Ka24det FAQ

[Jeff240sx]

Originally Posted by graham

"ok... i am running the aem ems on my setup now w/ the 5 bar map sensor.. which rocks.. it means no more maf and no need to worry about all that bs..."

there is one problem with a map sensor that a maf doesn't have. as the engine wears, vacuum decreases, but the map sensor continues to read it the same. Your ecu can compensate to a degree, but a maf sensor is much more accurate. you wouldn't use a carbeurator on a fuel injected engine (well some people might, but you lose any chance of having mileage and performance from the same engine), so why use a map when you can use a maf?

Here, I'd like to discuss this a bit. My car.. for 10,000 miles, has pull the same -22in/Hg. Previously, for 22,000 miles, I pulled 20in/Hg. The vacuum of the engine will be the same until your timing goes out of whack.. then it will change enough to screw up your settings. There are very few other reasons that you will lose vacuum, and they are pretty serious. Like a dramatic loss of compression.
1-2in/Hg won't really mess up the tune to any significant point. And for a higher loss of vacuum, you can ALWAYS retune it.

The major disadvantages of a MAP are 1) you need a IAT sensor. We have one, so this isn't really an issue. And 2) when you do a major upgrade that affects the vacuum or changes the power band - you need to do a full retune.
-Jeff