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High initial idle?
Posted: July 12th, 2006, 5:33 pm
by state_red
Hey guys, mx-3 n00b here. Just got my 95 GS three weeks ago and I love it. The one thing thats bugging me about it is that it's revving relly high when I start it up, (2000 rpm in neutral) but after driving it for about 15 minutes it settles back down to idling at 750 rpm. Engine is a k8 with 215 km on it... Doesn't burn oil and sounds good otherwise...
On top of this and probably related, my milage could be better and I'm having to shift at rather low speeds. I think if I shift at 3000 rpm I end up shifting at like 15/30/50 km/h which seems pretty low. Could this be I'm running rich cause of a leak? Any ideas?
Posted: July 12th, 2006, 5:42 pm
by hgallegos915
Hey i think thats normal.. your car s cold.. iac(sensor under the throttle body) detects cold coolant so it rises the idle a bit to warm it up.. once tis warmed up it goes back to normal. Anyone correct me if i am wrong please.
Posted: July 12th, 2006, 6:25 pm
by MX3ak
I agree with hgallegos915 about the high initial rpm's.
Talking about milage, you'll see you can run in 5th gear almost all the time even with a K8
if you realy need acceleration, then you can use the 4th
If you think you are runing too rich, just change O2 sensors.
You'll need to change them sooner or later
Ps: good luck with your mazda
Posted: July 12th, 2006, 9:04 pm
by jschrauwen
Hector is pretty close though. The cold engine / high idle kick down is normally governed by the IAC (or known by the ISC) valve. It's the black cylindrical item located at the bottom of the throttle body. On it is a 2 wire connector. Test the resistance value of the ISC valve at or close to an ambiant outside temp of about 68 degrees F. The resistance value should fall between 10.7 and 12.3 ohms. If it's not within those parameters than another ISC valve should be sourced. Preferrably from a junkyard while you carry your handy pocket multimeter with you to test a suitable replacement.
The gearing in the MX is extremely low, combined with a very low final drive gear also. That makes for a lot of early quick shifts. It's an engine that does love to sit at higher rpms though. If you have any mechanical prowess, than it would be to your best interest to have a look at the home page of this site. There's an online manual there that's all-encompassing. Between that and this BB's search function, you'll find a plethera of information and knowledge all specifically directed to only one car and only 2 engine variations. Welcome to MX-3.com
John
Posted: July 13th, 2006, 7:09 pm
by state_red
Hey thanks for the welcome guys. Yeah, I know that all cars rev higher initially and settle down, but 2000 rpm still seemed quite high. I tested my ISC and the resistance is quite a bit lower than it should be. When I get time I'll take my throttle body apart and take it a look at it. Its running well otherwise, so I'm not too worried, since it revs right after the engines nice and warm. What's the worst that can happen? I overheat and blow my engine and then have to put a KL in? For shame!
And yeah, the shop manual's pretty handy, now I just have to find a printer at work capable of printing of all 2000 pages...
haha.