Jump to content
Email-only Log-Ins Coming in December ×

IGNORED

Bad Air Flow Meter?


Lani Kai

Recommended Posts

I'm suspecting my air flow meter has gone bad. The car is running rich and occasionally stutters at high RPM, generally past 4,000. I've looked at just about everything else that factors into setting the fuel mix but I want confirmation before replacing the AFM because it's not a cheap part and only available on a core-exchange basis from MSA.

Is there anyone in Orange County, CA with a healthy AFM that I can borrow and test before I needlessly spend money? I'd reimburse you for gas costs and provide a beer or something

Link to comment
Share on other sites


It's a rather simple device, so I'd also test it and clean it up. In addition to the FSM tests, I'd use a mechanical (needle) type of multimeter to measure the resistance from one end of the potentiometer to the wiper contact, throughout the entire sweep of the potentiometer. You want to see the resistance move smoothly, with no stuttering or gapping in the needle movement.

Things that I'd also check, if you haven't already:

-- Stuck cold start valve.

-- bad thermotime switch

-- misadjusted or malfunctioning throttle position switch

Also pull your plugs and see if they all read the same. You might have a problem that affects only some cylinders.

FAIW, it's more common for these machines (particularly the '78's?) to run lean. A severe lean condition will give you carbon fouling of the plugs, owing to incomplete combustion, so it might look like a rich condition. Do you get backfiring through either the exhaust or the intake? If you have backfiring through the intake, you might have a severe lean condition. Backfiring through the exhaust would probably indicate a rich condition.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...

Important Information

By using this site, you agree to our Privacy Policy and Guidelines. We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.