So I just got a 2000 Honda Civic Si. Really happy with it however I am having a slight issue. If my check engine light comes on right after I start it my speedo does not work, and the car idles a little weird (jumps from around 900rpm(normal) up to about 1400rpms or down to 200rpms and about dies if it is just idling. It does not come on all the time tho (however it does most of the time ) Oh and BTW the car does not have the stock b16 in it. It has a b18b1 in it. Idk if this is part of the same problem but I can notice a considerable change of brightness in the headlights and dashlights when the car hits 3000rpms (lights get brighter). And when it is cold the stereo will suck the battery dry to the point to where it turns its self off. but when it warms up to about 40 degrees or up it is just fine. Is that a battery problem? Alternator problem? or is it something as simple as the ground? thanks for any feed back.