MAF and turning the injectors down a few clicks.

My table (the one on the paper work that came with the MAFT) doesn't show an option for AUX=D. My table shows that 550s for a 1g should be AUX=0, BASE=C

When I had the maft set for a 3" maf and 550cc injectors I couldn't get it running without bucking, misfiring, etc.

Easy to tell if its a G series turbo check and see if it has double blades on the compressor.. I would reset it to 3inch mass, and dial it in from there. I talked with full throttle's tech department years ago with problems similar to yours, and they said sorry cant help. The reason being this setup in blow through it to finicky it matters on your setup how far the mass is from the Tb and which way the plug is facing even... Thats why I said they are finicky you just have to tune, and play and tune and play... Then when the weather changes minor retune all in all it works ok for what it is. But be you will get frustrated with it.

Wow, I really appreciate your help.

And I'm glad to hear that I'm not the only one suffering with this problem.

Sounds like I'll be tinkering with the MAFT tomorrow

 

[okm12346]

Thats a manual car, correct?

 

[Bouche Dag]

It's all starting to make sense. Kind of seems like the car is over compensating because I have it set incorrectly

The car is running super rich because it assumes I have a huge MAF, hence the stumbling and misfiring and 100% duty cycles when I slightly increase fuel and boost... Also, leaning the car out a little is leaning it out way too much causing knock.

Thats a manual car, correct?

5spd with a terrible blown trans.

 

[okm12346]

Copied directly from Maft for 1g dsm

. Stock ECU = 450, 550's installed 1-(450/550) *100 = 19%
(the Translator must be set to 20% lean for 550's. The BASE 4 setting is for 550's

its really 18%, so either base=4 or 5 should work. The Aux doesnt matter since the aux wire isnt connected. Set it back to 3'' maf and reset the ecu. Go for a drive and let us know

 

[Bouche Dag]

Wow, I really appreciate all the help.

I will revisit my setup tomorrow and take her for a spin and post my findings.

 

[black91awdturbo]

No problem, and update us on what you find when you switch your stuff around.

 

[NOSLO2PT0]

If he has V2.0x, then he must set the base/aux knobs correctly in order to dial in the injectors. V1.3 uses only the base knob to set injector settings. And.....the GM MAF has an arrow on it that shows the correct direction of airflow passing thru it. If you have it backwards, it could be throwing your readings way off!

 

[Bouche Dag]

If he has V2.0x, then he must set the base/aux knobs correctly in order to dial in the injectors. V1.3 uses only the base knob to set injector settings. And.....the GM MAF has an arrow on it that shows the correct direction of airflow passing thru it. If you have it backwards, it could be throwing your readings way off!

I did double and triple confirm that I had the MAF facing the proper way!

 

[Bouche Dag]

The car is running so much better now. Had to richen idle a lot but I have it set at aux 0, base 6

Still recording 1 random count of knock here and there but a lot less than before.

Still letting the trims settle before I do wot pulls.

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[Bouche Dag]

Alright so I've put about 50 miles on her and its been a huge pain to dial idle in. But I think I've finally got the L trim set to 105%!
M=114%
H=100%

Due to the variance between M and H I set the base curve one injector click richer and leaned out the MID one click to try and close the gap between M and H trims. This will probably throw my idle off too. Ugh.

As I was driving today I noticed my Turbo seemed to be lagging more than usual. I was thinking "great why is this happening at the same time I'm tuning?!" I thought they may be related issues but turns out my Turbo bolts backed themselves out! Stupid DSM

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[black91awdturbo]

Its kinda like I said you have to drive and tune drive and tune. You will get it dialed in, and it works good for what it is. Do you have an eprom ecu in this car?

 

[Bouche Dag]

Unfortunately no. It is a 90 ECU but its not eprom.

 

[92AWDHX40]

Terry's Talon Troubleshooting Tips #3 - Fast Idle (aka. Idle Surge)


have you done your steps to solve idle yet withou the maft?