Ok a friend with a porsche 944 that modded his AFM by loosening the tension on the spring for the flap on the AFM. He did it with the help of his BOSCH fuel injection manual.

I was wondering if anyone tryied this and what came of it.

Santiago

 

anyone? anyone at all.

 

Make sure you mark the original notch!!!

 

So has anyone tried it? what happened? If what I beleive is correct you could run lean and blow the engine right?

 

I've done it on a spare AFM. I can't remember if it clockwise for leaning or counterclockwise. Without a dyno or a wideband I don't think you can really tell what your gains are. I'll leave it at this, I tested several notches and could never really notice any power difference.

 

Ok thanks for the input though. If anyone else has info post it. I am probably not doing it though I was just wondering if this guy is killing his porsche lol. I don't think you can gain much from it either so I would probably just port the AFM and be done with it.

 

Why would you want to do this? Modifying spring tension will make the car either leaner or richer across the entire range of the AFM. So you will still be too rich when you don't need the fuel, and too lean when you do.

 

Aaron it was a question that I hadn't seen asked so I asked it after my friend told me about it. I didn't say I was going to do it I was just wondering if any good gains could be had from this.

 

My "why?" was sort of rethorical. There could be gains if you lean it out, but only over a very narrow RPM range (top end). The rest of the RPM range will probably be too lean, causing power loss. To properly adjust the AFM signal, you need to set different corrections for different RPM points (ie. S-AFC).

 

Yeah that is what I thought the lean or rich condition thing. This is why I didn't want to do it on my FC unless someone had proof of it doing good.

 

It could be a "stop gap" or "hack" measure if you absolutely MUST slightly richen or lean your engine, and can't afford/figure out how to fix the problem properly.

 

SEARCH NOOB!

This question has been asked and answered (by me) several times before. As Aaron said, even if you manage to fix areas that need fixing, you'll stuff up everywhere else.

 

Is the screw that you get to by drilling out the black plastic plug the spring tension?

 

Hey aaron,

was searching the web for some amplifier layouts and came across your page,

didnt even know it was yours until I looked at the url, then double checked the site for an rx7.

looks like your a pretty creative guy, too bad you lost interest in electronics.

have you built any of the amp on your site?

 

i played with a voltmeter and my afm and the best setting was the stock one, i was kinda surprised at that but oh well

mike

 

loosening the spring will richen the car up, tightening the spring will lean you out...you need at least an EGT gauge to start playing this way, a dyno is best. (tight = clockwise if I remember correctly, mark the original point). I did it on my NA with good results, (better throttle response, mileage too) and leaned my car out about 7 clicks...every car is different though and my EGT's max out at 820 @ redline in 3rd, fine for an NA (the probe is in my downpipe right after the manifold). Grassroots motorsports did this on their project road race miata and picked up 3-5 ponies across the board, they stopped leaning it out when they saw a big flatspot on the dyno (backed it off a bit from there).

 

No, that's a bypass used by the factory to calibrate the AFM. The spring is under the black plastic panel that's glued to the top.

 

****!!

I did a search but I didn't see any good info but I did find this one where the guy completly removed the AFM and was going to tune it with an AFC hahahahaha https://www.rx7club.com/forum/showth...hlight=AFM+mod