Chipping and ECU relearning period

[ktteoh]

when you change a chip or make changes to the PCV or ICV vacuum lines, is there a "re-learning" period for the ECU or correct procedure for this ie let it idle for 10 minutes etc ?

i find that after chipping idle is unsteady for a while or whenver i make mods to the vacuum breather lines.

[632 Regal]

reboot the computer

[bahnstormer]

by that he means discon the battery for 30 min
the drive it like u stole it =]

[SRR2]

What do you mean by "make changes to the PCV or ICV vacuum lines"?

[632 Regal]

LOL
What do you mean by "make changes to the PCV or ICV vacuum lines"?

[ktteoh]

like putting a small k/n filter that vents humes directly out rather than them being sucked back into the intake.


What do you mean by "make changes to the PCV or ICV vacuum lines"?

[SRR2]

Throw away anything made by K&N and put the plumbing back the way BMW designed it. Your performance problems will probably clear right up. Just my opinion...

[mystical_wings]

I just purchased a k&n filter ,but havent installed it ,will it hurt my performance.Its just a normal insert

[632 Regal]

it's a known no-no to change the stock system. first thing you wont have cold ais induction, you will suck more dirt in, and it can ruin your MAF from the oil on it.

[SRR2]

Probably won't hurt performance, but any oiled foam filter will let through more dirt than the OEM paper filters do. You can Google "K&N" and "test" and words like "grit or particles or efficiency". There are a million posts on tests on K&N filters. I don't remember ever seeing one that proved that the K&N was better than the paper type, and there are hundreds that show that K&Ns result in more particle admission, dirtier oil, and more engine wear.

In practical terms, even assuming that an oiled foam filter causes less pressure drop than a paper filter, this will have an effect only at WOT and the top of the RPM range. At any part-throttle setting, the volume air intake is set by the throttle and the ECU sets fuel flow according to the net air flow. At part throttle openings, you could have an inch of Hg pressure drop across the filter (an inconceivable amount) and it would make absolutely NO difference in the performance of the engine, since the drop across the throttle will be much greater. IOW, at cruise power levels the engine requires X air volume that can be supplied at (I'm just making up numbers here) a manifold vacuum of 20". It doesn't matter whether the filter causes 0 drop and the throttle 20", or the filter causes 1" drop and the throttle 19" Same power and efficiency out of the engine in either case.

The bottom line is that any performance advantage, if there is any at all which is highly doubtful, occurs under operating conditions that make up maybe 0.001 percent of the total operating time of your vehicle. The benefits, if they exist at all, are certainly not worth the risks of the poor filtering of the oiled-foam type filter.

My opinon? The whole K&N thing is a scam equivalent to Slick-50. Neither should come within 100' of anyone's car.

[SRR2]

632 is right about the MAF too. I forgot to mention that. Visit any Porsche board and search on MAF and K&N to read about the many thousands of dollars spent on replacement MAF elements (at $500-$1000 a throw) due to crud emitted from a K&N filter.

I know it's hard for some people to accept, but BMW engineers are pretty smart people and have done a good job on air intakes in stock configuration. I don't think there's ever been an alteration to air intakes that produce actual documentable, statistically-significant, and repeatable increases in performance. There are a LOT of alterations that screw things up, but it's hard for anyone who's just spent $600 on a fancy brushed anodized aluminum Cold Air Intake to admit that it doesn't work as well as the $20 BMW plastic airbox he just ripped out.