Just bought an mx3. couple ?s

XL200 · Post by **XL200** » January 4th, 2007, 2:36 am

I just got a sohc 93 mx3 and am loving it so far except I have an idle issue. When I press the brakes and/or the clutch the idle dramatically drops and sometime dies and is worse when the lights are on. This makes me think its the alternator going bad. BUT it also idles rough without anything on such as lights, ac, stereo. Perhaps a vacumm leak i thought but I cant find one. what else could be wrong?(checked plugs too and wires are recent) the prevoius owner put k&n intake and aftermarket exhaust on it too. thanks for any advice.

also if I do decide to do a BP engine swap(yes ive swaped an engine in my old honda before so I atleast know what it involves and the consequences of ignorance) Should I buy from an import internet store or is the junkyard(cheaper) a better deal? the reason i ask is ive only bought from junkyards and am wondering if the extra money for the import store engines is worth it and anyones experience because i havent bought from them. thanks again

lochabay · Post by **lochabay** » January 4th, 2007, 7:07 am

Your idle problem might be the idle air control valve. Any kind of electrical or engine load can cause the idle to drop and the iac valve is supposed to prevent that from getting out of hand. Some variation depending on electrical and engine load is normal, but probably should not exceed 1-200 rpms. I, too, am new to the mx3, having bought my 93 SOHC a month ago. My idle was way too fast and I had about 500 rpms difference in idle from no load to significant load (a/c compressor, headlights, etc.). I was going to try and clean the valve, but could not figure out if it was cleanable from the manual I have (alldatadiy.com). I posted a question about this on this site but nobody answered. I could figure out how to adjust the idle, so I adjusted it down, but still had about 500 rpms difference depending on load. I cleaned my upholstery and the seats were still wet the next morning, so I turned on the a/c and let the car idle for about 2 hours. I now have the 1-200 rpms idle load difference that I consider normal. Go figure.

neutral · Post by **neutral** » January 4th, 2007, 7:39 am

I have the 1.6DOHC and shortly after getting the car had the same problem with a bad idle-drop when lights were on and braking. Seems those 27w tail/brake lights were the tipping point for this problem to occur in my case. Not running any special sound equipment in my car either. The little 70a alternator is known for being pretty light duty even under best of load conditions. Cleaned up the engine ground points and installed a daisy chained set of ground wires. No probs since then fwiw.

XL200 · Post by **XL200** » January 5th, 2007, 5:08 am

I will try the ground wires first and see what happens. It probably dosent help that my car has a nice powerful sound system either. what are daisy chained ground wires? never heard that term before. thanks for the help guys. I am excited to be an mx'er now!

neutral · Post by **neutral** » January 5th, 2007, 6:37 am

Daisy chained just means each ground wire is run from its ground point to the next ground point vs a circle earth design that homes each ground wire back to a multipoint connector at the battery.

I bought a 4ga circle earth set and cut it down (to save a little weight) to install daisy chained. This thread's 1st post has a link to a circle earth pic and the 3rd post has a how-to link w/diagram for installing daisy chained.
http://www.mx-3.com/phpbb2/viewtopic.ph ... 684#390684