I recently had my pcm tuned by Ion at MadZ28.com and I had the chance to hook a scanner up to it today. My dad helped me make since of all of it and the only thing I could think that could be wrong is that the reading on the MAF stayed at .26 at any throttle position. Is this normal? If not, what should the readings be at? The O2 sensors all checked out ok and the A/F ratio was right at 14. The engine misfire and the EGR Malfunction also went away. Thanks in advance.

 

Depends what units of measurement the scanner is reading in, but if its "grams per second" (gps) for the MAF, the readings should be in the range of 6.0-9.0 gps at normal idle, and airflow should increase up to the range of 240 gps at WOT/5,800rpm on a relatively stock engine. If the scanner reads in "pounds per minute", that would range from 0.80 #/min - 31.8 #/min. If the MAF reading doesn't move, it isn't working. You should be getting a code.

When you read the A/F ratio on a scanner, all you are reading it the "target" A/F ratio - the A/F ratio the PCM is trying to achieve. In closed loop, it will target 14.7:1. Doesn't mean that's what the actual A/F ratio is, only that is what it is trying to do.

Read this:

http://members.aol.com/InjuneerZZ/ScanMast.htm