Mass Airflow Sensor Test?

Is there a way for these sensors to be tested? We have an 1989 corvette that is idling poorly, and runs rich. They are kind of pricy to just buy to try
out.
Thanks! Travis
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i would suggest cleaning the maf first, then changing the iac valve. i had this same problem with my 89.
regards, charlie cave creek, az
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Travis Ogden wrote:

First, not said, but let's assume there are no codes. If you've got codes, stop reading now.
You've got the right idea. Don't start, "throwing parts at it." Could be something as simple as an emissions cannister purge valve or fuel tank vent valve being screwed up. On an '89, check to make sure the tachometer is reading correctly. If it's reading high, the engine will run rich--common cause is stray signals getting into the ECM due to a busted ground wire on the distributor shielding.
Generally, the MAF signal comes into play during changes in airflow, not during steady state operation. If the throttle is closed the MAF isn't in the picture. Think of the MAF and the Throttle Position Sensor as doing what an accelerator pump and dashpot accomplish on a carburetted engine. Steady-state running is more dependent on the O2 sensor and computed Block Learn. If the MAF circuitry is not throwing a Code 33 or 34 there are better places to start looking.
Get Section 6E (Drivability) of the maintenance manual. Run a scan. Follow the troubleshooting diagrams--avoid jumping to conclusions. Guessing and prayer won't help. (Praying for increased patience is OK).
The results of the scan may pinpoint the issue. At the worst, the scan will rule out a lot of stuff that's difficult to reach (like the EGR valve on an L98) or difficult to electrically test. If you can't borrow, build or rent a scanner, paying a couple of hundred bucks to have someone else diagnose the problem is money well spent.
Get a fuel pressure gage--good for checking on fuel pressure & exhaust back pressure. Also enables a simple injector balance test. (Cheaper than paying someone to flow-check injectors.) Again, replace the bad part, don't throw 8 injectors at a balance problem. Pick a gage that will measure 0-60 psig and let you read a 1 psig (or 5kPa) increment.
HTH -- PJ '89 auto coupe, '02 e-blu coupe
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