I noticed this a couple time in my evo..

a really really loud harley zooms close by while I'm waiting at a stoplight and suddenly my Idle drops like to 600rpm or something low, like it was about to stall. Is it just my car? or is there some scientific explanation for this phenomenon? hmmm..

Bernardio

 

Hi,

Assuming you are still on the stock MAF, it certainly is possible for the frequency (or harmonic) from a close proximity loud bike to interfere with the Karman Conversion frequency a little and cause a rough idle. And moving to Evo tech forum.

Speedlimit...

 

Not only that but the knock sensor can be pretty sensitive in these cars too. I have heard a few people complain of this when at the track next to open header cars but have never experienced it myself.

 

Wow I was at the dragstrip and I had a similar issue. I was next to a 10 second camaro and my RPM's dipped momentarily from the normal 860 range to like 710 or 750 etc. I was like WTF!! It did this about 4 times and I almost did not do the run. I said....well if she goes she goes and hit the gas.....all good so far. But interesting... possibly a pressurewave on the MAF I am guessing......?

 

If you can feel it in your chest, or if it makes your ears pop.. it will affect your MAF sensor.. you'd be surprised how much affect sound pressure levels can affect the Karmann MAF sensor (or a membrane maf sensor) since the shedder bar is very sensitive to the slightest vibrations (of the little vorticies that pass by)

 

I noticed that when I close the hood with the engine running it will stumble.

 

This has happend to me too,
cars hitting high rpms around me will make my car stumble
shutting the hood does it as well

Time for a Blow trough meter (eliminate the stock MAF)