I would like to known if there is a publication of known good PIDs. As I read my data, I would like to know what a good average is to make a diagnosis. Example MAF frequency, what is an ok average frequency or MAF gm/sec, what is a good known PID. Is there some kind of chart available?
Hello Peter I'm not aware of such a chart as it's different for every vehicle but as a rule of thumb your maf grams per second should be approximately your engine liters at warm idle so for example a 1.8 liter engine should idle at about 1.7 to 2.0 grams per second and a 5.4 should idle around a 5.2 to 5.6 grams per second, now manufactures give specs at 2500 rpms for checking higher flow rate but I like to use max reading on wide open throttle as it can show a dirty maf better than at 2500 rpms so for example if you have a voltage pid you want it to be able to go over 4.0 volts at wide open throttle full load(1st and 2nd gear) if voltage is not available I guesstimate on prior experience what the engine should be able to draw in the case of a 5.4 engine it should pull over 200 grams a second where a 1.8 will be closer to 70 grams I use a formula of liters x 40 for peak flow so 3.0 liter engine idles close to 3 grams and peaks at 120 grams. Sorry it's long winded but I wanted to make sure everyone could understand it , there are a few exceptions on this formula such as diesel vehicles aren't even close to this!
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The following user(s) said Thank You: Noah, Peter, Tutti57
Sometimes manufacturers will make "normal" pid values available in service info, but it's not always available or easy to find.
iATN.net is a good resource where you can find known good waveforms posted by techs and ask questions about PID values. And of course you can always open a thread in the repair questions sections of this forum if you're seeing something you're not sure of.
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