No trouble codes? why

[zohaibrose]

Howcome my bmw e36 isnt giving me trouble codes when my car clearly isnt running right? still doesent return to normal idle because it idles a bit high im assuming a tps because everything else ive cleaned like maf and icv but also the mechanic told me my cats are clogged i havent got codes for the cats or the tps or any sensor at all the only code i get is a P0446 which has nothing to do with the symptoms im having so does the ecu not care about any of these sensors or is my computer just going bad. Id love to have some trouble codes to get some help on my problems but when i took the car to a guy with a dealer level scan tool he found 9 codes, mostly with emmisions and cats but anyway i can see those codes too? i just dont have the paper to buy equipment like that, so i guess my 30 dollar scan tool isnt going to work in this case, i tried asking the guy for the codes but he blocked my number since i left him so many calls so that was a waste of time.

[328 Power 04]

You do know that cleaning a MAF doesn't exactly fix anything, right? The whole concept of cleaning a maf has an interesting history:

Back in the early 1980s Bosch came out with the first MAF. It used a hot wire filament much like an old lightbulb. This design was very sensitive to contamination. VERY. A lot of effort was put into the air filtration systems. And Bosch even built a cleaning system in like a self cleaning oven. At a key-off event, a capacitor unloaded and dumped a voltage spike through the filament to burn off an debris. This design was very short lived. New generations of MAFs were developed to be much less sensitive to dirt using large area wafers, even ultrasonics. Our MAFs are several generations from the troublesome first gen. And no one would have ever heard of cleaning a MAF except.

In the mid 1990's Ford switched from speed-density to MAF systems to meet the looming OBDii requirements. They did a hot wire MAF like a 19983 Volvo, EXCEPT, they didn't bother with the self-cleaning nor did they put much effort into improving the air filter.... not to say a Ford owner would maintain it to anywhere near usable if they did. So you now have a few million Ford out there with temperamental MAFs. Escort getting lousy mileage? Clean the MAF. Taurus banging each shift? Clean the MAF.

So now you have a new buzz word in the automotive world. About the time it became totally unnecessary, "cleaning the MAF" was all the rage. Because of three or four years worth of Fords., every PFY super-diagnostician behind the auto parts counter had something new to sell. And sell they did.

Bottom line. Our S52, and OPs M52 use a HFM2. It is so different they don't even refer to it as a MAF. It is very insensitive to dirt. Sure, there is a temp sensor hanging in there that people polish to a fine luster thinking they did something. But in reality there is nothing in there that cleaning will help. Indeed, there are things that can be hurt. The later HFM5 used on M54s can very easily be destroyed by a single spray. The sensor element itself is buried deep in a plastic maze, unreachable.

If your MAF needs cleaning. Or your throttle. Or the IAC.... you have a problem. They should not be dirty. You need to find and fix the contamination source. If your air fliter is that bad.... think what it's done to the inside of the engine. But hey, that's what Seafoam is for, am-i-right?

If you're going to skip over 'emissions' codes only (even from the earlier scan), you're likely ignoring the problems.

You and I both agree, you need a better scanner. Sometimes (just sometimes) the autozone scanners will give you BMW codes, especially if the person there is somewhat knowledgeable.


Unfortunately, a neglected BMW is not for the cash-strapped.