Did I hear you can adjust the spring tension on the AFM barn door that can give you a 10 whp increase?

Is this total bull****?

 

Adjustments of anykind to the AFM mechanisms other than the wiper to get on an unused trace area is strongly discouraged. If you change when that door opens you effectively change your AFR because the load calculations are based on the operating characteristics of the stock AFM.

 

So if I use a Promax chip, its plug and play, no adjustment needed of AFM and up to 17 hp gains then?

Sound right?

 

No aftermarket chips require adjustments to the AFM that I am aware of.

Regards,
Russell

 

Crap...
when prepareing for 944 spec racing you may want to tweak the AFM to improve the A/F ratio. Reason is when pulling the cat the mixture can change slightly. However the only way to do it is on a dyno as the adjustment is very sensitive and doing it anywhere else means a 99.9% chance of getting it all fouled up. Doing it on a dyno might yeiled 1-2 hp if your A/F was off to start with.

 

Its not crap...

A/F is usually bad lean on the na's. In order to flatten A/F adjusting AFM is required. Adjust the wiper to get your numbers lower and spring to help fuel curve. Went to dyno last week to see how low hp was getting. Its not liking fresh head but couldn't stand car just setting there while I'm work on new engine. Its had 36000 miles for ten years so its getting tired. Hate to show the numbers but here's the print out only adjustment was the spring. Made 5-6 pulls 10 notches lost 4 hp. I'm running Innovates LM-1 to keep track of A/F ratio so I wasn't just blind adjusting things. Before adjusting the wiper A/F ratio was 14.6- 15.9.

 

It might be 10 hp on car down on power to start with. I had my AFM adjusted years ago on the dyno and got 2 hp or so. My A/F ratio was off too. Did you have your injectors flowed? In my experinence on cars with very low miles the injectors gum up and don't flow very well. Taking them out and having them cleaned really brings the performance back to stock levels. 36miles in 10 years with little to no full throttle running is good way to gum up injectors. That would cause a lean condition at higher rpm.

 

I am still new to Porsche mechanics, but I see no reason that this device was created execpt to confound would be Porsche mechanics. My Honda has no AFM, no MAF, MAP, PAM or PUN before the throttle body. Execpt my DME's requirements to see the AFM reading, why can't it just simply be eliminated and that part of the DME bypassed? Spec racing rules state that if I replace it w/ a MAS I go up a class or two, but no rules stating it cannot just be eliminated w/o a class penalty.

PS: I am working on a removable clear plexiglass cover for this. Don't know how much I want to spend on the project, but if interested in a clear cover for the meter, let me know. I need a couple more of the black plastic covers if any one has any to give up for a few bucks or free would even be better.

 

Had the injectors done while the head was off but haven't checked pump in years. I'm upgrading fuel system when new engine goes in so I just stuck new filter on and rolled with it.

 

The AFM is intergral to the DME's operation. It uses the flapper door to measure air inlet volume and temperature. From that it can determine the air being sucked in the engine. Then given this air flow the computer determines the fuel requried to achieve efficient combuston. In closed loop mode the O2 sensor is used also used to fine tune this arrangement.

The car will not run with out the AFM or some other air flow metering device.

944 spec rules require the AFM and have now allowance for removing it. It can however be tuned so that you don't have really crazy mixtures which can result if you remove the cat converter.

 

Thanks Joe, I was hoping to keep my car in Spec classs to run in Cup in Mid-A, so I get mixed up with all the rules sometimes. Still, I would think that I could use a Air Fuel Ratio gauge to tune the car and then dump the AFM. The sessions are only 20 minutes or so, and with a gauge installed on the O2 sensor I could detect any deviations and shut down before it becomes an issue.

 

The DME does not work like that so you can't do it it. Unplug the AFM and the car stalls. BMW E30's for one use a nearly identical AFM. What ever you do to the car you will still need a way to meter air flow. In full throttle mode the signal from the O2 is ingnored and bits of data used to determine fuel flow are 1) air inflow (metered by some device) 2) engine RPM. Remember full throttle open just means the throttle plate is wide open. This tells you very little about how much air is actually going in the engine. That is why you need some air metering device.

 

how can i adjust the spring??someone have moved the spring before i got the car..and now,from when i got the car i have a big fuel consumption..and i would like to know if i can adjust the spring somehow?i do not have a o2 sensor..it was 'nt equipped with...i have moved the wiper to a different rote..but still i have hesitation and big fuel consumption,.i have replaced everything else...pls let me know if u have any idea to fixing this..i have a gas tester....

 

You need to be on dyno to tune the AFM and have a A/F ratio reading. Any other method will yeild poorer results than you have now.