norbak1258

just like the title says, how do I check/make sure that my afm is good? Some time ago I started screwing with the afm trying to fix my idle proble. I found that my lim gasket was bad and changed it yesterday. Now the car will not start, it floods. I can get the car started by pushing and starting it in gear and I think that my AFM is out of adjustment, any help would be much appritiated.

BTW its an s4 turbo.

Thank for the help in advance.

Evil Aviator

Need more detail about what you did to the AFM.

norbak1258

I moved the metal wheel inside, the one that has theeth on it and I belive opens or closes the flapper.

HAILERS

You have little or no chance of getting the afm back to the original configuration unless you marked a moving part against a fixed part inside the afm. Sort of a reference mark to return to. That's just an opinion, nothing more, nothing less. I'm sure someone out there has other opinions about that.

The AFM has nothing to do with the initial start of the engine (amount of fuel injected). The ECU does not look at the afm at all until the rpms get over five hundred rpm, and at THAT point the afm is used from there on.

Just an outside chance.........if the water thermo sensor is disconnected that can make for a difficult start when the engine is cold. Not when hot, only cold.

https://www.rx7club.com/forum/attach...8&d=1137379604

HAILERS

There is a method of getting the afm in the ballpark, but it requires access to a afm of the same series.

You could remove the afm from the filter housing. Put the plug on it and turn the key to ON. Now set the afm perfectly level on a flat surface. Your choice of how to do that. Now put a weight on top of the vane. Say a 1 1/8 inch deep socket. Then go to the ECU and with a meter measure the output voltage of the afm.

Then do the same thing with the OTHER afm you aquired, say off a friend temporarily. Look at the voltage output of YOUR afm and then the output of HIS afm. Use the same weight on top of the vane for both afms.

Now either tighten your afms spring or loosen your afm's spring to match as close as you can his. Done.

If you had a SAFC you could monitor the output voltage on it when doing the above.

And remember my thread above this one. The afm is not used for fuel delivery during START, UNLESS the water thermo sensor is disconnected OR the ECU is not seeing the START signal. In those cases the afm IS used for fuel delivery during START.

HAILERS

OR, if you have a Shop Vac like a RIGID , what you can do is remove the afm but leave its plug on. Put the shop vac to the engine side of the afm with a seal around the hose end to prevent leakage. Then turn the shop vac on.

I did this with a car of mine this moring comparing a couple of different turbo afm's, one of which I've previously *messed* with. I read the cfm of the afm on a RTEK2.0 I have, then adjusted the spring tension to match the afm that's never been *messed* with. Job done.

The output of a SAFC would do the same or just a digital meter on the output wire of the afm will do the job.

I'm only writing this because I've done it (adjusted the afm spring) using the two different methods mentioned above. The one where you put a given weight on the vane of the afm to make the vane open the same for both afm's your testing, isn't as easy because you have to make sure the *weight *does not touch the body when doing it that way. Plus the weight wants to slide off.

All you have to do with the shop vac is put some sealing material around the mate b/t the shop vac hose and the afm outlet.

coldfire

iTrader: (1)

HAILERS are you trying to set a record for sequential posts? haha
good info though.
the method in the last post is the best way to do it that i can think. but keep in mind after 2 decades the stock AFMs are not all going to read the same. and remember you must consider the total range of the AFM since the relation between airflow vs. voltage output is not linear.

HAILERS

At a given airflow all the afms should have read the same in the beginning. They all had the same spring tension to do that. If I take a afm that has not been messed with and apply a given airlow to it, then put the same airflow to the *messed* with afm, there's no reason for me to think that when I reset the spring tension in the *messed* with afm to match the non messed with afm, that the result isn't going to be close. Real close.

Beats just picking uut a cog in the wheel to put the stop spring. That's too random.

Plus on the messed with one, I set it initialy at 10.2, but thought about it and moved the wheel for a notch more tension which gave me 9.8. Just one run iwth the car and I don't see that low 10afr/high 9afr I've been seeing on inititial boost. High 9''s and low 10's suck. They bog a car.

I have no real help for the thread owner, unless he can find another afm or borrow another afm and do what was suggested. Yes, SHOP VAC works best.