how many people have done the stock afm mod where u back out the afm screw? how much boost can u run without hitting fuel cut?
stock afm mod?
- Thread starter bowtiebuba
- Start date
shaeff i already knew about that thread, i actully did the mod to my car yesterday. i read through the thread and one person said they could run 14 to 15 psi of boost, i just want to know how many others have done the mod to there afm and what resalts they have gotten with doing so,? please dont close this thread down im curious to see what resalts people have gotten
Im not, im only at 10psi but what so bad about going above 12psi on stock fuel?? I know this on kid who did 17psi for awhile on his car, well untill it blew up from rod knock, BHG and snapped timing belt all at the same time.
Adjuster
Supramania Contributor
All BS aside, did this for awhile, and had no problems, 440's, stock fuel pump and running 12 to 15psi.
No FC.
Stock CT with fabricated 3" elbow/DP and 75mm HKS Cat Back setup. (Basicly 3" out.)
Did not get 15 psi till I added the boost controller. Also ran with a metal conduit hard pipe mod that replaced the upper flat pipe, and the restrictive lower alloy elbow at the right frame rail. (That mod alone added 2psi of boost with no other changes, just freeing up the air flow between the turbo and the manifold.)
Spool up was instant, but it seriously ran out of power over 5000rpm where the CT exhaust housing/wheel size is very restrictive. (At least from what I can tell.)
No FC.
Stock CT with fabricated 3" elbow/DP and 75mm HKS Cat Back setup. (Basicly 3" out.)
Did not get 15 psi till I added the boost controller. Also ran with a metal conduit hard pipe mod that replaced the upper flat pipe, and the restrictive lower alloy elbow at the right frame rail. (That mod alone added 2psi of boost with no other changes, just freeing up the air flow between the turbo and the manifold.)
Spool up was instant, but it seriously ran out of power over 5000rpm where the CT exhaust housing/wheel size is very restrictive. (At least from what I can tell.)
Adjuster: How old was your fuel system when you were doing this. Mines all original(87) and I don't trust it. I have no doubts about what you're saying. I just don't want to tell someone that its ok to run gobs of boost on an 18 year old fuel system (not to mention a turbo that is that old also). I'm just playing it safe. Good post tho' and enlightening.
is it ok to remove the honey comb dont no if there would be any reason to but it it ok to do so?
Adjuster
Supramania Contributor
Keep the grid/honey comb. It's there, and you need it there for the AFM to work right. (I'd even keep the screen that protects it too since there is no loss in flow with it there.)
I agree that my fuel system was old. It was stock, and I did this about 4 years ago. Only ran it that way for less than a year, but I did have a EGT and boost meter, and the EGT temps were never over 1300, and generally dropped during WOT, to the 1200 range.
I think the key to running OK at this mod level is the open exhaust, IC pipe restrictions removed and replaced with metal conduit sections, a good K&N type filter, good fuel of 91 octane or better, correct base timing and I think I forgot one thing. An adjustable fuel pressure regulator. (How the heck could I forget that?)
Key to making the modded AFM work is being able to raise your base fuel pressure at idle to get 2.5v at the check connector. (Changes the entire fuel map to be accurate at the new found air flow rate of your "modded" AFM from what I can figure.)
Without the adjustable fuel pressure regulator, don't do this mod since your shooting in the dark fuel wise. (Ok if you are rich as most are, but dangerous if your not so rich as some have been.)
I agree that my fuel system was old. It was stock, and I did this about 4 years ago. Only ran it that way for less than a year, but I did have a EGT and boost meter, and the EGT temps were never over 1300, and generally dropped during WOT, to the 1200 range.
I think the key to running OK at this mod level is the open exhaust, IC pipe restrictions removed and replaced with metal conduit sections, a good K&N type filter, good fuel of 91 octane or better, correct base timing and I think I forgot one thing. An adjustable fuel pressure regulator. (How the heck could I forget that?)
Key to making the modded AFM work is being able to raise your base fuel pressure at idle to get 2.5v at the check connector. (Changes the entire fuel map to be accurate at the new found air flow rate of your "modded" AFM from what I can figure.)
Without the adjustable fuel pressure regulator, don't do this mod since your shooting in the dark fuel wise. (Ok if you are rich as most are, but dangerous if your not so rich as some have been.)
may be a dumb question but what does 2.5v mean at the check conector where and what is the check conector im guessing 2.5 is the reading from a volt meter, but what is that reading telling me, and if i have a adjustable fpr what do i do to tune with it like what fuel press do I run ect?
Adjuster said:
yes, Adjuster is correct, and to add to what he stated: the honeycomb separates the entering air into what is called Karman Vortex. (This is the type of AFM we have, KV signal, hence why whe set our SAFC's to KV
) if you take it out, your car will go into limp mode. Karman Vortex are swirls of air, which is read by our AFM's and allows the ECU to determine very precisely, HOW MUCH air is entering the motor. (which is how we get fuel cut, when it reads TOO much entering air)you can see a picture of the Karman Vortex here, in the top right picture:
http://www.cygnusx1.net/supra/library/TSRM/fi/FI_096.html
the SCREEN on the front of the AFM isnt only to PROTECT the Honecomb part, but also to straighten out the airflow for FOR the honeycomb part. this helps get an even more accurate reading. you wont gain anything noticable by taking out the screen on the FRONT, and you'll lose all your power if you remove the honeycomb.
-shaeff