Jersey Posted November 20, 2003 Share Posted November 20, 2003 Had a few internal shots of my turbo AFM and figured i'd post one for anyone thinking of adjusting it... possibly to compensate for larger injectors as i did. Hope it helps. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted November 21, 2003 Share Posted November 21, 2003 Just so as not to mislead anyone, this AFM gear adjustment will change your mixture for idle, lower RPM, and light throttle driving only. Idle mixture alone can also be adjusted by turning the large flat head screw in the side of the AFM. Counterclockwise on the screw is leaner and clockwise is richer. That screw adjusts the amount of air allowed to bypass the flapper. Therefore, air that passes under that screw is unmetered. Have fun and mark things before you adjust them like Jersey says. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted November 21, 2003 Share Posted November 21, 2003 I wouldn't say just light throttle cruise... it does effect a wide range of driving conditions, including WOT, up to a point. I saw results across the entire range when I had my N/A ZX, and was adjusting the AFM back and forth on the dyno. Yes, even on the top end (6000+ RPM at WOT) I saw changes when adjusting the AFM. I know some people will say that it only effects mixture up to 4000rpm but I highly doubt that is true. I think people got that number from SU carbed cars, as the pistons on the SU's were at their maximum height by 4000rpm. Put it this way, if an AFM only effected light cruise, low throttle operation, how does the ECU know how much fuel to provide when the AFM is fully open? Via the O2 sensor? Unlikely, if that was the case the car would run like crap with the O2 disconnected (many people actually think their car runs better w/o it). Does the ECU just run a flat fuel curve based on RPM alone? Unlikely, if that was the case the ECU would not be able to compensate for, say, high RPM, LOW throttle opening cruise, or low rpm WOT running. And further more, how would the ECU compensate for increases in boost if the AFM were already maxed out at low revs? The AFM is the NUMBER ONE provider of information to the ECU.. it wouldn't make sense to have it cover such an effectively low range. Quote Link to comment Share on other sites More sharing options...
Jersey Posted November 21, 2003 Author Share Posted November 21, 2003 cygnusx1 - absolutely right. Adjustment of the bypass screw on the side of the AFM will increase/decrease the amount of unmetered air to bypass the AFM, affecting idle. I didn't mean to confuse anyone. I just noticed a bunch of posts regarding this and had a bunch of personal emails asking how difficult it was, so i figured i'd post and hopefully show how it was done. Pictures can speak a thousand words sometimes. 525 - The AFM may affect a wider range of throttle position on a a N/A motor but on a Turbo Z, if you take the cover off the AFM and run the Z, you'll see how easily the flapper moves in responce to throttle position. I would think the increased pull of air from the T3 moves the flapper easier, but this is just speculation on my part since i haven't had the two side by side. Just a thought. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted November 21, 2003 Share Posted November 21, 2003 Okay so does anyone know for sure, exactly when the turbo AFM hits it's limit? This question has come up quite a few times now... I'm VERY curious to know just how wide of a range it really affects... it could make all the difference in just how useful it is to try and tweak the thing. Quote Link to comment Share on other sites More sharing options...
Jersey Posted November 21, 2003 Author Share Posted November 21, 2003 Pull the cover off of your AFM, bring the r's up until the AFM flapper is wide open, and you'll know - from idle to ???. Come on 525...lots of questions, you supply us with this info Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted November 21, 2003 Share Posted November 21, 2003 Pull the cover off of your AFM, bring the r's up until the AFM flapper is wide open, and you'll know - from idle to ???. Come on 525...lots of questions, you supply us with this info Unfortunately you have to do it under load. Airflow is not based on rpm, it's related to how much power you are putting down. I say junk it, I'm sure it drops a couple psi to the turbo, which then turns into a hair dryer. Edit: Just thinking about it, see if you can measure the force (vectored forward) needed to open it completely, then divide by the flap area to determine the pressure drop. Then calculate the airflow based on the pressure drop and the open area of the AFM. Quote Link to comment Share on other sites More sharing options...
Jersey Posted November 21, 2003 Author Share Posted November 21, 2003 Sleeper - right after i clicked "submit", i realized exactly what i said and you're 100% right, the amount of load will effect AFM movement. Sorry about that mis-info 525. TGIF... my brain hurts. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted November 21, 2003 Share Posted November 21, 2003 Actually... I would have already tried that for myself except for one thing... the damn plastic cover of my AFM AINT COMIN OFF!!!! Not that I dont want it to, mind you... it's just the thing is stuck on with like the super glue from hell!! Adjusting the AFM was actually one of the first things I wanted to try when I first got the turbo and it wasn't running so well... but after who knows how long of chipping and scraping away this hard plastic gunk I gave up and decided to pursue other avenues first. Since then I really have not wanted to mess with it. It makes me wonder if someone hasn't already opened this one and toyed with it? My N/A ZX had what I thought was the factory glue to hold that cover on and it didn't give me any problems when I decided to open it. Maybe someone messed with the turbo one and then used lord knows what to seal it back up? Quote Link to comment Share on other sites More sharing options...
Jersey Posted November 21, 2003 Author Share Posted November 21, 2003 Sounds like it. The 4 AFM's that i opened were very easy - slice the silicone sealant with a blade around the outside, pop it open. Probably just like you did with your n/a zx. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted November 23, 2003 Share Posted November 23, 2003 yeah exactly... this stuff definately aint silicone, it's a hard yellow substance that looks like old caramel. *sigh* now that I think about it I wonder if whoever messed with it just messed it up. I'm gonna try to get another one or test this one just to be sure it's working right and set right. Quote Link to comment Share on other sites More sharing options...
danman Posted December 15, 2003 Share Posted December 15, 2003 Dremel tools work wonders, just need steady hand. Quote Link to comment Share on other sites More sharing options...
CU Zcar Posted December 15, 2003 Share Posted December 15, 2003 D'ooh, I need to read more threads before posting after a several-month hiatus. I posted this in response to the injector thread: If I read correctly, some of you question whether the AFM flapper is maxed out in a stock Turbo car past a certain point? It would (should ) not be difficult to isolate the signal out of the AFM and put a low-impedance voltmeter -for example, a digital one- on it and just watch it as you drive (assuming the computer is reading output in the form of a voltage across the varying resistance representing flapper position...I haven't studied how this works, perhaps it's a current). This sort of investigation is what I intend to do before I start trying to modify my fuel system so I know what I'm dealing with. My car runs pretty much off-scale rich across the board according to the WBO2 readings in my dyno results, so I know I can pick up some power by getting things first sorted to where they run correctly stock. Sorry if some of this is a little OT Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted December 15, 2003 Share Posted December 15, 2003 Not OT at all. All you have to do is hook up a voltmeter to the signal into the ECU, and monitor what the value is when you open the flap. Then drive it and see at what RPM, full throttle, the door maxxes it's value, if it does. Sorry, I can't participate - I ditched that piece of junk years ago. Quote Link to comment Share on other sites More sharing options...
Jersey Posted December 15, 2003 Author Share Posted December 15, 2003 OUCH Quote Link to comment Share on other sites More sharing options...
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