M42club.com - Home of the BMW E30/E36 318i/iS

DISCUSSION => Engine + Driveline => Topic started by: gearheadE30 on July 17, 2007, 11:56:04 AM

Title: dead spot in RPM
Post by: gearheadE30 on July 17, 2007, 11:56:04 AM

My car has a bit of a dead spot in the RPM range, from 2500 to 3000 RPM. I think that it may be the coils, as they are the originals. Any ideas?

Title: dead spot in RPM
Post by: ak96ss on July 17, 2007, 01:57:25 PM

AFM. More than likely there is a dead spot in the sweeper.

I had mine rebuilt. Supposedly you can pull the cover off and slightly adjust the location of the arm to an area that still works, but I had no luck with that.

Title: dead spot in RPM
Post by: badboypolar on July 17, 2007, 04:18:06 PM

Where would you get it rebuilt at? and how much? New ones are about $200.

Title: dead spot in RPM
Post by: bmwman91 on July 17, 2007, 07:55:49 PM

Probably the AFM.  This is one of the WORST spots in the WOT powerband for intake resonance and stuff.  It wouldn't surprise me if the carbon track in the AFM was worn out around that flow range.  PelicanParts sells rebuilt ones for ~$180.

Title: dead spot in RPM
Post by: ak96ss on July 17, 2007, 08:23:29 PM

BMA offers a rebuild service for $175 or so, which is comparable with buying a rebuilt but you get to keep your original one, if that matters to anyone besides me.  :)

Title: dead spot in RPM
Post by: gearheadE30 on July 18, 2007, 09:35:04 AM

Well, if it is that much, I may just drive it as it is until it gets really bad or until I get the nerve (and money) to try a MAF conversion. Thanks for all the input.

Title: dead spot in RPM
Post by: bmwman91 on July 18, 2007, 09:53:06 AM

Nah just rebuilt it.  A MAF conversion will run you at least 4x a rebuilt AFM, with ZERO gains in power.  Yoo do get sweet throttle response and driveability, but it is pricey.  Check out the MAF thread(s) in the electrical section.